Some time ago, I realised how much I rely on these two devices for holding anything round while working on it, without damaging, scoring or crushing them.
They were given to me by my father years ago. He made them as an apprentice Fitter & Turner many years before that. Like back in the '40s.
I don't know what they are called, but was just wondering what other people use to hold tubing & rods etc to work on them.
They are simply a piece of 5/16" steel with a series of hole drilled in them and cut down the middle with a fine blade. One is Metric & the other is Imperial.
When held in a vice, the gap closes & holds even soft aluminium or brass tube tightly without crushing or scoring it.
I use them for cutting with hacksaw, dremel tool or ringing tool etc. Also for threading rods, & reaming out tubes. Even holding shaft stubs for grinding the flat spot for the drive dog grub screw.
They would be easy to make, the hardest thing being the saw cut. A fine blade in a band saw would do the trick.
Here's a few pics to show you what I mean.
