drilling holes with drill chuck

[Stan Calow]

I've been using a drill chuck in the tail stock to drill 7 mm holes for various projects, and have invariably gotten holes too large to hold the brass tube inserts. They slip right out. I can't tell if this is technique problem or runout from the chuck. What's the right technique? For holes longer than I can get in one pass, I do have to run the drill back and then move the tail stock forward, which creates quite a bit of chatter, and am wondering if thats what causes the problem. I am considering trying a head stock drill chuck if that would help. Any thoughts appreciated.

[John K Jordan]

Is this drilling on the lathe with a chuck in the tailstock? I find it is important to get holes started right or the drill may follow the grain and wobble on entry resulting in a bigger hole all the way down. Since I've been using center drills to start critical holes I have better luck. Center drills a are very short bits made for machining metal. They are quite inexpensive and widely available, for example on Amazon.
http://www.amazon.com/gp/product/B004MOJVKU
(http://www.amazon.com/gp/product/B004MOJVKU)
Also, I buy the best quality drill bits I can find and make sure they are sharp.

JKJ

[david privett]

you can always get metric drill bits that are graduated in smaller increments , I have seen into 1/2 mm or do a measurement with a caliper and convert it to sae and use a fractional or numbered or lettered drill a few thousand's undersized. There is pages of this stuff on the net you can print that covers metric and sae in a size progression , I have it to 1 inch on paper in the shop it is very useful. So if you are having a slop issue you can work around it.

[Kyle Iwamoto]

Do you have a caliper? If you measure the tube and the drill bit, I would gamble that the drill bit is too big. I've bought 7mm stuff and used a 7mm drill, and seen what you see. The tube has too much clearance. I use a letter drill, that is better sized. I just got the tube and the drill bit, put them both in the caliper, and when the caliper holds the bit but lets the tube drop out, the bit is slightly bigger and works fine......

[Stan Calow]

Thanks for the input. I will check into center bits - sounds like a good tool for many purposes. I had not thought about getting a slightly smaller bit, and Kyle's tip about testing sizes with caliper makes sense. I will endeavor to persevere.

[Tom Wilson66]

Another way to help center the bit when drilling is to make a dimple in the end of the blank with the point of a skew chisel prior to drilling. This can help quite a bit if you don;t want to use centering bits.

[Peter Fabricius]

The 7mm bit is .0014 smaller than the "J" bit I use, I am surprised that the tubes fall through the hole....
I think you might have the Headstock and Tailstock centres off centre.
Run two points up close to each other and check if they are in alighnment.
Also the suggestion to use a centering bit is great.
Peter F.

[Brice Rogers]

You've receive a lot of good advice. As others have touched on, there are a number of things that could cause you to drill oversize. Most have been covered. You should pursue all of the things that have been mentioned.

Another cause of going oversize is the drillbit. I have one set of Harbor Freight drill bits (Ti-Ni) that are horrible. They sometimes drill 0.020 holes (in metal) - - that's horrible if you wanted to tap some threads. Perhaps marginal for pens. I have another set of lettered and numbered drill bits that drill either on-size or slightly under. On the ones that drill oversize, I've looked at the tip under magnification and often find that the two cutting surfaces are different widths. Basically they were very poorly sharpened and essentially the "center" is off center. On metal the effect of this can be minimized by drilling pilot holes and a number of intermediate sized holes. The drill is acting a bit more like a reamer. I'm uncertain if this would work with wood though. Some of my crummy HF bits are not straight. If I put them in a drill press I can see that the tip wobbles. Try that with your drill bit and see if it is 100% straight. If it isn't, it would cause you to start your hole off center....

Brad point drills have a sharp point in the center and are more likely to drill on center than your "cheapy" drill intended for metal. All the points about center drilling, dimpling, etc. also apply here and should be done.


Forstner bits typically drill on center. If you drilled a 1/4 inch hole with a forstner, it will be about 0.025 undersize. But it may not be as deep as you need. But then you could redrill it with something around 7 mm. They also sell 7mm forstners.

For pen drilling, some woods will have grain that causes the drill to slide from the hard grain to the softer stuff next to it. If you are drilling plastic or wood with little grain, it would minimize having the drill move over. So, as an experiment, you may want to try drilling a hole in a piece of plastic or basswood, etc. and see if it drills oversize.

Also, when you start your drilling, look closely at the drill bit. If everything is done right you should not see it wobbly as it enters. If you do, that is a good part of your problem.

[Ron Rutter]

First thing I would check is headstock/ tailstock alignment.

