I’m trying to separate two components that are held together with metal pins. I’ve done this before, but those pins were tapered. These are not. I’ve read that they may have been installed by an industrial press, and that they may (or may not) have Loctite on them. I’ve tried hitting them with a punch and hammer, but admittedly not too hard. I don’t want to damage them. They didn’t budge a micron.
What’s the best way to remove them without damage? (The components need to go back together.) Heat the surrounding metal? Use a bigger hammer?
I assumed that one would heat the surrounding structure, but on the assumption that it has Loctite, I’ve found that it’s recommended to heat the pin (actually, on the page I found, the bolt) with a soldering iron.
I’m going to guess there’s not loctite in there. Even if there is, unless it’s the blue or green Loctite you should be able to break it without heat.
Anyways, without seeing the part, I’ll suggest the same punches that beowulff linked to. You need something with a flat head, the same size as the pin. Anything else (like a nail or a tapered punch) will cause the pin to deform, expand and wedge itself in tighter.
ETA, I’m assuming this is a small pin. I had to replace a wheel on something that had a huge pin (probably a half inch or so). Never did get it out.
Make sure the punch closely matches the size and shape of the pin: Obviously, it should have a slightly smaller diameter. If the pin has a convex end, it helps if the punch is slightly concave.
Heat can defeat Loctite. But you may need more than soldering iron - perhaps a serious heat gun or a small torch.
Liquid nitrogen shrinks metal - might free the pin.
If you suspect corrosion, the hot setup seems to be a 50/50 mixture of acetone and ATF (automatic transmission fluid) - better than commercial penetrating oils. Needs several hours to penetrate.
If a punch won’t work, you will need some sort of press. A C clamp will work for something small or a small hydraulic press such as I have in my garage for things a bit bigger.
This may not be suitable for your case, but to apply steady pressure you can chuck a pin punch into a drill press. You won’t get the kind of force that an arbor press would provide, but banging on the punch can sometimes deform a pin and wedge it in tighter.
I don’t see how heating the pin will help. If heat is needed to soften loc-tite, it should still be applied to the outer part to make that expand.
Maybe this would work- can you get around it with a big C clamp? If so, put a nut whose inside diameter is greater than the pin on the bottom, and something on top of the pin and press it out.
GaryM: In fact, it is. But there are other things held together with pins, and I wanted to keep it general.
Xema: I don’t think I’ve ever seen concave punches for sale. My punches all have flat heads.
TriPolar and racer72: I don’t have a drill press. (Rather, my drill press is the kind you strap a hand drill into.) Nothing heavy-duty. No hydraulic press.
Son of a Rich and racer72: I thought about a C-clamp, but what usually happens when I try to improvise like that is that the tool breaks.
Loctite turns to powder at 450F. So if you suspect Loctite, heat to at least that temp.
Is it a solid pin or a roll pin? Roll pins require a special punch.
You need to support the work but don’t forget a hole for the pin to go into when you drive it out.
Oh and one last thing. Don’t force it, just get a bigger hammer.
I’ve never seen a roll pin punch, but I hate those things [roll pins]. I usually get them out with a flat tipped punch, or in a pinch, a vary carefully selected machine bolt. One that’s the same size as the hole so it pushes on the face of the roll pin evenly and doesn’t make the problem worse. Using a nail or phillips screwdriver will make the problem worse.
Roll pin punches are the absolute only way to go with roll pins. If you deal with roll pins, once you try a roll pin punch you will never go back to a regular punch.
Fortunately, I have a set of punches. I don’t even remember what I bought them for, but I’d never use a screwdriver as a punch. I use screwdrivers frequently, and Phillips ones are too easily damaged by misuse.
I did support it, but it looks like it’s going to take more force than I anticipated. I need a bench block. There’s one made specifically for this, but it’s OOS. I think I’ll fashion a block out of a 2x4.
