Measuring a drill bit held in tailstock chuck for true?

[jrista]

I am trying to dial in my drilling. I have moved to the lathe for the last good number of pens. This has eliminated the occasional angled hole, which was problematic for certain kinds of blanks. I am still having one problem, though. It is subtle, but enough that it causes me some problems at times: My holes are often slightly larger, and sometimes slightly non-concentric or off-centered, on one end of the blank. On the other end, the hole is usually quite good with minimal deviation from the outer diameter of the tube, although sometimes the hole is too much larger than the tube overall (which results in the tube settling slightly offset when glued).

My question is: How does one measure if a drill bit held in a chuck in their tailstock is true or not? I have a dial meter, but a) there is no real way to rotate the drill bit when its held fast in the tailstock. Due to the flutes, b) there isn't really a good way to move the dial meter either.

Is there a good trick to truing up a drill bit held in a chuck in a tailstock?

 

[wouldentu2?]

To aid drilling on the lathe i found square stock and starting with a center drill was key.

 

[wimkluck]

Do you have a double morse taper then you can align the centers. It is a wood lathe. On a metal lathe you have other possibilities. Or use a dial indicator set https://nl.aliexpress.com/item/1005...list.product.mainProduct&gatewayAdapt=glo2nld.

 

[egnald]

I've found on my lathe that standard jobber length drills (or longer) can flex when initially piercing the blank.

When it is critical, I start with a Center Drill to pierce the blank and then follow it with a Mechanics Drill or a Stubby (Screw Machine) bit if I have them, and then finally finish up with a Jobber length.

I have a small assortment of Mechanics and Stubby bits, mostly in tap drill sizes as I want to keep the holes as straight and true as I can if I am going to tap threads.

Dave

 

[monophoto]

I'm familiar with this problem.

Like Dave, I've found that jobber-length bits can flex, and the smaller the diameter, the greater the potential flex. But another problem is that the tailstock on my lathe has a bit of 'wiggle' until it is locked down. So the approach I take includes a number of steps:
1. I mount the workpiece in a chuck (Jacobs or collet), and use the toe of a skew to cut a dimple exactly on-the rotational center of the blank.
2. I start with a center bit mounted in the Jacobs chuck. I move the tailstock up to the point where the tip of the centerbit just barely touches the workpiece, and center it on that dimple before locking down the tailstock. This eliminates the effect of the wiggle.
3. I start the hole with the center bit, and then switch to the bit needed for the project. Once again, I center the bit on the hole before locking down the tailstock.
4. Clear the swarf from the drill bit frequently. I keep a block of canning parafin next to the lathe that I can use to lubricate the bit if the wood is especially hard. Brenton Stemp, the Australian flute maker, always suggested pouring a little BLO into the hole as a lubricant. But If I'm drilling a hole that something must be glued into, and I'm concerned about the lubricant interfering with glue later, I will skip the lubricant and just clear swarf more frequently.
5. Initially, I advance the bit using the tailstock screw with the tailstock locked to the bedways. But I have found that once the hole has been established, you can advance the bit by simply sliding the tailstock - the bit will remain centered in the hole.
6. In cases where precision is required, I drill the hole in stages, starting with a small bit, and then swapping out for larger bits until I reach the required diameter. This is simple with twist drills, but it also works with forstner bits - you just have to be careful to center the bit when you shift to a larger size. If you are concerned about accuracy, you can use a skew or spindle gouge to taper the opening of the hole a bit so that the larger-size forstner self-centers.
7. I bought one of those large sets of drill bits at Harbor Freight that I reserve exclusively for drilling wood, and I have a random collection of bits (some older that I am) that I use for all other materials. The objective is to avoid the need to have to sharpen or replace the bits used in wood - that way, I know that while the sizes of specific bits may be off by a fraction, the progression of sizes is consistent. I also have an inexpensive set of large-diameter (up to 1") S&D bits that I also use for wood. Above 1", I have to use forstner bits. I bought a set at Lowes many years ago, and have added intermediate sizes when needed for specific projects.

 

[jrista]

To aid drilling on the lathe i found square stock and starting with a center drill was key.

I've found on my lathe that standard jobber length drills (or longer) can flex when initially piercing the blank.

When it is critical, I start with a Center Drill to pierce the blank and then follow it with a Mechanics Drill or a Stubby (Screw Machine) bit if I have them, and then finally finish up with a Jobber length.

I have a small assortment of Mechanics and Stubby bits, mostly in tap drill sizes as I want to keep the holes as straight and true as I can if I am going to tap threads.

