KZ 650 Front Fork Pinch Bolt Stud - Help Please!

wrote:

I have used Wookie58’s technique before. It does work. There are shops that will electrically burn out the broken stud. I did a search and come up with “MDM” process but that doesn’t sound like what I have heard in the past. If you have it drilled out have you tried Left Handed bits?

I think after this much heating and applying penetrating fluid if the stud has still broken off with the extractor socket " this stud ain't gonna unscrew" the risk with using an "easy out" left twist bit is that if you break that off "spark erosion" is the only option and I'm not sure what the process would do to the alloy. Easy outs work great on broken screws that have been over tightened but when they are corroded in I have had little success in the past (only my opinion) 
 

Wasn’t taking about an “easy out” they are junk in my opinion. I was suggesting left twist drill bits, in creasing size. Hopefully before you’d get to the threads the left twist might grab and back the broken please out.

EDM (spark erosion) is cheaper than I expected - below is an ad for a uk company as an example £18 ($24) for one bolt 

 

wrote:

I have used Wookie58’s technique before. It does work. There are shops that will electrically burn out the broken stud. I did a search and come up with “MDM” process but that doesn’t sound like what I have heard in the past. If you have it drilled out have you tried Left Handed bits?

Left handed bit is exactly what I am thinking !  Thank You!  If I can get my low speed/high torque drill and a Left Handed Bit to reverse out the remaining stud, I will call it a WIN!  
I have currently started my center hole with 3/32" bit.  In metric that is about 2.3 mm.  I have drilled down only a 1/4" to 3/8" depth.  It is a good nearly dead center pilot hole to use as a starter for a Left Handed Bit.  I will get a couple of different sizes.  If I am correct in my thinking(flawed as it is), I want to go big enough that the bit has strength to not break off and turn out the offending stud yet be small enough to avoid damaging any of the thread in the fork.  This would be no larger than a 1/4" or 6 mm drill bit.   I have read Wookie's comments as well.  If I can break some of the corrosion.  I might have a chance.  I switched to a PB Blast brand of penetrating spray that seems to have more promise than the light penetrating oil I was using.  My one hope is that the steel is still harder than the aluminum and will hold up better down in the aluminum threads.  Thread insert will be my final option.  If all fails I will mount this fork leg on my wall as stark a reminder to think through each repair process before taking any action.  

wrote:

Wasn’t taking about an “easy out” they are junk in my opinion. I was suggesting left twist drill bits, in creasing size. Hopefully before you’d get to the threads the left twist might grab and back the broken please out.

I get that.  Currently researching  a two step process:
1st - Use left handed cobalt drill bit.  Sure enough the kits specify 1/4" for an 8 mm.  
2nd - Then use the screw extractor.  In this case, size EX-4 would be the right fit.  Not sure I need this step but willing to try if I find and the stud has not backed out with the left handed bit.  
The Saga continues...

EDM Spark Erosion is an interesting concept.  I would like to see that in action.  Your cost in the U.K. looks good.  If all else fails, I got this to fall back on.  

I've tried drilling them out with varying success.  The correct way is to use a drill press, but I don't have one so I only experiment with parts that I can replace if I foul things up.  My advice would be to take it to a machine shop and let them do it.

Another EDM link I found:. brokentap.com/services/

I've had good success drilling out screws by hand (no drill press).  It's nearly impossible to get the drill perfectly centered on the screw.  The bit always walks.  But if you're lucky you can sneak up on it using progressively larger drill bits and get to the point where you just shave through one side of the bolt.  At that point you can often fold it in with a punch and turn it out with a pick.  But I'm rarely that lucky and I often get into the threads a small amount. 
Assuming you have enough material to make the hole larger, using a helicoil makes for a very strong repair.  That's the plan b for when drilling it out goes poorly. 

wrote:

  However, if any of you suggest I weld my toolbox shut, remember, I do not have any welding equipment.  You will need to bring yours over and do it for me. 

  ...Please.  
 

You can always use JB Weld.

(Sorry, I don't have any useful suggestions but wish you luck.)

wrote:

I've tried drilling them out with varying success.  The correct way is to use a drill press, but I don't have one so I only experiment with parts that I can replace if I foul things up.  My advice would be to take it to a machine shop and let them do it.

Thank You for the suggestion.  I have considered this myself.  Have not locally sourced as yet.  Considering checking my man card at the door and contacting a machine shop.  
My risk taker side  sez; I do have a quite nice nearly centered pilot hole started.  Why not give it a go!   Last night, I picked up a small kit of Titanium coated left handed drill bits including the 1/4" that should leave +/- 1 mm on each side.  I may cut into some thread.  My goal is to see if I can break the threads loose enough to back it out with the left handed bit.  As you have read through the chronicling of my unsuccessful attempts this continued DIY strategy has netted a negative sum gain so far.   SO, I WILL explore local machine shops today.

wrote:

wrote:

  However, if any of you suggest I weld my toolbox shut, remember, I do not have any welding equipment.  You will need to bring yours over and do it for me. 

  ...Please.  

 

You can always use JB Weld.

(Sorry, I don't have any useful suggestions but wish you luck.)

Thank for helping me keep a sense of humor and perspective Nerdy!     
I would JB Weld my toolbox shut.  However, I would just make a mess of that too.  

I have an early morning appointment tomorrow with a local machine shop!     Wish me luck.