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> Anyone ever break a head stud?, Looking for ideas, tools success stories, horror stories, what cha got
rick 918-S
post Apr 27 2008, 04:56 PM
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I'm building a 928 hybrid engine which is comprised of a 5.0L 32 valve short block with 16 valve euro spec "S" heads, spyder and CIS from the 4.7L "S" engine.

I stole some time from my busy work schedule to prep my 928 block for the machine shop. The head studs need to be removed for the boring process.

Now I've pulled studs before without incedent. But as Murphy would have it, this time I broke one of the studs flush at the start of the threads.

So I have the threaded section ( 1 1/4"long ) hardened head bolt stuck in the block. Normally this wouldn't be a problem, but the stud is free standing in a 3 1/2" deep hole in the block!

Here's a crude drawing of the problem I'm faced with.

Attached Image

Here's the stud.

Attached Image

Here's the stark reality of the stud in and out of the block. The stud slides down a 3 1/2" deep hole in the block before it starts to thread in.

Attached Image


I'm going to make a drill collet as a guide for a pilot bit. The problem is I need a long, reverse twist drill bit.

Most drill bits are approx 5" long. the hole is 3 1/2", the threaded section is 1 1/4" for a total of 4 3/4". See the problem?

Then, what the #$!! do you drill a hardened bolt with?

Anyone know of a good tool source? This is beyond most Mac and Snap on stuff I would think.
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VaccaRabite
post Apr 27 2008, 05:49 PM
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Let your machinist deal with it?

Probably end up drilling it out on a press, and then putting in an insert.

Zach
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SGB
post Apr 27 2008, 05:52 PM
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Looks like a "major malfunction".

What a bizzar manufactoring method....
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scotty b
post Apr 27 2008, 05:59 PM
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rust free you say ?
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Rick the guy I started out working for had the EXACT same thing happen while torqueing a head. His solution was to holler F*CK, throw his torque wrench on the floor, tell the engine what a M+%*$( %)@_%*%^@!(#)% piece of $#&$(^(#&@#*^(#!@$&^@#$% it was, and let the mahinist fix it. IIRC he clamped it in the mill and basically ate the stud away then put a time cert in the block. Sorry to hear. Sux big time (IMG:style_emoticons/default/sad.gif)
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spare time toys
post Apr 28 2008, 03:02 AM
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Could always use that spare block that came from California by way of Texas couldnt you (IMG:style_emoticons/default/shades.gif) Since your doing the hybrid thing and all (IMG:style_emoticons/default/confused24.gif)
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Richard Casto
post Apr 28 2008, 08:14 AM
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I have no idea what the cost of this is, but EDM (Electrical Discharge Machining) aka Spark Erosion may be the right tool for the job.

Maybe you can find someone local to you like this guy (found via Google search)...

http://www.brokentap.com/
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Richard Casto
post Apr 28 2008, 08:21 AM
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QUOTE(Richard Casto @ Apr 28 2008, 10:14 AM) *

I have no idea what the cost of this is, but EDM (Electrical Discharge Machining) aka Spark Erosion may be the right tool for the job.

Maybe you can find someone local to you like this guy (found via Google search)...

http://www.brokentap.com/


Another Google search for EDM services, but this time for someone in MN...

http://www.twincityedm.com/

Good luck on getting the stud removed! (IMG:style_emoticons/default/smile.gif)
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r_towle
post Apr 28 2008, 08:22 AM
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I believe the correct bit is made from Cobalt.
These or carbide bits.
Look at McMaster Carr, MSC, or Grainger for the correct bit(S)

You will need at least two bits to work up to the right size.
Drill press would be the way to go, but you can also use a hand drill.
Think about buying a long section of bronze to make a collar that keeps you straight.

The tap will be from the same industrial hardware guys also...it needs to be long.

Rich
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Bartlett 914
post Apr 28 2008, 08:22 AM
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QUOTE(Richard Casto @ Apr 28 2008, 06:14 AM) *

I have no idea what the cost of this is, but EDM (Electrical Discharge Machining) aka Spark Erosion may be the right tool for the job.

Maybe you can find someone local to you like this guy (found via Google search)...

http://www.brokentap.com/

(IMG:style_emoticons/default/agree.gif)
Totally!

