Safety Note -- Drilling with Lathe Tailstock

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KenV

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The April 2014 issue of the American Woodturner has a Safety Note (page 31 Volume 29 issue 2) by John Lucas.

I suspect that many IAP members do not belong to the American Association of Woodturners and with all the lathe drilling, it is worth repeating.


John was drilling with the tailstock mounted drill chuck with the Morse Taper. As he was backing the bit out of the wood, the taper came out, the bit jammed, and a lot of bad things happened very quickly. The bit ended up bent. Inquiry on ways to avoid a repeat elicited a note from Lyle Jamison that he has a pin through his taistock ram and the taper.

John modified that by drilling a hole in the tailstock ram and tapping it with a 1/4 by 28 tap (7/32 bit provides 80% threads) and installed a grub screw that would sit below the surface of the ram. He milled a flat on the MT insert and can now lock down his drill chuck. Photo from his article is attached.


In the same issue, Tom Coghill of Anchorage Alaska notes that small piece of Teflon pipe tape will keep grub screws from coming loose.

Something to think about to make your drilling more secure ---

Also think about becoming a member of American Association of Woodturners

(I found it interesting that we do not have a safety focus forum when I was looking for where to post this)
 

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Dan Masshardt

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While I realize it is NOT as fail-safe, simply holding the chuck when you pull it out of the piece you are drilling will accomplish SAFE removal. One hand on the chuck isn't a bad practice, whenever you are drilling on the lathe.

Plus 1

That is an interesting idea in the OP but I'm not likely to do it

I am extremely diligent about not only keeping a hand on the chuck but also pulling back on it a bit when removing

And standing out of the path
 

KenV

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While I realize it is NOT as fail-safe, simply holding the chuck when you pull it out of the piece you are drilling will accomplish SAFE removal. One hand on the chuck isn't a bad practice, whenever you are drilling on the lathe.


Ed -- I have had a couple of "near misses" with the taper coming out of the socket when drilling with bigger bits. Nothing bad happened, but could have. Forstner bits can be a greater risk to my thinking

The retraction of the bit is the most vulnerable period, and the deeper the drilling and the larger the drill, the greater the chance of needing 3 hands and discovering that I am one short.

I think I am going to drill a 7/32 hole in the ram, and tap it this weekend. The 1/4 by 28 (1/4 NF) is a pretty good choice -

Note that if I install it, I can lock down the taper in the socket --- I do not have to use it, but I can easily make sure nothing will come loose on larger and longer holes.

Everyone has to decide on risk-exposure-consequences safety triangle themselves. But it is worth thinking about.
 

Ed McDonnell

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One additional advantage of a variable speed lathe is that you can reduce the speed of the lathe to a very slow rate before withdrawing the drill bit. That and keeping a hand on the drill chuck are my preferred approach.

A non variable speed lathe could just be stopped before withdrawing, but if you pack the bit with chips in the hole it may be impossible to pull the bit out without the piece rotating. The obvious solution is to withdraw more frequently so the chips don't pack, which would be good practice in any case.

Alternatively, if your tailstock has a thru hole, you can use a draw bar to secure the morris taper in the tailstock. Easy to make your own and doesn't require any lathe modification.



Ed
 

monophoto

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The other thing to think about here is that with many MT Jacobs chucks, the arbor attaches to the chuck body via a second taper (often a JT33). As a consequence, using a drawbar doesn't solve the problem because all it does is firmly attach the arbor to the taper - the chuck body can still come off.

The practice of wearing gloves while turning is controversial - some turners routinely wear gloves, while others consider that to be a very dangerous practice. I normally avoid gloves, but make an exception when drilling because a gloved hand can get a more secure grip on the chuck body to hold it on the arbor.
 

ed4copies

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Ken,

I AGREE with your idea, I just realize that the best safety mechanisms are the ones we will USE. Speaking ONLY for MYSELF!!! I have a GREAT helmet, with fantastic air movement. I use it----WHEN I am turning cocobolo. If I were a SMART person, I would use it all the time!! I have been hit in the face with a ring, from the ringmaster--that HURT!! But, apparently not enough to make me grab the helmet before turning.

I hope you convince LOTS of people to tap their tailstocks!!!!

Equally important, I hope WE convince lots of people to do SOMETHING to be safe!!!
 

JTisher

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If anyone does this this I would recommend brass or nylon tipped grubs, or you will wind-up destroying the internal taper with scarred tooling if you don't have the flat lined up.


Joe
 
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southernclay

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Sounds like the best solution I've heard for the issue....but....

If someone could come up with a way to secure it but also have a quick release I would be a buyer. I'm not likely to do this because of time, convenience and human nature related laziness. Not that it would take a ton of time but Ed's example of the helmet is a great one, takes just seconds but rarely does it.

