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Discussion Starter · #1 ·
Put a few hours into my 68 Bonnie:
I've had a couple of bolts just snap at the head--one is on the fork stanchion.
Ive had several that are "threaded". Some of the bolts fit my Whitworth spanners, some didnt --they fitted SAE spanners.
The previous owner "re-caded" all the bolts, he said.

Questions: Is Re-cading a good approach for 40 year old bolts? Personally I think buying new ones would be safer.

Does re-cading add a layer of meteal that could cause problems when screwing back into a nut or housing?

Whats the best way to extract a bolt with a head broken off--drill, or use a dremel tool? Ive never done something like this. Any advice most welcome.

And here I was, just wanted to take the bloody front wheel off to check the brake pads!!!!!! :mad:
Cheers!
 

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Replating is a good thing. The old bolts should be fine unless you think for some reason they were overstressed.

Cadmuim is very thin and soft, wire wheel the old bolts before you send them out. They should look like new when you get them back.

There are a number of ways to get the broken bolt out. Occasionaly I get lucky with an EZ out. Go to your local hardware store and tell them what size bolt you broke off and they will hook you up.

I have had some success drilling the old bolt out too, just dont drill bigger than the minor (root) diameter of the bolt, you don't want to mess the threads up.

Joe
 

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Kev,

Most plating is only a couple of microns thick so there should
not be any problems.

However, are you sure it was cadmuim that he had done to the
bolts? Some of the plating processes like chrome cause
hydrogen inbrittlement within the metal.

Pookybear
 

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Discussion Starter · #4 ·
Thanks guys.
Ill head off to Sears and get some new tools.
What bothers me the most is a simple task like taking off the front wheel opens a pandoras box of 4 stripped bolts and one sheared bolt head.
Im wondering what else Ill find as I go along if the previous owner felt ok with using the wrong bolts types in the bike!!! :(
 

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Kev,

Either order a can or two of Kroil from Eastwood or go get yourself a can of PB Blaster and soak any fasteners you want to remove at least overnight before you attack them. The PO might have been the hamfisted type and overtorqued the bolts, making them ready to snap when you try to remove them.

The EZ out method is hard if the bolts is rusted in place. Also the tools are just about as fragile as a tap because they are hardened. If you break an EZ out off in a bolt, you're screwed because you cannot drill it out unless you have a carbide drill bit. Since it is the only way to remove the bolt if you cannot get a grip on the stub, be care, use a little heat, lots of penetrating oil and lots of patience. Tapping the stub with a punch and hammer to loosen it might help. Just don't mash any threads to make removal that much harder. Also, you have to drill a hole in the stub to insert the EZ out. Make sure you drill that hole dead center in case you end up having to drill it out. See drilling out below for how to assure you are in the center.

If a stub remains that you can get a set of pliers or vise-grips on, try that first. But for top tree, my guess is you have no stub showing.

If the EZ out will not move the bolt, you have a drill press and can set up the part so the bolt is in line with the drill bit, that may be your only choice. First, if there is some stub above the surface of the part, file it flat so you have a good flat surface. Then prick punch the center. Tap lightly and keep moving the punchmark until you have it dead center. Once perfect, give it a harder tap to make sure you have a good guide to start the drill. Now, go get yourself a center drill. I'm sure SEARS has them. They are short and stiff and will not walk or flex. They are used to drill center holes like you find in the ends of shafts, and to start drill holes. I'd suggest one with a 1/8th drill point. This will make the body about 5/16ths. Just drill a small hole with the starter point and then go to a regular drillbit. Start small, maybe 1/8 and work your way up. You'll have to look up the tap drill size for the bolt thread you are drilling out. Work up to that size because if you drill off center, you will start to see the threads show up on one side. If that happens, stop and try to collapse the remaining bolt into the hole with a small punch. Keep in mind you may need to run a tap thru the hole, which means you need Whitworth and SAE taps. The Whitworth won't be cheap.
Good luck,
Rob
 

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Be careful with the EZ out...They are great until they break off! What I find to work almost every time is a reverse pitch drill. Usually when drilling into a hard bolt, the bit will catch and bolt will spin right out.
 

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Discussion Starter · #8 ·
Thanks everyone for the info (especially rob and the detailed info -- too bad you dont live in my neigbourhood!)

Looks like I have a shopping list for Sears.

Ill let you know how it goes, its a bolt on the inside of the front fork that holds the mudguard plate on, so Im going to have to take the fork off to do this right, might not be able to get to it for a few days.

Cheers.
 

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Discussion Starter · #9 · (Edited)
What a mess....

OK, went to sears and bought one of their bolt extractor kits. It had a set of drill bits and reverse thread extractor bits.

Anyway, went thru the steps and bored the hole ok and then when i tried to dril using the reverse bit, the drill (and I was using a powerful dewalt variable torque drill -- not on a battery) just got stuck! That bolt is not moving.

Bear in mind, the other holt on the fork took ALL my strenght to remove. The PO must have known he was wrenching in a bolt THAT DID NOT BELONG IN THAT HOLE! Must have been in too much of a rush to be bothered to order the proper bolts. Makes me worried what else ill find on this bike.

