saving threads in a captive nut ?

[steveo3002]

ive caught the threads in a captive nut on a car , cant really see any obvious damage so im thinking it can be saved

im sure ive read somewhere running a tap up it isnt the right way to go , instead use a thread chaser or something ?

what do i ask for /order for the best chance of saving this ? its m10 x something (need to find out )

any tips /advise , ive hardly ever tapped any threads ever

 

[shocker]

As long as the intial few turns of the thread were OK then I cant see why a tap wouldnt do it.Of course you might want to think about WHICH tap you use.....if you have some good starter threads then a plug,No3 tap should engage the threads immediately and then chase up the correct turns.A No2 would be a better gradual start,again so long as you could see and were sure it was following the initial turns and it might do a better job of cutting gradually into the area thats crossthreaded due to its taper.
As usual with taps any less than HSS is a waste of time and money and could leave you with a worse problem.Also go easy and lubricate a lot,backing out often to clear debris.
Now someone who knows much more than me will come along and say thats all ********!!

The other option is of course to drill out and tap a size up,or helicoil it.

Good luck!And let us know what happens......

 

[wyn]

I'd say use a tap as well...as you say, just need to be careful as to what the pitch is.

 

[shenion]

If you can get from the back, running the tap from the back will work well. Usually taps will find the thread quickly from the front. If only the first few turns are fubar'ed, then a tap should work.

 

[steveo3002]

its the start of the thread ive damaged ..

how do i go about getting it started , its in the most alkward of places ..as you would expect lol

 

[gordon stephenson]

If you are worried about removing some of the metal with a tap,you could try using a harder bolt(allen bolt) etc,to reform the thread,Just put a couple of hacksaw cuts about thread depth along the length of the bolt, plenty of lubrication and apply a good pressure as you wind it in and you should pick up the original thread,

 

[steveo3002]

gordon i had thought of that ..just scared im going to make it worse

 

[Shox Dr]

Drill it out and put another one in

 

[pedrobedro]

A taper tap should start and clear the thread for you.

 

[gordon stephenson]

Shox Dr is correct, try to restore the thread first plenty of lube and use a forward and back system same as using a tap. and if not successful drill out (if you have room) and fit a replacement rivnut etc.What sort of load is this nut carrying?

 

[Shox Dr]

I should add captive nuts are notorious for binding up and working loose. Even after cleaning up, if not worse. You then have a bigger problem of removing the bolt as well

Save yourself a lot of grief and drill it out

 

[steveo3002]

its holding the rear beam /axle on the car ...cutting it out and fitting a new one would be extreme hassle as i dont have power where i can drop the axle off , plus its right next to the fuel tank

fingers crossed it can be saved , i didnt force it

 

[Welderpaul]

If you tap it, go for a no 3 tap first. Its more likely to quickly engage with what threads are left. 1st/2nd tap have a long lead-in and are more likely to start tapping a second thread which will cut most of any decent threads away. I'd try a bolt first.

 

[brookie456]

If you tap it, go for a no 3 tap first. Its more likely to quickly engage with what threads are left. 1st/2nd tap have a long lead-in and are more likely to start tapping a second thread which will cut most of any decent threads away. I'd try a bolt first.

With Paul on this, rolling taps cost the proverbial 2 limbs

 

[steveo3002]

you mention 1,2, 3 cut ....which is the most tapered one ? ive luckily found a set of 3 in my dads old tool kit

 

[Welderpaul]

1 is most tapered, up to 3 which is least tapered. Have a close look at them. Should be obvious when you compare them

 

[steveo3002]

yep ok got it ...got one of each here

 

[Shox Dr]

Good luck and be careful as I've already said captive nuts have a habit of breaking lose, the last thing you need is a tap stuck in a spinning nut

 

[Uniqueusername]

If you tap it, go for a no 3 tap first. Its more likely to quickly engage with what threads are left. 1st/2nd tap have a long lead-in and are more likely to start tapping a second thread which will cut most of any decent threads away. I'd try a bolt first.

Seconded.........

 

[steveo3002]

thought id update this

used the tap 3 as instructed ..was a bit nerve wracking but it went ok after i got it started , bolt back in and a happy bunny now

thanks for the infos