Thank you very much for the suggestion. I'll try the highest grade bolts I can get a hold of and report back. I have some 4130 to machine this week so that will put it to the test.
Thank you Bob,
I'll be sure to add a hole in the spindle cartridge to measure temp. I'll probably just use an arduino lying around, they're so easy to program to display multiple temps.
I think I've landed on the final design for the cartridge: two angular contact bearings in the front with two deep groove ball bearings in the back. I'll have to precision grind the spindle to 55mm for the ID of a 7211 bearing. It'll all be an assembly that bolts together and can be serviced outside of the machine if necessary. The headstock will be based around a granite epoxy mix. Thanks for all your help so far, your blog has been invaluable.
Thank you for the suggestions Runner. Could you by chance post a link to that thread? I'm having trouble finding it. I think tapered roller bearings will be difficult to control preload as the temperature of the spindle changes. I'm really shooting for a repeatability of this machine to be between 1-3 tenths so I'll have to be very careful about how I design the spindle. I like the idea of having two preloaded angular contact bearings in the front with support bearings in the back.
So I got most of the linear motion in the other day. Precision ground ball screw for x by Issoku, and linear guides by THK. I still need to order the Z screw, I have a rolled ball screw for the moment but ground is a must to meet the precision. Now I just need to verify all the designs for the motion system before I can start drilling some holes in my plate. I also got a duplex AC bearing set but they're ABEC 1. I want to figure out how to make the spindle cartridge before I spend $300 on a set of nice bearings. Thanks everyone for the help, keep it coming. If you see something I'm doing incorrectly please feel free to post and/or email me directly at [email protected]. Until next time.