The drill guide should also work. The biggest problem is getting the drill to start in the center of the stud and not wander off center. Then you are drilling the case and not the stud. A properly setup EDM should be able to remove all the stud except the threads which may still be tricky to get out because of how deep the stud is in the block. Take the block to someone with equipment like EDM and / or a mill. Lots of luck Rick.
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rick 918-S
post Apr 28 2008, 08:52 AM
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Larry, I broke that CA. block when I had a valve fail.

I found a EDM place. Their 180 miles away. Not the worse thing, at least there's one in the state.

http://www.twincityedm.com/contactus.htm
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rudedude
post Apr 28 2008, 09:04 AM
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Rick,

There is a tool dealer in st paul, Norseman drill & tool, 651-227-8911 or 800-328 -4655 that has wonderful drills and cutters.

They have made mill tools to spec for me and might be able to help you.
Good luck!

Jule
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Richard Casto
post Apr 28 2008, 09:52 AM
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Rick,

If you go the EDM route, I would be curious to hear what they charge for that type of work. Just for future reference. I think something like this is pretty much in the future of anyone who does their own engine work.

Richard
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rick 918-S
post Apr 28 2008, 10:23 AM
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I contacted the EDM guy. He didn't think he could work 3 1/2" deep inside a 5/8" inside hole.

It's up to me. Thanks for the lead for the drill source in St. Paul.
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rick 918-S
post Apr 28 2008, 10:49 AM
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QUOTE(rudedude @ Apr 28 2008, 07:04 AM) *

Rick,

There is a tool dealer in st paul, Norseman drill & tool, 651-227-8911 or 800-328 -4655 that has wonderful drills and cutters.

They have made mill tools to spec for me and might be able to help you.
Good luck!

Jule


I called them. They only have left hand bits in jobber length, (3/8"=5" long) and only sell to jobbers like the Tool Crib, etc.

Still looking. I need left hand drill bits approximatly 7" long. And a thread extractor as long
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rick 918-S
post Apr 28 2008, 10:57 AM
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BTW: My machine shop offered to drill it out and install a time sert (sp) then remembered the threaded part is 3 1/2" in the block... Maybe not. (IMG:style_emoticons/default/dry.gif)
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Cap'n Krusty
post Apr 28 2008, 11:32 AM
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A good EDM guy can probably do it. I have a number for one, but he's in LA, CA. He does work for many of the bug Top Fuel guys, including Johnson Racing here in Santa Maria.
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Katmanken
post Apr 28 2008, 06:58 PM
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Aircraft work sometimes requires extra long drill bits- say 12 inches or so......

These are not reverse twist but they might be a workaround and the prices aren't too bad.....

Aircraft 12 inch long drills linky link

I do like the guide pilot idea if the bore isn't tapered.

Ken
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rick 918-S
post Apr 28 2008, 08:58 PM
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OK, I did some deep thinking about this today. Unfortunately, I didn't have the light bulb moment until most places closed for the day.

Here's how I'm going to fix this. If it works I'll post pics.

I located left hand drill bits on http://www.mcmaster.com/

They also have left hand taps and bolts!

I'm going to machine a drill bushing that doubles as a chuck for a (short) left had drill bit. Sometimes during the drilling the threads will back out. If it doesn't,,,,,

I am going to use the left hand tap to cut threads in the pilot hole.

This sometimes will cause the threaded section to back out. If it doesn't,,,,

I am going to thread in a left hand grade 8 bolt. This will repair the broken bolt and give me a positive bite on the threaded section. If the bolt breaks I can just drill it again.

If I used an extractor and it breaks, I toss the block in the scrap pile.

Extractors = bad.... (IMG:style_emoticons/default/dry.gif) bolt = good... (IMG:style_emoticons/default/biggrin.gif)
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r_towle
post Apr 29 2008, 11:02 AM
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I bet you could get a new block for cheap....seriously.
There was a 928 motor at Hershey for short money...

Rich
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r_towle
post Apr 29 2008, 11:03 AM
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Have you called 928 international??? Maybe they have a cure for this???
Or Pevec (SP) the guy who hot rods these motors???

I am sure someone has dealt with this in the 928 community before.

Rich
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