Tolerance problems with Turcite TA

[Alan0Bond0MPC]

Hello!

I am having a problem with keeping tolerances on this ACME I.D. thread. We are using Turcite TA. Has anybody else used Turcite, or heard of any similar problems with it?

Thank you

 

[SincoTC]

I've never had any real problems machining Turcite and we use a lot of 1/4" x 16 TPI Acme Thread leadscrews that we buy in fitted with Turcite anti-backlash nuts. How are you cutting the thread? If it's being tapped, then I think you will definately have to use a set of progressive taps to prevent poor finish end sizing.

Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

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[Alan0Bond0MPC]

Yes the thread is being tapped. The thread is fine in the machine but once it settles down overnight, the size changes. Then in the morning the go thread gage will not go. We are yielding about 70%.

 

[patprimmer]

The tap needs to be very sharp and the hole that is being tapped needs to be the correct size.

The material will yield under the load from a blunt tool or to small a hole and will recover to leave a tight thread.

Also if it is warm when tapped and cold when measured that could contribute. Acetal ha about 10 times the co-efficient of thermal expansion as steel.

Regards

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