# Enlarging a template by exactly the size of the cutter-bushing gap?



## AshleyJ (Dec 1, 2017)

This a request for your collective expertise as I try template routing for the first time. I'm certain the problem I face has been solved many times before...

The goal: I'm creating something that requires a grid of 20mm holes, spaced precisely on 96mm centers. A Festool MFT or Ron Paulk bench is a reasonable comparison, though neither is exactly what I'm building. The number of holes required is large, and this is an operation I'll likely repeat many times in the future, so speed and repeatability are very desirable. Precision is essential.

I do have a pattern to work from, a piece of 18mm baltic birch with the required grid of 20mm holes. Let's call this the "original", since it matches what I need to make and has no additional margin to allow for template-cutter gap.

I have four options to cut those holes, listed from least to most desirable...
D. I could drill them with a 20mm forstner bit that I already have.
C. I could buy a top bearing bit, suitable for plunging, perhaps 3/8" diameter; clamp the original on top of the workpiece as a template; carefully align and plunge into each hole, and use the top bearing along the original to complete the cut.
B. I could create a template from the original (more later), buy a bushing set, and route the holes using a 1/4" solid carbide spiral upcut bit that I already have (Freud 75-102).
A. I could create a template, buy a bushing set, buy a 20mm bit, and complete each hole with a single plunge.

I have strong preferences on this, and I'll share my thinking so your experience can question my logic as appropriate...

Option D is my last choice because I strongly prefer routing over drilling, as it's faster more precise, and fits details of the context better.
Option C saves me the hassle of making a template (as required by A & B), but it's far slower and more error prone. A single error in alignment before plunging could ruin my project. I have hundreds of these holes to drill over my next 3 projects, so I _strongly prefer_ making a template and using approach A or B.
I prefer option A over B for speed. I'm willing to buy a 20mm bit for that benefit.

Assuming I proceed with option A, I'll need...

a 20mm router bit (and probably a new collet, since my Bosch 1617 came with 1/4" and 1/2", and metric bits probably come with metric shafts)
an appropriate guide bushing, in this case large enough to use with the 20mm bit
a way to enlarge the original to work with the bushing.

The challenge here is that last point - how to enlarge the original to work with the bushing... ensuring that the enlargement exactly matches what's required by the bushing.

I think the general process is:
Route a rabbet around each hole in the original.
Run a top bearing bit along that rabbet, enlarging the entire hole to match the rabbet.
Select a guide bushing & cutter combination that precisely matches the amount which the rabbet enlarged the hole.

My problem is that I'm somewhat lost in a maze of router bits and specs, trying to find combinations of rabbet + bushing + final cutter (probably 20mm) which works. This is nicely complicated by my target metric measurements and my imperial tools and thinking.

Can anyone point me in the right direction out of this maze?

Here's a few details of my setup in case they're relevant...

My router is a Bosch 1617 with both fixed and plunge bases. I have only the 1/4" and 1/2" collets but I'm willing to buy a metric collet if needed.
I don't yet own a bushing set. As I'm using a Bosch router, I expect to buy the Bosch quick change bushings... but I'm willing to purchase a different set, buy adapters, and/or make a replacement sub-base to hold PC or other bushings if needed.
I don't own a rabbet bit, so I can buy whichever one is appropriate to match the dimensions needed.

Thanks in advance for any help!


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## Inor (Aug 15, 2019)

Option B is how I would solve the problem. But, depending on how clean you need the final hole to be, I might use a downcut bit instead of an upcut.


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## TWheels (May 26, 2006)

I would go with option A, but you would need a 1 inch OD guide bushing. Freud sells a 20 mm bit with a 1/4" shaft.


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## Stick486 (Jan 4, 2013)

this might help..

.


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## AshleyJ (Dec 1, 2017)

After another hour or so looking at bits and bushings, reading other forum threads, and then seeing the replies in this one, the problem is coming into focus. The issue isn't option A vs option B - it's _where can I get the metric rabbet bit and metric bushing needed to make these work_?

Being specific... let's assume option A... and let's pretend we have good access to metric sized bits and bushings (which I'm not sure is true)...

Given those assumptions, I might do it this way...

Use a rabbit bit, say a 5mm rabbit, to enlarge the top half of each hole in the original from 20mm to 30mm.
Use a top bearing flush trim to enlarge the remainder of each hole, so the original now contains 30mm holes at the required spacing.
Mount a 30mm OD guide bushing on the router so it perfectly fits in the newly widened holes in the original...
Clamp the original on top of the workpiece
Mount a 20mm bit and "drill" out all the required holes

That sounds fairly straightforward, except for these issues...
1. I must find a rabbit bit that cuts exactly a 5mm rabbit.
2. I must find a 30mm OD guide bushing.
3. I must find a way to mount that 30mm OD guide bushing on my Bosch 1617. Ideally it works directly with the Bosch quick change bushings, but perhaps I need a PC adapter, or some other adapter.
4. The 30mm size of the guide bushing must actually match the hole I created by using the 5mm rabbit bit to enlarge my preexisting 20mm hole. (Math is supposed to be that easy, but cross-manufacturer math isn't always that easy.)
5. I must find a 20mm bit that plunges straight down.


Of these issues, only #5 is a clearly solved problem. At a glance, there seem to be many viable bits from Freud, Amana, Bosch, CMT, and Festool. Some of these will work with my existing 1/4" or 1/2" collets, and some will require a metric collet, but I suspect/hope that's not hard to find.

On the other hand, finding metric sized rabbet bits and bushings is a big problem. I haven't found a single option for a rabbet bit that specifies it's cut in mm. Any suggestions here?


