# guide bushing size chart



## mharwell01 (Jan 25, 2008)

this may be a dumb question and i may be missing the point entirely but i just got a template guide set and would like to find out if anyone knows of a chart or guide that lists the guide bushing size to use for making holes and then the correct bushing to switch to to make the patch to fit the hole precisely for a particular bit size. i may be making this harder than it is, but without having to calculate each time or use trial and error, it would be nice if someone more experienced already has it written down. 

most of the time id be using a 1/8" bit but there might be occasions where id use a 1/2" if i had to remove a lot of material within the hole im making. i have a 1/8", 1/4", 5/16", 1/2" straight cutting bits. 

or is there a standard addition or subtraction everyone uses that i dont know about. any help is appreciated. also standard (US) is what i need rather than metric.


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## bobj3 (Jan 17, 2006)

Hi mharwell01

This should help 

http://www.routerforums.com/email-router-tips-members-only/4348-guide-bushing-chart.html


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mharwell01 said:


> this may be a dumb question and i may be missing the point entirely but i just got a template guide set and would like to find out if anyone knows of a chart or guide that lists the guide bushing size to use for making holes and then the correct bushing to switch to to make the patch to fit the hole precisely for a particular bit size. i may be making this harder than it is, but without having to calculate each time or use trial and error, it would be nice if someone more experienced already has it written down.
> 
> most of the time id be using a 1/8" bit but there might be occasions where id use a 1/2" if i had to remove a lot of material within the hole im making. i have a 1/8", 1/4", 5/16", 1/2" straight cutting bits.
> 
> or is there a standard addition or subtraction everyone uses that i dont know about. any help is appreciated. also standard (US) is what i need rather than metric.


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## mharwell01 (Jan 25, 2008)

excellent bob. exactly what i was looking for. thanks a lot. now if you could just get the US to fully convert to metric it would make life easier for everyone.


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## bobj3 (Jan 17, 2006)

Your Welcome mharwell01

" US to fully convert to metric" = that's not going to come about but the free software may help 

http://joshmadison.com/software/convert/

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mharwell01 said:


> excellent bob. exactly what i was looking for. thanks a lot. now if you could just get the US to fully convert to metric it would make life easier for everyone.


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## harrysin (Jan 15, 2007)

How refreshing to find someone in the USA asking for metrication. I, and a few others have been pushing the benefits of metric in template guides and cutters for some time, it's not surprising that plunge routing is in it's infancy there, calculating offsets when designing templates in imperial is a nightmare. Another gripe of mine is that most of your routers appear to have small openings, restricting the size of guide. Things will only change when woodworkers start to demand these changes and to realise the benefits, an open mind is required. I'm about to put on my flack jacket!


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## bobj3 (Jan 17, 2006)

Hi Harry

I'm going to disagree with you on one point, almost all routers have a big opening it's the bottom base plate (black plate the norm) that's in error so to say but that's a easy fix if someones want's to use the big bushing, but that's the kicker, we in the States can't get the big guide bushing...like the 40mm ones.

And you know what I think of the metic system,, we have a system that works why switch...

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"It's fine to disagree with other members as long as you respect their opinions." 
MIKE
Senior Moderator


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harrysin said:


> How refreshing to find someone in the USA asking for metrication. I, and a few others have been pushing the benefits of metric in template guides and cutters for some time, it's not surprising that plunge routing is in it's infancy there, calculating offsets when designing templates in imperial is a nightmare. Another gripe of mine is that most of your routers appear to have small openings, restricting the size of guide. Things will only change when woodworkers start to demand these changes and to realise the benefits, an open mind is required. I'm about to put on my flack jacket!


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## Hamlin (Dec 25, 2005)

Hi Harry,

My Craftsman Pro router has a poor sub plate design, ie., the small opening & you have to use Sears guides. (Which is why I love OP's plates, adversity ). However, as you very well know, the Makita's have a decent sized hole even in the sub plate. It's usually the sub plate that screws things up for routers.

Now, for the metric system. It's as I've said before, I don't know it but, always willing to learn it. Rather people truly realize it or not but, the U.S. is slowly changing over to metric. It's just a gradual change.

Just my thoughts.


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## bobj3 (Jan 17, 2006)

I love to pull Harry's chain,, if anyone pop's the metric sub. up Harry's off and running  LOL LOL hahahahaha You know I'm only joking Harry  


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## TWheels (May 26, 2006)

Harry, I am with you all the way for metrification in the US. We were going to start a campaign to do just that earlier. 

I have been occupied with other concerns in recent months which is why I have not been more outspoken on the subject. I hope these other issues can be resolved in the next two months.


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## TWheels (May 26, 2006)

mharwell01,

Where are my manners? You raise a point very close to my heart (look at some of the previous postings), HarrySin answers with great enthusiasm, and I respond to HarrySin. I fully agree with you that the U.S. should join the rest of the world and start using the metric system. Perhaps a new thread needs to be started on how we can integrate the metric system into our common interests.

