10EE backgear mounting 3 phase motor

[Karl_T]

Turned the motor shaft down to 1.25 and keyed it. Got the sliding backgear shift (beside motor shaft) working nice.

Now, at least for me, every job has at least one fark up. The marked hole for the motor was off 15 thou and I did not oversize the bolt bore - dumb. On first install, I stripped the threads on the motor. Got to heli coil this one before motor assembly. Then manufactue motor mounts and put it all together

 

[Karl_T]

OK, now I think farked myself but good...

Being a cheap a$$, I ordered this heli coil kit from Amazon:

https://www.amazon.com/gp/product/B096TVHFPX/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Drilled and tapped, no problem. But their helicoil absolutely will not turn into the freshly tapped hole. tried multiple things. I have done this job several times over the years, normally no big deal. Teaches me not to cheap out, McMasters has worked every time.

OK, the tap I used was 13 TPI but oversize. No specs on the tap itself. I drilled 1/2" for this tap. So using the tap formula I remember you add the lead to the drill to get the thread diameter 1/13 + 1/2 = .077+.500 = .577 or 37/64 by 13 TPI tapped hole.

Is this the way standard heli coil works so I can buy from a better vendor??

Or am I really screwed and need to come up with some sort of custom insert? That is drill way over size to maybe 3/4x10 and then drill and tap back to 1/2x13? Better ideas could be used here.

 

[dfloen]

Do you have the install tool to wind it in? I very much prefer timeserts for thread repairs. You could make a custom insert on the lathe as well

 

[Karl_T]

Yep, it was a complete kit with everything for multiple sizes -drill, tap, install tool, break off tool, and the insert itself.

Mcmaster gets $507 for theirs, Amazon is only $70 but crap quality

I have done this enough I want to have a set on hand.

 

[dfloen]

a helicoil for a 1/2-13 thread uses a 33/64 drill

 

[Karl_T]

Yep, I think the tap and dril are undersized in the cheap a$$ kit I bought. That's why the coil won't go in.

Looks like just one size and five coils from McMaster is going to hit me over $200. AND it may not work now that I've already drill and tapped the hole

THE REALLY BIG QUESTION HERE??? Is the Mcmaster tap going to be 13 tpi so i can just chase a new tap in? I have been rading all the product details with no answer.

 

[dfloen]

If the internal threads are 13 tpi, the outer threads will also be 13 tpi, on a coil type insert

 

[Karl_T]

<GULP> went with McMaster Carr

 

[Karl_T]

made side plates and test fit. Original DC motor in back. See pic. Just need to weld bottom to side plate, then paint. Assemble and install in lathe

 

[dfloen]

looks REALLY good!