Removing Freely Rotating Swaged Steel Pin

How about setting up so the opposite side is pressed against a multi-flute countersink to act to stop the pin from turning?

If you can tolerate the pin spinning in the hole perhaps quite a bit I've f ound drilling rotating pins works if you angle the piece, idea is to angle the part so the drill spins the pin but off-center, on 'average' there will be a part where the bit is hitting where the bit surface speed will be lar ger than the pins.

Maybe you could CA or loc-tite a small metal rod in the drilled end and cla mp the rod in the vise?

Dave

found drilling rotating pins works if you angle the piece, idea is to angl e the part so the drill spins the pin but off-center, on 'average' there wi ll be a part where the bit is hitting where the bit surface speed will be l arger than the pins.

lamp the rod in the vise?

BTW CA gets gummy and lets go at a fairly low temp if you get tired of wait ing for acetone to do its thing.

Maybe a job for an EDM shop?

bob prohaska

That would be my suggestion.. Clamp the gun so the pin is forced against either a countersink or another drill bit. Using a drill bit on both sides, one end or the other (or both) will be drilled out enough to release the pin.

I can see that.

Likely 8mm then. That is one of the ponts where metric and inch measurements come close. (5/32", 5/16", 5/8").

How shallow? I can't tell from the photo.

My thought is to get a 5/16" diameter multi-flute countersink bit (used to be Severance, now some other company, IIRC), and mount it vertically so it sticks out just enough to allow the force to be applied to the cutting edges. Use it as an anvil to support one end of the pin, and use a smaller drill bit (perhaps 5/32" or so) to drill most of the way through. (You use the smaller drill bit so the torque from its cutting edges is likely less than the torque needed to start the countersink cutting.)

When you get say 3/4 of the way through (set up the quill stop on the drill press to prevent the tip of the drill bit touching the tip of the countersink), flip it over and drill from the other side.

Then increase the size of the bit to do something like the same hole area increase (5/32" would be about 0.245 square inches, so increase by the same for 0.395" diameter -- too big, looks like you can target the final diameter of 0.315" (8mm) on the second step. (Or, maybe you'll find that you need to start smaller, and increase by the area of the first bit which works. Maybe start with a 0.125" bit, then the next would be 0.176", and then the 0.216", and finally 0.315".

Or -- maybe skip the final 0.315", and put it over a bench block and drive it out with a pin punch, as the walls will be thin enough to give way by this time.

I strongly doubt that the crazy glue will be strong enough, even if you could get it into the holes between the pin and the walls.

You have what I would try, at least.

It looks like you can remove that linkage assembly from the action by removing C-clips, so you won't be juggling as heavy a bunch of metal, and controlling it will be easier.

Good Luck, DoN.

I see that I should have read ahead instead of just posting. The only thing that this doesn't have which I suggested is the starting with a smaller bit, and increasing sizes in steps of equal added hole area to keep the torque applied to the countersink about the same.

Enjoy, DoN.

snipped-for-privacy@snyder.on.ca fired this volley in news: snipped-for-privacy@4ax.com:

That's not only how it 'would be' done, that's very often how it IS done. One of my prior bosses had a block set up to accept any one of about a dozen different stub-length drills for just that sort of job.

The other way (on with things that don't care about heat) is to weld or braze an extension onto the pin, and vise the extension.

Lloyd

"Pete C." wrote in news:52bccd9c$0$29568$862e30e2 @ngroups.net:

I thought about that. I suppose if I put a cutter on both ends, one fixed & one under power, one of them will do the job before the other one does. Or both will be the same, I don't care. My only concern is not being able to see what's going on underneath, and fixturing it so it can't scoot sideways.

Doug White

snipped-for-privacy@yahoo.com wrote in news: snipped-for-privacy@googlegroups.com:

Because the holes are mashed up, getting a good fit will be tricky. I don't want to spin the pin too much, because I don't want any more wear in the holes I'm trying to save.

So far, the winner seems to be a double cutter set up.

Doug White

snipped-for-privacy@yahoo.com wrote in news: snipped-for-privacy@googlegroups.com:

Yeah, I'm actually concerned that the heat from amchinign will soften it up too much unless I'm VERY careful.