I have a Makita router but I use the Oak Park base plates and the Oak Park template guides. HarrySin is correct that there is no way to use a 40 mm guide. I do wish there were larger template guides and base plates to accommodate them available. What I really want to see is an Oak Park base plate with 10 cm (4 in) opening and template guides and inserts available to reduce the opening to appropriate sizes.


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## Hamlin (Dec 25, 2005)

Hi mftha,

The closest that OP has to a 4" opening is their plate used for large bits & raised panels. It has a 3 1/8" opening, unfortunetly, if you're wanting to get bushing guides that large, you'll have to machine them yourself or have a machine shop do them for you. Preferrably from brass stock.

Sad truth is, unless all State Senators are informed for the push to (as Harry calls it), "metrication". It won't happen. Thus how things are now, a mixed batch of metric & SAE sizes.


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## bobj3 (Jan 17, 2006)

Hi Guys

Not to hard to make your own ,,,(bushing guides out of plastic that fit over the standard brass guides or to say on to the brass guides) and the one Harry and Tom like to use the 40mm one is showed in the link below...

http://www.routerforums.com/49128-post1.html

Just a note about the OP plate that has the unstardard 3 1/8" hole, it's not a big job to resize it to 3 3/4" hole so it can take on the stantard 3 1/2" panel bits...
Without the resize job you can't use many of the better panel bits that are 3" to 3 1/2"..in diam. 


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## Hamlin (Dec 25, 2005)

bobj3 said:


> Hi Guys
> 
> Not to hard to make your own ,,,(bushing guides out of plastic that fit over the standard brass guides or to say on to the brass guides) and the one Harry and Tom like to use the 40mm one is showed in the link below...
> 
> ...


Hi Bob,

Thanks for the tips there.  I really like your sanding jig too!! :sold: 

You by chance wouldn't have a pic or two of a "modified" OP plate?


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## bobj3 (Jan 17, 2006)

Hi Ken

Thanks and you'er welcome

Here's some shots of the reworked OP base plate..

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I used the fly cutter below to open the size to 3 3/4"
Not a big job but it must be done on the drill press and clamped in place.

http://www.grizzly.com/products/Round-Fly-Cutter-Set-3-pc-/H7537

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Hamlin said:


> Hi Bob,
> 
> Thanks for the tips there.  I really like your sanding jig too!! :sold:
> 
> You by chance wouldn't have a pic or two of a "modified" OP plate?


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## Hamlin (Dec 25, 2005)

Hi Bob,

Thanks, I think in the near future I'll be sending ya an email for some more help with this.  I got a few other "irons in the fire" at the moment.


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## bobj3 (Jan 17, 2006)

Hi Ken

Ok please do, just ask... by the way one of the irons in the fire " wooden hinges" ???


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Hamlin said:


> Hi Bob,
> 
> Thanks, I think in the near future I'll be sending ya an email for some more help with this.  I got a few other "irons in the fire" at the moment.


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## Hamlin (Dec 25, 2005)

bobj3 said:


> Hi Ken
> 
> Ok please do, just ask... by the way one of the irons in the fire " wooden hinges" ???
> 
> ...


Hi Bob,

Yuuup!! :sold: Already got a friend who wants me to build a small cedar chest, something like the size of 2' X 3'. Figure a 4" hinge "wood" work. LOL Not sure how deep to make it, prolly 18". 

The problem for me right now is, finding the time, work seems to always interfere.  But, gotta pay bills.


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## blobile (Aug 17, 2017)

If I understand the original question then I don't see an answer in any of this. If I understand the original question, which is the same question I have, is what size ID bushing to use with whatever size router bit. I have a 1/2" up cut router bit, what size ID bushing do I need for that. I can't find this answer anywhere! I can't find answer in the link Bob put in. For me, chart is confusing and tells me nothing. In the part below the chart it says there should be 3.5 mm between the cutter and the OD of the bushing for chip removal. I don't care about the OD. I don't care if the OD is 20", I'll adjust my template. My question is what should the distance between the cutting edge of the router bit and the ID of the bushing be?
If someone can help I would greatly appreciate it.


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## DaninVan (Jan 1, 2012)

Hey blobile; welcome!
Bill Hylton covers this extensively, with all the possible combinations, in his book 'Router Magic'...
https://www.amazon.com/Router-Magic-Fixtures-Unleash-Potential/dp/0762101857

Does your library have a copy? I bought the book a few years ago and found it hugely informative. Highly recommend it.


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## Stick486 (Jan 4, 2013)

will this help???

..


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## harrysin (Jan 15, 2007)

The inside diameter of the guide is proportional to the outside diameter and is of no consequence in the design of a template. There is no substitute for designing templates using the largest dia. guide, that is OUTSIDE diameter, this allows the collet to pass through the guide allowing a deeper cut, it also allows the operator to SEE what the bit is doing and it also doesn't allow the swarf to build up causing heat build up.


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## Cherryville Chuck (Sep 28, 2010)

Hi Blobile and welcome. I agree with Harry if the OD makes no difference. Normally you only need to worry about how much offset there is with any guide bush if you are enlarging or reducing a pattern, or making a negative pattern so that you can make the positive (the finished piece) on the next pass, or something along those lines.


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