Micro lathe Zero backlash* conversion

[John S]

No not tried it, bought a C1 to play with but the little TOS got hungry and ate it.

[JAZZCNC]

Jonathan,

I've been given a Myford Super 7, really don't see why folks get so excited about these things but anyway no prizes for what going to happen to it, much to the relief of my lovely little boxford who was under serious threat. So a few Q's if you don't mind.

Did you get the Screws from Chai.? and was that the lowest pitch he does.? (I know I'm being lazy and could ask him direct but hey oh he can't answer th rest so here ya go.!!)

Where did you get the Bellville washers.?
What strength did you get and how many per screw.
How did you stack them series or parallel IE: )))) or ()()

Nice job by the way, what MAx cutting dia can you do and when do we see the video.????

[Jonathan]

Did you get the Screws from Chai.? and was that the lowest pitch he does.? (I know I'm being lazy and could ask him direct but hey oh he can't answer the rest so here ya go.!!)

As far as I know RM1204 is the smallest pitch (and diameter) he does, although I didn't ask directly. He doesn't state the ballnut dimensions, but they are a lot smaller than RM1605. RM1204: overall length=28mm, diameter=24mm,flange length=6mm, flange diameter=40mm, between flats=25mm.

Where did you get the Bellville washers.?

http://www.leespring.com/

What strength did you get and how many per screw. How did you stack them series or parallel IE: )))) or ()()

For preloading the nuts I got:
http://www.leespring.com/uk_product_...ype=W&subType=

For preloading the bearings I got:
http://www.leespring.com/uk_product_...ype=W&subType=

I chose the springs based on:
Preload force=10-20% of ballscrew static load rating
Belleville washer compressed no more than 75%

I stacked them like () to get greater adjustment whilst maintaining the same spring constant. The Z-ballscrew has two Belleville washers at one end, the other end fixed and one angular contact bearing on each end, so the screw is tensioned. On X the end of the screw is floating, so clearly both washers and bearings at one end.

what MAx cutting dia can you do and when do we see the video.????

About Ø75mm would clear the saddle, so in theory that diameter once I have found external jaws for the chuck. That reminds me I need to get/make an MT1 live centre. In practice clearly the spindle isn't strong enough to be doing that on a regular basis. I'll convert my Colchester Student lathe once this one's finished for much bigger parts.
Video I kinda forgot...just got one rather boring shaky video but I guess I'll upload it anyway.