This solution at least stays out of the way of the hand wheel. I think there's a great business opportunity here for someone that can make a safe but convenient one but I'm far from being a machinist so hopefully someone can figure it out. Be happy to try out a prototype for free!:biggrin:

Thanks for posting Ken
 

lwalper

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I've wondered about using a drawbar, but that eliminates the ability to use the quill to advance the drill bit. Maybe I'm just trying to push too hard and should actually just use hand pressure on the tailstock for drilling?
 

randyrls

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I think I am going to drill a 7/32 hole in the ram, and tap it this weekend. The 1/4 by 28 (1/4 NF) is a pretty good choice -

Ken; That is a good idea, but be careful not to raise a burr on the taper. It is pretty easy to lock the surfaces together permanently. I don't often drill on the lathe, but some drill chucks have a threaded bore in the base of the taper. I have a hollow tailstock and use a drawbar to lock the drill chuck taper and tail stock together.

Metal working chucks have a grub screw that bears on a flat on the spindle nose. Others have a groove that the grub screw fits into.
 

toddlajoie

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I've always been keenly aware that my drill chuck taper gets pushed out MUCH earlier in the draw back than my 60 degree centers, so I usually have the quill quite a ways out and I'm paranoid when cranking it back not to go past that point where you feel it bottoming out. I drill on the lathe at the slowest speed anyway (non VS lathe, so the slowest belt setting) and try very hard to not be in a rush and get the drill bit bound up with chips, so it is usually quite easy to crank back the quill with the lathe off, and if it gets a little tight, at least so far, I have always been able to hand-turn the lathe while cranking back on the quill...

That's not to say that this incident has not opened my eyes to the dangers involved in lathe drilling. I've had the head taper come loose on a drill press that was set up with that style of taper (the JT33 mentioned above I would assume...) so I'll keep in mind in the future that that is also a weak point...
 

Jim Burr

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Ken,

I AGREE with your idea, I just realize that the best safety mechanisms are the ones we will USE. Speaking ONLY for MYSELF!!! I have a GREAT helmet, with fantastic air movement. I use it----WHEN I am turning cocobolo. If I were a SMART person, I would use it all the time!! I have been hit in the face with a ring, from the ringmaster--that HURT!! But, apparently not enough to make me grab the helmet before turning.

I hope you convince LOTS of people to tap their tailstocks!!!!

Equally important, I hope WE convince lots of people to do SOMETHING to be safe!!!

Thanks Ed!!! But put that helmet on every time darn it! :biggrin:
 

Whaler

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I have been drilling on the lathe for years and have had no problems.
I have had a bit melt into a blank once and am glad that I didn't have the chuck locked into the tailstock with a drawbar, etc.
I drill slow, 400 rpm and a hand on the chuck and think that is all that is required.
 

Adillo303

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I think how you start the drill into the blank is a very important factor.

I gently touch the drill bit to the blank to make sure that I am entering on dead center, otherwise you get vibration and an elongated hole. The vibration will easily unseat the Chuck long before bottoming out in the tailstock.

I am also a plus one for a hand on the Chuck.

Also slow speed and don't stand in the line of fire.
 
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buttonsHT

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I was drilling a blank for a pepper mill with a forstner bit and something similar happened. Scared the s*#t outta me. I now keep my left hand on the chuck at all times and stand off to the right of the lathe.
 

flyitfast

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I think how you start the drill into the blank is a very important factor.

I gently touch the drill bit to the blank to make sure that I am entering on dead center, otherwise you get vibration and an elongated hole. The vibration will easily unseat the Chuck long before bottoming out in the tailstock.

I am also a plus one for a hand on the Chuck.

Also slow speed and don't stand in the line of fire.

+1 on your comment. Someone told me a long time ago to use a center drill which starts the drill and makes sure the actual drill bit stays on center and reduces flexing and vibration.
5 Piece Center Drill Countersink Set

Still have to hang on to the chuck and steady it in and out. Also, make sure the quill lock is not tight, but not too loose either. That will cause vibration and oversized hole. Otherwise, slow and lubricated......
Also, the new Nova pen jaws do a great job of reducing vibration and keeping the blank centered...
gordon
 

Cmiles1985

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When I began drilling in the lathe, I did some learning via "near misses". I had issues on my HF lathe, but may have been my newness in drilling on the lathe. I am +1 for left hand on the chuck, right hand driving the quill and speed of around 700 rpm max! Another ine of my major rules is to make sure shavings aren't packing into the bit, and that heat isn't building up too much. Packed bit = friction = heat = changes in material properties then before you can blink, the bit is stuck in your material and the chuck comes out of the tail stock.
 

Adillo303

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Oddly enough, I find that a standard split point bit "finds the center" of the blank better than a brad point bit. I like the hole made by the brad point bit better.

Maybe Mark the blank with a split point, size wouldn't matter, say 1/4", then quick switch to your brad point finish.

Left hand is always on the Chuck, always stand to the side.

I use either the PSI pen blank chuck or my one-way Chuck with spigot jaws depending on which lathe I drill on.

700 - 800 rpm no faster
 
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yaroslaw

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I've had flying chuck with a big bit near my head once. I moved very fast! I've been lucky to stand to the left of the lathe when drilling. So now I not only stand on the left, but ALWAYS keep a hand on chuck on retracting.
Drawbar would be a good solution, but not always. I use some of the bits in Chuck, other bits having Morse tapper so I need to change instruments while drilling (I've found that I always get better performance and straighter holes with a Morse taper drill bits).
 
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