What type of thread is this in a leg for a variable height desk

[Qmavam]

My son was given the frame for a variable height desk because one side had a problem. It turns out a nylon part with internal and external thead broke into two pieces.
He has made a model in sketchup (?) and is going to 3D print it. But, is now trying to get the threads even though he expects to cut those with a tap, he is trying figure out what they are. It is most likely made in China, but it looks like 10 threads per inch. that about all I know. I have attached picture to see if anyone can glean info.
Thanks, Mikek

 

[MrWhoopee]

Looks like a double-lead Acme.

 

[Qmavam]

>Looks like a double-lead Acme.
I'm not knowledgeable about threads but does double-lead have something to do with the angle of the thread perpendicular
to the rod length? I thought the angle of the thread was a little odd. ( a high angle, to my eye)
Thanks, Mikek

 

[Winegrower]

Looks like a double-lead Acme.

does double-lead have something to do with the angle of the thread perpendicular
to the rod length? I thought the angle of the thread was a little odd. ( a high angle, to my eye)

Agree on all counts. Common threads have a single spiral thread wrapping around the shaft, and double-lead threads have two spirals twisting around the shaft. So yes each thread spreads out and so the angle is larger, higher, you might say.

 

[Provincial]

If you measure 0.100 between successive thread peaks, a single lead would be 10 threads per inch. If it was a double lead thread, there would be two leads, starting 180 degrees apart, and each thread would be twice as "fast", meaning 5 threads per inch.

Double lead is a way to get rapid movement while having each thread be "finer" and leaving more material in the central part of the screw.

The photo looks like an Acme with rounded peaks. It may be special for plastic, in order to reduce the "notch" of the sharp corner which could be a starting point for a crack. The failure of the original nut makes sense.

 

[brino]

Two ways to determine if it's double-lead:

1) Have a good look at the end of the shaft, do you see two "entries" to the thread?

2) put a tool (screwdriver, thumbnail) into a root and turn the shaft around, does it track in every groove(single start) or every other groove (double start)

Brian

EDIT: an inexpensive thread gauge will help with identifying the pitch.

 

[682bear]

It looks like a double-lead to me... that's common in furniture and appliance levelers... you get more travel adjustment with fewer turns of the leveler.

-Bear

 

[MrWhoopee]

Most likely a metric thread, so something like 10mm OD x 5mm pitch (10mm lead) double lead Acme. Unlikely to find a tap for less than the new price of the desk. Looks to be a candidate for molding a nut out of Delrin. That or 3D print one, including the thread.

 

[GeneT45]

I concur with @MrWhoopee. It's not 10 TPI, nor does it appear to be anything standard per inch, so probably metric. Helix angle looks like a double-lead to me as well.

GsT

 

[Qmavam]

Thanks guys, I have sent all the info to my son, at work. He took the part with him or I would have
posted a picture of the end and followed the threads with a screwdriver to see if it was double. I'll post
back later this evening.
Mikek