Trouble with centre-drilling resin pen blanks

[Doktor_Zeus]

I've recently been getting into pen turning. I'm fine with most of the process, but I've run into a major annoyance. I just can't seem to drill my blanks properly any more! The first two projects I did perfectly well on a drill press, but it's not reliable. I share it with a number of other people and it frequently goes out of alignment, resulting in flared holes.

To get around this problem, I bought a two-jaw self-centering square-edge chuck for the lathe so that I could drill them using a tailstock drill chuck. However, this seems to also be producing flared holes - often a millimetre or more too wide. I'm pretty sure the square chuck isn't to blame as the hole seems to be perfectly centred.

Can anyone tell me what I'm doing wrong here?

My process is this:
1. Fit the square chuck and drill chuck into the lathe
2. Bring the tailstock up to the square chuck.
3. Leaving the tailstock loose, place the drill bit between the square chuck jaws
4. LOOSELY close the square chuck around the drill to centre it (there's quite a bit of play in the tailstock)
5. Tighten the tailstock and loosen the square chuck, ensuring the bit does not move out of alignment as I do so
6. Fit the blank into the square chuck, bracing the end against the base of the chuck
7. Run the lathe at its slowest speed
8. Advance the tailstock using the hand wheel
9. If the blank is long, stop and move the tailstock up using the part-finished hole as a guide
10. Once I've drilled almost, but not entirely, all the way through, stop and remove the blank
11. Cut off the excess using a band saw to reveal the drill hole and avoid blowout

This seems to me like it's the safest way I could accomplish this task, and yet the hole is still flared! The flaring seems to be at the end furthest from the drill. I've mostly been drilling resin blanks so far.

Is there something about the lathe I need to fix or check?
Am I using the wrong kind of drill bits? (standard wood bits)
Am I using too large a drill? The near end of the hole fits the tube perfectly
Or am I just expecting too high a degree of accuracy?

I'd be grateful for any tips anyone could give me, as I don't really want to waste any more blanks without knowing what I'm doing wrong.

[Valkrider]

Have you checked the the morse taper in the tailstock is clean? A little bit of wood dust / waste can throw it off.

[Doktor_Zeus]

Thanks, I will check that the next time I'm in the workshop. I'm fairly confident it was OK as I did give the drill chuck a good wiggle to see if it was properly fitted, but you never know!

Anyone got any other possibilities I can check at the same time?

[Duncan A]

Are the tailstock and headstock in perfect alignment?
Put a centre in each and see if the tips of those centres meet.
Then slide the tailstock back and fully extend the quill and see if those centres still meet.
When you say you are tightening down the tailstock, are you tightening both the tailstock to the lathe bed, and the quill. If not doing the latter, wobble is very common.

I would also suggest buying a good quality drill for pen-making; not absolutely necessary but they do tend to do a better job. Look on the reputable pen kit suppliers websites e.g. www.taylorsmirfield.co.uk, www.beaufortink.co.uk

Duncan

[Bill21]

Does the head of your lathe rotate? If it does then the headstock and tailstock may not be aligned. These are useful.

https://www.axminstertools.com/axminster-lathe-alignment-centre-2mt-102427

You don’t say what Chuck you have but I’ve drilled pen blanks without the accessory jaws fitted. The jaw slides themselves grip the blank just fine.

The last few pen blanks I’ve done have been turned between centres first and then placed in the chuck. I also use a spotting drill to start the hole.

https://www.cnccookbook.com/when-to-use-a-spot-drill/

[Derek]

Something not mentioned is are you trying to push all the way through. You may need to drill say 1/4" to 1/2" deep and retract the drill bit and clean the flutes with a brush then do the same all the way through. This is more so when drilling acrylic blanks as over heating can cause problems so take it easy.
Acrylic blanks can get a build up of melted material which will push the drill bit off centre. With wood blanks a course grain can also do the same so by pecking as I just discribed will help over come some problems

[Bill21]

The OP did say:

The first two projects I did perfectly well on a drill press.

So I’m guessing it’s not the drill bit or technique?