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## Stick486 (Jan 4, 2013)

> 1. I must find a rabbit bit that cuts exactly a 5mm rabbit.


that's controlled by a bearing...
w/ all your talk of metric, I take it you're not in the United States as you state you are...

https://www.whitesiderouterbits.com/products/1960?_pos=10&_sid=ceee3c547&_ss=r
https://www.whitesiderouterbits.com/search?q=bearings&type=product
https://www.whitesiderouterbits.com/search?q=template&type=product
https://www.amanatool.com/products/...ssories/metric-steel-ball-bearing-guides.html
Router Bit Bearings | Retaining Collars | Carbide Processors
https://www.toolstoday.com/woodworking/Metric-Router-Bits


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## Cherryville Chuck (Sep 28, 2010)

There is some information missing that may be key to the final decision, namely how deep a hole and how smooth the hole needs to be. I also disagree with the statement that routing is faster than drilling. A sharp drill bit will usually out perform a router bit especially if that bit is not an up cut spiral. If the hole is any depth at all you'll need to use an up cut so that the chips get cleared out of the hole.

As far as enlarging holes, the easiest way I know is on a drill press. Chuck a 20mm bit and locate your jig so that the bit fits the hole and clamp the work to the table. Then remove the 20mm and chuck the larger bit and drill. That's the easiest way to guarantee that the larger hole stays centered with the original.


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## Stick486 (Jan 4, 2013)

fostners to the rescue....


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## AshleyJ (Dec 1, 2017)

Thanks for the additional input guys. I'm responding to Chuck’s comments first, then returning to Stick’s…

Chuck, I appreciate your suggestion that an up cut spiral may be preferable for chip clearing. Given that the final hole depth will be about 3/4” in this project (and vary from 1/2” to 1” in the next two projects), that's great advice.

My bias away from the drill press is because of my jig plans. It’s not that I think the router bit is faster than the drill bit… It’s that my setup and operation is faster with the router (if I can find the right bushing & bit combinations). I’m sure there’s a way to do this with a drill press too, but my thinking in that area lags far behind my clarity on how to do it with a router… and, my drill press is a recent $20 craigslist deal that needs a bit of reconditioning, then a project to build a decent stand, then...

Chuck’s suggestion on enlarging holes with the drill press does make perfect sense. Using my 20mm forstner bit to align the existing hole, swapping bits, then drilling... that will definitely work. It will take a long time to do that for all the holes in my original/template, but for a template I'll use often, that’s a time investment I may be willing to make if I don’t find a perfect solution with the rabbet approach.

Stick, I understand the bearing to rabbet bit relationship. What I was missing before your reply was sources for bits/bearings that spec the size of rabbet I’ll get from a given bearing/bit pair in mm. Your Amana link, and the Amana products at the ToolsToday link have a ton of metric bearings and bits so I’m pouring over them to piece it together. I’d love a simple link to a metric spec’d set if anyone has one… that tells me it supplies the bit and bearings needed for 2mm, 4mm, 5mm, etc… but lacking that, I hope I can figure it out from those Amana links.

At this point I've narrowed to the following candidate parts to do the job..

Bosch RA1128, if I don't already have the included RA1126 to allow attaching Bosch quick change template guides to the Bosch 1617.
Bosch 2609200142 30mm template guide.
The alternate choice to the Bosch guide (which has some fit concerns on some sites) is this screw-on style 30mm from Trend. That would attach to the Bosh 1617 using the RA1100 adapter in the above Bosch RA1128 set.
20mm router bit choice now pending as the ones I named previously would be best replaced by a spiral upcut as Chuck suggested.
rabbet bit, with bearing sized for a 5mm rabbet is pending... but I'm deep in Stick's docs looking for it.

Finally, Stick you wondered if I'm not in the US since I'm looking for metric. I am in the US - Texas and Montana - but wanted to build this around 20mm holes to take advantage of some nice add-ons made for the Festool system. Thus far, my experience with the pain of finding metric stuff in the US is seriously tempting me to go to 3/4" instead. I'm just starting a road that might be expensive and painful if this is typical.

Again, thanks for the help!


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## Inor (Aug 15, 2019)

AshleyJ said:


> Finally, Stick you wondered if I'm not in the US since I'm looking for metric. I am in the US - Texas and Montana - but wanted to build this around 20mm holes to take advantage of some nice add-ons made for the Festool system. Thus far, my experience with the pain of finding metric stuff in the US is seriously tempting me to go to 3/4" instead. I'm just starting a road that might be expensive and painful if this is typical.
> 
> Again, thanks for the help!


*Disclaimer:* The following rant is mostly meant in humor, but there a few tidbits of truth to found as well. I leave it to you, the reader, to figure out which is which.

We are woodworkers! We don't DO metric! The English invented the Imperial System of measurement and they are still the best woodworkers in the world. Yeah I know, the Limeys caved in to the rest of the world and stupidly adopted the metric system years ago. If that bothers you, go punch a Limey. As for me, I would prefer to get them to teach me to properly sharpen Robert Sorby chisel.

Yes I agree, it is much easier to add and subtract numbers using the metric system. But division is a serious pain in the neck! What is half of 1/16 inch? Double the denominator and come up with the answer 1/32 inch. What is a third of 1/16 of inch? Triple the denominator and come up with 1/48 inch. Easy math to do in your head. I do a LOT of division when building stuff.

What is half of a millimeter? Now you have to switch number systems entirely. What is next smaller system from millimeter? - A penismeter? So half a millimeter is 5 penismeters? Dumb!

