Originally Posted by
handlewanker
Hi, I quite agree with your choice...….. if it works out OK it'll be quite neat.
The long job part is one thing you would gain advantage from a 4th and servo drive with a through hole.
I see you are opting for 5C collets...…..one problem with 5C is that it needs to have exact size collets for the material holding and a draw tube too tightened from the end which makes the 4th spindle diam and bearings a bit on the large size.
I think I would go the ER40 collet option....25mm diam material size is handy..... as it has a squeeze down factor of a mm and so can cater for raw material diams a few thou undersize.....I've never found any bar stock in cold rolled to be an exact size.
My personal preference for the 4th I'm building is an 80mm diam 3 jaw chuck with an option for a 125mm 4 jaw chuck too......the main reason is the large through diam.
One problem with those chucks is they are rated at max 4,000 rpm but as I won't be doing any turning for me it won't be a problem.
Ian.