Real expert

[67hat34c]

Prior threads discussed experts and what is considered one, well I think i found one.

Machine shop in orlando Fl. guy that owns and runs the shop is most likely in his 70's or more. He made some small parts for me in the past so I used him to repair my intake and exhaust manifolds from my old onan mcck. I removed exhaust and broke off a bolt so took off the intake as well could not get the bolt out so I decided to let machine shop do it and also mill all gasket surfaces. Anyhow I had a neighbor drop the stuff of today and when he walked in to the shop the guy looked at him and said, "those are from an onan". Would expect this from someone by the coast but not that far inland and from a hole in the wall shop. Anyhow his work order consists of taking only your first name and phone and putting it on a scrap paper with other first names and numbers and says you can pick them up in 2 or 3 days. Never asked him how much, stay tuned for that but from last experience I am not expecting a very big bill either.

 

[Bob Bradley]

Speaking of experts...

A few years ago, I found a snapped off a valve cover screw in one of the heads on my 327 from my old 32' Chris Craft Seaskiff after buying the heads used and having a valve job done on them. Having just reassembled the engine, I was, to say the least, unhappy at the prospect of pulling a head to have it machined out. I was also a bit unhappy with the machine shop that I bought them from and where the valve job had been performed. I just wanted to go fishing.

The owner of the boat next to mine, a 35' Chris Seaskiff, and fellow woody lover, also happened to be a machinist. He asked me if I had a punch, and told me that he would try to "tap it out" for me. Now this thing was snapped off flush - it looked like a drill and tap job to me. I told him "you're nuts, that's not coming out."

Well, he took that punch, angled it against the snapped screw, and tapped it gently with a hammer. I watched him, shaking my head, as he patiently repeated this 10 or 15 times. Finally, he said "hey, I think it moved." A minute or so later, he gently unscrewed the broken piece out with his fingers. I gained a whole new respect for Angelo that afternoon.

 

[Starman]

Now those two guys are Pro's

Nothing beats experience.

 

[rswirtz]

Bob, please ask Angelo about my plan.

My generator (6.5 KW Onan) lost its flywheel/pully. The 1/2" bolt broke off about 2.5" inside the main shaft.

My plan when I get to the boat is this:

1) Soak the bolt with wd-40 or PB
2) smack the bolt with a home built center tap (1/2" #4 or something bolt)
3) run a small drill bit into the shaft with a 1/2" wood coller around it
4) try a left handed drill bit (found on ebay) with the drill running in reverse, grab may twist the bolt out.
4) insert a easyout in the there that I had a bolt welding to due to the depth
5) replace the bolt with a #8 hard bolt

What do you or anyone think? Rick

 

[Bob Bradley]

Unfortunately, I haven't seen Angelo in several years. Have you considered redrilling, and tapping new threads into the 2.5" hole and just using a shorter, larger bolt?

 

[rswirtz]

Unfortunately, I haven't seen Angelo in several years. Have you considered redrilling, and tapping new threads into the 2.5" hole and just using a shorter, larger bolt?

Yes, the shaft is most likely hardened steel and I'm not sure about tapping that, that procedure however would be plan B if my plan failed. Whatcha think?

 

[Starman]

Rick,

You can get a cobalt drill bit and what I call an easy out. It is a tapered left hand in bolt remover.

You can find these at any hardware store. Once the hole is drilled in the bolt, re chuck the drill with the bolt remover, put drill in reverse and it will cut into the bolt " Hole" until it grabs and turn it right out.

Good idea to soak the broken bolt in liquid wrench or penetrating oil first.

 

[MikeP]

Re easy outs...

Be careful - They are hardened so if you over-torque them trying to remove a recalcitrant bolt, they snap with no warning. You cannot get a feel for their strength as you can with a wrench on a standard steel bolt. Being hardened, after they snap they are VERY difficult to remove. In 40+ years of mechanic work I've probably seen as many snap as worked - a pretty poor percentage.


Be careful with them; I would certainly try them carefully. But if they don't work initially, abandon them and drill out the old bolt and install the proper size helicoil.

 

[garyd]

I agree with Mikep seen as many work as fail. Sneak up on it. Do not buy the easy out on ebay. Buy the highest quality possible. Plus start off with a left handed drill bit.

If you can't get a feel for the easy out working stop.

Here's the fun part. Ya need professional help at this point. Find an explosives expert, they are around usually x-military. They will put a small charge in the drilled out stub and with a little pop out it comes.