Complain all you want about the Imperial Measurement system, based on hexadecimal numbers, but it has served us pretty well. The computer, phone or tablet that you are typing on as you read this is also based on the same system.


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## Cherryville Chuck (Sep 28, 2010)

Inor said:


> *Disclaimer:* The following rant is mostly meant in humor, but there a few tidbits of truth to found as well. I leave it to you, the reader, to figure out which is which.
> 
> We are woodworkers! We don't DO metric! The English invented the Imperial System of measurement and they are still the best woodworkers in the world. Yeah I know, the Limeys caved in to the rest of the world and stupidly adopted the metric system years ago. If that bothers you, go punch a Limey. As for me, I would prefer to get them to teach me to properly sharpen Robert Sorby chisel.
> 
> ...


Try reading through this thread and then get back to us Inor: https://www.routerforums.com/guide-...36-utter-stupidity-imperial-measurements.html


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## Cherryville Chuck (Sep 28, 2010)

Ashley the best way to see if a router bit will work at those 3 depths is to try one. 3/4 is only about 1mm smaller than 20 so it would give the same results. I think the 1/2" depth would be okay but I'm not sure about the deeper ones. If the bit can't clear the chips then they tend to run hot and the heat shortens the bit life. A US company that I know that makes a lot of metric sizes is Onsrud. You might try them and the bits are excellent quality.


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## JOAT (Apr 9, 2010)

I'm having a major problem imagining what you are going to make. So I would need to know that, and see a picture of the pattern you say you have, before I could picture it in my mine. I'd likely have different ideas of how I would do it with that info. And if the holes are to be 1/2" deep I'd probably drill holes thru 1/2" material, then glue that to a solid piece of 1/2" material, or 1/4", 1/8", or whatever..


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## tomp913 (Mar 7, 2014)

Take a look at the Parf Guide - make the top any size that you need.

https://www.youtube.com/watch?reload=9&v=2DMtIiyfRXk


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## scottgrove (Sep 4, 2016)

https://imaginewoodworking.com/ sells a oversized 1-1/2 and 2" template guide bushing which makes using a 1/2" bit. Much easier math too.


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## TWheels (May 26, 2006)

@AshleyJ Can you possibly provide a drawing of what the final product will look like. A drawing one hole in the pattern will suffice. It seems to me there are simpler ways of achieving tour goal than what you propose.


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## MEBCWD (Jan 14, 2012)

I'd used the original template and something like this https://www.toolstoday.com/flush-trim-3-flute-plunge-template-router-bits-w-upper-ball-bearing.html


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## Biagio (Mar 2, 2013)

Have you considered the Lee Valley dog hole bushings and bits (pg 270 of the Canadian catalogue download). They have 3/4” and 20 mm available.


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## gmedwards (Oct 12, 2018)

Here's a complete template, including the guide bushing. You can buy for 3/4" or for 20mm. It's designed for use with a Whiteside 1/2" upcut spiral bit. https://www.woodpeck.com/routing/router-accessories/hole-boring-jig-2019.html

It's pricey, but that's par for the course for Woodpeckers stuff. I have one of these for 20mm, but haven't tried it out yet. I bought it when I was between CNCs, but didn't get to the project I bought it for. I'm just finishing up my CNC, so will probably use it to cut my MFT-like cutting table (longer than an MFT). I also have the UJK Parf Guide System Tom mentioned. Both are very nice and will speed you on your way. Since you have a preference for using a router, the Woodpeckers system would probably be more to your liking. If you are interested in the UJK Parf Guide, get it here: https://tsoproducts.com/workholding-accessories/ujk-technology-parf-guide-system/ The shipping will kill you, if you order from UJK in England. Take a look at the cool stuff they have from UJK, and TSO's own products. Not a lot of products, but what they have is worth looking at. If you use a Festool track saw, their clamp on GRS-16 works remarkably well. I've used one for a couple of years or so. It's one of my go to accessories. Very accurate.

Gary


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## JOAT (Apr 9, 2010)

gmedwards said:


> Here's a complete template, including the guide bushing. You can buy for 3/4" or for 20mm. It's designed for use with a Whiteside 1/2" upcut spiral bit. https://www.woodpeck.com/routing/router-accessories/hole-boring-jig-2019.html
> 
> It's pricey, but that's par for the course for Woodpeckers stuff.


If that's what you all are talking about, be no biggie to make one. I don't like to buy what I can make, especially at Woodpecker's price. :surprise:


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## AshleyJ (Dec 1, 2017)

For those trying to picture what I'm doing, look at any of these...
First 30 seconds of 



First 20 seconds of 



First 30 seconds of 




None of them are exactly what I'm making... but all of them illustrate the grid of holes I need to create.

@tomp913, I'm familiar with the parf guide system, and it definitely could work, but I've been looking for a router based solution.

@Biagio, are you talking about these? Dog Hole Bushings and Bits - Lee Valley Tools

After the suggestions here yesterday and a night of working on the project in my dreams, I have at least half a dozen alternate approaches I wasn't seriously considering previously... some of which dodge the hole enlargement problem. And, between that and the comments above, I'm reconsidering drill based options too. Let's see what another night of attempted sleep brings.


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## AshleyJ (Dec 1, 2017)

The woodpeckers template system that gmedwards referenced is almost exactly what I was trying to create.

I say was because I’m also considering a couple other alternatives now, but that approach is definitely still open. I’m holding back from bringing all those alternatives in here because they don’t really fit the template theme of this forum... but I may yet do so.

I do strongly resonate with joat’s preference to make a template rather than buying one. This isn’t only a matter of price as I could easily spend at least half that price hunting down the metric rabbet/bearing combinations and other things I need. 

