ET: Engine (Twin) Extracting Stud ET109/13

[RedRyder]

Howdy pals. I noticed on a ride last week that the subject stud and it’s nut had gone missing. This is the one at point A, which is anchor for the security tab ET168 that secures top of magneto cowl on my Rapide. I safety-wired the tab to the gear oil filler cap and motored on, no problem.

Upon getting home I see the stud is broken off entirely or partially where Whitworth threads start.

So, how best to get the broken bit out, without splitting cases? Are there extended drill bits and EZ outs that will work? Anyone done such a trick?

 

[Robert Watson]

If you mean it is broken off at the threads in the bottom of the hole where it screws into the crankcase that will be a fun little fix! I assume you have peered up the hole and it's not just the whole stud unscrewed and fallen out and that you can't see any part of a threaded hole in the bottom.

If that is the case i would make a sleeve that is 5/16 OD and say 1 /8 ID and start by drilling say about 5/8 to 3/4 in deep or until you feel the drill exit the far side of the broken end of the stud. Drills are make several inches long and you can by a cheap set as you only will use them rarely. On trick I have had success with is getting the hole the right size and taking an allen key that is slightly larger than the hole, grinding the end round to the dia of the hole making sure you have a nice sharp edge on the hex part and tapping it into the hole and using the hex to unscrew the broken bit. I don't recall have seen easy outs long enough to reach in there.

Bring it over Bev and well have a go!

 

[brian gains]

EZ outs sometimes end up in a fight, for me. Other go to is to weld a nut to broken stud, as long as not too far below surface, and then turn out as you would a bolt.

 

[Bill Thomas]

Just bought a pair of Comet Cases,
With the same problem only the other side of the barrel,
An owner in the past, Tried to drill it out and gave up !,
Then took a HUGE drill and drilled through both cases, While together,
Then Tapped a thread through both !!,
What a mess !,
I will have to have a try myself, The cases are now apart,
But if not lucky , The BIG bolt did work , It was even Chromed !.

Can't be sure , But I think it was raced in the T.T. As a 624cc outfit by Mick Farrant ?.

 

[Pushrod Twin]

If that is the case i would make a sleeve that is 5/16 OD and say 1 /8 ID and start by drilling say about 5/8 to 3/4 in deep or until you feel the drill exit the far side of the broken end of the stud. Drills are make several inches long and you can by a cheap set as you only will use them rarely. On trick I have had success with is getting the hole the right size and taking an allen key that is slightly larger than the hole, grinding the end round to the dia of the hole making sure you have a nice sharp edge on the hex part and tapping it into the hole and using the hex to unscrew the broken bit. I don't recall have seen easy outs long enough to reach in there.

Bring it over Bev and well have a go!

I agree with Roberts suggestion, use a steel sleeve to drill down, but I would spend some extra cash on a long series left hand drill. I have had good results on aircraft components using left hand drills to pick up studs and unscrew them. The stud likely failed due to fatigue, cases heating, expanding, then cooling and shrinking. The moment you run a RH drill into there, the stud could run down & thread bind, a LH could hook it out. Good luck!

 

[litnman]

I think you can find a high quality LH bit here: https://knkut.com/drill-bits/left-hand
I have some of their jobber bits but none small enough for this job.
Just thinking, if this bolt had been SS, it likely would have not broken in the hole.

 

[Pushrod Twin]

I think you can find a high quality LH bit here: https://knkut.com/drill-bits/left-hand
I have some of their jobber bits but none small enough for this job.
Just thinking, if this bolt had been SS, it likely would have not broken in the hole.

Good find litnman. I was thinking of these guys; https://www.mcmaster.com/drill-bits/
My thoughts were 3/16" If you cant find one long enough, braze or TIG weld, a piece of 1/4" rod on to extend it.

 

[Robert Watson]

But did you get it repaired yet????

 

[litnman]

My first choice would be the square type extractor as it is less likely to expand the broken
part. The blind hole would require the extractor to be shortened so as not to bottom out.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[RedRyder]

But did you get it repaired yet????

No! Still noodling on which tools to use and then I need to source them. There are other “distractions” going on, too. Thanks for the quick response. APPRECIATED!