Dave

Interesting! I have a set of center drill bits. I'm gonna use them when I drill these sets of blanks here in a minute. Hopefully that's all that is the problem, some wander...

I do fear I have an issue with the bit being true, though... Looks like Louie, thank his soul, has detailed a procedure for me, though.

 

[jrista]

I'm familiar with this problem.

Like Dave, I've found that jobber-length bits can flex, and the smaller the diameter, the greater the potential flex. But another problem is that the tailstock on my lathe has a bit of 'wiggle' until it is locked down.

Yes!! This is definitely part oft the issue!! I've actually wondered what people do about the wiggle in the tailstock. The tenon that fits into the break in the ways is definitely not precise on these lower end lathes (heck, even on my $2000 Laguna Revo, it wasn't totally great). The Powermatic is superb, but, its a significantly more expensive machine.

Your procedure sounds pretty strait forward. It looks like Walmart here has something called "Gulf Wax", which they say is a canning wax? Is that what you are talking about? I also have that 114 drill bit set from Harbor Freight. It has nearly every imperial, numeric or letter bit known to man. I have also been collecting Fisch wave cutter fortners for a few years now. I have everything up to around 1 5/8", then missing a few up through 2" and something. The wave cutters are amazing, and give really good holes. So I think I'm set pretty good on bits. I also have a pretty extensive set of bradpoints. Personally, I like the bradpoints for drilling harder materials...since they actually cut at the outer edge, I've found that works better for things like trustone or other hard and brittle materials with careful advancement. Same issue sometimes, though, which hopefully following the advice of everyone in this thread will help me eliminate.

Regarding advancing the tailstock by sliding it...what do you do about that wiggle in the tailstock? If I loose mine, then that wiggle becomes a problem again. Is there a way to permanently eliminate that wiggle? I've wondered if I could glue on layers of aluminum, wrapping around only one side of the tenon (that square bit that protrudes into the separation between the ways. Wondered if that was a viable solution or not.

 

[rixstix]

I have a Harbor Freight full drill set which caused me similar grief. It has been replaced with a better quality set which has drills that are not bent, out of round or off-center. The HF set is now in my carpentry toolbox. Maybe I got a HF lemon but have not had any drill problems since. YMMV

 

[egnald]

Yes!! This is definitely part oft the issue!! I've actually wondered what people do about the wiggle in the tailstock. The tenon that fits into the break in the ways is definitely not precise on these lower end lathes (heck, even on my $2000 Laguna Revo, it wasn't totally great). The Powermatic is superb, but, its a significantly more expensive machine.

Your procedure sounds pretty strait forward. It looks like Walmart here has something called "Gulf Wax", which they say is a canning wax? Is that what you are talking about? I also have that 114 drill bit set from Harbor Freight. It has nearly every imperial, numeric or letter bit known to man. I have also been collecting Fisch wave cutter fortners for a few years now. I have everything up to around 1 5/8", then missing a few up through 2" and something. The wave cutters are amazing, and give really good holes. So I think I'm set pretty good on bits. I also have a pretty extensive set of bradpoints. Personally, I like the bradpoints for drilling harder materials...since they actually cut at the outer edge, I've found that works better for things like trustone or other hard and brittle materials with careful advancement. Same issue sometimes, though, which hopefully following the advice of everyone in this thread will help me eliminate.

Regarding advancing the tailstock by sliding it...what do you do about that wiggle in the tailstock? If I loose mine, then that wiggle becomes a problem again. Is there a way to permanently eliminate that wiggle? I've wondered if I could glue on layers of aluminum, wrapping around only one side of the tenon (that square bit that protrudes into the separation between the ways. Wondered if that was a viable solution or not.

I don't know what lathe you have, but Rick Herrell makes and sells a custom Tail Stock/Banjo Clamp (the tenon that fits in the break in the ways) that might be able to help reduce the "wiggle" in your tailstock unless it is already only a very tiny amount. I know it made a big difference on my Jet 1221VS lathe when I switched from the round factory Banjo Clamp to the rectangular one that Rick made for me. Mine still has some wiggle, but it is minimized as long as I keep pressure on the tailstock to the front and downward when it is loose or when I am moving it. Here is a link to Rick's "Custom Made" tool page. - Dave

PS I don't use wax on my drill bits, but I do spray them with Bostik BladeCoat Blade and Bit Lubricant (used to be called DriCote) after each use before I put them away.

