Steam and valve chest studs

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Steam and valve chest studs

Post  atomenter on Wed 15 Feb 2017, 8:14 pm

Hi all
Over the 5 years steaming of my Foden I have had 5 of the 5mm studs securing the steanm and valve chest covers shear off for no apparent reason.  This happens not when being tightened or removed but during steaming.  The latest one happened when removing a valve chest cover after an air test.  One stud was virtually sheared through.  Unfortunately it has sheared about 3 mm down inside the hole in the casting and it is proving a bitch to remove, it is managing to defeat all attempts at drilling and even blunts diamond burrs in a Dremel.  It is too deep to get a small chisel on it to drive it out.
Two questions:
1. Has anybody els had this problem and
2. Any suggestions as to how to remove it!!

I don't know if any of the other engines, Burrels etc use the same type of stud.  It is actually a hex socket grub screw type.

Regards

Tom
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Re: Steam and valve chest studs

Post  lynnr on Wed 15 Feb 2017, 8:31 pm

Left hand cobalt or Tungston carbide drill and oil. Only needs to bite in a bit and should screw out the broken bit.


P.S. The dremel is way too fast. Battery or if you can borrow one and can mount it  a mag drill
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Re: Steam and valve chest studs

Post  LiveSteam on Wed 15 Feb 2017, 10:23 pm

One other tip is warm up the casting in the area where the bolts stuck, not that I've had it happen on a steam item but on other items where I've had stuff sheer off it definately helps.

The issue when drilling cold is you tend to warm the sheered bolt up fairly quickly which expands in its thread and makes it harder to get out, warming the casting up helps to alleviate the problem.

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Re: Steam and valve chest studs

Post  lynnr on Fri 17 Feb 2017, 8:43 am

Nice short video showing the method. 

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Steam and valve chest studs

Post  atomenter on Fri 17 Feb 2017, 10:16 am

Hi Lynn
Thanks for the advice and the video.  I Have ordered cobalt drill bits so I will see how that goes, it would be a lot easier doing it on the bench rather than on the side of the valve chest!!
How's the wrists??
Regards
Tom
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Re: Steam and valve chest studs

Post  lynnr on Fri 17 Feb 2017, 7:45 pm

Very sore and all bandaged up as had surgery yesterday.  So a bit lame at the moment.
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