***This is very much about the challenge of bootstrapping a reasonably precise solution without a lot of fancy/expensive tools.***

So, having an original with the exact hole size and spacing required, enlarging those holes with a rabbet bit followed by flush trim was an appealing solution. However, the three piece challenge of a rabbet that enlarges by exactly the amount that a bushing + cutter reduces is proving more difficult than I anticipated. I originally asked because I can’t imagine this problem hasn’t been solved before. I thought someone might say... “Yes, use a size X rabbet from vendorX with bushing size Y from vendorY with spiral upcut Z from vendorZ... that’s how I do all my original to template resizing transitions.”

But since the woodpeckers template gmedwards pointed out, and joat’s preference for making his own *do* fit with the template theme of this forum, I’ll expand to ask a different question...

...How would you DIY a template like that if precision was critical? Say you need to keep the spacing error of the grid under ten thousandths of an inch max... what’s the simplest way you can think to create such a template? (I’m not asking in the CNC area because that’s the obvious answer!)




Sent from my iPad using Tapatalk


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## AshleyJ (Dec 1, 2017)

BTW, my current sidetrack is determining whether big box pegboard is consistent enough to be used as a reference to create such a template and keep the hole spacing error within a few thousands of an inch.



Sent from my iPad using Tapatalk


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## Cherryville Chuck (Sep 28, 2010)

The pegboard is consistent. The way I drilled my bench holes was by taking a block of wood like in the Lee Valley link and drilling a hole through it on the drill press to make sure it was 90* Then I just marked out the holes with a pencil and tape (they really don't need to be all that accurate for bench dogs) and I drilled the first 1/8" by hand so that I could stick the bit in it and know I was in the right spot once the block of wood was over it and I couldn't see it anymore. I drilled as far as I could with the block and then pulled the drill bit out and carried on by hand (4" think bench top). No issues. Yes the block of wood guide wears faster without the guide but not enough to worry about doing one work bench.

If you are really fussy about getting the holes even then build a "leap frog" type drill jig. That's where you drill two holes in the wood block and you put a second drill bit or steel rod through one hole in the block and into the last hole you drilled and use the second hole in the block to drill the next hole. The distance between the holes in the block never changes so the spacing pattern of the drilled holes also stays the same. If you decide to go that way I'll describe and easy way to make it.


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## AshleyJ (Dec 1, 2017)

Chuck, yes I am very fussy about getting the holes perfect, since I hope to use them as references for keeping things straight and square. Your description made perfect sense... thank you! The leapfrog technique to guarantee exact hole spacing is clear, and I see how to do that with either a drill or router jig. (I still prefer router, in part because it simplifies keeping things vertical, but either could work and I may reconsider.)

The leapfrog technique will guarantee hole spacing in a single dimension (ie line). _The challenge is getting it perfect in two dimensions_, ie identical spacing in both X and Y dimensions, and ensuring those dimensions are exactly perpendicular. Your answer that _pegboard is consistent_ means that it's probably the simplest reference. If you have another way to get consistency in both dimensions and ensure they're square, then I'm all ears.

I'm thinking of a pegboard based an approach like the following... and any improvements are welcome...

Acquire a piece of 3/8" clear acrylic, say 12" x 12", to make a new router sub-base. 
Acquire pegboard. Cut a smaller piece sized to match the new router base.
Acquire some metal rod or bolts that snugly match the pegboard holes. (That's 1/4" diameter for the pegboard linked above, but some pegboard has smaller holes.) From this rod, cut four pins that are 1/4" longer than the pegboard holes are deep.
Clamp the acrylic to the piece of pegboard. Using the pegboard for precise alignment, drill four holes 1/4" deep into the acrylic in a square pattern, say 4" on a side. Drill a fifth hole at the center of that square, this time penetrating all the way through the acrylic. Use the drill bit to perfectly align to the pegboard holes, so the resulting holes in the acrylic perfectly match the pegboard.
Remove the acrylic from the pegboard. 
Position the acrylic on the router base with the four holes in a square facing away from the router. Use either a centering cone, or a bit precisely matching the center hole, to align the new sub-base to the router. Once alignment is perfect, use the router base as a template to mark holes to mount the new base to the router. Drill and countersink those mounting holes. 
Install a pin in each of the four remaining holes. These are the pins from step 1, which precisely match the pegboard holes. 
Install the plate on the router with pins facing down.
Cut a larger piece of pegboard, matching the size of the workpiece to be drilled, and clamp it atop the workpiece.
Mark every 4th hole on the pegboard in each dimension (4th hole for 4" spacing), as these are the holes the router base pins should align to for drilling all the required holes. 
Install the desired router bit (plunge capable 20mm or 3/4"), and start making a mess.

Other thoughts...

In step 10, I'll probably fill unnecessary holes with woodfiller or bondo to eliminating error opportunities.
In step 4, it's easy to drill additional alignment holes other than that 4" square, but I'm not thinking of any reason that it will ever be needed when used with pegboard as described in steps 9-10.
In step 7, the pins can easily be secured with a drop of epoxy. However, I'd prefer removable pins so the base is useful for other routing operations. I may see if they're snug enough for a press fit to work.
Another solution for removable pins is to thread the end of the rod and tap the hole in the acrylic. Not owning a tap & die set and lacking experience with one, maybe I'll skip it and let this be a special purpose base. Or maybe it's time to learn?
Alignment of the router mounting holes in step 6 is quite critical. My explanation of that procedure is lacking, but more robust explanation can be found in this thread.
Alignment of the router mounting holes in step 6 is actually not critical *IF* the new sub-base is always used in the same alignment. If the sub-base is rotated, then I'll incur an error matching any error in centering the sub-base. For this reason it makes sense to avoid rotation.
I expect the pegboard to be reusable many times before it's holes wear too much to precisely position the sub-base with pins. I may drill out the pegboard _only_ first (step 11) before using it with a workpiece, to make it easier to position it exactly as desired.
A similar procedure could be used to make a base for a drill guide based on either Chuck's block of wood or the Lee Valley bushing. Such a base would allow the drill guide to reference pegboard for exact spacing in the final pattern of drilled holes.
If I want to end up with a template like the woodpeckers one, which uses a bushing guided bit instead of a bit the full size of the target hole... then the above procedure with pegboard can produce that template... as long as I use the bit size needed for the final _template hole_ rather than the original hole... otherwise I end up where I started this thread, needing to enlarge the original to be a viable template.


