Pin drive bolts splitting Help Please

[David Kirkham]

Gents:

I am sorry to say, the education is about to continue.

When I measured the Trigo pins the first time, I just grabbed a simple protractor tool. They obviously did not have a 90 degree taper and 82 looked pretty close so I figured that is what it was.

Well, today I bused out the Mitutoyo angle gauge to check our pins as we made them...it wasn't pretty. Our pins are right on the money at 82 degrees, but I held the taper up to a Trigo taper and noticed it was slightly off...hmmm???

What gives?

Remeasured our pin...82 degrees. Remeasured the Trigo pin (this time with a proper angle gauge...76 degrees!!!!!!!



Let's see. Standard tapers in machining. 60, 82, 90, 100 and 120 degrees. NO 76 ANYWHERE I have ever seen.

Oh well. I'll wait to see what the adapter is actually machined to and then we will fix the pins. No big deal, but irritating, none the less.

Perhaps, (and only perhaps) this is why some people have had problems with the pins. Perhaps the taper of the pin doesn't match the taper of the hub adapter. If the tapers don't match, you will have very high point loading on the parts, exceed the yield of the material, and have a galling fest. Galling could very well cause the pins to tip and cause all sorts of grief.

David


ps. CNGreen
Better send me along the tracking number. Fed Ex didn't deliver today.

[Dominik]

Hi David!

The taper on the exisiting pins are not machined, rather hammered on in a die. Probably the same time the internal hex is done.
That's why the taper is off, wrong angle, and not concentric. The thread is probably also chased in that die.

Please measure if the thread is concentric, or just let the Trigo pin run on a 1/2" stud in a drill press.

Let's measure adapters, and if they are NOT 90 deg, offer pin in 90 deg nevertheless.
People could taper them on a drill press using a standard 90 deg taper.

Of course, if we can confirm that they (and Superformance) share all the same angle, you could offer the pins drive nuts in that angle.

Dom