helicoil use

[Dean O]

Hi guys any one out there used helicoil to fix a thread before?

 

one of the captive nuts that hold the bolt for the jockey wheel to the frame of the chipper had somehow become damaged - so in my wisdom re-tapped it using the 3/8 tap provided in the kit to 3/8 in order to insert a helicoil.....

 

then realised I dont have the right size bolt - duhh

 

does anyone know if i can just use a 3/8 bolt to finnish off the process without inserting the helicoil

or does the sizing given on the tap allow for the down sizing of the hole size that would happen if it were inserted - so i actually need a 1/2 inch bolt?

 

 

hope that makes sense to somebody

 

Ta:blushing:

[Justme]

Normally when using a helicoil you reuse the existing bolt as after you increase the hole size with the combined drill/tap you sleeve it back down with the insert. I guess you bought the wrong kit for the job.

 

I dont know if they use standard sized taps. Would it not be easier to just get the correct bolt for the kit you have got?

[Dean O]

thanks justme

un-fortunately the bolt just worked itslef out whilst driving along (just one of the many niggly probs ive had with the chipper since i bought it)

the second bolt appears to be bent and probably wasnt the correct size to start with.

 

the helicoil kit ive got is one i got hold off the father in law.

 

the thread that ive drilled and tapped using the kit so far looks good to go if i can find out what size bolt will do the job.

 

ta

[treequip]

The heliciol tap is bigger than the finished bolt size thread so, if I understand right, no you can’t just put a 3/8 bolt in it.

 

What chipper is it and why are you using imperial sizes.

 

My suggestion would be not to muck about with helicoils. Grind off the old captive put a new nut and bolt in situ and mig the nut in place.

[Dean O]

the bolt is behind a plate welded to the frame so inaccessable without grinding this off first.

didnt want to go there as the frame is in lovely condition. (timberwolf 6 inch)

 

the alternative is for me to take the helicoil to a fasteners on monday and get one that fits it - but wanted to get it sorted sooner.

 

so sounds like the size given on the tap takes the down sizing of the sleeve into account.

[treequip]

No need to grind off the back plate.

 

Drill the old captive out from the front, grind the corners off a plain nut till it fits the hole and weld it in place from the outside and grind the weld flush.

 

Any welding and new paint will be covered by the jockey wheel clamp.

[Dean O]

ahh

good idea tree quip

 

might give a couple of bolts a try first though specially if anyone has any idea/ experience in what might fit. (especially as i dont have a welder handy)

[C.J]

I'm guessing your original bolt was 10mm and that you were replacing with a 3/8" because it was about the same size.A 3/8" thread has 16 tpi so the helicoil tap will have also cut 16 tpi but the hole diameter will be bigger.A 7/16" bolt has 14 tpi and a 1/2" bolt has 13 tpi so none of these will fit.M10 and M11 bolts are 16.9 tpi but will be too small for your new hole as well ,as the wrong pitch,and a M12 bolt is 14.5 tpi so also no good .You may still be able to drill and tap the hole to M12 but this may require a bigger hole on the plate that carries the jockey wheel.

[treequip]

The trouble with “friging” the wrong bolt into a helicoil is that you can dislodge the insert.

 

What size and threads are you working with?

[Dean O]

ooh bugger - i get you CJ

the bolt was (or atleast looks like a 10 mm /m10)

went to 3/8ths as that was what was available in the kit.

 

not much of an engineer i'm afraid so learning by my mistakes.