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rawgerz
The hell was that?
Premium
join:2004-10-03
Grove City, PA

retapping threads

I need to have a bolt hole re-tapped. The threads stripped out just from disassembly which I can tell it was overtightened during assembly.
The bolt is steel and the housing the bolt goes into is cast aluminum. The bolt still catches inside and will stay in but I have no idea if it can be saved. I can get the same bolt online so that's not an issue. The circumference of the hole is about 8mm.

Can they usually be saved without going to a larger size?

Since I have no experience rethreading I'm just going to try and find someone that does.
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You can't make all the people happy all of the time. But it should be common sense to shoot for the majority.



Ken
Premium,MVM
join:2003-06-16
Markle, IN

I have re-tapped a couple things and I have always had to go one size larger. For example current hole is 8mm, new hole would be 9mm.



Dennis
Premium,Mod
join:2001-01-26
Algonquin, IL
kudos:5

said by Ken:

I have re-tapped a couple things and I have always had to go one size larger. For example current hole is 8mm, new hole would be 9mm.
Ditto....and it doesn't help that aluminum is so soft. Watch your torque when you put the new bolt in.
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Warzau
Premium
join:2000-10-26
Naperville, IL
kudos:1

1 edit
reply to rawgerz

Concur go up in size and tap it out, go slow use lube and back it out to clean it up.
Or you can sleeve it.



TODarling
U.S. Army Retired
Premium
join:2004-11-27
Fort Smith, AR

1 edit
reply to Dennis

This is what you need, by using this you maintain the same bolt size.

»www.emhart.com/products/helicoil.asp

Barfly

join:2005-03-22
Richmond, CA
reply to rawgerz

Another vote for helicoil inserts. I've used them for Volkswagen engine block repairs and they're stronger than the original threads. Not to mention, as TODarling See Profile said, that you can keep the same fastener size.

But I recommend having a machine shop do the repair---they'll have the proper drill sizes and taps, as well as the special helicoil insert driver. It was an inexpensive repair for my Volkswagen block, but I admit, that was 20 years ago!
--
Not only is there no God, but try getting a plumber on weekends. - Woody Allen



rawgerz
The hell was that?
Premium
join:2004-10-03
Grove City, PA
reply to rawgerz

I called a few machine shops. One sounds like they would do it, but doesn't know if they can or not since he thinks it's too small or is some proprietary bolt or something.

I just don't want to end up doing it myself. I have a tap and die set somewhere, but I don't know if it's standard or metric. Let alone I have no idea how to measure threads even with the little gage. And I defiantly don't want to try to use those helicoils, I just know I'd screw it up since theres no margin for error here.

Maybe once the new bolt comes I could get away with some locktite...
--

You can't make all the people happy all of the time. But it should be common sense to shoot for the majority.



dolphins
Clean Up Our Oceans
Premium
join:2001-08-22
Westville, NJ
kudos:7
Reviews:
·Comcast

1 edit

You could use epoxy »www.acehardware.com/product/inde···005&cid= but if you have to unbolt it in the future, you'll need a torch.
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robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1
reply to rawgerz

OK -- re-tapping it is easy. They sell individual taps at Lowes, etc. Just go slowly and keep backing it out to clean the cuttings (a little oil helps a lot - just regular household oil like 3in1 will be fine). No reason to worry because if you screw it up you can take it to somebody and have a helicoil put in as it takes a still bigger hole. Oh yeah -- definately go one size larger. If that is a problem with what you have to drill out on the part this bolt connects to the tapped part, then you will have to go with helicoils to keep the same size bolt.

This is not hard. You can easily do it.

For measuring threads take it to Home Depot or Lowes -- they should have a guaging set mounted there somewhere that you just screw the bolt into. Try each hole until it screws in easily -- that's it!



mrmagoo55

join:2001-05-11
Cartersville, GA
reply to rawgerz

I have had a Helicoil holding the rear axle shaft in my truck for about 8 years now!



whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9
reply to rawgerz

Helicoil insert or re-tap it a larger size. Those are your only real options.



alphapointe
Don't Touch Me
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join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..
reply to rawgerz

I have an aluminum relay rack that has quite a few of its' holes stripped out. (10/32 screw size)

