A COC muses about armbraces

"Arch" wrote: (clip) I suppose that a catch basically drives the bit down and the handle up, but If the brace moves laterally holding a captured forearm is flesh or steel the winner? (clip) ^^^^^^^^^^^^^^ I have never heard of a broken arm from this, but I have heard of catches that produced scary arm-twisting. This may sound silly, but how about putting in a shear-pin to limit the severity of the arm-jolt?

Consider one of those auxiliary antirotation toolrest types of handles - Jamison tool - or one of those swiveling V block rests to get you a broad support rather than a narrow fulcrum.

====>Arch! All ya gotta do the figure the breaking moment of your forearm or the amount of force required to put your shoulder out of joint. Then dial in just a bit less than that in a torque wrench and weld that into your Goldbergian arm brace!

As to folks not wanting to join the COC? Since when did "wanting" have anything to do with it? COCs are to the manor born and are appointed and in certain cases elected. I'll start the ball rolling, I nominate you for an additional term! I would rather have you appointed COC-for-life, but there may be others who are better qualified! As to a newbie COC, might I, with some tremulousness, nominate George. I detect the fine quality of COCishness from some of his posts!*G*

Leif

Arch, there is a certain amount of danger in using the arm brace in a deep piece. I have a Stewart tool with a lot of mileage on it. The standard "hooker" is 14 inches. Dennis also sells one that's 21 inches, and I have one. If you get a catch when you're working 16 inches or more off the tool rest it can be a dandy. Very arm-wrenching! I speak from experience.

Perhaps a captive tool such as the Jamieson is the answer for some people. There are other makes on the market. I have one made by John Nichols. I feel a lot more secure when working inside a deep piece with that than with the Stewart.

Wally

Arch, I imagine you remember starting a car with a hand crank. I've started a car with a hand crank and started an airplane by hand spinning the prop. In both instances I figured I could fracture an arm, or worse, if my attention wandered for an instant. Starting the car or plane was not optional. When I look at the arm brace tool holder, I see something waiting to eat my arm. And it's optional.

Just my tuppence ha'penny.

Arch,

Hollow tool control is all about two things:

1 - Leverage over the tool that is suspended over the tool rest. 2 - Control of rotation forces due to off-center cutting tips.

I have always heard and subscribe to the rule that for every inch of tool hanging over the rest, you need five inches behind it. As Wally mentioned, the Stewart 21" tool is dangerous because you can end up with almost a 1 to 1 ratio. In the scheme of things, its the cup at the end of the armbrace that gives you the extra 10" or so of leverage. Without a good cup, you have given away what little leverage you have. If you are afraid of injury, scrap the armbrace idea and use a long handle where you can grip it way back.

The armbrace does seem to give better than average control of the rotational forces as compared to other noncaptured systems. I personally have two armbraces and they get used on my largest hollows. But my favorite hollowing tool is a captured system that removes the human leverage and torque problem all together. It allows me to focus on tip control which is what the turning is all about anyway. My system is good for medium size vessels.

If I may make an unofficial COC statement: why are turners so willing to drop five grand on a Oneway or a Stubby, but so easily screw around for hours with plumbing parts to save $50? Arch, Buy the d-mn armbrace, get in the shop and turn! :-)

Joe FLeming - San Diego

Joe It takes me about 15 minutes to make an arm brace and two hours to drive to and back from the nearest store that sells one. Make the darn thing and get on with turning I say. Besides, making tools is fun.

Arch I like the cup on the arm of each of my arm braces. I also like having a 90 degree turn to the handle instead of using a pair of 45's but to each his own. That is part of the fun of "roll your own" tools.

Thanks to each for your good responses..

Leo, seems like a practical solution to me. Certainly no more silly than the first vacuum chuck. I fear shear pins more than armrests because I've been caught up the creek too many times without a paddle ...or a shear pin for my outboard motor.

George, I did try adding a T coupling and short nipples to make a wing to slide on the tool rest, but the contraption was too bulky even for me. What me weld a nice neat wing to a shaft or heaven forbid, buy one? Anyway, neatness isn't the same as craftsmanship.

Leif, I thought about your torque wrench, good idea. I am trying to figure how tight to screw the shaft to the handle so it will slip just before my ulna breaks. Maybe a loose setscrew for a turner wih a screw loose. Do you have a formula?

Wally, Stewart and Nichols indeed! We have come a long way since those

1/4 hp sleeve bearings Sears Roebuck Dunlaps.

Lobby, Yeah and those happy days when self starters arrived and we don't mean aggressive yuppies. Slainte.

Joe, Your usual good summation, but you won't make COC at this rate. Saving fifty bucks by spending hours is a compliment. More to the point is my saving fifty cents by wasting days. As with turning a nice bowl, there is a pleasure in making and using a good tool.

Darrell, I thought the 45s made the tool look sporty & streamlined. :) I did use 90deg for a pistol grip, I also inserted a T fitting and 4in nipple for a 90deg up-handle.

Turn to Safety, Arch Fortiter

Just do like I do and don't get catches!

Well, Arch was promoted to COC first class some time back, so I guess we outta maintain his good standing.

Hmmm. OK, as long as I don't have to always agree with him. Hrmph. Whatcha say Arch, we gonna vote him in? Lyn gets a vote too of course, if he's got the radar on...

...Kevin

Chief, if Lyn doesn't jump in and veto the nomination, I'll propose George if he will use restraint with his "feel good" essays about his doings down home in 'uppa u s' that we all can relate to and enjoy. Bah!

Robert, Leif & Lobby can also get a little crotchety from time to time. Hate for them to wait another year to be inducted, but may be too many rookies at once, tho as someone said "dilution is the solution to pollution! COC, 1st class

Turn to Safety, Arch Fortiter

I do try to restrain myself here. Really.

Ya THINK??!! (Better be careful or I'll wind up getting nominated my own self.)

I use armbraces extensively, many hollow forms per week. When I see discussions like this I am reminded that they are possibly the most misunderstood tool in the woodturning universe. You *CANNOT* reach far over the toolrest with those things. With the standard Stewart setup, 8" deep is about maximum for my comfort level, and I'm good at it. I have a

15" extension that I add which gives me around 33" in front of the handle, and with all that I figure 12" deep is pushing the limits. When I saw Clay Foster demonstrate a 30" deep hollow form, he had a bar about 10 feet long that was HEAVY. It gives you an idea of what is really needed to counterbalance the forces working against you. Use the Stewart tool within it's limits and it's a wonderful tool. Try to do something you shouldn't, and you get in trouble.

Kevin's remark about just don't get a catch is not merely a wisecrack, despite his well deserved reputation for wisecracks, it's for real. Scraper tip hollowing tools realistically should absolutely never get catches. All you have to do is keep the tip above center. Then the rotation of the piece is trying to force the tool away from the wood, not into the wood which is where catches come from and what can happen when the tip is below center. This assumes you have drilled a center hole, make your cuts from the center outward, and don't jam the tip into the end grain. When sweeping across the bottom, you have to keep the tip below center, of course.

Arch, post a picture of your plumber brace when you get a working model you like, I'd love to see it. best wishes,

-mike paulson, fort collins, co