[Bill Boehme]

I agree with Ron. You didn't say what lathe you have ... some are worse than others when it comes to alignment of the headstock and tailstock centerlines, although none are perfect. The two misalignment errors are radial (where the centerlines are offset horizontally and vertically) and angular (where either or both of the centerlines isn't parallel to the ways of the bed.

Given the above alignment errors and that all woodturning lathes will have some alignment error, it should be obvious why there are wallowing out problems when drilling from the tailstock end. Drill from the headstock end using your preferred method of holding the pen blank until you have a hole that is about 1/2 to 3/4 inch deep. Then just handhold the blank for the remainder of the hole making sure that you do not side load the drill. While the drill may drift slightly, it won't be wallowed out.

[Fred Perreault]

I have found that even though my centers align properly, some times I get oversize holes. The holes are actually a little oval, as the extended bit some times will get thrown around (wallowing as stated above) by the wooden target piece. If I make a modest pin prick or other starter hole first, it usually makes a better hole. I did a few holes before I realized that a truly round hole is not an easy task every time. The longer the bit I use for deeper holes, the more likely that I have to be cautious and take care to keep the bit from moving around. Of course, it could just be me. :-)

[Geoff Whaling]

Stan, wood lathes have much more play in the bed ways / tail stock and don't have the adjustable gibs of a metal lathe. So it is very possible that your lathes tail stock will only be in alignment in a particular position relative to the bed ways. Once you work out where that position is it will make drilling much easier.

One process to help center holes,


make a pilot center, like a counter sink with the point of a skew chisel, make sure it is a clean Vee with no center nipple.
make sure the Morse taper is free of debris & install the Jacobs chuck. Keep the quill extension to an absolute minimum.
Lock the quill clamp very lightly to take up any free play in the quill.
then bring up the tail stock with the jacobs chuck but don't clamp down the tail stock locking lever just yet leave it just very lightly clamped only.
Start the drill bit into the pilot center which will kick the drill bit, Jacobs chuck and tail stock into alignment, - note the position of the tail stock relative to the bed ways - i.e. is it kicked to one side or slightly skewed in the bed ways? Use this as a reference for future setups.
now lock down the tail stock locking clamp.
Drill away, but start by advancing the drill bit very slowly which helps to align the hole, then increase the drill bit feed rate.
clear the drill bit very regularly


Hopefully this may solve your problems.

[Stan Calow]

Thanks everyone for the great advice. (Its a Jet Midi, I think a 1042). I did check with calipers and the bit size was right on with the tubes. When I checked the alignment, its fine, at first, but I see it go out of vertical alignment by a visible amount when three inches of drill bit are projecting out of the drill chuck and I clamp down on the tailstock. Yep, there's a lot of play and movement I will need to deal with -may need to shim. I think I'm on the right track now. I appreciate the input. Its that kind of detail I wish the reference books would get into.

[John K Jordan]

but I see it go out of vertical alignment by a visible amount when three inches of drill bit are projecting out of the drill chuck

This is a problem with longer bits.

I think two things contribute to oversized holes when drilling wood on the lathe (not counting a poor bit that is too large). One is if the tailstock is misaligned, say too far to the side, but doesn't have much slop - one flute on the bit can cut one side of the hole more than the other side leading to a much bigger hole than the bit. I haven't seen this with my wood lathes since the alignment is good. Starting off center can also lead directly to the wobble mentioned below, as can a cheap, poorly made chuck.

The other, and more likely is when the bit doesn't get started correctly and is not drilling in a perfectly straight line. Most of the time I think this is when the bit gets started wrong when it first enters the wood. It might touch perfectly then get deflected a tiny bit by the grain and drop into a softer spot. The bit then often doesn't straighten up but can follow the grain, especially in deep end-grain holes. This is easy to see since the bit will visibly wobble as the wood turns. This is a problem with wood turning lathes since there is no gib adjustment as on a metal lathe.

This starting problem is what can be minimized by starting a hole with a center drill or a skew chisel or other means. Spotting drill bits, made for CNC are also good for this since they are short and stout: http://www.amazon.com/gp/product/B009NNFK96 As someone mentioned, always make sure the morse tapers on the lathe and chuck are clean with no scarring or burrs. I clean the lathe tapers with a tool made for this. I clean up any problems on the chuck taper as needed. A quality chuck helps. (A precision collet is far more precise than a chuck, used a lot on milling machines but not commonly available for wood lathes - and you have to have a different one for each bit size.)

