what is the best way to bend tube without kinking it?
i use up to 4mm and have a cheap s@@tty clark bender which seems to kink the thinner wall stuff.
i know its not the best bender but its all i have available any help will be good thanks chris
If the formers are too big for the tube that your trying to bend; kinking is almost inevitable.
What diameter tube are you trying to bend? You've mentioned 4mm is that the wall thickness?
I pretty sure some people have tried filling the tube with sand prior to bending - this prevents the tube from collapsing as the former rolls round although presents the problem of how to keep the sand in the tube...
You're probably using pipe formers to bend tube. The dimensions don't match accurately enough to prevent kinking. You need to use the correct former for each material.
Clarke / machine mart benders only come with pipe formers.
Packing with sand is a pain if you do it well enough to make any difference. It takes quite a while and unless done thoroughly won't have the desired effect.
Do you have facilities to machine your own former?
Filling a tube with sand to make a bend, does not work. Heres why, sand is granular in shape. Between the grains of sand is air space. The bending action will compress the sand grains, fracture them and fill the voids.
You can use moulten lead, but lead shrinks when it cools.
You can also use melted Rosin (the stuff, fiddlers use on thier Bows). It will crack and make noise, but it works.
Living about 45 deg. N. Lat.- 90 deg. W. Long. I can use water and let it freeze. Frozen water has about 7% expansion rate so it will push out at all sides and keep the throat from collapsing. Been there, done that.