# Drilling deep holes



## dan_house (Feb 18, 2009)

In an effort to hide the connection, I thought it be cool (first mistake, being cheeky) to drill from the bottom of a 4 inch thick stock. I used a 12 inch 3/16th bit with a power drill and an adjustable drilling jig. (my drill press doenst have the "reach")the bit came out of the top about an 1/8 off the mark on one hole and about 1/16 for the other.

Can think of a couple of reasons it did this. First, the bit being that long and that thin flexed under pressure and "walked" as it cut thru. Then the drilling guide may not have been dirlectly over the hole, and the above mentioned off target hole may have simply spotted wrong from the get go.

I did start a deep pilot hole with a jig then switched to the long bit.

Is there a better, easier way to drill holes with out a drill press thru thick stock and have it come out where you want it too? 

TIA 
dan


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## Bob N (Oct 12, 2004)

Dan,

If you came out that close over the course of 12", I really don't think you can ask for much more under the circumstances. Even a drill press would not have gotten you any closer. Just too many factors involved to do any better. About the only thing you could have done different would have been to drill from the top down and let the varance be hidden down below. I think you did pretty darn good myself.


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## Ghidrah (Oct 21, 2008)

I have a bunch of what I call drill blocks, I keep a set in the trailer and one in the shop. I use 3/4" plywood and set each bit in the drill press and make one plunge into the block starting at the outside of the block and work my way around the perimeter eventually ending in the center where the largest bit hole is. The 2nd block, gluing 2 blocks together, as the bit diameter grows so does the length of the bit the highest block is 3 lams at 2 1/4". I have blocks covering from 1/16" to a 1/2" in 32nd and 64th increments.

Quite often when perfect 90° holes are required in material too large for the press I use the blocks. Make the block long enough to clamp when necessary.


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## Ralph Barker (Dec 15, 2008)

Other factors that might come into play are the speed of the drill (rotation speed), the speed of the feed, and the type of bit being used. Slower speeds would likely result in less wander, allowing the bit to cut better, and a brad-point style bit might track more accurately.


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## dan_house (Feb 18, 2009)

Bob, the piece was only 4 inches deep/thick..... For me that was really good, but not good enough for the project.

thinking maybe to plug the the last inch of the hole (can hide the mend...), redrill down to the almost to the plug with a bigger bit, and redril the last inch with the smaller bit. Taht doesnt work, I'll plug the whole thing and redrill from the top..... not as elegant....but thats what prototypes are for, right? 

Ralph, since I was drilling with my powerdrill, and hand feeding thru the jig, I bet your right about feed rates. I had to put s afiar amount of pressure to get it to drill,,,,,,

Ghidrah.. thats brilliant! I can see many applications for those.....

thanx guys


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## bobj3 (Jan 17, 2006)

HI Dan

It may be time to tune up your drill press 

Put a square on the table top, and hold it to the side of the chuck it should be dead on, if not look under the top for a bolt/nut adjust the table so it's dead on with the chuck now move the square 90 deg. and do the same thing, if it's true your done it not find a business card and use it for a shim,you will need move the bolt or nut to get it in behind the mount, put one in, then check it one more time,if you are dead on move the top so it's square on the other side of the chuck.. it takes a bit of time to get it done but it's worth it in the long run..


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dan_house said:


> In an effort to hide the connection, I thought it be cool (first mistake, being cheeky) to drill from the bottom of a 4 inch thick stock. I used a 12 inch 3/16th bit with a power drill and an adjustable drilling jig. (my drill press doenst have the "reach")the bit came out of the top about an 1/8 off the mark on one hole and about 1/16 for the other.
> 
> Can think of a couple of reasons it did this. First, the bit being that long and that thin flexed under pressure and "walked" as it cut thru. Then the drilling guide may not have been dirlectly over the hole, and the above mentioned off target hole may have simply spotted wrong from the get go.
> 
> ...


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## Bob N (Oct 12, 2004)

dan_house said:


> Bob, the piece was only 4 inches deep/thick..... For me that was really good, but not good enough for the project.
> 
> thinking maybe to plug the the last inch of the hole (can hide the mend...), redrill down to the almost to the plug with a bigger bit, and redril the last inch with the smaller bit. Taht doesnt work, I'll plug the whole thing and redrill from the top..... not as elegant....but thats what prototypes are for, right?
> 
> ...


Sorry about that! I mis-read and was thinking 12" deep


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## harrysin (Jan 15, 2007)

I'm not sure what I'm missing here but what's wrong with drilling from both ends.


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## bobj3 (Jan 17, 2006)

HI Harry

I think that's something like burning the candle from both ends 

It takes the fun out of it... 


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harrysin said:


> I'm not sure what I'm missing here but what's wrong with drilling from both ends.


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## dan_house (Feb 18, 2009)

harrysin said:


> I'm not sure what I'm missing here but what's wrong with drilling from both ends.


Me? I'd never get them to line up...... so its all in one shot for me.

Maybe after another decade or two of experience.....