Since I dont have a drill press, and the bolt is on fork, I think I might take the fork into a machine shop and get it done right. Probably have to go with SAE thread too.

Any thouhgts?

(Note: in the pics I mounted the broken head on top of the bolt hole in question--the bolt head in the picture is of the bottom side of the washer that is somehow stuck to the bolt head.)



 

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Once you get the bolts removed, when it comes to plating, if you want originality cad plate them. The only problem is its tougher to find platers who still cad stuff. Very toxic stuff. I have afew good recommendations if you need them. Just PM me.
 

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Discussion Starter · #11 ·
Once you get the bolts removed, when it comes to plating, if you want originality cad plate them. The only problem is its tougher to find platers who still cad stuff. Very toxic stuff. I have afew good recommendations if you need them. Just PM me.
Thanks very much for that info. I know everyone talks about re-cading everything. But, from the 10 + bolts I have seen already stripped on my bike that have been re-caded, I'm staying away from re-cading bolts. My approach is now to replace all the bolts with new ones. Yeah, it will cost more and wont keep the bike 100% original but I dont want to have to go thru a helicoil everytime I take a bolt off!

Hey, British-Only are flogging everything at 25% off so that's my incentive: Im going to replace all my bolts with new ones :D
 

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Whew... those be some ugly pictures, Kev. Almost looks like someone welded something there. It looks like that is a blind hole. Those are normally the worst because you have thread engagement for the entire length of the bolt. That means all that more siezed or corroded thread to keep you from getting it out.

You know, for what you will spend at a machine shop, you can probably buy a nice little benchtop drill press at Sears or Harbor Freight. Last time I looked they were something like $59.99. You might find one on Craigs list or your local want ads for less. Might even find a floor model, which would be preferable for the same price as a bench model is new. This is something to consider if you are going to be doing this kind of work for years to come like the rest of us have. Having the tools to fix things is always a good thing. If you don't know this already, stuff always breaks late on Sunday night. Being able to fix it gives one excellent piece of mind.

Not confident that you can do the work, go get a chunk of steel, drill and tap a 5/16-24 hole in the steel, then beat up the threads on a 5/16-24 bolt and run it into it into your threaded hole and cut or break off the head. Then try to drill it out without ruining the threads. Good practice, no risk, small investment.
regards,
Rob
 

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Discussion Starter · #13 ·
Whew... those be some ugly pictures, Kev. Almost looks like someone welded something there. It looks like that is a blind hole. Those are normally the worst because you have thread engagement for the entire length of the bolt. That means all that more siezed or corroded thread to keep you from getting it out.

You know, for what you will spend at a machine shop, you can probably buy a nice little benchtop drill press at Sears or Harbor Freight. Last time I looked they were something like $59.99. You might find one on Craigs list or your local want ads for less. Might even find a floor model, which would be preferable for the same price as a bench model is new. This is something to consider if you are going to be doing this kind of work for years to come like the rest of us have. Having the tools to fix things is always a good thing. If you don't know this already, stuff always breaks late on Sunday night. Being able to fix it gives one excellent piece of mind.

Not confident that you can do the work, go get a chunk of steel, drill and tap a 5/16-24 hole in the steel, then beat up the threads on a 5/16-24 bolt and run it into it into your threaded hole and cut or break off the head. Then try to drill it out without ruining the threads. Good practice, no risk, small investment.
regards,
Rob
Thats a bloody good idea Rob! Funny thing is the bloke I bought the extractor kit from at Sears gave me a special "friends and family" extra 10% off coupon for this weekend. Looks like ill be using it.

Next silly question: what is the advantage of a floor model? Just flexibility in ability to get stuff under the drill bit?

Anyway, yes, I like the idea of having my own gear to fix this stuff. For $100 or so its worth it.

I'm still having trouble understanding how these bolts wound up like this. The PO had the original bolts re-caded and fitted about 5 years ago. The bike has not been ridden in 10 years--the PO never finished the restoration. How did the bolts (there are others - this is the worst) get this way? My un informed guesses:

1. He fitted the wrong re-caded bolts.
2. The bolt holes were already stripped and he forced the re-caded bolts in anyway.
3. The cading process added too much thickness to the bolt and therefore sort of welded itself in the hole.
4. The PO thought he'd never have to take the bolts out again so used expoxy resin to secure them!

Whats wierd is the way the washer looks welded to the bolt. Like I said, same problem on the other fork: took all my strength to get the bolt out of that one.
 

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Hi
Couple of points to make
1.Replating(or plating for that matter) makes the
tensile strength go to hell in a handbasket.
If you want brittle bolts be sure to replate them!
Always use new stuff, you will be way more
happy.
2. Depending on the hole size, material
and brain power,one can easily take a course
thread bolt and force it into a fine thread hole,
cutting new cross threads along the way
You can do this the other way round too.
I have fixed lots of this kind of stuff on old brit
iron.
3. Those are some ugly photos!
Jeri
 

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Discussion Starter · #15 ·
Hi
Couple of points to make
1.Replating(or plating for that matter) makes the
tensile strength go to hell in a handbasket.
If you want brittle bolts be sure to replate them!
Always use new stuff, you will be way more
happy.
Jeri
Jerry - thanks for that. Im not an expert but that has definately been my expereince. Im buying new from now on. Re plating might be good for mudguards but for me its a no no for bolts.
Cheers.
 

