[Solved] Making a steel coupling of 2 different thread types. What size rod would I use?

[Iron Filing]

Hello,
I find myself in need of making a coupling. From (11.1125mm) 7/16 20TPI to (0.39370079in) M10x1.0.
I'm curious, what size steel rod would I use? It's unclear to me what thickness of material would be sufficient for my application.

And what is my application? A soldering station arm holder device. My problem is that the plastic arms broke after a few years. And I'm only using it as a hobbyist!!! I decided to replace them with metal arms, but the thread is incorrect.

Thanks!

PS: Feel free to tell me how to calculate this. I'm happy to learn.

 

[ddillman]

1/2 to 9/16 I think would be sufficient.

 

[VicHobbyGuy]

Is this a male-female coupler/adapter you are considering? Do you have to make 6 of them? If you are replacing everything above the base, it might be faster to make a new base by threading some holes in an iron dumbbell weight or similar?

 

[Iron Filing]

Is this a male-female coupler/adapter you are considering?

I was planning on making it a F/F coupling and use a M/M 7/16 threaded rod. I do not have a lathe, though I am saving up for a mini, and so I cannot turn down any stock at this time.

Do you have to make 6 of them?

Yes.

If you are replacing everything above the base, it might be faster to make a new base by threading some holes in an iron dumbbell weight or similar?

I'll grant you that I could do that. I just don't have much in the way of (spare) metal laying around here. I think I'll create a thread on this. I could use some.

 

[VicHobbyGuy]

If you don't have a lathe, it will be more difficult to drill a hole in the center of the workpiece, so probably use a bigger diameter piece of metal. If it were my project, I would be inclined to do a 'quick and dirty' job - roughly re-tap the base and then epoxy in the new arms. But adapters or a fresh base would be a better solution, for sure. BTW, iron exercise weights are pretty common here on the used sites like Craigslist or in thrift stores. Not prime machining material, but they work as good heavy bases.

 

[RJSakowski]

A 7/16" nut is either 5/8" or 11/16" across the flats. Your application is very light duty so you can go with thinner walls but 9/16" will give you 1/16" walls and 1/2" will give you 1/32" walls. Thin walls are possible with single point threading although my preference is to turn down the o.d. after threading to prevent any breakout of the wall. It would be difficult to thread with a tap without collapsing the tube. Unless esthetics are an issue, I would go with thicker walls.

 

[Iron Filing]

Thin walls are possible with single point threading although my preference is to turn down the o.d. after threading to prevent any breakout of the wall.

What do you mean exactly by "breakout of the wall"?

 

[Iron Filing]

Thanks everyone. I consider this question answered.

 

[RJSakowski]

What do you mean exactly by "breakout of the wall"?

When the wall is thin, the cutting force of a tap will sometimes bulge the wall out, leaving an impression of the threads. By leaving the wall thicker, and turning to final o.d. after threading, you can prevent this.