just received an acme screw and delrin nut.. Question about tightness

[blau_schuh]

The delrin nut seems to turn pretty easily on the screw until maybe 5 threads in, where it becomes pretty hard to crank by hand.

How tight should it be?
Should I be able to crank it by hand without putting much effort?

[widgitmaster]

Is it one that I made?
Is it a rolled ACME thread?

If it is a rolled thread, you need to inspect it with a magnifing glass to see if there are any nicks or dents in the thread! If there are, it is going to chew up the plastic nut in no time at all!

Eric

[blau_schuh]

Is it one that I made?
Is it a rolled ACME thread?

If it is a rolled thread, you need to inspect it with a magnifing glass to see if there are any nicks or dents in the thread! If there are, it is going to chew up the plastic nut in no time at all!

Eric

You made?
Not sure, unless you are selling them on ebay...

Is it a rolled ACME thread?
Yes

I'm inspecting now, so far i dont see any nicks or barbs on the screw... thanks for the advice.

[Madclicker]

Sounds like the threads were messed up by the person that made the screws, or they used inferior stock. No reason for the nuts to bind part way down otherwise.

[Guldberg]

I made a nut out of something similiar to deldrin for a TR16x4mm trapezium screw. Even though the screw is rolled it still chewed up the nut enough to cause exstensive backlash, just by running it back and forth a couple of times. So if you can try doing this with a metal nut first to "clean" the screw. Even with the deldrin nut i cut see tiny chips coming of the screw