 

[jrista]

I have a Harbor Freight full drill set which caused me similar grief. It has been replaced with a better quality set which has drills that are not bent, out of round or off-center. The HF set is now in my carpentry toolbox. Maybe I got a HF lemon but have not had any drill problems since. YMMV

FWIW, I am not blaming the drill set. I actually like this set a lot, its been superior to any other bits I've used so far, and as far as I can tell they are all very strait. These are cobalt steel, and with a basic roll test on a very flat, smooth surface they seem to be extremely strait. The concern I have is not that the bits are not strait, but that my tailstock chuck, or the tailstock itself, was not holding the bit strait. The bits themselves, though, cut extremely well, the flutes work extremely well, and they hold their cutting edge extremely well.

 

[jrista]

I don't know what lathe you have, but Rick Herrell makes and sells a custom Tail Stock/Banjo Clamp (the tenon that fits in the break in the ways) that might be able to help reduce the "wiggle" in your tailstock unless it is already only a very tiny amount. I know it made a big difference on my Jet 1221VS lathe when I switched from the round factory Banjo Clamp to the rectangular one that Rick made for me. Mine still has some wiggle, but it is minimized as long as I keep pressure on the tailstock to the front and downward when it is loose or when I am moving it. Here is a link to Rick's "Custom Made" tool page. - Dave

PS I don't use wax on my drill bits, but I do spray them with Bostik BladeCoat Blade and Bit Lubricant (used to be called DriCote) after each use before I put them away.

Hmm, I might have to contact him. There is enough play in my Wen lathe that it is an issue, and I'm constantly checking alignment of things, and figuring out whether to push the tailstock against the back way, or pull to the front way, or something, before I do any work. I honestly don't know which is actually "correct"... I think I need to get one of those double-ended morse tapers and just check it that way.

So, regarding bit lubs... Does that affect the wood in any way? Will parffin or any kind of bit lubricant absorb into the wood? Does that affect glue bond? I understand using a bit lube when drilling, tapping or otherwise cutting metals. With wood though, I would imagine it would absorb anything liquid enough that gets on the fibers.

 

[egnald]

Hmm, I might have to contact him. There is enough play in my Wen lathe that it is an issue, and I'm constantly checking alignment of things, and figuring out whether to push the tailstock against the back way, or pull to the front way, or something, before I do any work. I honestly don't know which is actually "correct"... I think I need to get one of those double-ended morse tapers and just check it that way.

So, regarding bit lubs... Does that affect the wood in any way? Will parffin or any kind of bit lubricant absorb into the wood? Does that affect glue bond? I understand using a bit lube when drilling, tapping or otherwise cutting metals. With wood though, I would imagine it would absorb anything liquid enough that gets on the fibers.

I just check my alignment by putting a 60-degree live center in the tailstock and a 60-degree dead center in the headstock and move them close to each other to see how well the points align.

The BladeCote that I use is a dry lubricant in an aerosol spray. I can't even detect a residue on the bit other than maybe a slight odor. I don't know about wax though. I suppose it could affect adhesion of the tube.

Dave

 

[jrista]

I just check my alignment by putting a 60-degree live center in the tailstock and a 60-degree dead center in the headstock and move them close to each other to see how well the points align.

So, this I do, and...I don't think its actually all that accurate, at least in terms of complete alignment of the system. This ONLY tells you that the points meet. It actually does not tell you that the entire distance between the headstock and tailstock is actually in alignment. The tailstock could actually be angled such that if you drive a drill through a blank held in the headstock, it might be centered at the back end, and off-center at the front, even though your points align. A point only tells you that, at that POINT, they meet.

Just to exaggerate, you could technically make the point of the headstock center and the point of the tailstock center meet, even if the tailstock was misaligned by 90 degrees.

A double-ended morse taper would force alignment over a much greater distance than just a point. I think this is what I need, to ensure that I'm completely in alignment overall. Still, this wouldn't tell me if my drill chuck is holding the drill bit strait. That was where I was wondering if anyone had a way to check alignment of the bit with a dial meter. I've been thinking maybe if I could find a tube of the right size for the bit, or maybe wrap the bit in something that would stay round, then I might be able to check if the bit is held true. Maybe I could put the drill chuck in the headstock...then at least I could rotate the bit. Maybe I could just check along each non-flute surface...near the tip of the bit, and see what the deviation is side to side...

 

[monophoto]

"It looks like Walmart here has something called "Gulf Wax", which they say is a canning wax?"

Yup - even down to the brand. I got mine at the supermarket - a box lasts a very long time.

