First Rule of Woodturning...

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While I have turned a few items in the past, I am relatively new to woodturning as a whole. Today, I developed some rules...

Rule #1: Until you learn, and follow, the rules of woodturning, keep bandaids in both front pockets...

I developed this rule shortly after I decided to check the thickness of the wall of a bowl I was turning with my left hand. In an instant my left index finger found its way between the rest and the rapidly turning bowl rim. While it only remained there for a a fraction of a fraction of a second, it was still long enough for me to get the point. Fortunately, the only loss was some skin and as the friction generated by the rim against my finger had a cauterizing effect and there was no blood loss. Still, remarkably, I did have some bandaids in my shirt pocket and after a short pause, could continue to work and learn.

Rule #2: Do Not touch the work on the lathe with your bare hand while the lathe is still spinning.

(See explanation to Rule# 1)

Rule #3: Do Not look up from the work until you have completely removed the tool from anything that is still spinning.

I accidentally touched the far side of the bowl with the point of the tool and it popped it up and back toward my body. I did have a good grip on it and lived to learn another important lesson. I don't think a skew derives its name from the act of skewering, but the effect would be the same.

Rule #4: A face shield does more than simply keep the shavings and chips out of your face and shirt.

I had move around to the other side of the lathe to work the inside of the bowl wall and I was doing quite well until the bowl simply disappeared... I saw something skittering away out the door of the shop and heard something else clattering around behind me. I had hit a crack and physics took over. Judging from the rate of disappearance, the face shield would have paid for itself 100X over had my head been a few more inches to the right. I found one half under the boat about 20 feet away and the other half wedged behind some shelving behind me.

Rule #5: Know when to quite an activity for the day.

The first bowl I did today turned out great. The second one had a giant chip come off the blank during the initial truing and after cutting another blank, it became the finger eating disappearing bowl. So, I decided to stop turning for the day and do something else that didn't entail the use of sharp tools or machinery.



I'm sure there are many more rules but these are what I learned today...

Alan
 

Vaughn McMillan

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Sounds like you're well on your way to becoming a seasoned bowl turner, lol. (Have you turned a funnel yet? All of us make at least one funnel.) :yes: It's good that you're paying attention and learning from the lessons being taught, though. :thumb:

Also, it kind of sounds like you were using a skew on a bowl. That's generally not a good idea. Not only is it prone to catches, the tang on a skew is often not robust enough to withstand a bad catch on "faceplate" work. Same story with spindle gouges and spindle roughing gouges. (I put faceplate in quotes because bowl turning is considered to be "faceplate" work, even if you're using a chuck instead.) A skew can be used as a scraper, though, but a heavy, thick scraper is a better choice if you have one available.
 

Vaughn McMillan

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Later today I'm going to post pictures of my WT tools and you guys can tell me what they can and cannot be used for. I suppose I should find out before I go much further. I've watched a bunch of YouTube videos and read a bunch of stuff on Google and a lot of the tools they use don't look much like what I have. All of mine were my dad's, as was the lathe. I bought a chuck and a free spinning tailstock. He did a little bit of turning years ago (30-35) but pushed the lathe and tools to the back of the shop after that. It just wasn't his thing. He wasn't one to do a sloppy job or give up on something (especially something he had spent money on) easily. He must have had his reasons.

I know I don't have any scrapers except the ones with the half round bits. I guess it's all in the way you sharpen them. I have just been dressing the profiles he had. I don't know if they are right or not. I know what a skew is, and a bowl gouge and there are some that look like parting tools.

Another thing that may have contributed to the bowl flying apart is that I was using a mortise cut in the bowl bottom for attachment to the chuck. If I use a tenon it may serve to hold the bowl together if there is a break.

Alan
 

Ryan Mooney

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A couple other notes on your adventure.

If you do want to touch the piece while it's spinning for some reason, is safer to do so by reaching under the tool rest. I still wouldn't use my hand to check thickness while it's spinning though to much of a chance of it grabbing and going poorly. Indeed I usually stop the lathe to check thickness and use that as an opportunity to also clear built up shavings. You can use the tool to check round though, simply set it on top of the spinning piece, if it's not round it'll bounce.

I usually turn the outside of a bowl first, then turn the inside to match. I usually turn from the rim in and don't go back. That is turn a 2-3" section to "good enough sand" at a time. The reason for this is that the wood will move as it gets thinner and there's not much you can do about that. Sometimes the amount it moves doesn't matter but even a little can cause chatter and catches that'll have you chasing you're tail.

Both tenon's and recesses work quite well for holding bowls. They don't have to be long or deep, indeed that can be counterproductive especially with tenon's. What does matter is how well the shoulder of the tenon or recess fits against the jaws of the chuck. If the shoulder isn't firmly butted up against the chuck jaw you're pretty much guaranteed to have a bad time. You can prove how this matters but turning a dowel between centers, chuck it and observe how easy it is to pull off center. Now turn a new dowel or flip that one and put a tenon on the end you haven't buggered up making sure the tenon walls are clean and straight and chuck it up while pressing the wall tight against the chuck. You'll find this substantially harder to move.

