What is the air speed velocity of an unladen Box Elder Bee?

[Ian Parish]

Now I have your attention, I will say that this caught my attention last night. I was learning how to rough out a bowl from a big green box elder tree log we (me and Joshua) got and processed a week or so ago. (I wish I had a good gas chain saw I could get 40 more blanks) Well anyway I was being careful and really learning cuts and technique on the outside with the intent to leave a nice surface and avoid tear out. I wanted to cut this log into a bowl blank for summer drying. I had the outside about right and was confident with my skills to hollow out the center. I got everything set and was making about my third pass at hogging out the center and instantly I was not.

I was able to get my wits about me and re-chuck and re-tennon and then I was able to hollow it out without any more significant surprises. I have a much greater appreciation for you guys that can hog out a bowl blank in minutes I am still at the stage that this took me hours, but they were super fun hours.

I did leave this blank extra thick as I was chasing 2 small crack that I hope will stay put during drying and then I can thin them away.
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[Joshua Dinerstein]

Awesome. Do be careful tho. I cored out the first of my Box Elder log blocks and they are in the DNA bath ready to be finished off without warping, cracking of splitting hopefully.

Joshua

[charlie knighton]

that the thing about wood, things happen, it happened to me on a piece of china berry

[David E Keller]

Glad you're OK, Ian. The only thing that I do differently is to make a flat shoulder for the top of the chuck jaws to rest against... Not sure it would have helped, but I feel more secure with it there. I eventually remove that little step when reversing the piece to finish the bottom.

[Maria Alvarado]

That must have been a heart stopper! Glad you're o.k.

[Scott Crumpton]

I've generally taken to hollowing out bowls with the tail stock in place, leaving a cone in the center. Then I start making cuts down and up the cone until it's thin enough to break or part off. I then finish off the bottom. I figure that the longer I can keep the tail stock in place, the safer the process is. The bigger the blank, the more likely I am to use this technique.

[Steve Schlumpf]

So... did you figure out what you did to cause a launch? It's all part of learning how to turn - just some parts are more exciting than others!

Looking forward to seeing the bowl once finished!

[Jeff Moffett]

Ian, in the first picture it looks like your tenon may have been too long and bottomed out on the body of the chuck. Next time, try making the tenon a little shorter, and like David said, make a flat shoulder that rests on the top of the chuck jaws. That should give your chuck a more stable hold.

[Ken Whitney]

One thing I learned the hard way -- if your tenon is cut on the bark side of the blank make sure you DO NOT leave any significant bark in the tenon. Bark can look like perfectly good sapwood. Bark, it turns out, is relatively, soft.

Ken

[Cody Colston]

I've had that happen quite a bit. ERC is particularly bad about it. On a soft wood, you can try soaking the tenon with thin CA to help strengthen it.

[John Keeton]

Ian, it happens to all of us - and, it will happen to you again!! You didn't ask, but I would suggest you rechuck this roughout and take some off the height - for two reasons. First, it would improve the form, but, more importantly, it would get rid of the pith that appears to still be there. Removing that will decrease your chances of a crack.

[Alan Trout]

Ian,

I agree with some of the others your jaws do not have a flat for the front of the jaw to set on and also the diameter of the tenon is a bit to large to get a good grip. Wit a dove tail jaw the closer you get to the closed diameter of the jaws the better. Just remember you still have to be able to tighten the jaws down.

Alan

[John Hart]

Ok. I calculated the velocity of your box elder, based on a few assumptions. I assumed a 6" diameter bowl and a speed of 1200 RPM.

Based on those assumptions, 2(π)R = 18.84" circumference @ 1200 RPM....giving you a tip velocity of 22,619 inches per minute or 376 inches per second. Travel time to breach the plane of the tool rest is approximately 50 milliseconds. Impact velocity at that point is approximately 21 miles an hour...a little faster than a typical punch by a fist attached to a man who is 6 feet tall. Add the mass of the wood....a few jags here and there, and you got a difficult combination

Increase the bowl diameter to 10 inches, and the velocity is roughly 35 mph...which is faster than a typical Kung Fu kick.