Tailstock wiggle comes about when the tenon on the bottom of the tailstock is more narrow than the opening between the bedways. On my lathe, that difference is a fraction of a millimeter. In theory, you could add shims on the tailstock tenon to fix the problem, but the shim would have to be extremely thin.

And as Jon says, the consequence of wiggle isn't that the drill bit and headstock don't meet, but rather that the axes of rotation of the headstock and tailstock aren't aligned. In my case, the worst case angular misalignment is about 0.6 degree. Seems to be a mighty small error, but its angular, which means that the lateral error increases as the tailstock is positioned further away from the headstock.

Once you get the hole started, the hole itself will keep the drill bit aligned. So you can advance the Jacobs chuck by sliding the tailstock without concern for error due to the wiggle.

 

[Woodchipper]

"I just check my alignment by putting a 60-degree live center in the tailstock and a 60-degree dead center in the headstock and move them close to each other to see how well the points align."
I do as Dave.

 

[Aurelius]

So, this I do, and...I don't think its actually all that accurate, at least in terms of complete alignment of the system. This ONLY tells you that the points meet. It actually does not tell you that the entire distance between the headstock and tailstock is actually in alignment. The tailstock could actually be angled such that if you drive a drill through a blank held in the headstock, it might be centered at the back end, and off-center at the front, even though your points align. A point only tells you that, at that POINT, they meet.

Just to exaggerate, you could technically make the point of the headstock center and the point of the tailstock center meet, even if the tailstock was misaligned by 90 degrees.

A double-ended morse taper would force alignment over a much greater distance than just a point. I think this is what I need, to ensure that I'm completely in alignment overall. Still, this wouldn't tell me if my drill chuck is holding the drill bit strait. That was where I was wondering if anyone had a way to check alignment of the bit with a dial meter. I've been thinking maybe if I could find a tube of the right size for the bit, or maybe wrap the bit in something that would stay round, then I might be able to check if the bit is held true. Maybe I could put the drill chuck in the headstock...then at least I could rotate the bit. Maybe I could just check along each non-flute surface...near the tip of the bit, and see what the deviation is side to side...

On my lathe, I check that the points meet but also extend the tailstock to it's maximum and ensure they still meet. This tells you instantly if your tailstock is misaligned. If you meet at both points, it's straight and you're good to go. If not, then you need to take a few minutes to dial in your tailstock.

 

[jrista]

On my lathe, I check that the points meet but also extend the tailstock to it's maximum and ensure they still meet. This tells you instantly if your tailstock is misaligned. If you meet at both points, it's straight and you're good to go. If not, then you need to take a few minutes to dial in your tailstock.

I still don't think this would really tell you everything is aligned. It doesn't matter how long the distance is when you get the two points to meet...the back end of the tailstock could still be shifted such that along the entire length of the quill, the overall alignment still deviates. We aren't necessarily talking about a lot here, but there can still be deviation when the alignment method only involves matching up the tips of two centers. Point to point is not a means of aligning the entire distance between headstock and tailstock... Again, you could align the two points, with the quill fully extended, when the tailstock was rotated 90 degrees out of alignment...

I mean...I could push the back of my tailstock to the back way, then adjust the live center to meet the dead center. I could also pull the back of my tailstock to the front way, and still adjust the live center to meet the dead center. At least, I can with the amount of play I have with the wen and its tailstock. There is enough there that I can generally make the points meet regardless. I guess if I had newer centers with super sharp points, I might find there was a fractional discrepancy, but sadly none of my centers are that new.

For a long drill bit, say, I think this lack of guarantee that anything held in the tailstock is well and truly strait with anything held in the headstock, could be a problem. Not huge, but enough that if you were to drill anything with parallel lines, or say a thin blue or red line blank, etc. that you could notice the deviation at the other end of the blank. It would be subtle, but...this is the kind of thing I'm trying to optimize. That, and getting my hole diameters as small as possible.

 

[dogcatcher]

Checking point to point, headstock to tailstock by eyeballing it is only as close as your guess/opinion. In my opinion this is close enough for most people.

But 5 inches out from point A is wider than that perfect at point A.

 

[Aurelius]

I still don't think this would really tell you everything is aligned. It doesn't matter how long the distance is when you get the two points to meet...the back end of the tailstock could still be shifted such that along the entire length of the quill, the overall alignment still deviates. We aren't necessarily talking about a lot here, but there can still be deviation when the alignment method only involves matching up the tips of two centers. Point to point is not a means of aligning the entire distance between headstock and tailstock... Again, you could align the two points, with the quill fully extended, when the tailstock was rotated 90 degrees out of alignment...

