Crank Shaft Pin Falls Out

Hey there,

I’m running a new style C&P 12x18” press and usually it works with no major issues. Lately, however, the crank shaft pin has started to pop out regularly. Now it’s happening 2-3 times a day. It’s really oily around the gears, so I’m sure it could use some cleaning. Is this occurrence something we should worry about, as in the overall health of the press? Is there a good way to make the pin stay put? I’ve tried roughing up the sides and edges with a file, but that didn’t help (could do more). I’ve also tried packing some thin paper strips with the pin to provide more pressure in the fitting, with little effect. What else can I try?


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For starters, clean out the oil. If that doesn’t work, it may be too small, and you may need to buy a new one. Have it milled to fit your specific application. These are a pretty standard type of wedge key.

These are frequently filed down too far. Get a new one. They are usually called gib keys. A good hardware store might have them. McMaster-Carr has them I believe.

Gib-Head key. mc master has them. measure yours and order a couple.
on a used machine, you may be able to use it as it comes. on new machines we had to “fit” them by filing carefully.
in the mean time, if you “arc” it by slightly bending it, it should snug it up. this usually only works for awhile.

Excellent! Thanks for the tips! I’ll look to see f we can get a new one because ours looks to be worn down. I’ll try arcing it in the meantime and see if that helps this week. All good suggestions and much appreciated!

All of the press friction and impression resistance ends up on that key. It is a big duty for a small part.
We would tap them in (use a piece of brass or copper so not to damage steel keyway) then remove then with a key puller., looking for contact marks. Then file just those contact areas off to allow the key in deeper. This process can take time as it needs to done carefully. You want the key to fully engage the gear to the shaft.
The key puller is a generic slide hammer with a custom made tip to engage the key. Mine is made specifically for this job.
I am in Milwaukee, Wis. USA. if you wanted, i would let you use my key puller. I would ask that you pay the shipping on it and a refundable deposit.

Just to reiterate ericm’s comment. TAP it in. Don’t bash it in.

All good comments, and so I added a new pin which was actually WAY larger in dimension than the old one we used, and the press runs great now. The impression is regular and doesn’t change. The sound is consistent. The new pin doesn’t move or fall out and stays put. All in all, a great resolution to the issue and now I don’t have to tap in the pin 3 times a day. Thanks to all!

Awesome! good job!