[AT] Drill size for bolt tap question

[Al Jones]

What would be a recommendation on the epoxy?

Al

On Thu, Apr 13, 2017 at 3:05 PM, Stephen Offiler <soffiler at gmail.com> wrote:
> Yup.  My chart actually says the 7/8" tap drill on a 1"-8 thread gives
> 73%.  You'll have substantially less engaged thread if the tap drill hole
> is already 15/16", down in the 30% range I'd estimate.  I would fill that
> gap with a good epoxy rather than Loctite.
>
> SO
>
>
> On Thu, Apr 13, 2017 at 2:45 PM, <rlgoss at twc.com> wrote:
>
>> If I remember correctly, those drill/tap size recommendations are so you
>> retain 75% overlap in the thread engagement.  It should work, but will be a
>> loose fit during assembly.  It will easily be stipped out again, so use
>> caution.
>>
>> Larry
>>
>> ---- Al Jones <farmallsupera1 at gmail.com> wrote:
>> > I've got some wallered out holes on a Farmall Super A torque tube that I
>> > want to fix.  They need to be 5/8" coarse thread, but somebody stripped
>> 'em
>> > out, then did some sort of funky drilling, and now my holes are 15/16" in
>> > diameter.  I'd like to fix it myself but the longer I look at it the
>> more I
>> > fear a machine shop visit is in order.
>> >
>> > My notion is to try to tap the holes for a threaded insert.  If I drill
>> the
>> > holes out any larger for a larger tap, it's going to eat away the square
>> > boss on the side of the torque tube, so I want to avoid that. Now, the
>> > chart I am looking at says you need a 7/8" hole for a 1" tap. That means
>> > the existing holes are 1/16" too big.  Can I still tap it with the 1"
>> tap,
>> > Loctite the daylights out of the insert, and get it to hold? These holes
>> > are on the left side, and there weren't many implements that used these
>> > holes, plus it's going to be mainly a show/plow day tractor.  But I do
>> want
>> > them functional and they have to "look good."
>> >
>> > I have a good torque tube, but this is an early (probably built the first
>> > or second day of 1950 production) white demonstrator tractor, so I'm
>> trying
>> > to keep the castings original.
>> >
>> > thanks!
>> > Al
>>
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