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## Stick486 (Jan 4, 2013)

Drill Guide - Lee Valley Tools


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## AshleyJ (Dec 1, 2017)

I just found this video of someone using pegboard exactly the way I envisioned: 




If the repetition doesn't put you to sleep right away, you'll see him make positioning errors in a couple places. This convinces me that filling unnecessary holes with woodfiller or bondo is a very good idea.


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## Stick486 (Jan 4, 2013)

AshleyJ said:


> I just found this video of someone using pegboard exactly the way I envisioned: https://youtu.be/TuPC7aVYpmk
> 
> If the repetition doesn't put you to sleep right away, you'll see him make positioning errors in a couple places. This convinces me that filling unnecessary holes with woodfiller or bondo is a very good idea.


Tape over what you don't want...
you may change your mind later..


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## AshleyJ (Dec 1, 2017)

Thanks for suggesting tape, Stick. That's much easier and faster.

Back to the big picture, I finally figured out the puzzle that's been haunting me... a router centric solution that works even if pegboard spacing wasn't perfect...


Make a custom router sub-base and attach to the bottom of it a length of miter-slot-rail 3/4" wide x 3/8" deep. The chosen spacing from the rail to the bit will ultimately determine the spacing of holes, in my case either 4" or 96mm (not sure yet).
Put a 3/4" dado or mortising bit in the router and attach the custom base to the router.
Get a piece of material to use for a jig, 3/4" thick, and as big as you want the jig to be. Ensure the jig stock is square, as it's squareness is the reference to square the grid of holes.
Running the miter-slot-rail of the against one edge of the jig stock, cut a dado in the jig stock. The final depth must be slightly greater than the depth of the miter-slot-rail (3/8").
Running the miter-slot-rail in the just completed dado, cut another dado parallel to the first. Repeat this procedure until the entire jig stock is covered with parallel and perfectly spaced dados.
Repeat steps 4 and 5, but referencing from a perpendicular edge of the jig stock. The result will be a grid of perfectly spaced dados all over the stock.
Mount a second miter-slot-rail on the router base, perpendicular to the first and spaced from the bit the same distance as the first. To do this, place the first rail against the first referenced edge of the workpiece and align the bit to the first perpendicular dado created in step 6. Now the second miter-slot-rail may be positioned against the edge of the jig, and clamped to the base. Test to confirm spacing perfectly matches the bit to both dados, then drilled through the base and rail for mounting screws.
The custom sub-base with two perpendicular miter bars can be used to accurately position the router at each dado intersection in the jig stock. Mount the desired router bit for dog holes (3/4" or 20mm), and plunge the bit to bore the required holes referenced from each dado intersection.
You now have a fully bootstrapped jig which may be clamped to a workpiece with holes positioned as desired, then the router with the custom base may be plunged at each intersection to create the required holes.

The accuracy of this procedure depends on the miter-slot-rail precisely fitting the slot cut by the dado bit in making the grid of dados. Any size rail and bit could be used as long as they match without slop.

The accuracy also depends on the squareness of the two edges which are referenced in beginning the initial dado (step 4) and perpendicular set of dados (step 7).

Any size hole spacing is possible, as determined by the initial distance from the miter-slot-rail to the bit in step 1.

Any size hole is possible, as determined by the final bit chosen in step 8.

Now that the puzzle isn't haunting me anymore, I'll probably use the pegboard solution anyway and save routing all those dados. I still haven't found the right rabbet/bushing/cutter combination to enlarge the original by exactly the amount required to use it as a template, but that's ok because this procedure will work just fine! 

Thanks for all the mental stimulation to get me this far... and please tell me if you think there are glaring holes in either the pegboard or dado based procedures.


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## Larry42 (Aug 11, 2014)

Inor, If you learned to use the metric system you would never go back to 64ths. The Brits also gave up their Pound, Shilling, Tre pence long ago. They use the decimal system for everything. At least we do for money. 
As for the project at hand, find a shop with a CNC router and have them make your parts. Way easier and very precise.


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## Cherryville Chuck (Sep 28, 2010)

AshleyJ said:


> Chuck, yes I am very fussy about getting the holes perfect, since I hope to use them as references for keeping things straight and square. Your description made perfect sense... thank you! The leapfrog technique to guarantee exact hole spacing is clear, and I see how to do that with either a drill or router jig. (I still prefer router, in part because it simplifies keeping things vertical, but either could work and I may reconsider.)
> 
> [/LIST]


A small leap frog jig is easy enough to do that with. When you make the guide block you attach it to a scrap of plywood that is at least 12" long and and wide enough for your table (the wider you go the longer the ply needs to be for stability). Then you add a cleat of the bottom side that will run along the edge of the table. You just have to make sure that the block and the cleat are square to each other (by aligning them with a framing square from the rear or front end of the ply scrap).