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## dan_house (Feb 18, 2009)

bobj3 said:


> HI Dan
> 
> It may be time to tune up your drill press


Ive squared it when I first got it..... dont think I made it clear that the drill press isnt big enough to drill something that deep/big.

I need a bigger bandsaw, a bigger drill press, a plunge router.....

When I bought the drill press it was drilling parts for gunsmithing.... then I starting stock making, and nothing I have is big enough or has enough power... eh who knew...


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## tmiller (Feb 8, 2007)

If all the parts you're drilling are the same size, you should make a template and drill from both ends. Being a machinist and doing lots of drilling, has taught me that drills seldom drill staight. Double ending is a pretty good option imost of the time. You might also consider a drilling guide and doweling the parts for alignment then using a different drill for thru holes.


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## Ghidrah (Oct 21, 2008)

The bit is creeping through the material, length and diameter of bit, density and grain pattern of the material, table could be off a smidge, and lastly the drill assembly might have some slop in it.

As for drilling from both ends the wider the stock the greater the error.

My point about the drill blocks in this case is no stroke limit, (my press is 3"). If the error is bit wobble, table or press slop the blocks will eliminate it. Glue up a 6" high block for a 12" long bit. Clamp it to the work piece, stand above it and just bottom out the bit. Remove the block and complete the hole.

If the error is because the material isn't square and parallel then the blocks won't help either


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## dan_house (Feb 18, 2009)

Ghidrah said:


> The bit is creeping through the material, length and diameter of bit, density and grain pattern of the material, table could be off a smidge, and lastly the drill assembly might have some slop in it.


Ghidrah has very succintly listed probably every thing that was wrong with the drilling.... except one... me. 

I like the blocks idea. Since, I assume, this will be the first of many, I'll work on some scrap to get it down.

You guys are great!


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## harrysin (Jan 15, 2007)

The more I think about this post the more I wonder why in the world a 12" drill is being used when the wood is only 4" thick, a drill closer to 4" would I'm sure, go straight through dead centre.

Here is a shot of what I have in mind, this one happens to be a 1/4" but 3/16" should also be available in the extra long series.


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## bobj3 (Jan 17, 2006)

HI Harry

It's no big deal but they do make a 3/16" x 6" drill bit, I have one,it's for the EZ SET Marker jig, by March S.of sommerfeld tools,it's used to drill the holes for the handles for the cabinet doors,etc.

I also have 1/8" x 6",9" ,12" for the Incra hinge jig,, they are called aircraft drill bits, they can be had at SEARS for just one place...also at just about any aircraft supply outlets...they are all high end drill bits,,, 

http://www.routerforums.com/table-mounted-routing/6913-wooden-hinges.html

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harrysin said:


> The more I think about this post the more I wonder why in the world a 12" drill is being used when the wood is only 4" thick, a drill closer to 4" would I'm sure, go straight through dead centre.
> 
> Here is a shot of what I have in mind, this one happens to be a 1/4" but 3/16" should also be available in the extra long series.


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## dan_house (Feb 18, 2009)

Harry...
it was 10 pm, I dont have a 6" 3/16 bit (yet...) and did have the 12 inch....

Until I read your post about why not use the 6" bit.... um, er, I never thought of it.

Another reason why this forum is quickly becoming my fav.....


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## dan_house (Feb 18, 2009)

tmiller said:


> You might also consider a drilling guide and doweling the parts for alignment then using a different drill for thru holes.



yea, that. Now, in retrospect, I can see a combination of Tim's guide and Ghidrah's drill blocks being the answer. It also opccurs to me, if I had started the hole from the top, where it can be seen, and drilled DOWN, the off-target result could have easily been camoflauged.

the reason I drilled from bottom up was I had a nice flat square surface to clamp down to the bench. Drilling from the top doesnt, but again, had I though it thru the effort necessary to get it clamped down would have been minimal.


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## harrysin (Jan 15, 2007)

dan_house said:


> Harry...
> it was 10 pm, I dont have a 6" 3/16 bit (yet...) and did have the 12 inch....
> 
> Until I read your post about why not use the 6" bit.... um, er, I never thought of it.
> ...



Ah, at last I'll be able to sleep nights, I thought there had to be a reason for the 12" drill.


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## bobj3 (Jan 17, 2006)

HI Harry

When I was a kid we called them spot light drill bits,,used to drill the hole to put the long shaft of the spot light in the door or in the corner post of the car or truck and in the roof  then we got smart and started to buy fake spot lights, most didn't use them, just for looks most of the time,,,COOL things we did back when...but that was when the cars had steel doors and frames  LOL,, a pair of 44's on your car 

The " _Appleton " was the cool one and every one wanted it  at 40.oo bucks each if I recall 

_
http://www.classicaccessories.org/list003101.html


This should help you sleep now LOL LOL 


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harrysin said:


> Ah, at last I'll be able to sleep nights, I thought there had to be a reason for the 12" drill.


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## Ralph Barker (Dec 15, 2008)

Bob - those spotlights were indeed handy when aiming the Thompson out of the car window at night. 

The only good Revenuer is a dead Revenuer.


