Lathe Safety and Chucks

[Andrew More]

So I've done a very little turning, but enough to have a small idea of what's involved. Mostly I watch people do both wood and metal turning on YouTube, so maybe this is just obvious if you've been doing it for a while.

One thing that jacks up my pucker factor is watching people get very very very close to the spinning chuck, usually holding something like a piece of sand paper, or maybe a tool.

What happens if they connect? Is it spinning so quick that it's not possible to actually stick something in there, rather bouncing off, or are people just performing dangerous operations? I mean I get dangerous operations, I've worked with table saws, and other types of tools, but I don't don't put my fingers any where near as close.

Since somebody is likely to ask, here's a good example. I know it's a metal lathe, not a wood lathe, but I've seen people do exactly the same operation on wood turning.

https://youtu.be/cEfhDqMup2Y?t=242

[Thomas Wilson80]

I’m fairly new too but I’ve bumped into my chuck a time or two while sanding and it just skinned my knuckle - very minor. Not sure if that would be worse if you were to bump into it hard, but when sanding it hasn’t really been a significant concern. More scary is if you had loose clothing/hair get caught - that can do some real damage!

[John K Jordan]

Good question. In almost 20 years of turning I haven't touched my fingers or knuckles to a spinning chuck once and I work very close to it. I think it's a matter of being aware of the hazard. (I HAVE accidentally touched a tool to jaws - you probably know you can machine steel with woodturning tools, right? )

If used with a recess for a bowl or platter, the jaws are embedded in the wood and only the outer part of the jaw base is exposed. If chucked properly there should be only small gaps between each jaw, not really enough to do major damage if you do touch. But don't! The speed is usually fairly high compared to a metal lathe which gives less time to stick something in those small gaps.

If used with a tenon, if chucked properly the jaws should close down almost completely on a bowl or platter, again leaving only very small gaps between the jaws.

If used to grip square pieces for spindle turning, jaws do often have wide gaps between them and could be damaging to fingers. Don't even touch! BTW, I often turn #2 morse tapers on spindle blanks and insert them directly into the headstock spindle - no chuck to deal with or get in the way. I use collets the same way. You can get a collet chuck that has no projections.

Some people wrap tape or something around the jaws to protect the fingers from an accidental touch. Even masking tape will work.

The same level of awareness is important when "turning air", turning things that have corners or are like propellers. It that case, I insist on a bright light and exercise extreme care. An uncareful move here would probably be painful at minimum, damaging at worse. An uncareful move with the tool could be noisy and destroy the work. Don't do that!

This is one with corners. With the bright light I can see the wood fairly well. I'm using a negative rake scraper here to clean up the tool marks on the "wings."

NRS_IMG_7515.jpg

Like anything, if new to turning and something doesn't feel comfortable, maybe back off and do it a different way or do something else.

BTW, my metal lathe has a guard that protects from touching the chuck. The lathe won't spin unless the guard is in place. I'm usually using it with a 3-jaw chuck with jaws constructed much differently than those usually used in woodturning scroll chucks - three narrow jaws spinning like a meat processor!

JKJ

[robert baccus]

Decades ago I went from the original 4 jaw chuck, a tommy bar Nova to a bigger chuck, introduced by several firms. I immediately noticed the nova did not allow the jaws to protrude from the chuck body when opened all the way and most others did--really scarey! Now I use 2 Nova 2's on very heavy long vase shapes with no problems. The range of opening is not as great as some other chucks but safer yeah.

[Ted Reischl]

If your chuck has sharp, non functional, edges it is a good idea to remove those sharp corners with a file followed up with some emory paper. This is especially true on the ends of jaws that may stick out past the chuck body.

If a person is doing quite a bit of metal turning they should really get a metal working lathe with a cross slide and compound to avoid these problems. The trouble starts when someone hangs a metal working chuck on a wood lathe and then starts free hand cutting with woodworking tools. A very bad idea. Just because you can does not mean you should.

[John K Jordan]

If a person is doing quite a bit of metal turning they should really get a metal working lathe with a cross slide and compound to avoid these problems. The trouble starts when someone hangs a metal working chuck on a wood lathe and then starts free hand cutting with woodworking tools. A very bad idea. Just because you can does not mean you should.

I have a metal turning lathe but still use the wood lathe at times to turn metal. I grip the aluminum or brass stock in a Nova woodturning chuck and turn freehand. I personally don't see a difference in hazards between turning wood and softer metals with woodturning tools. As always, be aware and be careful.

aluminum_brass_plastic.jpg IMG_20150420_115928_884_se.jpg turning_IMG_20150420_121555.jpg IMG_20150420_122415_440_se.jpg

But when I turned steel on the wood lathe I do use different tools than with softer metals - I find a Thompson scraper ground close to how I grind the HSS metal-turning bits works well. (I turned down some pin jaws on a Nova chuck for a special purpose.)

turning-steel_IMG_20170605_081521_124.jpg

The hazard with turning steel this way is the needle sharp steel "shavings" and managing the coolant. I did have to sharpen the scraper more than when I turn basswood.

JKJ

[Ted Reischl]

Hello John,

What you are doing is no big deal. Notice when I posted I said the following:

"The trouble starts when someone hangs a metal working chuck on a wood lathe and then starts free hand cutting with woodworking tools."

I run a Delta 1460 which can cut metal and quite nicely. So I have a 4 jaw chuck for metal working and the cross slide for the machine. There is no way that I would free hand anything, even wood, using that chuck. Like someone else posted those jaws are like a 4 bladed propeller.

I don't see a free hand tool getting caught up in wood working jaws anymore than they would get caught while turning wood.

Pretty sure we are both in agreement about this. If I did more metal working I would get a real metal lathe, the Delta 1460 obviously has no feed screw for the saddle so it's range is very limited. But darn handy for lots of small shop stuff!

[John K Jordan]

... Like someone else posted those jaws are like a 4 bladed propeller.

Pretty sure we are both in agreement about this. .. But darn handy for lots of small shop stuff!

Yes, I think we agree about what is possible and I hope we all agree about the potential danger from anything with rotating/moving parts driven by powerful motors! I do think that whatever the material, tool, and machine, working safely is largely about awareness. Someone without experience is far more vulnerable simply because we can't protect against what we are not aware of.

I actually wonder if getting struck with large propeller-like pieces of wood is potentially more hazardous than sticking the knuckles or tool into chuck jaws. I don't want to to an experiment to test that!

My metal lathe is not a big one and I don't use it a lot but when I need/want to use it I am SO glad it's there. Same for the milling machine. Actually, the same for my sewing/embroidery machine. And the oscilloscope and microscopes. And the tractor and bobcat. And the chainsaw and sawmill...