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I'm not a metalurgist, but I'm pretty sure that cad plating does not alter the strength of steel. Chrome does. The term is "Hydrogen embrittlement". But even that is somewhat over-stated as a problem from what I've learned in talking to industrial platers.

Cadmium is pretty soft and the hardware you are replating was previously plated and sized appropriately for plating. I'm very doubtful that your seized bolts are from replating cadmium on the hardware. The plating process would involve stripping off the old plating, and removing any rust as well. So I would expect them to be undersized, if anything. I tend to think you are looking at new hardware store UNF or UNC fasteners screwed into BSW threaded holes. Or even metric fasteners screwed into BSW threaded holes. I am always amazed at people who force coarse thread fasteners into fine thread holes, or vice versa. They simply have no concept of thread pitch. Hell they don't even know that there are two types of thread pitches in US threads, let alone metric, BSW, CEI, BA and all the rest that have been out there over the years. I'm still learning. I just learned about BA threads a month or so ago. I thought I was working with pooring made 8-32 or 10-32 threads until I learned they were actually 2BA which are just slightly less than 32 tpi and cut at a different angle than UNF.

I guess the best rule of thumb for working with vintage stuff, especially if not from your home country is if it does not screw in by hand, it is probably not the right thread type. Before now I would suggest you buy a Machinery's Handbook or similar pub for your country. But with the internet available to all of us, just google threads and the country from which the machinery is from and see what the possibilities might be.
regards,
Rob
 

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Discussion Starter · #17 ·
Rob,
Yes, that all makes good sense.
My situation is probably a little different since the PO re-caded most all of the bolts on the bike. So, im wondering why so many of the bolts dont fit properly and Im left with a lot of stripped threads? Why would anyone go to all the trouble of re-cading the wrong size bolts? Thats why Im suspicous about the cading process itself somehow added too much material to the bolts. Maybe a rare thing or maybe the PO had no idea what he was doing so just re-caded any bolts he could lay his hands on that were the right length (most probable) not caring about stripping the holes. This probably is the more likely scenario since he did say he originally picked the bike up as a basket case.
 

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Kev,

As somebody mentioned, Cadmium is nasty stuff and not many small platers are doing it anymore. The hardware you buy in stores now is zinc plated. Although zinc is a glide metal and is also soft relative to steel and chrome, it may go on thicker than cad in the plating process. It could be he got zinc instead of cad and this is contributing to the problem. Maybe somebody more familiar with plating can talk to the newer zinc plating processes and how they compare to cadmium.
regards,
Rob
 

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I'm not a metalurgist, but I'm pretty sure that cad plating does not alter the strength of steel. Chrome does. The term is "Hydrogen embrittlement". But even that is somewhat over-stated as a problem from what I've learned in talking to industrial platers.

Cadmium is pretty soft and the hardware you are replating was previously plated and sized appropriately for plating. I'm very doubtful that your seized bolts are from replating cadmium on the hardware. The plating process would involve stripping off the old plating, and removing any rust as well. So I would expect them to be undersized, if anything. I tend to think you are looking at new hardware store UNF or UNC fasteners screwed into BSW threaded holes. Or even metric fasteners screwed into BSW threaded holes. I am always amazed at people who force coarse thread fasteners into fine thread holes, or vice versa. They simply have no concept of thread pitch. Hell they don't even know that there are two types of thread pitches in US threads, let alone metric, BSW, CEI, BA and all the rest that have been out there over the years. I'm still learning. I just learned about BA threads a month or so ago. I thought I was working with pooring made 8-32 or 10-32 threads until I learned they were actually 2BA which are just slightly less than 32 tpi and cut at a different angle than UNF.

I guess the best rule of thumb for working with vintage stuff, especially if not from your home country is if it does not screw in by hand, it is probably not the right thread type. Before now I would suggest you buy a Machinery's Handbook or similar pub for your country. But with the internet available to all of us, just google threads and the country from which the machinery is from and see what the possibilities might be.
regards,
Rob
Hi
Its not only the material that is used but
also the process
https://dspace.lib.cranfield.ac.uk/handle/1826/3238
If the plating company involved uses the correct process
many problems can be obviated.
Now lets talk about small job-lot platers
Jeri
 

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Snakeoil mentioned "hydrogen embrittlement" above. I've heard that is a somewhat temporary problem after plating. I've seen it talked about in regards to electrolysis which can trap hydrogen in the metal. But, they say that you can heat the parts for "a while" to get the hydrogen to diffuse back out. Seems like you would have some microscopic potential spaces left in the metal, resulting in weakness. Maybe they are never 100% afterward.
 
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