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(Q) How to modify a roughing gouge to cut bowl interiors, Sorby Hollowmaster and Tool Rests

Greg, since you will be limited to cutting over the bed, you might be interested in the information at:

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put yourself in the throw zone. You can cut as well if not betterfrom outside.

Then, to review

Take leverage, don't give it. Keep the toolrest close. Tools don't break unless you're careless.

Energy still equals mass times velocity squared, so keep your speed low. A good edge doesn't care how fast it's pushed - or pushed against.

A - Anchor the tool on the rest. If you have your off hand over the tool, you'll never pinch a finger, no matter which toolrest you use, and you'll avoid bounces that can steal your leverage.

B - Bevel on the work, heel first. When roughing the outside of a bowl, place it center bottom - the point of least kinetic energy - to start. Work out as you establish an uninterrupted surface to reference the bevel. Don't RIDE the bevel, GUIDE the bevel.

C - Cut the wood as it wishes to be cut - across the fibers. Rotate the tool to obtain as continuous a shaving as possible. You want to sever the shaving as the edge exits. This is much easier to do with broader gouges, though people who grind back the edge of their bowl gouges can get close to the same by dropping the handle severely and cutting on the edge. They give away a good anchor, however, which often leads to a catch, and lose one intrinsic safety feature of a flatter fingernail-ground gouge, which curves away from the cut in two dimensions instead of one.

Your shav>

Reply to
George
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Actually, the injury potential would be related to the speed of the lathe, the weight of the broken piece, and it's distance from the centerline. ;-)

I understand what you are saying, however my point was that due to the smaller diameter of things you can FIT over the bed, the risk is reduced. The kinetic energy contained in a broken bowl edge, for instance, is far less for a smaller diameter than a larger one. I didn't mean to imply that there was NO danger, only that turning a 5" vessel at 500RPM is far less dangerous than a 12" bowl at 1000RPM.

I ran a piece at higher speeds just to see what it was like. I didn't even put a tool to it. It was just too fast for comfort. I cannot imagine why you would use anything other than the two bottom speeds on the Jet - at least for things over 1" in diameter. Having also worked in the mechanical/automotive world, I have a great respect for things that spin at high RPM - and what can happen when things go awry.

I used to build 10,000 RPM Rotary engines as well as more conventional automotive engines. A flywheel disintegrating at even 4000 RPM is a frightening and possibly deadly experience.

Now don't go and say that... I have a shop full of scary sharp motorized tools, and occasionally someone posts a picture of some bloody, severed appendage. It gives me the willys everytime I look at that WoodWorker II sticking out of the tablesaw spinning at 4000 RPM.

Stories of carbides tips flying off blades and oak boards sticking out of concrete block walls. Gee - maybe I should go back to collecting Lepidoptera and assembling 1000 pc. puzzles. :-\

But I try to be careful, and never work when tired. I've been fortunate to have avoided major injury in my life, and have done more personal damage with a freshly sharpened chisel than anything else. Here's to keeping it that way!

I hear you!

Thanks, Oh Slippery One!

Greg G.

Reply to
Greg G.

I try, but when roughing or trueing/shaping the outside of a blank, difficult to do. Much easier to accomplish when working the inside.

Haven't broken anything *yet*. I don't force the tools, and do keep the rest as close as possible.

I'm still trying to figure out what the 3900 RPM speed is for. I'll probably never use anything but the lowest two speeds. I wish they had included a couple of even lower speeds! Maybe 100 and 250. Roughing a bark covered, uneven blank at even 500 is pushing it, in my opinion. I try to clean up a lot of it on the bandsaw, but it's still unnerving to have an 8", unbalanced piece spinning at 500RPM.

Done - I value my fingers and eyes more than any other body parts. It's how a make a living...

I have been using the bevel to limit the amount of penetration into the cut. Although when I began, I used the bevel heel first method, I soon learned that I could approach the piece directly with the proper angle. Of course this changes with different tools and everytime you move the rest - forcing you have to adapt, but I think I'm getting the hang of it.

This is a technique I am still working on. And I still need better, more appropriate tools before continuing with other box and bowl projects.

This is quite true, as I've gradually noticed

Thanks Again, George!

Greg G.

Reply to
Greg G.

I've seen some people in this thread dancing around the issue but no one I've read has come right out and said it:

Under NO circumstances should you use a roughing gouge against end grain, as in bowl turning. Roughing gouges are designed for one thing and one thing only - spindle turning. Some did mention they'd a friend who had snapped a roughing gouge off at the tang using it against end grain - that is exactly the danger.

Roughing gouges have relatively small diameter tangs in relation the diameter of the cutting end. In spindle turning only a small part of the gouge is actually cutting at any one time, and that is at right angles (more or less) to the grain, so there is little chance of it grabbing. The nice thing about all that edge on a roughing gouge is that when the bit of the bevel you are using gets a little dull, you can rotate it and use a different part of the bevel without having to stop to sharpen.

If follows that there is no justification for modifying the profile of a roughing gouge.

Reply to
John Weeks

SNIP .......... I stay clear of the "throw

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This line of thought can get you a quick trip to the hospital!! The Mini/Midi lathes have a smaller capacity than some of the larger lathes, but the danger comes more from the speed than the overall size of the work piece. The Minis (most) have a minimum speed above 500 RPM. this can cause some serious problems if you have an unbalanced or off center piece mounted. At a minimum 500 RPM, a 10 inch long by 8 inch diameter hardwood log can become a deadly missle in the event of a catastropic catch or separation ot the piece due to internal faults. The tool can act as a lever to "throw" the piece out of the centers and into suborbital flight. There are many in this group who can tell you of damaged shop ceilings and or roofs from flying work pieces small enough to be worked on "mini" sized lathes. Don't equate small size with safety. Don't under estimate the energy (damage capabilities) of a smaller piece of wood at high speeds.

Ken Moon Webberville, TX

Reply to
Ken Moon

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