Doc green describes the work holding issues very well with pictures and photos in three part harmony on his web page, highly recommended as it sure made a lot of this clearer to me.


Indeed I'd recommend a gander through his while site, he explains a lot of things in nice easy to understand ways that saved me a lot of hassle.

You'll note that the scraper Vaughn suggested is curved. There's a temptation to use a flat scraper to make a flat inside surface. While that can be done it often ends up like your situation. The problem is that the corners will almost always find a place to catch and dig in unless you use it just very precisely so with exactly the right tool angle. The curved end scraper is much more forgiving (not that it's impossible to mess that up, I've certainly found a number of ways hah). Note I'm not saying it can't be done, just that it requires and abundance of skill and technique which most of us lack, and all of us lack initially.

Rule #5 is pretty good advice even off of the lathe!!
 

Ryan Mooney

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I'd like to note that understanding how tenon's work for turning was super relevatory for all woodworking. Basically all anti wracking strength in a mortis and tenon (or dovetail, or sliding dovetail or rebate or...) joint is derived from the shoulders and how they interface with the part their meeting. The direct pull out strength is more from the internal structure of the joint. This feature is very clearly demonstrated when chucking lathe work up because almost all of the forces are lateral so the effect when you get it wrong can become immediately and obviously clear. But the less obvious implications for other types of work are just as profound. Completely changed how I thought of joinery.
 

Dave Hoskins

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Yep. You are definitely learning some of the hazards of turning. I generally try and follow the rule that if it doesn't feel right, follow your instincts and don't stick your face or fingers in there. Turn the lathe off. Check your thickness or whatever with it off. The thickness will be the same whether it is off or on. I prefer to wear out an on/off switch to taking body parts off.
 
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Well, to tell the truth, I do know better. I just need to do a little better job of practicing what I preach. I'll check and re-check the chamber on a firearm to make double sure it is unloaded, and with the action open, hand it to someone else, but for some odd reason I will reach out with my bare hand and feel of an object making 3500 RPMs to see how thick it is...

Alan
 

Chuck Ellis

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Rule #4: A face shield does more than simply keep the shavings and chips out of your face and shirt.

I had move around to the other side of the lathe to work the inside of the bowl wall and I was doing quite well until the bowl simply disappeared... I saw something skittering away out the door of the shop and heard something else clattering around behind me. I had hit a crack and physics took over. Judging from the rate of disappearance, the face shield would have paid for itself 100X over had my head been a few more inches to the right. I found one half under the boat about 20 feet away and the other half wedged behind some shelving behind me.


I will attest to the value of a face shield... posted this picture a while back... one second of in attention and whamo....
Day 3 - 2.jpg I was sanding the bottom of a bowl when I felt a slight bump, using a scraper to take the bump out, a slight catch and the bowl flew out of the cole jaws and bounced off my face... I'm faster at ducking now, but I duck with a face shield on.
 

Vaughn McMillan

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Well, to tell the truth, I do know better. I just need to do a little better job of practicing what I preach. I'll check and re-check the chamber on a firearm to make double sure it is unloaded, and with the action open, hand it to someone else, but for some odd reason I will reach out with my bare hand and feel of an object making 3500 RPMs to see how thick it is...

Alan
I'm with you on checking and re-checking the chamber of a firearm, and always handing it to someone open. (Occasional exceptions when I'm coaching someone on the firing line.) That's something that was ingrained in me since I was a kid.

That said, 3500 rpm for a bowl is WAY faster than I feel comfortable with. On a large and well-balanced bowl, I seldom get above 1000 rpm, and maybe up to 1500 or a bit higher on smaller ones. Speeds in the 3500 rpm range are more suitable for small-diameter spindle work. Here's a pretty good discussion of the subject:


And here's a great calculator for figuring out the surface speed of a turning objects compared to the rpm of the machine:


Using that calculator and then converting feet per minute to miles per hour, you can see that the outside edge of a 6" bowl spinning at 3500 rpm is traveling at about 62 mph. That's gonna leave a mark if it breaks off and hits you. ;)
 
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I just pulled a number out of the air. I think it's how fast a bench grinder turns. 3500 rpm or 1000 rpm is still too fast to be sticking my fingers in. I need to get a belt that goes from the smallest pulley on the motor to the largest pulley on the lathe. The one I have now will stretch to fit but I'm afraid of putting uneven pressure on the motor bearings. I don't know what the pulley sizes are offhand but I'll measure tomorrow.

The bowl that broke would have left a mark.

Alan
 

Ryan Mooney

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Actually doing the "how fast is outside of the piece moving when the thing is turning" was kind of enlightening past the obvious safety and tool management issues.

It really put into perspective why you have to sharpen lathe tools so dang often! I can't remember the specifics but a pretty short amount of time doing a not to big of spindle turning was literally MILES of tool->wood application. Once I thought of it like that and figured out (again very roughly and with a lot of margin of error) how many linear feet of wood you might put say a hand plane to before needing to resharpen it I was pretty much at the "holy smokes" response.

I dunno, mostly useless trivia but still I find things like that kind of amusing.
 
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