X1 CNC Conversion thrust bearings

[lensman57]

Hi to everyone,

I have started the conversion of my X1 but I have a question. What is the best way of mounting The thrust bearings on to the standard lead screws? I have already mounted one by boring the stock bearing block just in front of the hand wheel on my taig lathe. I just wonder if there should be another bearing on the other side of the block or is there another way of doing this?

Thanks for all your advice.

Regards,

A.G

 

[Tin Falcon]

depends on the thrust bearing in some cases these are just a plastic ring holing bearing balls an a couple of smooth washers, in this case you just need a thrust collar on one side and a machine casting on the other. the two surfaces do need to be somewhat parallel.
Tin

 

[RonGinger]

Generally you want a thrust bearing to act in each direction of the screw- you want that screw captured so there is no end float. Typically these bearing are pre-loaded so there is a bit of drag but ZERO end float.

This is critical for ballscrews- why invest in a ball screw then have backlash in the end mounting of the screw?

Even with acme screw you must reduce backlash at every possible source. In CNC backlash is you enemy, eliminate it at every point.

 

[lensman57]

Hi Tin,

Thanks for your reply, I eventually got the courage to take off the bearing blocks of the X and Y axis (cast iron I think) and bored them on my Taig lathe to accept two sets of thrust bearings from either end, these are some 16mm OD, 8mm id and 5mm thick which are loose, the ball race is sandwiched between two steel washers with locating grooves they are supposed to be for RC helicopters. I can not detect any significant improvements in smoothness but the back lash has dramatically improved for both axis, about 0.05mm or 2 thou. I have decided to use direct motor coupling hence the use of two sets of thrust bearings rather than the thrust radial bearings which I think would have been required had I chosen to use a toothed pulley and belt arrangement these bearings are not so easy to source here in the UK or at least I have not been able to find them. I hope I have not miscalculated.
For the Z axis I had to take the lead screw off and machine off approximately 10 mm off the threads on my Sieg C1 ( at last something usefull ) to make room for the two sets of the bearings as the Sieg's Z axis "bearing block " does not have much meat on it to bore. The bearings are sitting on the top and bottom of this block. This has had the most dramatic effect on the smoothness and reduction of the back lash on the Z axis. I have not however, measured the back lash yet and I really wonder why Sieg does not fit the bearings as standard as they do make a lot of difference.
Now I have to start thinking about machining the motor mounting blocks for all 3 axis, the X and Y are somewhat straight forward but again the Z axis is different.
Will post once I have got everything sorted out . Hope it all works.
Thanks for the reply again.

 

[HS93]

I did the conversion some time ago and hear are a few pictures it could also be used manually as well and all handles are left on bit I use folding ones from Arc Euro
belts and pulleys are very easy to source in the UK hear are two suppiers.

this is where I normally buy from http://www.hpcgears.com/
or
http://www.technobotsonline.com/pulleys-and-cams/timing-belts/synchroflex-t5x10mm-timing-belts.html

My mill,being tested. I found the thrust bearing made a fantastic difference made them so smooth I also fitted a ball race on each way as well, all machining was done on the X1

[ame]http://www.youtube.com/user/onehs93#p/u/22/vvNn0qE0KJc[/ame]
Peter