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## bobj3 (Jan 17, 2006)

Hi Ralph

Didn't have a Thompson but they worked great for pee-shooters 
A mouth full of beans and a straw and I was set  LOL 


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Ralph Barker said:


> Bob - those spotlights were indeed handy when aiming the Thompson out of the car window at night.
> 
> The only good Revenuer is a dead Revenuer.


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## dan_house (Feb 18, 2009)

An Update

After taking everything that was critiqued and suggested, I tryed again.

First I filled the existing off center holes with 3/16 dowel. Ugly, yes, but its a prototype, and between everyone's help and doing the actual work, Ive learned a lot for the real one.

Then I made a drilling jig to put the holes where I wanted them. Got it square and solid on the workbench and drilled one hole from the top with a regular length drill. Pinned the jig in place with a piece of wood dowel using the just drilled hole. Now that I trust the jig to not move, drilled the next hole with the same bit. Before unpinning the jig, I swapped the regular bit for the long one and finished the full depth of the hole.

Realigned the jig, repinned on the now full depth hole and repeated. Drilled slow and careful, pulled the bit up several times to allow waste to remove and viola!

holes still came out off center, but considerably closer to the "target" than the other attempt. Countersunk a hole for the bolt head, and it looks great.

One more thing that may have contributed the better results this time: practice. This having been the 2nd attempt, I had some idea of what to expect, how the drill/bit and wood would react and how much pressure and guidance to give it as it worked thru.


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## Handidad (Dec 31, 2008)

To help get the bit aligned you could use a bushing. Lee valley as some 
These would be especially useful to make jigs if you have to do mulitple holes.

Sorry, I couldn't post the URL becuase I have not yet done 10 posts.
These are hardened steel bushing that screw into inseerts that are pressed into wood.


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## Ghidrah (Oct 21, 2008)

Dan,
Regarding your efforts, is the stock your drilling through square and parallel? If you're attaching a true jig to a rhombus, trapezoid, quadrilateral or parallelogram your results will still be off.

If you have a perfect square or rectangle, a true jig and you're setting the jig in the correct spot with the error it may have something to do with an uneven grain pattern causing the bit head to drift. A pilot hole may improve target alignment.


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## dan_house (Feb 18, 2009)

Ghidrah

the stock is rectangular with one face having been shaped into a half round. all sides paralell. Should have (now he thinks of it...  ) drilled the holes first, then shaped it. Drilled into the half-round face, using the jig.

I did drill pilot holes with the shorter bit, and finished it with the long one. The jig was drilled on my drill press (since it was 3/4 thick, the press could handle it) so I'm fairly certain its square.

no, wait. By "pilot hole" do you mean an even smaller bit? like drilling a big hole in metal? Start small, and redrill with progressivley larger bits to arrive at the desired size? No. I didnt even think of that. But I'll file that away. I'm sure its only a matter of time before that tidbit will be useful.

Margin of error this time was so small. I'm pleased at how it turned out, and maybe more important, I learned alot. I'll try to take pics to night and post them.


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## Ralph Barker (Dec 15, 2008)

I'm unclear on what you mean by pinning the jig in place, Dan. Can you post a photo of the setup? Unless there is some play somewhere in the setup, the hole should be dead on. Also, if something is making the bit track to one side, I would think there would be a fair amount of vibration.

FWIW, The Delta 20" #20-950 drill press, with tilting table, has a 6" quill travel spec. And, it's only $800 at CPO!


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## dan_house (Feb 18, 2009)

Ralph Barker said:


> I'm unclear on what you mean by pinning the jig in place,



Ralph,

After I drilled the first hole with the short bit, I used a short piece of the dowel as a pin to hold the jig in place when I drilled the..... oh I see now....

Um, I never mentioned the jig has 2 holes spaced for what I need. After drilling the frist hole, I pinned it, then drilled the second hole in the piece from the second hole in the jig, as described elsewhere.

Apologies. I guess it did sound kinda funny/strange..... 2 hole in the jig. Hope that clears alot of the mystery and confusion up. Pictures... I'll take some tonight


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## Ghidrah (Oct 21, 2008)

Dan,
Had you been more specific, (drilling into a round overed face) I would have suggested jig pic below 1st.

This jig would likely have solved your problems. You may have been able to use your drill press, if not then you could have used the drill block and placed it on top.


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## dan_house (Feb 18, 2009)

Ghidrah said:


> Dan,
> Had you been more specific, (drilling into a round overed face) I would have suggested jig pic below 1st.
> 
> This jig would likely have solved your problems. You may have been able to use your drill press, if not then you could have used the drill block and placed it on top.


Big apologies for omission. Your drawing is almost spot on what I came up with. Used a couple of chunks of 2x2 spaced 1.5 inches apart (width of the stock), screwed them to a piece of 3/4 plywood. Measured holes and drilled them on the drill press. Used the jig to drill the holes, as described above.

Great drawing BTW


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## dan_house (Feb 18, 2009)

Posted pics i the Jigs and Fixtures section

http://www.routerforums.com/jigs-fixtures/12825-my-jigs-template.html


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