View Full Version : Fitting new screws

Robin Hewitt
15-02-2009, 08:34 PM
Time has come to fit new X and Y screws to my poor old mill to try and coax another few thousand hours out of it. First attempt was done without the benefit of CNC and hindsight. Hoping to make it better and prettier this time around.

First I want to hold the screws using angular contact bearings and Belleville washers. I'll stretch the X axis, but the Y can only be supported at one end. I seem to remember 500 lbf tension is about right, round about a quarter ton.

I'm going to get the screws cut to length with the ends turned down, threaded and flat spotted to fit my design.

Having trouble finding 12mmx1.00 nuts to go on the ends. Need the pukka high tensile kind usually found on ball screw ends. Marchant Dice used to sell them on fleabay but not any more. Someone must sell them. I need dimensions for something I can get before I finalise the screw dimensions.

Last time I mounted the ballnuts using aluminium, but I think that was a mistake. You can't go wild tightening a bolt into aluminium if you don't have the depth. If they aren't tight they flex under load. I'm using 1" steel plate this time, see if that can take it.

Actually remembered to fit a mount for the cable gland on the X axis stepper this time so the plastic trunking should look ultra ship shape.