Tips to clean up a thread into a blind hole?

landmarkjohn

I've got a damaged thread into a rear wheel carrier, M14 bolt goes through bottom of shock into this threaded blind hole.

Got a new bolt. Waiting for taps, tapered and plug, to arrive to try and clean up the thread.... it's going to be fingers crossed (as opposed to threads crossed ).

Any tips? Thanks.

jca

landmarkjohn wrote: »

I've got a damaged thread into a rear wheel carrier, M14 bolt goes through bottom of shock into this threaded blind hole.

Got a new bolt. Waiting for taps, tapered and plug, to arrive to try and clean up the thread.... it's going to be fingers crossed (as opposed to threads crossed ).

Any tips? Thanks.

Don't get impatient and rush it. Start with the first taper tap it could give you the first thread, then the second taper, use plenty of lubricant 3in1 oil is very good for threads. When I did that work we used a lube called deftap, it was brilliant especially on small diameters machining threads. If there's a machine shop near you they might use it. Use a good strong light and a try square to make sure the tap is square. Good luck!!

You can use wd40 for tapping also.
Good look !
I did something like this year ago and the bolt was a really weird pitch and the tap was hard to get.

DublinDilbert

If you don't have a tap, you can cut / grind 4 slots along the sides of the correct size bolt. Run the bolt in/out of a nut a few times. Then use it to clean out the threads.

landmarkjohn

Thanks for the support folks, you know where I was at :eek:

Got it sorted, ran through a taper tap, tricky enough as it was on the horizontal and no space for tap wrench, had to use a 1/4" drive socket of some imperial size or other! I could feel it cutting through the bad thread and then it freed up as it hit the good threads (I think). There was a bit more swarf than I would have liked but hey ho.

Then ran through the plug tap by hand and then the bolt. Must be honest I didn't tighten up the bolt to specified 164 Nm but I gave it a good tighten. FYI a new wheel carrier would have been €900 odd + VAT + whatever other bits I would have needed so there was a bit riding on it.

CJhaughey

landmarkjohn wrote: »

Thanks for the support folks, you know where I was at :eek:

Got it sorted, ran through a taper tap, tricky enough as it was on the horizontal and no space for tap wrench, had to use a 1/4" drive socket of some imperial size or other! I could feel it cutting through the bad thread and then it freed up as it hit the good threads (I think). There was a bit more swarf than I would have liked but hey ho.

Then ran through the plug tap by hand and then the bolt. Must be honest I didn't tighten up the bolt to specified 164 Nm but I gave it a good tighten. FYI a new wheel carrier would have been €900 odd + VAT + whatever other bits I would have needed so there was a bit riding on it.

You could always have tapped it for a Timesert if the threads didn't clean up well.
Timeserts are very strong.

case_sensitive

I read a tip somewhere that you should alternate direction periodically when tapping long threads; for every full rotation clockwise, half a turn counter-clockwise. Since I started doing that I haven't had a tap fail on me. I use cutting grease and a tap on a variable speed cordless drill, there's rarely room for the big tap wrench.

Got a big tub this https://www.actioncan.com/product/ct-90-compound/ from All metal fasteners in Finglas about 3 years ago, about halfway through it now. Smell like cola-bottle sweets too.

jca

case_sensitive wrote: »

I read a tip somewhere that you should alternate direction periodically when tapping long threads; for every full rotation clockwise, half a turn counter-clockwise. Since I started doing that I haven't had a tap fail on me. I use cutting grease and a tap on a variable speed cordless drill, there's rarely room for the big tap wrench.

Got a big tub this https://www.actioncan.com/product/ct-90-compound/ from All metal fasteners in Finglas about 3 years ago, about halfway through it now. Smell like cola-bottle sweets too.

Lesson one, tapping and screwing. You mustn’t have done metalwork in the Tec:D None of that fancy grease though:pac: you’d be lucky to have a tap wrench that the clamp isn’t stripped...

case_sensitive

jca wrote: »

Lesson one, tapping and screwing. You mustn’t have done metalwork in the Tec:D None of that fancy grease though:pac: you’d be lucky to have a tap wrench that the clamp isn’t stripped...

Yep! Didn't offer it in my school past Junior Cert, I learned by breaking tools and ruining car parts in my 30s. And just like everyone else, my tap wrenches are both wrecked.