Longer drill bits are more of a problem. Unfortunately, most of the bits sold are jobbers length which are long. There are shorter bits called Screw Machine Bits which are harder to find and usually more expensive but well worth it. I bought some from the Little Machine Shop for metal work but have used them occasionally on the wood lathe. For the most precision with deep holes you can drill a short hole perfectly centered by starting with a center bit, switch to a short bit to get the hole started, then finish up with the long bit. Once the first part of the hole is drilled cleanly, a long bit will follow it like a guide.

All this is way too much trouble for pen blanks so I would try a better quality bit and perhaps one with a different type of point, such as a split point, bullet point, etc to see if that works. (I don't do many pens but when I do I drill them on a drill press.) Many years ago I learned that all bits are not created equal and buying cheep bits was counter productive in the long run.

The bits I use the most are sold by the industrial suppliers and come in a set with 1/64th inch increments, maybe $80-$120 a set. Another smaller and cheaper set I like is sold by Bosch. When building my shop I used one to drill a bunch of 1/2" holes in 1/2" thick steel and it was still sharp. I bought 4 sets of these a couple of years ago when they were $19.75 on Amazon but I see they are over $30 now. Ack! Maybe priced for the Christmas rush...

JKJ

[Rick Gibson]

I have yet to see a wood lathe with zero horizontal play so what has worked best for me is to start the wood turning and bring the bit up to the wood. without locking the tailstock. the bit will center itself and then lock the tailstock and drill your hole slowly.

[Geoff Whaling]

I thought I would have a play with the Jacob's chucks today on my Vicmarc VL150 lathe. Drilling Sierra pen blanks that have been turned to 19 mm dia between centers then held in a Vermec ER32 Collet Chuck on the head stock, and conventional setup with MT2 Jacobs chuck with drill bit in the tail stock, using the drilling sequence I posted above.

Jacobs chuck #1 - best I could achieve was a 0.5 to 0.6 mm off set hole on the hole exit end of the pen blank. i.e. the resulting tube wall thickness difference from thinnest to thickest ranged between 1 & 1.2 mm. I was becoming concerned as I had achieved far better results in the past then the penny dropped - different Jacobs chuck!

Jacobs chuck #2 - far superior result with far less than 0.1 mm off set hole on the hole exit end of the pen blank. i.e. the resulting tube wall thickness difference from thinnest to thickest was less than 0.2 mm.

Repeated this with dozens of blanks and with both 27/64" & a 10.5 mm quality reduced shank (10 mm) drill bit in both chucks. I can't explain the difference other than Jacob's chuck #1 is a cheapie and #2 a much higher quality chuck. I cleaned the MT, even tried multiple positions of chuck #1 in the MT2 in the tailstock, reset the drill bit in the jaws of the chuck etc. etc. - same result, very occasionally the drill actually wandered onto the correct axis.

[John Keeton]

Geoff, you left us hanging! What brand is the better chuck?:)

[Geoff Whaling]

Geoff, you left us hanging! What brand is the better chuck?:)

John, I didn't know when I posted. I'm in Far North Queensland, Australia, so often the generic brands we see are quite different to what is available to the majority of readers of this forum so please excuse me leaving off the brands.

I just went out to the shop/shed to check for you (it is a bit early here 4 am, cursed as an early riser), truth is I cannot find a brand name on #1 and it is now indecipherable on #2. Ive had both for around 10 years and have always set aside #1, know I have proved why!

What I can say though is that #1 is a typical keyed 1/2" Jacobs Chuck, designed and operates so that the jaws extend well out at least 5/8" or 15 mm past the body of the chuck; whereas #2 is a 10 mm keyed Jacob's Chuck but the jaws remain internal to the body when used on 10 mm stepped / reduced shank drill bits. In length extending past the face of the tail stock quill #2 is some 20 mm or over 3/4" shorter than #1.

The results I get with #2 is about the same as I get when using a threaded (not MT2) ER Collet Chuck body or with the MT2 Collets & Collet Nut on my tail stock quill. So any drift is more operator error or due to grain in the blank. I will take a couple of photos later today and post them.

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The offending #1 chuck is pictured on RHS in photo 3. These photos are of our now in retirement Nova Mercury. The thread on the tail stock quill was standard however I have had my VL150 quill customized to. With the 1" x 8 thread I can use all of the accessories in photo 4 directly onto the quill. The MT2 collets are not as accurate as the ER collet chuck setup but still pretty good but unfortunately the Nova range of MT2 collets only came in 4 sizes from memory and the 3/8" collet will not accept a 10 mm reduced shank drill bit (buggar!).

[John Keeton]

Thanks, Goeff, for the pics. You have some nice setups! I get reasonably good results from my keyless Jacobs chuck, but I am rarely drilling deep holes that require precision for the entire depth. But, I am always open for the acquisition of a new tool had you determined the brand. 😉