WBX broken stud replacement notes

[silverbullet]

I'm building a 2.5 for Aidan, he supplied me with a core a while back and after being bored for the big barrels, it was ultrasonically cleaned.
This revealed a few "pickled" looking studs that I wasnt going to leave and of course, two were not going to budge regardless of heat applied to the case or shocking them with a hammer.
They wrung off, so here's the photo essay for posterity/wiki:
Stud snapped off close to the bottom

Accurate centre drilling
Drill approx 6mm and then slot drill to 9.5mm
Slot drill out to 10mm (no pic) and if it's gone well, pick up the end of the thread and pull/wind it out
Its that easy

How anyone thinks they can do this with a pistol drill is beyond me, I had to regrind the small drill twice and the tools squeal as they cut.
These 12.9 studs are very hard on the end and do not like the final break-through at the bottom of the hole.
Low rpm circa 500 and high cutting pressure is essential.
Bridgeport BRJ milling machine or similar required.

[Stesaw]

Oh that's a fancy way of removing them. I have four to deal with.

[Mr Bean]

I believe this kind of work can also be undertaken by spark erosion but the job of finding the center is still hampered by the uneven thread exposure. 
When one of the selector linear bearing housing zones on my five speed box became worn offset after a failed warranty repair - defo not Adan), It was clear my man was waiting for a scrapper to come in. So I got the damaged housing back off the repairer and using a home made fly cutter, bored out a concentric oversize aperture for a sleeve. The way I centered the cutter for concentricity was to turn up a dummy sleeve with a 6mm bore and manipulated the machine into the correct position referencing the remaining good surface of the original bore. I force fitted the sleeve and locked it in position with an Allen screw and clamp. Well over ten years running and still going strong.
Hopeless job without a mill and lathe though - and a UOL degree in salvage schemes (bodging) is a big help.

[scotttie]

I imagine its very satisfying to peel out the perfect remains of that stud thread! 

[Ciaraneng]

Fantastic work.

[philmcC]

Absolutely brilliant. Spark erosion cost £50 per stud.philmcC

[keynsham1]

If there is any stud showing at all, I have always welded a nut on and got the remaining piece out wit a spanner. The weld can be rubbish, as mine usually are, but it's usually strong enough. Nothing lost if it doesn't work either!!

[tobydog]

Nice work silverbullet.

I know a couple friends that have local toolmaking companies from having worked with them in the past (sadly they're a dying breed).  They often get asked to spark brocken studs/bolts out, they usually drill them out . It's much easier when you have the right gear and have experience....

 

[huggy76]

That is some lovely work silverbullet.

How do you pick up the centre of the broken stud so accurately?

[josephcarey1]

Excellent work!

I have a 2.1DJ casing with some snapped studs. I tried welding bolts, welding nuts, heating and nothing worked.
I paid some guy to spark 1 of then and got charged £100 so in the end bought another case for £200

[what2do]

This is pretty much what I had to do with a casing belonging to Itchyfeet.  Took longer to clamp that it did to machine.  

[silverbullet]

That is some lovely work silverbullet.

How do you pick up the centre of the broken stud so accurately?

I was lucky in that the studs weren't rotten, so with a keen eye and good lighting, just a dot from the centre drill to test, then adjust position accordingly before committing.

Had they been rotten then I would have faced them back and used the machined counterbore in the case to find the centre.

Always bear in mind that the stud core is softer than the (rolled) threads, but being 12.9 they are still very tough.