Screws efficiency

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Hi all, after reading swede really instructive post, I have a question about efficiency.

Now that I know ballscrews can go up to 90% efficiency and ACME around 30% I just wonder how in-efficient is all-thread?

I ask cause I just found out today that my metal supplier has ACME rods. I wanted to replace my 5/16-18 X and Y to 1/2-13 but now bought the 1/2-10 ACME and some thrust bearings. Much more expensive than all-thread and direct coupling tough but I understand why. That'll make much stiffer drives.

Also replaced my 1/2" cold-rolled Y and 5/8 gas pipe X slides to 3/4 cold-rolled on both. I can't wait to see how it goes...

So, as a simple question deserve a simple answer, how more efficient should the lead-screw issue be now as I got from 5/16-18 all-thread to 1/2-10 ACME? Well, just knowing how bad is all-thread is all I need to know...

Para