[Doktor_Zeus]

Are the tailstock and headstock in perfect alignment?

I'll check that too. I think we have two live centres and I can always turn a small point in the four-jaw chuck to test it. We also have a metalwork lathe so I can probably make a simple homemade tool for the purpose.

When you say you are tightening down the tailstock, are you tightening both the tailstock to the lathe bed, and the quill. If not doing the latter, wobble is very common.

That sounds like a definite possibility. I wasn't sure about whether this was wise, since the quill has to be extended during the process of drilling. The handle on the quill tightening knob is one of those nasty plastic ones that you have to push in to get it to engage with the bolt and it's quite worn away through use, making it difficult to tighten. I might look to see if there's a way to replace it with something more durable.

Does the head of your lathe rotate? If it does then the headstock and tailstock may not be aligned.

Yes, it does, but I'm fairly certain that the head is in the right position or a dowel clamped in the tailstock wouldn't sit perfectly flush in the square jaws. Still, I need to check the alignment anyway, so I'll check this at the same time.

...I’ve drilled pen blanks without the accessory jaws fitted. The jaw slides themselves grip the blank just fine.

It's fine with wood, but slippery resins tend to get pushed in as I advance the quill. I'll see if I can find a spotting drill bit and try that.

Something not mentioned is are you trying to push all the way through.

It was in Step 10. I usually stop about 5 mil from the bottom and saw the end off with a bandsaw to avoid blowout. I found out about the issue with overheating resins early on when an experimental tube resin shattered on the drill press. I take it very slowly and clear the flutes often. But thanks for the tip, it is a good one.

So I’m guessing it’s not the drill bit or technique?

Probably not, although I will say that the clamp I was using was poor quality. One of the reasons I gave up on the drill press was that the blanks kept slipping out of true. I considered getting a specialised clamp, but when I realised that the drill itself often went out of alignment I thought using the lathe would be a better option since I at least know how to true that up.

[Bill21]

One thing I’ve heard some pen makers do is to turn their blanks, wood or resin, to round as soon as they get them. They can then more easily see what the finished item may look like. Once in the round it’s easily held in most chucks. Some use metalwork lathes for pen making so a collet Chuck would be good for drilling.

[julcle]

I always start my drilling on the lathe with a machinists centre drill bit to start it off, the longer drill bit doesn't wobble then. Good quality long bit and drill half way through then turn the blank and drill from the other end right through. And as has been said tail/ headstock alignment is a must also the quill movement adjusted to a minimum. Julian

[Doktor_Zeus]

I always start my drilling on the lathe with a machinists centre drill bit to start it off, the longer drill bit doesn't wobble then. Good quality long bit and drill half way through then turn the blank and drill from the other end right through.

So THAT'S what those weird drill bits with the nipple on them are called! There's one lying around in the workshop that might do the job, if it's small enough.

I always worry about whether the two ends will meet up cleanly in the middle, but I could give it a try.

[Bill21]

Many machinists use centre drills for starting holes. It’s not their intended purpose and spotting drills are better, but if that’s all you’ve got it’s better than nothing.

[julcle]

That's interesting Bill, so please tell what is the purpose of the centre drill and for those that are not mechanical engineers what is a spotting drill (not one i've come across sorry).

[Doktor_Zeus]

That's interesting Bill, so please tell what is the purpose of the centre drill and for those that are not mechanical engineers what is a spotting drill (not one i've come across sorry).

I was just doing some research on that front myself and came up with the following interesting article. The main thrust of it is that the spotting drill, which has a tip angle of 90 degrees rather than 60, makes less contact with the piece as it enters, resulting in less friction and less chance of the bit 'wandering'.

https://www.workshopshed.com/2014/01/spotting-drills-vs-centre-drills/

[julcle]

Ah yes that makes a lot of sense, I have to say though that using a centre drill rather than a spotting drill doesn't seem to have been detrimental in wood. I would say that using a high quality bit after using the centre bit (or spotting bit) is probably more important. But then I am not a mechanical engineer --  Julian