Wednesday, April 24, 2013

How to make a TRP (Tension Release Pin)

A while back I was working on a machine that needed a tension release pin.  I can't remember what machine or why it needed a pin.  I think, actually, that the machine had a pin, but I wanted one a little bit longer.

I had some small nails that looked to be just about the right size.  So I got out the  nippers and cut one to size.  It worked quite well.

Recently, a reader emailed me about the tension release pin on a Singer 301.  I promised that I would cut  a TRP to the correct size and send it off in the USPS.  I finally got to it today.

I took the tension assembly out of the Singer 301A long bed that I bought last spring.  I had performed some aluminum rot surgery on it then and  never really finished that job.  I have yet to prime and paint it.  But the surgery was apparently a success.  No evidence of further corrosion.  At least on this spot.  Since the weather is going to be nice this weekend I think that I will finish this job and prime and paint the repairs.  Don't know why I didn't do it in the first place...

TRPs have a darling little nub on one end that prevents the pin from falling out of the tension assembly.  I cannot replicate that nub, so when using a custom made TRP, one must be careful not to let it fall out.

The TRP is 1 1/8 inches long.

The nail is 1 1/2 inches long
I cut off the sharp end and filed it down so that is was smooth.  Then I lined up the two pins next to each other in the  nippers

 And cut it to size.

I stuck the nippers and nail inside a large yogurt container when I cut the nail.  That prevented the nail and cut piece from ricocheting around the shop.  I did not do that when I cut off the sharp point.  Luckily the nail didn't fly far.  Who knows where that little pointed sharp piece is.

I did have to cut the nail again because the first time I didn't get it short enough.  Better that than the other way, eh?  


This pin will fall out of the tension assembly, unfortunately.  I guess one could put a tiny little dollop of JB Weld on one end to prevent that.  Hmmm may have to try that.  

8 comments:

  1. If you use common nails (softest metal) you can take a hammer and place the nail end on some flat thick steel surface (I used the head of a 5 lb pounding maul), you can hammer the the end of the pin (like a blacksmith) to make the stop-flange. It's easy - takes about 30 seconds.

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  2. In reference to my former comment: I would make the stop-flange end first; do a little clipping and sanding (if necessary) and then measure to the flat end before making the final clip to length.

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  3. Awesome, I am going to try that when I get my hands on a pair of nippers. As for replicating the nub, do you have a vise? I'm wondering if you can smush (technical term) the nail head flat, and if that would work well enough to hold the pin in place.

    - Rain

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    1. Another good idea. I think I will try that.

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  4. You guys make me think of my grandma; Use it up, wear it out, make it do, or do with out! Good job! Way to make do with what you've got!!! Good ole brain power!

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  5. Thanks for this tip. I have a monster vise. I'll try pinching one end of the nail to the proper flatness. Regards, Ron

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