Making 6-32 threaded Rod

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Re: Making 6/32 threaded Rod

Post by Rwilliams » Wed Mar 31, 2021 1:32 pm

One could always find the correct diameter metric round stock and change the thread from the more difficult to cut 6-32 to a 6-40 thread. The dies are easy to find and make your own nuts from some hex stock tapping them with a 6-40 tap. The 6-40 threads are easy to cut compared to the 6-32 variety.

With the hex nuts, one could first tap the nuts with a 5-40 tap and then follow with a 6-40 tap to make the task even easier. Usually finer threads look more pleasing in our model building world if accuracy to scale is the desired goal.

One could always just use a 5-40 nut and run a 6-40 tap to enlarge the thread for your needs. Perhaps even find some 6-40 nuts to start with.

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Re: Making 6/32 threaded Rod

Post by Greg_Lewis » Wed Mar 31, 2021 1:38 pm

John Hasler wrote:
Wed Mar 31, 2021 9:56 am
Try looking for 3.5mm rod or wire.

Here 'ya go. McMaster has it in brass:

But I cast one more vote for 5/40 thread on 1/8 rod if possible, particularly if looks are important.

And if appearance is important, you can get what's called "small pattern," or "radio nuts," also from McMaster. And if you decide to go 5-40 and want scale looking nuts, send me a pm. I've got more than I'll ever use and would gladly sent you what you need.
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Re: Making 6/32 threaded Rod

Post by RET » Wed Mar 31, 2021 2:52 pm

Hi Bob,

Each metal tends to have its own characteristics and I don't pretend to be an expert, but most of them will work harden to varying degrees and from your drawing, you really want a sharp bend which increases the likelihood of cracking from work hardening. Since you want 50 parts that have to look the same, it makes sense to make some tooling with a stop so the rod is properly positioned for bending, then a "punch" that makes both bends at the same time but only bending half way (urethane might work for a "die," but that may not be worth playing with unless you were going to make a lot of these).

At that point, anneal the bends with a torch (to red heat), then using a second punch and die setup, complete the bending operation.

Should be interesting.

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Re: Making 6-32 threaded Rod

Post by tetramachine » Fri Apr 02, 2021 11:25 am

I often hear the 5-40 vs 6-32 pitch story, it mostly BS. A 32 pitch thread is double depth .047", a 40 pitch is .037 double depth. A #5 rod is .125" - .037= .088 minor dia. a #6 rod is .138" - .047= .091" minor Dia. .003 is not much, but disproves the story of more strength with a 5-40 size.

I make alot of small bolts in scale type dimensions, 5-40, 6-32, 8-32. often with a 4 chaser die head, sometimes with a die if I don't have that size chaser, or can't chuck it in the lathe. The only time work breaks while threading, is if the chasers hit a large step in the work.

Most hardware stores have zero nuts, bolts washers in #5. I would suggest 6-32 if you are selling these to others, as they may sometime need nuts, and you are not around.
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Re: Making 6-32 threaded Rod

Post by ccvstmr » Fri Apr 02, 2021 1:33 pm

Bob...let me throw some suggestions into the mix here. Think I too would go the 1/8" material route. Here's why...

Couple of years ago, built several old time passenger car trucks with swing centers. Needed to make U-bolts for the swing links. Went with 1/8" silicon bronze rod (can purchase this on Ebay). Copper coated steel wire will also work. Figured out the length needed and added a "small amount" before cutting and beveling the ends.

Threaded the ends 5-40 in the lathe with a floating die holder. Heated the center of the rod. When cooled, bent the rod pieces on a forming block. Used a hollow piece of 1/4" brass rod to grab the end of the rods and "pull" the rods around an 1/8" dowel pin. Made another forming block to squeeze the U bolts in a vise so the rod "legs" were parallel. Excess thread was cut off with a Dremel tool after the trucks were assembled and the swing links adjusted.

Here's some pix...

The threading went quickly with a floating die holder in the lathe tail stock. When it came time to forming the "U"...there were no problems with the rod material cracking. Think all the rods were glass bead blasted afterward to "erase" the heat marks.

Your diagram did not show how far apart the "U" legs were apart. Another option would be a small die holder in a drill...but the threads won't look as nice as what the lathe can produce. If you have a hand tapper...can hold the rods vertically in a vise while you crank the handle...again with a die holder in the spindle. But you're looking at a lot of cranking...up and down.

Suspect you're making U-bolts for stake pockets. In your case, the nuts would be out of sight. You might still consider Nylok nuts or nuts and thread locker. When the above mentioned old time passenger car trucks were built...many times I was drilling/tapping smaller stainless steel square nuts with larger threads. 2-56 nuts were used to make 4-40 nuts and 5-40 nuts. 4-40 square nuts received the same treatment to make 6-32 square nuts and 8-32 nuts. Think 6-32 square nuts were drilled/tapped to make 10-32 square nuts. This way, the square nuts did not appear to out of proportion.

Just goes to show...with a selection of taps and dies...various tools and various can fabricate most any combination you might need for your projects. Hope this helps. Carl B.
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Re: Making 6-32 threaded Rod

Post by Bill Shields » Fri Apr 02, 2021 2:00 pm

Maybe purchase threaded rod and some hollow brass tubing that will slide over it to provide the 'unthreaded' section.
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