PM-728 Conversion to CNC

[koenbro]

I have just reached the same point in my 728 to CNC conversion and was stumped by the Radial Locknut. Thanks for starting this thread. It resolved all the questions I had.

I was able to find the specifications of this particular locknut (YSR-M12x1.75P) here: https://www.yinsh.com/product/more-1-7

The maximum torque is specified as 3.5 Newton meters or 31 in-lb.

How much backlash did you have after all your adjustments?

Do you know what McMaster equivalent this is or where can I buy this locknut?


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[sakumar]

Do you know what McMaster equivalent this is or where can I buy this locknut?

No, I don't. M12x1.75 seems to be an unusual size due to the coarse thread. Even the manufacturer, Yinsh, don't list this exact precision locknut on their web site. You may try their contact page: https://www.yinsh.com/jp/contact/ or inquire with Precision Matthews tech support.

 

[gene_weber]

I corresponded with YINSH, and 31 in-lbs (3.5 N-m) is the setscrew torque, not the locknut torque. See this post.

 

[koenbro]

[...]
I bought this spanner wrench from McMaster Carr https://www.mcmaster.com/6975A12/ The spanner wrench is an excellent tool to spin the axis before you have the stepper motor installed.
[...]

FWIW, I can confirm that https://www.mcmaster.com/6975A12/ is the correct spanner for these locknuts.

As for the locknut, McMaster does not seem to offer a similar one.

 

[gene_weber]

Is anyone interested in buying some YINSH YSR-M12×1.75P ball bearing locknuts? Re-torquing the locknut after you have tightened the setscrews is inaccurate. So I inquired about purchasing a replacement directly from YINSH. The part is $4.75, but if the order is less than $1,500 there is a $68 charge to share the FOB cost. I'm too cheap to pay $72.75 for one locknut. But if the order were for say 10 locknuts, it would drop to $11.55 per locknut. If there is interest I'll coordinate an order.