We've just had an interesting discussion about methods of starting and holding bowls; between centers, on pin chucks, screw chucks, etc. For those thin of wallet or cheap of skate, I offer two suggestions that work for me.
1, On open form bowls keep the tail center while hollowing and leave the retained core post quite fat. On almost reaching the bottom of the bowl cut off the post. I use a slitting saw on a flexible shaft, but a boring bar with an inserted bit ground to cut toward center might be a good cutoff tool. By leaving a fat post you hollow quicker and save a blank for making an ornament, chain pull etc. Not a bowl saver but maybe an ornament saver, and much more affordable. :)
- To stabilize a moderatedly long hollowing tool try inserting the tool thru the horizontal arms of a iron pipe 'T' fitting. A nipple screwed about half way of the threads of the vertical arm of the T is a tool post to fit your banjo. This allows the T to swivel and is adjustable up/down. To further restrain a boring bar, nipples and/or reducing bushings can be added to the T. The t is softer than the boring bar and need not be machined. My N3K's banjo hole for the post is too large for a 1/2" nipple and too small for 3/4" so I did have to do a little machining) :( Again, this may not be a real hollowing system, but might help until...
Now my question: Is the temperature adequate to bend a hss bit below that which destroys the temper. IOW, can I bend hss bits without having to harden and temper? TIA, Arch
Fortiter,