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Stripped hole in old Mantua boiler -- what to do?

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  • Member since
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Sunday, May 8, 2022 2:31 PM

This is from HOSeeker



It’s hard to determine where the screw would terminate in that drawing.

You obviously have the locomotive opened up, can you tell where the threads would be.


Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
Turned 84 last July, aging is definitely not for wimps.

  • Member since
    November 2005
  • From: Phoenix, AZ
  • 693 posts
Posted by woodone on Sunday, May 8, 2022 2:23 PM

Well the only threads that mater on the screw is where it is tappreed.

This was a self tapping screw(gessing here a bit) and when you try to screw it back into the boiler it just will not catch a thread. You might get lucky just by using a new machine screw without the tapper.

I would remove the front boiler (smoke box cover) and look inside.

insert a new screw into the boiler then thread a brass nut onto the screw and tighten it a bit, then solder the nut into place inside the boiler.

 

 

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Sunday, May 8, 2022 1:56 PM

I would go with filling the hole with epoxy and retapping it.  You might try getting a slightly larger screw and trying it to see if it will actually fit all the was through.

It takes an iron man to play with a toy iron horse. 

  • Member since
    February 2021
  • 1,110 posts
Stripped hole in old Mantua boiler -- what to do?
Posted by crossthedog on Sunday, May 8, 2022 1:37 PM

Hi all,

An old Mantua 2-6-2, recently acquired, needed cleaning and lube, so I followed instructions to remove the long 2-56 screw holding the chassis to the boiler. It was tight enough before, but now when I go to replace it the threads don't grab. The screw goes through the chassis and all the way into the boiler down to the head, and won't grab on anything.

The guy at the hardware didn't have a 2-56 that long, but he studied the screw carefully and noted that the threads seemed to be in fine condition, which might indicate that the problem is that the hole threads are stripped. Maybe the screw was holding on by just a thread or two, which eroded or broke when I removed the screw. This sounded plausible since I imagine the screw threads are probably harder than the cast metal (what Ed or Mel or someone here called "pot metal")

It looks like my options are either filling the hole with some epoxy and then tapping a new hole, or tapping the hole for a larger screw. I'd be interested in hearing what you would do. I could also get a new screw and just see if it grabs better, and maybe that would be the first thing to try. Thoughts?

As a final note, the only time the screw is actually doing any work is when you pick the engine up off the track, or out of its box. While running, the boiler sits on the chassis by its own weight.

Thanks,

-Matt   

 

 

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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