Be careful out there!!

[Trevor Howard]

Ok. I calculated the velocity of your box elder, based on a few assumptions. I assumed a 6" diameter bowl and a speed of 1200 RPM.

Based on those assumptions, 2(π)R = 18.84" circumference @ 1200 RPM....giving you a tip velocity of 22,619 inches per minute or 376 inches per second. Travel time to breach the plane of the tool rest is approximately 50 milliseconds. Impact velocity at that point is approximately 21 miles an hour...a little faster than a typical punch by a fist attached to a man who is 6 feet tall. Add the mass of the wood....a few jags here and there, and you got a difficult combination

Increase the bowl diameter to 10 inches, and the velocity is roughly 35 mph...which is faster than a typical Kung Fu kick.

Be careful out there!!

Some people just have to much time on there hands, and that probably includes me for reading it all. :D

[Ian Parish]

One thing I learned the hard way -- if your tenon is cut on the bark side of the blank make sure you DO NOT leave any significant bark in the tenon. Bark can look like perfectly good sapwood. Bark, it turns out, is relatively, soft.

Ken

I do think I learned (thought about after the fact) a number of things about how and why this happened. I think the first tenon I had as too close to the bark. Part of it was made from the softer wood. I also needed to make a nice square tenon but, I did not flatten off the base of the bowl enough to make flat area for the jaws. When it came off the lathe I was way out of the way and I was turning at a pretty slow speed about 500 rpms. I was also being very aggressive with the first cuts. In hind site I needed to clean the surfaces up and the take better better bevel supported cuts. The next bowl I roughed out next day worked out a lot better.

Thanks,
Ian

[Roger Chandler]

Ok. I calculated the velocity of your box elder, based on a few assumptions. I assumed a 6" diameter bowl and a speed of 1200 RPM.

Based on those assumptions, 2(π)R = 18.84" circumference @ 1200 RPM....giving you a tip velocity of 22,619 inches per minute or 376 inches per second. Travel time to breach the plane of the tool rest is approximately 50 milliseconds. Impact velocity at that point is approximately 21 miles an hour...a little faster than a typical punch by a fist attached to a man who is 6 feet tall. Add the mass of the wood....a few jags here and there, and you got a difficult combination

Increase the bowl diameter to 10 inches, and the velocity is roughly 35 mph...which is faster than a typical Kung Fu kick.

Be careful out there!!


Hart........I think you've been at the lacquer again................

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[Ian Parish]

Ian, it happens to all of us - and, it will happen to you again!! You didn't ask, but I would suggest you rechuck this roughout and take some off the height - for two reasons. First, it would improve the form, but, more importantly, it would get rid of the pith that appears to still be there. Removing that will decrease your chances of a crack.

Thanks for the suggestion. I knew the pith was still in the top of the bowl I was planning to remove it once the bowl is dry. I guess this is a flawed idea, as it may crack and the cracks may go beyond what I had planned for the final bowl. I did leave a lot of extra wood on this blank, the walls are 1 inch thick and the bowl is about 6 x 6. I also think I created a bit of a tin can shaped bowl vs. a basketball shape that may be more desired.

The funny thing is I have read and studied, and watched lots of live demonstrations and videos, without having much actual turning time, once I stand in front of the lathe I have that "umm, What do I do now feeling" But that is ok, I'll get it and making that huge pile of shaving was fun.

Thanks,
Ian

[Chip Sutherland]

I was sure the answer was "Warp 4... Captain"

[Dick Strauss]

A couple of things come to mind other than the other good suggestions already posted.

Don't be in a hurry and enjoy the process...it looks like you were being pretty aggressive with the inside hollowing.

Does your chuck have dovetail jaws on it? If so, it is easy to break off the tenon by too much tightening if the the tenon and jaws don't match pretty closely. The other jaws are a little more forgiving IMO.

It is best to orient the tenon in the jaws so that all of the jaws run about 45 degrees to the grain. This way you get equal grip all the way around even if the tenon shrinks during the turning process, etc. All jaws compress the wood in roughly the same direction and by the same amount.

Take care,
Dick