I should also say that the blocks are plenty accurate enough for what you are doing. It's the method I used to drill my bench. It works better with brad point bits but it could be made to use Forstner bits. I show how to make a jig for drilling 90* with a Forstner in post #22 of this thread: https://www.routerforums.com/jigs-fixtures/127737-carb-tech-24-pc-forstner-bit-set-3.html

The peg board is also a good method and I don't know if I would bother trying to transfer it to any other medium. The high density board it's made from is pretty durable. I would decide on what spacing you want and pick the closest peg board hole and enlarge it (same way as I described before on a drill press) and keep going in that pattern.If you only enlarge the ones you need to the size that fits your router guide bushing then you cant make mistakes. When I decided on my spacing I just picked one that would allow me to use my bench dogs from Lee Valley (Veritas® Wonder Dog® & Wonder Pup® - Lee Valley Tools ) and be able to reach from one hole to the next and at angles from one to another. My bench end vise jaws have dog holes in them and with the dog holes in the bench and the bench dogs I haven't found any shape I can't clamp. They are a bit pricey but I think they are worth it. I have 3 of them.

By the way, if you plan on using the peg board as I described for multiple tops you might want to toughen up the holes with a coat of crazy glue.


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## AshleyJ (Dec 1, 2017)

Ok, that’s a dramatically simpler pegboard approach. Instead of making the router baseplate that indexes into the pegboard, simply enlarge the appropriate holes and use them to index the router bushing. Thank you, Chuck!

I hadn’t previously heard of using krazy glue to harden something like those holes. Will it soak in enough to do it’s job without changing the hole dimensions?



Sent from my iPad using Tapatalk


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## Stick486 (Jan 4, 2013)

it's a coating that will be a mil or two thick unless you gob it on..


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## AshleyJ (Dec 1, 2017)

Cherryville Chuck said:


> A small leap frog jig is easy enough to do that with. When you make the guide block you attach it to a scrap of plywood that is at least 12" long and and wide enough for your table (the wider you go the longer the ply needs to be for stability). Then you add a cleat of the bottom side that will run along the edge of the table. You just have to make sure that the block and the cleat are square to each other (by aligning them with a framing square from the rear or front end of the ply scrap).


Chuck, when you previously mentioned the leap frog jig I was certain I knew what you meant. However, in this additional description I'm beginning to think I didn't... or at least I'm unclear on the two dimensions application. Can you elaborate on how you'd construct it to make a _grid_ of holes that are square and spaced identically in both directions?


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## Cherryville Chuck (Sep 28, 2010)

It will easily make an even row but spacing between rows might not be precisely the same although I think I could figure out how given a little time. The pegboard will give you very precise spacing. The gentleman in the video was using a leap frog method when he drilled one row then registered the jig in two of those holes to drill his next row. My idea was only a two hole block but you add a fence to control the distance from the edge of the top at the same time. That gives you both x and y.

True precision is often not needed. Only what appears to be precise. Quite often the appearance of precision is easily accomplished but true precision can be very difficult. In other words, if it looks perfect and you can't tell that it isn't then it usually is good enough. A tenon in a mortise has to be pretty precise as do finger and dovetail joints. Dog holes in a bench only need to look perfect.


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## Biagio (Mar 2, 2013)

@Biagio, are you talking about these? Dog Hole Bushings and Bits - Lee Valley Tools

Yes. Instead of the wooden base illustrated in the catalogue, you could use a piece large enough for four holes at the required spacings (am I right in thinking you already have a sample that you could use to lay out the spacings?). You would need two 20mm steel bushings.
After drilling the first double row using the edge of the board/bench as a reference, you could remove the side cleat, glue two 20mm dowels in place to register in the already-drilled holes, and the next row would be aligned in x and y, two holes at a time. Poor man’s version of the Woodpecker jig, no router, no template guides. 
And if you needed a similar thing in 3/4”, just make another jig - Theo’s mantra.

I am the last who should be asking this, but are you not overcomplicating the matter?


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## AshleyJ (Dec 1, 2017)

@Chuck, thank you, that confirms my understanding of what you meant by leapfrog. BTW, I've been poking around looking for the thread with photos of your workbench build. I'm certain I've seen it before but I'm not finding it again. Can you post that link here if you have it handy? 
@Biagio, yes I do have a sample to work from, and using Chuck's drill press Forstner alignment technique I could use it to quite accurately build the jig you propose. Your paragraph explanation about how you were thinking of using that Lee Valley bushing added one more good option to my list of choices. I'm now up to exactly a dozen ways to bootstrap this, :smile: (not counting CNC, buying the woodpeckers template, and using the parf guide system).

So am I making it too complicated or worrying too much about precision?

This isn't my first experiment with a 20mm dog hole system. My first one looks fine and works for dogs/clamping/etc, but not at the level required for what's next. My intent for this one is to experiment with using the hole pattern in the bench as a reference for cutting with a DIY tracksaw. The festool crowd often uses an MFT with a tracksaw this way, and Peter Parfit and Dave Stanton's youtube videos show excellent examples of a slightly different way than the MFT's track support. Will all this work? I don't know. Asking for precision from a material that moves with humidity changes is a tough thing. But I'll have fun finding out.

If it was only about precision or getting the job done, I'd use a CNC or buy commercial solutions. But that's not the point. Few of us here do woodworking because our results are less expensive (money & time) than commercial ones. We do it for the sheer joy of doing it. At least I do. 

