Oh-oh: Need help with a side plate bolt extraction

**rigspelt** · 09-23-2008, 05:34 AM

While mentally regrouping an approximate Zen-like center overnight (ommmm....) I did some googling. Apparently I am not alone: there are other DIY bolt-extractors who have experienced broken hardened rescue bits and extractors embedded in sheared bolts. Fortunately I seem to have some options that fall short of the awful ultimate: pulling the whole engine and shipping it to a shop somewhere that can do EDM (Electric Discharge Machining). All require a deep committment to patience and planning.

The outer end of the sheared bolt is now an irregular surface just inside flush of the outer surface of the block. The broken drill bit tip is embedded in its channel further inside the center of the sheared bolt. I suspect the tip is just about flush with the inside surface of the block. The inside tip of the sheared bolt extends about 1/4" into the coolant space inside the block.

I don't think heat, penetrating oil and a left-handed bit are going to work now. This isn't about trying to turn out the stuck sheared bolt remnant, it's about clearing the bolt and drill bit metal from inside this 5/16" wide by 1/4" deep corner of the universe that now has my attention.

One poster somewhere used a Dremmel chainsaw sharpening bit to carefully cut away bits of sheared bolt/broken drill tip until they could salvage the situation. Apparently old dental burrs are good enough for this too. Looking for solid carbide.

I may be able to cut away the back of the broken bolt with a Dremmel disc by lining the area with aluminum foil, and then juggling a mirror and lighting. If I can cut off the tip of the sheared bolt inside, then maybe I can tap out the broken drill bit tip from the outside, allowing me to carry on drilling out the sheared bolt with 1/8" then 3/16" and 1/4" bits.

I may be able to drill some small relief holes in the sheared bolt alongside the broken drill bit tip after shaping the surrounding sheared bolt with a Dremmel to regain a flat face surface, allowing me to remove the center mess.

Some say to hammer out the bolt with a hardened punch, but that seems very risky for this delicate situation: too much risk of damaging the side of the block around the stud.

MIG-welding a bolt onto the sheared bolt is not a practial option for me, not with the engine in the boat, the bolt in a vertical surface, the bolt sheared off just inside the surface of the block face, and potential lack of MIG welders who do house calls.

Thank goodness Don offers those side plate bolt kits: I suspect I will end up needing one. They raise another option too: abandoning the two sheared bolt holes and drilling two new ones alongside, both in the block and the new side plate, and then attaching the side plate with the replacement bolt kit. For that to work, I would have to either cut the tip of one of the sheared bolts flush inside, or drill out the second sheared bolt and plug its hole. I'll save that idea as a backup plan.

Comments and suggestions more than welcome.

Couple of references for my future extractions:

Page not found - Automotive Service Association - National

http://www.asashop.org/autoinc/may2003/techtotech.htm

http://www.sears.com/shc/s/p_10153_12605_00946338000P

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http://www.openroad.ca/volkswebbin/viewtopic.php?id=85185

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http://www.peterson-international.com/safeandvault.htm

**rigspelt** · 09-25-2008, 06:50 PM

Well, after 3 evenings of drilling, I might be a couple of millimeters deeper and I can see an irregular bottom in the hole. I cut the tip of the inside of the bolt with a Dremmel disc, so all I have is a piece of side plate bolt inside the threads of the bolt hole in the block, and a hole about a quarter to a third deep with that broken bit tip buried in the base of the hole.

The bit I broke was a commonly available 7/64" M35 cobalt. Can't find out much about them on the net, but one source suggested that cobalt HSS bits are harder but more brittle than some other high quality HSS bits. Some also said that ordinary hardware store cobalt bits are just coated. Whatever the truth of the matter, that broken tip is hard. The photos below show the large broken bit I pulled out of the hole. It fits perfectly on the main stem. On closer examination tonight, I see that the piece jammed in the side plate bolt is a very small fragment off one side of the tip. You can't see that clearly in the photo, but just under half of the original cutting edge tip is still there, and a small flake of the rest is gone. Just enought to bring a halt to my refitting until I get past it.

I've been through four high quality 1/8" HSS bits that I bought at two specialty suppliers. The cutting tips just dull, but I think I am getting a few tiny flakes off all the time. I think I have no choice other than to keep drilling slowly and patiently, keeping everything cool with slow rpms and cutting paste to avoid more breakage. I have to keep patiently chipping away until I break up that tip fragment, unless someone else has another idea. Just 3/16" of bolt left in that hole now. Grrr.

Attached Files

**Kelly** · 09-26-2008, 04:18 AM

Rigspelt,

I only have words of encouragement to offer having never been through this sort of pain.

I'm amazed by your methodical approach and patience. And thanks for passing on the experience in text and photos.

Best of luck,
Kelly

**Cellnav** · 09-26-2008, 03:52 PM

This is like reading a horror novel! I've used dental burrs to hog out the broken drill bit then clean up the hole with a fresh drill bit. Tough to do if you can't see into the hole. Hang in there.