Should I just take all of the equipment out of it and take it to a machine shop and have it retapped to 12/24? That's a LOT of holes.
--
Resistance is NOT futile...It's voltage divided by current.



whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9

said by alphapointe:

I have an aluminum relay rack that has quite a few of its' holes stripped out. (10/32 screw size)
Chances are that you are just going to strip out the 12/24 holes in short order. Scrap it, and buy a new one. (Likely cheaper than getting all of them re-tapped.)


alphapointe
Don't Touch Me
Premium,MVM
join:2002-02-10
Columbia, MO
kudos:2

That's kind of what I thought. Would you suggest a steel one if I can get it? (I assume steel won't strip as quickly as aluminum)
--
Resistance is NOT futile...It's voltage divided by current.



rawgerz
The hell was that?
Premium
join:2004-10-03
Grove City, PA
reply to rawgerz

I asked around if anyone used those coils, I got a few pauses. And the bolt is proprietary, so I can't go up a size with out using those coils.

I already ordered a new bolt and tomorrow I'm going to try to get the housing added to that order since it's only $50 extra. But if I can't add it in time I think I'll try the epoxy.

I would do the home depo approach, but the closest 2 are 40 minutes away, I can't tell you how many times I wish there was one locally. Situations like this make me envyious
--

You can't make all the people happy all of the time. But it should be common sense to shoot for the majority.



whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9
reply to alphapointe

said by alphapointe:

That's kind of what I thought. Would you suggest a steel one if I can get it? (I assume steel won't strip as quickly as aluminum)
Yes. The reason your threads are stripping out is that (besides not being careful), you're using steel bolts in an aluminum frame.


alphapointe
Don't Touch Me
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join:2002-02-10
Columbia, MO
kudos:2
Reviews:
·Socket Internet ..

said by whizkid3:

said by alphapointe:

That's kind of what I thought. Would you suggest a steel one if I can get it? (I assume steel won't strip as quickly as aluminum)
Yes. The reason your threads are stripping out is that (besides not being careful), you're using steel bolts in an aluminum frame.
I bought it used, and it was in pretty piss-poor shape anyway.
--
Resistance is NOT futile...It's voltage divided by current.


Hall
Premium,MVM
join:2000-04-28
Germantown, OH
kudos:2
reply to rawgerz

Helicoils are pretty acceptable especially when the other option is to scrap the cast part and start over. Using a helicoil would also allow you to use standard bolts instead of proprietary ones.
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whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9
reply to rawgerz

said by rawgerz:

I asked around if anyone used those coils, I got a few pauses. And the bolt is proprietary, so I can't go up a size with out using those coils.
You're getting bad information. Every good machine shop or mechanic knows what a helicoil insert it. If they don't know, move on quick.

Proprietary bolt? Very unlikely, if you mean the threads are not standard; unless you mean it has a very unusual head on the end. Again, I suggest you're getting fed a line from some idiot. And if the threads were indeed 'proprietary', which would be beyond rare, then you can still go up in size with either a helicoil or re-tapping it. I suggest you need to find a professional. Surely you must have some serious racers out there in Grove City. Ask one of them.


dolphins
Clean Up Our Oceans
Premium
join:2001-08-22
Westville, NJ
kudos:7
reply to rawgerz

Upon reading further I see that epoxy would not work for you as you need the threads to tighten this casting to something or something to it.
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Pacrat
Old and Cranky
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join:2001-03-10
Cortland, OH
kudos:2
Reviews:
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1 edit
reply to rawgerz

What the heck is a "proprietary" bolt/thread size? I've never heard of such a beast. There are UNC,UNF and metric(several standards), and there are bastard (uncommonly used) but in over 40 years of being around machine/die shops, I've never heard of a proprietary size.

What is the stripped out hole in... you say cast aluminum, but cast aluminum what. is there enough "meat around it to just drill it out and tap it the next size up? How deep is the tapped hole? If you can get this piece off what ever it's on so you can get a good, straight shot at it, there should be no reason why it cannot be retapped. What's this piece on... mower, motor, what? That might give you an indication of whether or not it's a metric size.



Hall
Premium,MVM
join:2000-04-28
Germantown, OH
kudos:2
reply to rawgerz

said by rawgerz:

I would do the home depo approach, but the closest 2 are 40 minutes away...
When many people refer to Home Depot or Lowes, it's kinda like using a "Kleenex" or making a "Xerox", you know, generic terms for a tissue or a copy.

