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View Full Version : trouble completing parting off small pieces



starr
6th December 2004, 01:59 PM
Can anyone give me some hints to successful completing and parting off of small spindle work held in a chuck on one end only?
I have been trying to turn some small Christmas ornaments in blackwood and when I get to completing the end near the chuck they invariably break off, thus ruining the piece.

Dean
6th December 2004, 03:25 PM
what tool are you using to part them off?

barnsey
6th December 2004, 04:08 PM
G'day starr,

Welcome to the forum. ;)

Dean asks a good question.
I find I try to reduce to a diameter with a parting tool that will still give strength in the material being used then shaping/finishing with a skew chisel.
You need to support the work gently and with practice and a sharp skew you will get it off with no damage at all. :D

If you go to the library you'll find as many different ways of doing it as authors if not more :confused:

Jamie

Kev Y.
6th December 2004, 05:12 PM
Star, could you over come the problem by making a JAM fit chuck?, that way the excess would be parted off easily leaving the finished article to be removed from the chuck.

One of the easiest Jam fit chucks I have seen was made from a piece of PVC pipe. Slots were cut in the pipe to help form 4 "jaws" then the work piece was inserted into the chuck and held in place by a rubber band.

From memory, there was a piece of scrap timber turned to the INSIDE diameter of the PVC and then the pipe was pushed onto this with a section protruding used as a spigot. then this was held in a standard 4 jaw chuck.

macca2
6th December 2004, 11:14 PM
For parting off small pieces I use a very thin parting tool made from a power hacksaw blade. Very gently.

Macca

rsser
7th December 2004, 06:31 AM
One option is to turn it right down with your parting tool - it's surprising how few fibres are needed to still hold the piece, but you don't need to gamble with this method - and then stop the lathe, cut through the stub with a fine saw and sand away the waste by hand.

A better way, and it's not clear whether you're doing this, is to keep turning the stub right away one-handed, while reaching around to very lightly wrap your fingers around the piece with your other hand (barely touching). Then catch it when it's cut free.

Jeff
7th December 2004, 05:25 PM
I like the method rsser uses, it's easy and prevents tearout. When I do ornaments, knobs, etc I try to devise a way I can use a jam chuck. Since it will be production work and the size is uniform, I can make up a little jam chuck out of scrap wood attached to a faceplate. I always drill a hole in a jam chuck in from the side to the center. This hole allows me to use a quick shot of compressed air to pop out the work from behind. That way I can make a good snug fit into the jam chuck and not worry about getting the work out intact. I've made jam chucks for ornaments that have a small centering pin inside that correspond to the small hole at the top where I attach the hardware. I generally set up a jaw chuck, turn several of the pieces with the "top" portion completed, including the hardware mounting hole, then switch to the jam chuck and finish off the "bottom" portion. By doing it this way there is no parting off at all, and much less waste of material. Basically I try to avoid parting cuts. I sometimes use my power miter saw if the project is big enough to take off the lathe and do it that way, or if small I'll use a coping saw. If I do need to part off a piece I almost always use a well sharpened skew at the lowest possible speed. Sometimes the speed I use is hand-rotating the piece! Have FUN.

gatiep
8th December 2004, 02:05 AM
Use a skew as posted above or sharpen your parting tool with a V in the cutting edge, make the one leg of the V longer than the other. Use it with the long leg towards the chuck side. I t will part off leaving a little blob with a very thin stem to the base of your article. Now sand this off. The beauty is that you do not get tear out in the foot of your article. This last method works well for the ppl that are allergic to a skew!

:)