2-56 Heli-coil?

[SAM in LA]

I'm looking for ideas on how to repair :wall: a striped 2-56 internal thread on a piece of brass.

I prefer not to increase the thread size. This is the cylinder head for the Wood Beam Engine that I am currently building.

Thanks for your help.

SAM

 

[rake60]

I have seen courser threads repaired with JB Weld.

We'd jamb the JB Weld into the hole, coat the bolt with light grease
and screw it into the hole. After the JB Weld had set up the bolt would
turn back out.

I don't know if that would work on something as fine as a 2-56.
I would certainly want to try it on a test piece first!

Rick

 

[doc1955]

Here is what we use at work they come in self tapping or not they work good if you have a little room.
http://www.mcmaster.com/#threaded-inserts/=76wfnz

 

[mklotz]

Drill it out oversize, Loctite in a brass rod and retap.

 

[Cedge]

Marv....
Had to do just that on my current project. Stripped a 1-72 thread, re-tapped it to 2/56 and broke the damned tap off flush. Grabbed a piece of carbide to D bit the tap out and wound up with a 1/8 inch hole to fill. Pressed in a bit of brass, filed it contour and then drilled and tapped the 1-72 thread successfully. The repair does not show and saved having to remake a cylinder. I'm with you on this one....

Steve

 

[rake60]

I like Marv's solution better than my own original suggestion.

That was also a common repair method in the machine shops that I have worked for with a
slight exception. The holes were drilled oversize and tapped to receive a piece of threaded
like material. We would apply a little Loctite to the threaded rod, screw it in, mill it flat and
give it another go.

A threaded repair piece is a lot more stable than a straight plug repair.
Then again, we are talking 2-56. It may not be of any real benefit at all.

Rick

 

[Blogwitch]

If anyone is interested in carrying out repairs, stripped threads, worn bits, holes in the wrong place, I rescued a very badly made Stuart V-twin, that refused to run after it was made.

The first couple of pages give you an insight into how I achieved it.

http://madmodder.net/index.php?topic=1370.0

It might give you a few ideas, or even the courage to have a go yourself, rather than scrapping off that bit that has taken you days to make. Unfortunately it won't work with ali, that requires slightly different techniques.


Bogs

 

[4156df]

Rick, Doc, Marv & Bogs,
I hope you realize how valuable this kind of info is to us inexperienced machinists. Thank you for posting.
Dennis

 

[SAM in LA]

Steve, Rick, Doc, Marv & Bogs

Thanks to all who replied. :bow:

Its nice to have several options available to repair a bad thread.

When I titled this "2-56 Helicoil", I did not realize there was one available in this size.

Since I needed to solder another item, I filled the two holes with solder, then drilled and tapped. I was able to drill deeper and get into the parent material. So far it looks like a good repair.

Thanks again.

SAM