I do like to make useful things, and that certainly helps the family support the time & money I do spend... but behind all that is the pure joy of experimenting, learning, and seeking mastery. As my teenage children are now voluntarily spending time with me on my projects, and wanting to create things of their own, I enjoy watching the seeds of the quest for mastery light up their eyes.

Part of my personal curiosity is bootstrapping systems... using primitive means to create more precise means... using base tools to create more powerful ones. Thus this project... and the fact that I'm attempting to do it with only the router, circular saw, and drill press. I didn't trouble ya'll with those details because they weren't about template routing, and who avoids using a perfectly good table saw or jointer?

Yes, I'm a bit crazy, and I like it. Next up... you're deep in the forest with a pocketknife and the clothes on your back... how do you make a router? :grin:

So am I overcomplicating? I'm having fun learning from ya'll and enjoying the journey. Between your suggestions and the thinking/dreaming I've done in the last 72 hours, I now have multiple approaches that are significantly better than where I was going when I asked the question at the beginning of the thread. If that's complicated, sign me up! Thank you all!

My father used to have a poster hanging on his wall at work saying, "There comes a time in the life of every project when it's necessary to shoot the engineers and build the damn thing." I do think it's time to get on with building this one.


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## Biagio (Mar 2, 2013)

@Ashley, 
I kind of figured that this was more of a crusade for you than a pragmatic project. 
Just a thought: the Festool system uses holes at (I think) 96mm centres. I imagine you can get very close to that precision with whichever way you decide to go, and mdf or good plywood will not move that much with humidity, especially if sealed. But what about the dogs themselves? A few of the commercial ones have quite a bit of slop in them, and if they can wobble a degree or two, that might be worse than being .01 mm out in the hole spacing - Charles will be able to give us chapter and verse on that.
If your holes will be blind, i.e. not through the board, you may be able to get/make exact-fit dogs, without worrying about springs to stop them falling through. Or else have a collar on the exposed part, like the parf-dogs.
If you go the way I suggested, just remember that the reference edge for the first two parallel rows of holes, must be dead straight, otherwise you will have an elegant wavy matrix of holes. Good for op-art, less good for mft.


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## Cherryville Chuck (Sep 28, 2010)

Are you being overly complicated? I think yes, a bit. During our lives certain things wind up having a big impact on you. One of those for me was an episode of the TV show the Tycoon. Not many people will remember it. It starred Walter Brennan (after the Real McCoys which many also may not remember) as a multimillionaire industrialist. The episode I remember was about one factory that had a major bottle neck in the production line. He got four young engineers about to graduate from university together to solve the problem. The one that came up with the solution would get a permanent job. They had a week to solve the problem and three got right at the problem sitting at their drafting tables drawing plans. The forth sat and stared into space for the week. At the end of the week Brennan came and asked for their results which the three showed him. He turned to the fourth young engineer and told him that he was disappointed in him and that he had had higher hopes for him and what did he have to say for himself. At which point the young engineer said that he had just come back from the production line and that the problem was already solved. Brennan asked him how he did it. The young man said "I convinced the foreman to put a left handed person at that job." Sometimes the solution really is that simple but we automatically tend to think that a problem is hard and that is because we don't fully understand it and understand what is required to solve it so we wind up over thinking it. 

I'm not familiar with using an MFT with a track saw so I can't be sure exactly what is required to make that work. As far as clamping jobs go, a bunch of randomly spaced holes would get most jobs done. It just wouldn't look that good. The human eye can see a difference of about 2 to 3 thousandths of an inch but only if you have something to compare that to. In a set of dog holes on a table that difference would have to be getting up to around 1/16" out, maybe more. So for looks small differences won't be detectable. For functionality it depends on what you need it to do.

I took fresh pictures of may table. I like all my small F clamps handy as I use them a lot. I also like my main squares and rules handy (mounted underneath). I have spring clamps under the other side. I like the center trough to keep tape measures, pencils, knives, and some sanding tools handy but not get in the way of my work. Some benches have the trough on the back side but I wanted access from both sides to what ever is sitting on the bench. There has been a miter saw on the dog leg most of the time but it was meant to have space to work on a small part of the larger piece sitting on the main bench. I'm expanding my shop so maybe the saw will get moved but it sure is handy to have it that close my work too when adding trim and small pieces. The picture shows my twin screw Veritas vice which I think might be the best there is with two bench dogs in it and my other two in bench holes as well as my Wonder Dogs in a couple of holes. I've never had anything I couldn't clamp including circles. This bench has served me well but the MFT is pretty good concept too.


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## AshleyJ (Dec 1, 2017)

Chuck, thank you for the pictures. Also, thank you for the story of the engineers... I love it.


Cherryville Chuck said:


> Sometimes the solution really is that simple but we automatically tend to think that a problem is hard and that is because we don't fully understand it and understand what is required to solve it so we wind up over thinking it.


That's the essence of my day job right there... helping people learn to "let it be easy". 



Cherryville Chuck said:


> I'm not familiar with using an MFT with a track saw so I can't be sure exactly what is required to make that work.


If you want a clearer picture of this, here's a video of Peter Parfit doing a 4 cut test to determine the accuracy of his cuts with a DIY MFT table and a tracksaw. 




If you want to skip watching the cuts and hearing him explain what a 4 cut test is, the final results and calculation of error begin at 6:05 in the video.


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## Cherryville Chuck (Sep 28, 2010)

Thanks for that video. I see now how the track saw is being used that way. So neither the distance X between holes is critical nor is the Y distance between them critical so long as the individual holes in an X row or a Y column are at 90* to each other. So what I would do to make sure that happens is to use the pegboard (since that seems to be the easiest solution) and put a physical stop along the bottom edge that will butt up against the edge of the top. The pegboard ensures that the holes stay at right angles to one another by ensuring that the sheet has the same Y relationship to the top each time it gets moved to make a new column of holes.

