best wood and grain orientation for jam chucks?

[Shay Vings]

Although I use my scroll chuck extensively, I have only one set of jaws for it. Also, there are still many situations where I require a wooden jam chuck or cup chuck

Is there a general rule to make them:

1 - from hard wood?
2 - between centres or bowl fashion?

 

[tekno.mage]

Hmm - I make jam chucks from whatever is lying about! Short nasty piece of wood with a chucking spigot already cut on one end? That'll do

As mine are normally for smallish items like boxes they are mostly ends left over from stuff turned between centres. I usually use scraps of ash, sycamore or beech to make them and I re-use them until there is nothing left - cutting a larger one down to fit a smaller job until there's not enough left of it to be useful.

For larger pieces I'd make them from cross-grain pieces of wood - the last one like that I made was from beech and it's still around and gets re-used occasionally.

I wouldn't use really hard exotic scraps for making jam chucks - but that's mainly because I keep such bits for making inserts into other work. I also wouldn't normally iuse softwood, but that's because I don't have many suitably sized softwood scraps kicking around.

 

[Jonzjob]

This is one of the chucks that I made to turn a scoop. It's end grain pine and clamped in my K8 Axy chuck on a dovetail tenon. The bronze ring is from the wonderful set of Vitctorian pinch chucks I was given by a mate in England.

Mind you if you turn these it really concentrates the mind about where yer fingers are!

As far as jam chucks where the wood you are turning is actually jammed on the ourside of the chuck then it doesn't really matter what wood is used?