Awl--
I've sort of posted on this before, but I've got a little more experience now, hopefully will get a few more tips.
First, let me address Bottle: Yeah, Bottle, I know, *buy* the goddamm detent pin, already, buy it.... But, really, I can't... really... :) or... :(
I'm trying to retain a 3/32 ball in a 1/4" OD detent pin (brass), w/ a 1/8 inside shaft (steel). If you run the numbers, you'll see I've got .015 leeway (before the hole lip encounters the full diameter of the ball), ito peining over the lip of the hole to retain the ball--not a whole lot, but theoretically enough. After sufficient agony, I *can* get this thing to work. But it *is* an ordeal. I can make my life easier w/ .118 (3 mm) steel rod (more leeway), but I think I should be able to get the 1/8 to work.
I think I've narrowed the problem to punch geometry ito of giving a "proper" lip on the hole, and the Q is: What type/geometry of punch/set is best to use?
Initially I used a piece of 5/32 drill rod, turned down near the end to about .125, and then a nub to .089 or so (to "locate" the punch in the .096 hole), and then would whack it. Problem is, the ball most often would not protrude as it should, and thus wouldn't clear the inside 1/8 shaft, without a (w)hole lot of hassle.
What I'm doing now, with better results is this:
Instead of turning down the punch/set w/ a 90 deg. tool, I angle the tool
5-10 deg, giving me a slight cone, so that the punch just doesn't mash the material flat and downward, but sort of pinches the top of the mat'l inward more than downward, allowing more protrusion of the ball. When you look at the pin, you now see more of a "cut" around the ball hole, rather than a just a depressed area where the punch impacted.Better results, but still a little persnickety.
I know I can affect the "pinch" effects of this punch by varying the angle of the cone, and the diameter--maybe pinching more toward the edge will be better, etc.
Am I on the right track here? Is there any literature on ball retention techniques?
What I'm tempted to do is a machining solution:: Drill a thru hole of about .085-.090, and then c-bore a .096 hole, stopping just short to leave just enough lip to retain the ball properly. Problem w/ this is you need some perty accurate fixtures and a very good Z, and my limited skill set is strained as it is.... :(
Any opinions on this machining method vs. the peining methods?? Axing for trouble machining the lip, or go for it?
If I still have problems, I may just have to go with a .118 (3 mm) shaft, to give me a little more room to play with, peining-wise. Good way to go? Am I un-necessarily killing myself w/ the 1/8 shaft ito of narrow leeway for the lip?
Appreciate all input.
-- Mr. P.V.'d formerly Droll Troll