Doug White

Another suggestion is to mount 2 drills in a lathe, place the center punched pin between them and slowly turn it. One or both drills will intermittently grab and give you a hole that you may use an easy out in to allow you to drill out the other end. Please let us know what works. To reply to this message please remove the AT after the kgs1 in the reply to address.

To a conservatist's it truly is a free country, YOU may do whatever they wish. KG

User Bp wrote in news:l9inat$3ln$ snipped-for-privacy@news.albasani.net:

I'm trying to do this on the cheap. The team lost their varsity status several years ago, and runs mostly on donations now.

If I could get parts more easily, I'd just replace the whole assembly. The US importer would only sell me the pins & broken arms, and only two of each. For some reason, they abruptly stopped selling parts entirely last spring. I found another source for some more common parts, but no one who works on these has ever seen a broken linkage before, so they don't have those pieces.

Doug White

"DoN. Nichols" wrote in news: snipped-for-privacy@Katana.d-and-d.com:

This seems to be the concensus. I'll check out my countersink supply & see what I can find. The swaged bit is quite shallow. If I start out small and drill with ever increasing drill bits, hopefully I can open it up without the countersink slipping.

Doug White

You may be able to angle the Dremel such that the pin rotates slowly as you open up the dimple, so you can thin the wall fairly evenly all around enough that it can compress when you drive it out. Supporting the far end may help.

A drill bit held at an angle may deepen the hole while it spins the pin. I wouldn't use a good bit from a set for this.

Drillbit in lathe chuck, opposing bit or csk in the tail-stock.

you beat me to it! That'd be my approach too.

Gunner Asch wrote in news: snipped-for-privacy@4ax.com:

In theory, this is a one time deal. Some bright students decided that closing the action by pushing the cocking lever against the bench was easier than doing it by hand. Before we could stop this practice, they'd put their weight behind the process & broken two of the linkages. These two got busted a couple years ago, and we haven't had a repeat performance since.

We still have to keep an eye open in case one of the older students remembers this trick & recommends it to one of the newbies. With time, it will fade from the collective memory and then we just have to watch out for somebody re-inventing it.

Every year the students come up with new ways to screw up. We keep adding things to our list off do's & don't's, but its a challenge to keep up with them.

This is at MIT. If you are interested in science & technology these days, the path of least resistance is to play with computers. The students have never taken hardware apart, and just have no mechanical intuition at all. Most of them don't have any idea how to operate a screwdriver properly. They either let things get loose & wonder why they can't shoot well, or they overtighten them, either cross-threading them, stripping the threads or breaking things.

It wouldn't be quite so bad, except all of the target pistols are European or Russian, and many are out of production. Getting parts for the ones that are still being made is hard enough.

The previous coach was difficult to get along with, and largely did everything himself because nobody wanted to deal with him to help. He was no gunsmith, and was disorganized. We inherited a lot of broken guns with no idea what was wrong with them, and quite a few that weren't labled as being broken. One student has been shooting a single shot .22 free pistol with no extractor. Nobody told him he wasn't supposed to have to fish out every fired round by hand, so he never mentioned it to anyone. I only found out it was missing by accident.

At least now I know what I will be doing with my retirement...

Doug White

KG wrote in news: snipped-for-privacy@4ax.com:

The double cutter approach seems to be the favorite. I had originally been thinking of doing this in a mill, but upon further reflection, I agree that a lathe is easier. I don't have to make a fixture for the cutter on the "bottom" end, I can just put it in a collet. I also have full visibility on both ends to see how things are progressing.

With all this in mind, I took a few measurements. The pin is smaller than I thought, it's 6 mm in diameter. The dimple is too shallow to allow using even a 90 degree countersink, so I'm left with drill bits or end mills. I think a pair of 1/4" ball end mills might work, but something smaller would be better. The swaging isn't perfectly centered, and I want a little margin so I don't end up cutting into the link. I only need to get the swaged part thin enough that I can easily press out the pin without distorting the link.

A pair of 13/64" ball end mills should do it. That works out to 0.203", compared to 0.236" for 6 mm.

Time to go shopping.

Doug White