If you break off the easy out it's all over only complete disassembly will get the job done after that usually.

garyd

 

[34Hatt]

I do this more offen then I like ( once friends know you can fix it ) they are right stay away from the easy out you break that off your DONE. Start with small bits and start drilling. If you keep it centered you will be able to pick the old bolt out once you get close to the root of the threads. If not you can tap it and keep it the same size do it all the time. There will be some bolt left but the tap will find the old threads specially if it is a harded mat'l. Take your time pay attenion to being centered it all come's down to the drilling. If during the drilling you see it turn then get the easyout and give it a shot this happens a lot when you take most of the bolt out.
Good Luck

 

[Avenger]

One of the big drawbacks to most "Easy"-outs is that they tend to expand the bolt when they are driven in. The left-hand drill is definitely the way to go. I know it's difficult, but if you can locate your centering punch dead center (maybe you can modify a bolt or make a guide that fits in the bolt hole) then you can use progressively larger drills until you get to the ID of the threads. If you get it close enough you can often pull the old bolt out like a Heli-Coil. If not it's tap time. I'd doubt that the crank is hardened. If it was it would probably work in your favor when trying to tap out the old bolt.

BTW, the inside diameter spec. of 1/2 in. UNC coarse thread is .4167" The closest you can get to this is a "Z" bit which is .413. However, the "tap size" is 27/64" (.4219) which in the real world should work. Remember, the most significant tool you can use on a job like this is patience. Hope this helps.

 

[Bob Bradley]

Many years ago I snapped a main bolt while rebuilding a SB GM engine. I got a good center punch in the broken off bolt (a hardened bolt no less) and managed to drill a 1/8" hole straight thru and out the other end of the broken stub. I progressively increased the size of the bit until I could start to see the threads along the side of the hole. Only then did I employ the ez-out, and the piece came out with little effort.

At the time, I didn't know that left-hand bits existed, but I suspect that it would have worked better than the ez-out.

 

[garyd]

Like I said if you can find a good bang guy, it's like majic. A little of this a little of that a little pop and all you got left is the original threads. If saves a bunch of hassle. Ask around they are amongst us but tend to keep a low profile.

garyd

 

[Maynard Rupp]

I agree with Mikep seen as many work as fail. Sneak up on it. Do not buy the easy out on ebay. Buy the highest quality possible. Plus start off with a left handed drill bit.

If you can't get a feel for the easy out working stop.

Here's the fun part. Ya need professional help at this point. Find an explosives expert, they are around usually x-military. They will put a small charge in the drilled out stub and with a little pop out it comes.

If you break off the easy out it's all over only complete disassembly will get the job done after that usually.

garyd

And boy, will that make you swear. Those broken easy-outs are close to impossible to get out. Best you can do is try to wiggle them out with a hammer and punch. Of course you can also use a dremmel or die grinder, but you might not live long enough to get the job done. I have seen many fail, some not work because the guy didn't want to push it to failure, and the rest just don't do anything. The only thing they are sure to do is piss you off.

 

[Trojan]

The crank can be drilled and tapped it is only tuff. When you drill the first hole. Make sure you use a guide on the bit. It must be as close to center as you can get. Then progress up to larger sizes. The reverse drill bit is a good try. If that does not work. You will need to try the largest easy-out you can get in there. Don't bang the hell out of it putting it in or you will expand the bolt in the hole. Use a wrench to turn it not a power tool. If that does not work. do as Scrod suggested. If that does not work. Drill and tap the hole for a bigger bolt or a helie coil. That deep of hole it would be hard to drill to the root dia and keep it straight. As everyone said, take it easy. GO SLOW. Good Luck.


BILL

 

[jim rosenthal]

I think if you can centerpunch a dot in the middle of the broken bolt, drilling it out with progressivly larger drill bits is the way to go. At the end, you can use an easy-out or whatever to peel what's left of the bolt out of the threaded bore. Then clean it out and run a tap down it to make sure the threads are clean and straight. Good luck. Stuff like this is a pain, but the upside is that if you succeed you will feel like KSTRM.

 

[doc g]

I do not know if anyone considered that the bolt that broke off could be a left hand thread or not ,but sometimes those bolts on the end of shafts like that are. It depends on the rotation of the engine. I know on my old 671TIB's the port engine had a balancer on the front of the crank which needed to be replaced and it had a left hand thread bolt holding it on, even though it had a woodruff key . I would be damn sure what thread is there before any attempts at removal.......................................Pat