Home Depot = Lowes, Ace Hardware, True Value, Menards, local mom-n-pop hardware store.
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sdgthy

@optonline.net
reply to Pacrat

They probably just used that term in case it was something like Whitworth (BSW), which they probably wouldn't have taps for. Heck, some may have only limited metric taps.

BTW: about heli-coils, I'd be careful about using those in a AL part. Heli-coils are stainless, AL and SS don't get along well, they are far apart in nobility, and the AL will corrode quickly in the wrong enviroment.



Coma
Thanks Steve
Premium
join:2001-12-30
NirvanaLand
reply to rawgerz

In the past, I have used a pop rivet type of thing, where the rivet is actually inside threads of what ever (bolt). Without going out to my shop and looking, I would take a look at these to see if they would work for you.



Hall
Premium,MVM
join:2000-04-28
Germantown, OH
kudos:2
reply to sdgthy

Concerned about dissimilar metals ??

»www.emhart.com/products/helicoil···/tt5.asp
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dolphins
Clean Up Our Oceans
Premium
join:2001-08-22
Westville, NJ
kudos:7
Reviews:
·Comcast

1 edit
reply to Pacrat

Click for full size
Topped out 145mph
said by Pacrat:

What the heck is a "proprietary" bolt/thread size? I've never heard of such a beast. There are UNC,UNF and metric(several standards), and there are bastard (uncommonly used) but in over 40 years of being around machine/die shops, I've never heard of a proprietary size.
Non-common or specialized, happens when proprietors(owners) only want you to use their products and want to make it difficult to replace parts without first consulting them.

That's my best explanation as I couldn't find an online definition.

Edit: Many moons ago, I had to order parts,bolts,nuts,jets directly from Yamaha for my son's 80YZ. They all are considered proprietary. Then later I restored an 82' 280ZX with a few after market specialty items which also required me to order directly from Datsun/Nissan
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dolphins
Clean Up Our Oceans
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join:2001-08-22
Westville, NJ
kudos:7
Reviews:
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reply to Hall

said by Hall:

Concerned about dissimilar metals ??

»www.emhart.com/products/helicoil···/tt5.asp
Right on target, Bullseye!
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sdgthy

@optonline.net
reply to Coma

Thread-serts are nice if you need a strong thread in something like sheetmetal. I don't think that is what the OP was looking for though.



sdgthy

@optonline.net
reply to Hall

Yeah, I am. I've run into so many issues mixing SS and AL, that I tend to strongly recommend it be avoided.

Interesting link though, I'll have to look into that futher.



rawgerz
The hell was that?
Premium
join:2004-10-03
Grove City, PA
reply to rawgerz

I meant that the bolt was a proprietary type, not the threads as you can see. I'd be hard pressed to find a bolt like that, but a larger size I'm sure.

This isn't for a car or engine, it's for a vacuum. The bolt you see holds on the armature, for lack of a better word, that holds on the attachments to the motor. Since it got a quarter stuck in the housing I started to take it apart to get to it instead of picking it up and shaking it. But someone on the assembly line overtightened this one bolt and the threads couldn't take being disassembled.

I would get into taps and dies if I busted up more bolts. It would be nice to have the tools to do it and some experience, but I just can't justify the cost when it happens so rarely.
I called up the guy I had do some cylinder honeing for me awhile back, I thought they were pretty good but he told me he wasn't sure if he had the tools small enough to do it. Or wouldn't want to waste time on something they can't charge a lot on?

Either way, instead of going all over the place trying to get what I thought would be a quick fix for most of these outfits, I'm just going to buy a new housing and do it that way.

I was just curious if the current threads could be saved or not, since I had no idea of those helicoils before it's interesting to read about now. Remembering back, I actually had to have a dealership fix a bad thread in the casing of an ATV I had. Two bolts were 10mm on the outside, but the hole diameter was different so I mixed them up during reassembly and it had to be retapped, it was also aluminum. So they must have used those helicoils to redo it. At least I don't have to wonder about that now

Thanks for the explanations!
--

You can't make all the people happy all of the time. But it should be common sense to shoot for the majority.