Pin drive bolts splitting Help Please

[David Kirkham]

I have some photos that I took earlier today, but I just can't break free to post them. For some reason, we are selling parts like crazy right now.

I will try to post them soon.

David

[David Kirkham]

WOW! What a day. Lots of parts to ship.

Anyone who is following the thread knows the Trigo pins I measured were at 76 degrees. I assumed (very BAD thing to do) they were a standard 82 degree taper and so we made about 100 of them at 82 degrees. When things started to not look right, I busted out the angle gauge and found I was a dummy...and so was someone else. The tapers on the pins were 76 degrees??? WTH (For you non-Utah people, that means "What the Heck." We later found out the Trigo hub adapters have a 90 degree countersink in them. Someone had a little too much weed when they were making thos pins.

So, we had a bunch of bum parts. Concentricity, is critical in this part (along with most parts) so we specially machined the jaws on the lathe to fit a collet chuck. We then chucked the pins up in the collet chuck to make sure they were absolutely straight, and we corrected the taper to 90 degrees. Bummer to machine the parts when they are already hard, but carbide doesn't really care too much. You just have to go a bit slower.

[David Kirkham]

You see, what most people (who don't machine) don't realize, is how easy it is to chuck a part up in the lathe and not get it in straight! Happens ALL the time. A collet chuck really helps to bring that concentricity back to 0.

I HATE crappy parts.

David

[David Kirkham]

Notice how we cut the tapered end (the pointed end of this part) right off. Compare to CNGreen's part above with the crack in it

The original Trigo part as a very sharp area where the thread starts (the taper area). The problem is, as that area gets thinner and thinner the steel obviously gets weaker and weaker. Cutting the thread into the part only exacerbates (I learned that word from Jamo ) the problem. Then you torque the boogers out of that thin little starting thread and BAD things start to happen. That first thread will "pull" out and raise up. It will raise up where it is the weakest--right at the end of the thread. That weak area will raise up (remember, only on one side now--right at the beginning of the thread as it only starts in ONE area) and it will cause the pin to tip!

Sounding familiar???

So, we trimmed the point off (remember CNGreen's crack in the taper) and then deeply deburred the thread so it could not pull. This becomes a very important object lesson. Many times you can REMOVE material from a part and make the part a STRONGER part. Here is a perfect example.

Now you know why our parts cost so much. We try to think about everything. Thinking takes time; deburring takes time, programming takes time, finding the right alloy takes time; you get the point. You can purchase cheap parts...but sometimes (well, usually) it will come back to bite you on the bum bum.

Notice the large nose radius on the taper.

[David Kirkham]

Here is a final pic of the finished part. The cool bronze color is from the precipitation hardening. Notice the color was lathed off when we corrected the taper to 90 degrees.

OK, they are now officially for sale. All takers, please contact me!

kirkhammotorsports at gmail dot com

REMEMBER!!!

These are 90 degree tapers!!!

[Paul F]

David, most excellent.

22 please. What's the total with shipping and tax?

[David Kirkham]

Paul,

22 each is $8 shipping anywhere in the continental US.

This thread is so long I can't even remember what I said I'd sell the first batch for???

Just call me tomorrow and give me a visa and I'll ship them tomorrow. (I know I have a check of your's too; happy to deal with that any way you want. We have not cashed it.)

David