Mike

**rigspelt** · 09-26-2008, 06:30 PM

Originally posted by Cellnav View Post

I've used dental burrs to hog out the broken drill bit then clean up the hole with a fresh drill bit.

I can see into the hole very easily, and I do have a sailor dentist friend, so I will give him a call. Maybe he has an old burr.

**High Hopes** · 09-26-2008, 10:45 PM

Rigsy,

Here is one of my trade secrets. I use a dremel tool cutting disk in situations like this. Using the disk, I create a new slot in the face of the stuck stud. This involves scoring the sides of the block too. I am not shy about this. There is usually quite a bit of depth to the block, so the extension of the new slot into the block will not matter. See the drawing below. The slot width will really be about 1/4 of diameter of the bolt, much wider than shown below. Use a thick cutoff disk.

Once you have a new slot, sharpen a screw driver. I usually sacrifice one to the cause. Pick one that you can grind to a perfect fit. Use a lot of DW-40. Rap the stud on both sides of the slot. You may want to squirt some DW-40 on it and wait overnight.

I have found that if the screwdriver fits perfectly into the new slot and the corners of the screwdriver blade are sharp, I can remove the stud. Be careful not to let the screwdriver blade slip and tear the slot. If this happens, re-grind the slot and re-sharpen the screwdriver. Don't be afraid to make the slot deep. This weakens the stud by splitting some of it. This method hasn't failed yet for me.

Good luck. Let me know if it works for you. When it does, I will send you my bill.

Steve

P.S. Maybe there is clearance behind the stud to screw the remainder of the stud into and through the block, if clockwise is easier to turn?

Attached Files

**rigspelt** · 09-27-2008, 01:09 PM

Fourth day grinding, and defnitely gittin' somewhere!

Stopped by a friend's clinic this morning to bum a couple of used dental burrs. I used them dry in my drill at slow speed, with double eye protection. They worked great: moved more metal with more control than a drill bit, and seemed to allow me to work around the jammed broken bit tip. They eventually wore down, so I'll need more than a few, but they opened things up enough that with another new 1/8" bit I was able to more than double the depth. And I used a 3/16" bit to open up the hole too. Now about 2/3-3/4 through the bolt hole.

I took a break but had lots of energy, so I switched to the second sheared bolt. Got it drilled right through nearly center using a 1/8" and a 3/16" HSS bit, kind of in tandem. I was able to manipulate the 3/16" to centre up the wander in the hole caused by the smaller bit. Top quality bits from an industrial supplier make a big difference too.

Once I get more used dental burrs, then I can try to finish the first hole and start thinning the metal toward the threads in the second hole, enough to start chipping bolt metal out of the threads with a tap.

Light at the end of this tunnel!

**Cellnav** · 09-29-2008, 04:17 PM

Hole

This is high drama in Rigs vs the bolt (in double over time). Rigs, my money is on you so keep drilling

**rigspelt** · 09-29-2008, 05:37 PM

I took yesterday off to clean the bilge under the engine and other sundry refit chores. Today after work, I stopped by a local industrial supplier to pick up my favourite HSS Jobber drill bits. Right beside the bit display I noticed a selection of burrs by Metal Removal Industrial Tooling. I had never noticed that kind of tool before getting my hands on the dental bits. The photo below shows two of the MR burrs ($20 each) and some examples of used dental burrs ($0). I'll let you know how they work out after my next session with that broken bolt. Up half of last night watching the marina after Kyle came ashore, so I think I'll pass on tackling that ticklish operation again tonight.

Update: lots of interesting information and reference material in the Metal Removal catalogue at http://www.kennametal.com/images/pdf...ed_AD06-29.pdf.

Attached Files

**rigspelt** · 09-30-2008, 07:45 PM

Got 'er done!! Yippee! Both sheared bolts are now holes. The flake of broken bit tip popped out finally at the end of the evening. It was no bigger than a hangnail, and just as nasty. Cost me 8 days and about $80 in drilling bits and burrs. That'll teach me to drill holes more carefully: slower and with a good handle on the drill.

I am not going to be able to restore the threads, so when Don's side plate bolt repair kit gets here I'll clean up the holes just enough to fit the kit bolts.

Now, on to everything else.

**High Hopes** · 09-30-2008, 11:12 PM

Congrats! I know how you feel. Well done.

**Cellnav** · 10-01-2008, 03:09 PM

Bolts

A cautionary tale! I'm glad you got them out.

Mike

**blackdove** · 10-01-2008, 08:40 PM

Great job! What's next

Bet you're pleased this is over. What's on the horizon other than a nice cold martini. Thanks for sharing the adventure with us.

**rigspelt** · 10-02-2008, 06:01 AM

Originally posted by blackdove View Post

What's on the horizon other than a nice cold martini.

Rum, not martini. As to next steps - every system on the boat is getting an overhaul. Can't afford to charter south any more, so this is my new adventure.