I mean...I could push the back of my tailstock to the back way, then adjust the live center to meet the dead center. I could also pull the back of my tailstock to the front way, and still adjust the live center to meet the dead center. At least, I can with the amount of play I have with the wen and its tailstock. There is enough there that I can generally make the points meet regardless. I guess if I had newer centers with super sharp points, I might find there was a fractional discrepancy, but sadly none of my centers are that new.

For a long drill bit, say, I think this lack of guarantee that anything held in the tailstock is well and truly strait with anything held in the headstock, could be a problem. Not huge, but enough that if you were to drill anything with parallel lines, or say a thin blue or red line blank, etc. that you could notice the deviation at the other end of the blank. It would be subtle, but...this is the kind of thing I'm trying to optimize. That, and getting my hole diameters as small as possible.

My apologies, I was thinking in terms of my metal lathe not a wood lathe. My point was that if you are "aligned" with the tailstock fully retracted but then extend it and you are no longer "aligned" then that indicates that the tailstock is angled with respect to the headstock. I would imagine you could do the same thing on a wood lathe but, as the only wood lathe I have is a little Harbor Frieght thing I use for polishing, I can't speak to that with any kind of certainty.

 

[jrista]

My apologies, I was thinking in terms of my metal lathe not a wood lathe. My point was that if you are "aligned" with the tailstock fully retracted but then extend it and you are no longer "aligned" then that indicates that the tailstock is angled with respect to the headstock. I would imagine you could do the same thing on a wood lathe but, as the only wood lathe I have is a little Harbor Frieght thing I use for polishing, I can't speak to that with any kind of certainty.

Ah! Yes, I'd agree here. I've ordered one of those Nova alignment dual-morse tools, and hopefully that will help me quickly align each time. But until that arrives, this little check near and far at the point should help.

 

[jrista]

"It looks like Walmart here has something called "Gulf Wax", which they say is a canning wax?"

Yup - even down to the brand. I got mine at the supermarket - a box lasts a very long time.

Tailstock wiggle comes about when the tenon on the bottom of the tailstock is more narrow than the opening between the bedways. On my lathe, that difference is a fraction of a millimeter. In theory, you could add shims on the tailstock tenon to fix the problem, but the shim would have to be extremely thin.

And as Jon says, the consequence of wiggle isn't that the drill bit and headstock don't meet, but rather that the axes of rotation of the headstock and tailstock aren't aligned. In my case, the worst case angular misalignment is about 0.6 degree. Seems to be a mighty small error, but its angular, which means that the lateral error increases as the tailstock is positioned further away from the headstock.

Once you get the hole started, the hole itself will keep the drill bit aligned. So you can advance the Jacobs chuck by sliding the tailstock without concern for error due to the wiggle.

I forgot that the Wen has this oddball separeate "tenon" part that fits between the ways. I suspect, that I could wrap that in layers of foil (at least the flanges of it that fit between the ways), bond them to it and each other, and tighten up that slack. I'll probably do some measurements and contact Rick about maybe getting a custom part manufactured that will keep things tight in the long term in a more wear-free manner.

Regarding small errors, you nailed it...when its angular, the farther from the source the bigger the effect of that error you suffer.

I went through your procedure, BTW, on a number of test blanks. Works pretty well! Sadly, I've misplaced my 25/64ths bit, which I need for this next set of pens. Of ALL the bits to replace...25/64ths...one of the most commonly used!! In any case, started a small divot with the skew to find that dead center. Used a center drill bit to drill a starter hole and chamfer it out a bit to help center the next bit. Centering the next bit was a little problematic with this Wen...the slop in the tailstock, is maybe 1.5-2mm, but its enough that it is problematic. I am not quite sure I was able to actually line up the bit with this starter hole, despite trying a few angles with the tailstock. I finally picked the best one, and drilled from there. I think the starter hole and all DID help (thanks all!!), but...I think with the discrepancy in centering with the jobber drill bit...I am still getting an error in the hole. I used a bit that was just a fraction of a hair too small to actually fit the tube in, so I wasn't able to test how good the hole was relative to these particular tubes. I am going to try and drill these same test blanks again once I find my 25/64ths bit and see how neatly I can expand these holes to fit the tubes. Hopefully, I'll minimize the error, which I am then hoping will lead to fewer issues once I've turned the blanks down to the bushings.