As for spacing, you don't want the first and last columns to be different distances from the edges and unless all tops will be the same size then this will require that you set the jig to account for this. Since only the 90* relationship between rows and columns is what is important in this circumstance exactly how far in from either edge isn't important, only that they are about the same amount. So you can locate the first row by just doing the math and locating the jig so that it will do that since the pegboard doesn't allow changing hole spacing easily.

The easiest way to get even spacing between columns after the first one is drilled is to just put a bench dog in the first and last holes and butt the edge of the pegboard against the dogs and the cleat attached to the pegboard against the bottom edge of the top and essentially leap frog that way from column to column. This is simpler than pegging it if you are using a guide bushing and router bit because a peg for that would need to be stepped with an upper diameter equal to the guide bushing and a lower diameter equal to the router bit diameter. That would require a lathe and some very careful turning. The one criteria here is that the rows on the pegboard have to be parallel to the sides and the bottom of the pegboard square to the edges. You'd need to make sure of that.


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## bfblack (May 2, 2012)

*your included material*



Stick486 said:


> this might help..
> 
> .


It looks like the included material would be useful to save for future reference. Do you have the charts in a format that could be saved?


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## Stick486 (Jan 4, 2013)

bfblack said:


> It looks like the included material would be useful to save for future reference. Do you have the charts in a format that could be saved?


the PDF is saveable as is...
the charts also...
right click on them and click on ''save as'' in the drop down menu...


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## gmedwards (Oct 12, 2018)

Biagio said:


> @Ashley,
> 
> Just a thought: the Festool system uses holes at (I think) 96mm centres.


The Festool solution Biagio mentioned has been done. You'll need to have the one of the "holey rails", a Festool router guide and a Festool Router. Here's the video: 




The 55" rail is $145. The Router (1400 EQ) is $600. The guide plate is $140. Very expensive stuff (obscenely expensive, like everything Festool). I tried using a Bosch 20mm bit (needs 10mm collect adapter), but the holes were oversized and the dog fit was too sloppy. Ditto with the Festool bit. These are not spiral bits. I know Festool sells a 20mm spiral bit in Europe, but not in the U.S. It can probably be ordered, but the shipping is a killer. I know Amazon UK sells the Festool. 
I don't know about other brands, and I don't know how accurate the Festool spiral is. The problem with 20mm bits available here is that they are for Euro cup hinges and are oversized to accommodate. Your finished holes will only be as good as the cutter (or the template). Aside from the Woodpeckers router template, the only accurate holes appear to come from 20mm forstner drill bits (e.g., UJK Parf system). 20mm forstner bits can be found here: https://tsoproducts.com/accessories/ujk-technology-20mm-cutter-split-stop-collar-for-parf-guide-system/

Oh, and I recall mention of using a bearing guided bit. They aren't accurate enough - or at least none that I've found. I've tried Freud and Whiteside. No dice. I don't remember for certainty, but I believe the holes were undersized.

FWIW, *I wouldn't spend too much time trying to figure out jigs and such until you find a bit (router or forstner) that cuts an acceptable hole.* I've tried the pegboard and other methods, and the weakest link was always the hole size - always too large with router bits. If you go with a forstner, a drill guide is a must have. However, getting the tram right on your drill press is essential. Side-to-side is no problem with a tilting head drill press, but front-to-back is another matter altogether. I don't know know of any column drill presses that can be adjusted front-to-back. Remember, if the bit goes in at any angle, however slight, you are going to have a hole where the dog won't fit like it should. If you are contemplating using a drill bushing, I wouldn't even think about it freehand. Every drill guide I've ever used, and I've used a few over the past 45 or so years, has been way too loose for the precision you need. It would just be dumb luck to get a hole with the degree of perpendicularity you want and need. If I was going to drill something for a guide bushing, I would use my PM25MV mill (perfect tram) to drill the hole(a).

I'm not sure whether you are aware of it, but you can make custom patterns with the UJK Parf Guide System. So, if you want some sort of custom layout, you can probably do it with the Parf Guide.

I've read the back and forth about about expectations and accuracy. As noted, you need a properly sized hole, or nothing else will matter much. It's surprising just how little things can be off to produce a 1/16"= error in a kitchen cabinet sized piece of plywood. I'm thinking an error that large isn't something you'd want to accept.

Here's my view. Errors tend to be cumulative. If I just settle here and settle there, I'll likely end up with a finished product that I'm unhappy with. Perfection is unattainable, but you can get darned close. Strive for perfection and the odds are good you'll be happy with the end result. Depends on the project. I take much more care with a furniture piece than I would with construction project. Just my 2 cents. 

Gary


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## Straightlines (May 15, 2013)

tomp913 said:


> Take a look at the Parf Guide - make the top any size that you need.
> 
> https://www.youtube.com/watch?reload=9&v=2DMtIiyfRXk


YES! You beat me to it. 

To this, I’ll add that depending on the material you are cutting and its glue content, your projects are likely to kill multiple router bits. 

How do I know this? Because, and this brings up my alternate suggestion, I found a CNC guy on Craigslist who charged me $50 to cut what you’re describing in a 3’ x 6’ MFT Slab. The CNC is the ideal approach (highly repetitive and precise), and after the lightweight MDF sheet was cut I noticed that my bit was noticeably more dull. 

The CNC is so much more efficient and faster, with the added benefit of zero errors along the way. There are lots of folks out there who are heavily invested in their CNC’s and are often looking for paying customers for these very simple one-off projects.


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