Stripped burner jet seats

This is an idle idea, but to have good ideas you have to have lots of ideas (attrib. Linus Pauling)
If the thread strips out on a jet seat, the 4.5 mm diameter left is the tapping size for M5x0.5. It seems to me a custom nipple with the M5x0.5 thread should be possible to make on a small lathe.
It would side-step the issue of repair nipples and the unobtainable special tap required.
What's wrong with this idea?

Regards

Murray

 

Hi @Murray Access to the jet seat through the maze of vaporiser tubes of the burner.
Best Regards,
Kerophile.

 

Phoebus no 1

 

Certainly true for most roarers except for the type with a screwed plug in the middle, but not a problem for most silent burners, I'd have thought?
Which begs the question - how were the taps sold by Primus meant to work with a roarer burner?

Regards

Murray

 

Hi, Perhaps the tapered thread repair jets cut their own thread?

Source for tapered jet on Campus 4?

 

A thread insert will fix it once, then no custom jet needed next time.

 

Correction: Not self-tapping:

 

Extract from Primus Catalogue showing thread repair taps to cut taper threads.

 

So - a very short tap, maybe meant to be used with the jet removal key?

 

Seems that way....I have difficulty screwing a standard nipple in on some days!

 

I’ve had to resort to silbrazing a nipple in place on really badly damaged burners that I wanted to keep and not replace.

Tony

 

Yes you can make them. But, as you mention, I have only been able to fit them into silent burners, and roarers with a screwed hole in the top.

I find the best way is to make them in 'mirror image' pairs.



Start off with oversize brass rod to minimise bending moments when threading, and after threading mark where the parting cuts are to be made.



Then turn the heads to the finish diameter (5mm), and part off into individual blanks.
File the flats on the heads so they fit in the jet removal tool.

Drill a 1.5mm hole in the bottom of the jets (hand drill)



Use the same drill to countersink the top of the jet, and then carefully drill a 0.3mm hole for the jet



I have part of an old burner (below) with a nipple housing containing a good condition female thread, and I use that to test fit the new nipples before I try to fit them into the burners to be repaired.





You can make a custom tap from an old 5mm drill bit shank (or 5mm steel bar) with the same thread dimensions as the nipples, squaring the none threaded end to fit into a normal tap holder.

If you cut the nipple thread with a 55 degree thread cutter rather than a 60 degree one, you get a slightly deeper depth to the thread, and you can taper the end slightly on the finished nipple for an easier fit.

 

Thanks - that's really helpful. I'll give it a try.

Regards

Murray