Challange Gordon goes thunk

Long range assistance in diagnosis is about like reading tea leaves. You sound like you are fairly knowledgable in trouble shooting. If something makes noise, something is moving. It is either because it is broken or has come loose. The trick is to find it. Try to isolate where the sound comes from. Difficult as the whole machine is connected and the sound is transmitted from one part to another. By moving the flywheel back and forth a small amount you should be able to make the sound repeat. An assistant can cycle the flywheel while you get ear and eye close to the press. The hand to feel is appropriate too, but not inside the press while the assistant is moving the wheel. You may wish to try the old mechanic’s trick of holding the tip of a screwdriver to the part and the handle to your ear. Have someone take a photo of that.

Thanks inky. I guess I’m looking for wisdom like “pull the bull gear, here’s how” or “don’t even think of pulling….”

Otherwise it’s a matter of the stick-in-the-ear method or dropping links to seemingly unrelated parts to see if the thunk is still there. The problem is easy to hear and feel by rocking the flywheel at the right point in the cycle (and only takes a few degrees of movement).

I’m hoping it’s as simple as a dry spot in need of grease or a broken spring.

When you say there is no lost motion in the roller mechanism, have you moved the roller mechanism about to the middle of the bed, grabbed hold of it, and tried to move it up and down (which will take some strength) without the rest of the press moving? I would be surprised if it didn’t move AT ALL, especially in a press that old. In my C&P 8X12, I had to shim the bearing where the roller actuating arm is connected to the press, to reduce the “play,” because it was getting worn and therefore loose. The looseness allowed the roller system stop for a tiny amount of time at the end of its travel and/or when gravity took over (can’t remember exactly), which caused a knock.

Geoffrey, I didn’t do that, but will give it a try. By lost motion, I was referring to all the various links between wheels & frames. Those seem tight.

One thing we did discover is that the vertical link from treadle to crank rubs part of the platen frame, and has been for some time, but that doesn’t account for the rest of the sound..The metal is too stiff to bend by hand, and I couldn’t get it out of the press to apply to an anvil.

There is also a frame on the front of the press, moved by a cam on the left, that appears should slid in under the platen frame during impression, but for some reason, it doesn’t quite make it. (Would be much easier to describe if I knew the proper names for the parts. If anyone knows of a drawing labeling all the bits, please let me know.)

The following is not the same press as yours, but hopefully it will give you the names of some of the parts….

http://www.boxcarpress.com/community/manuals/cp-newseries-parts-list.pdf

Scroll down to the bottom to see diagrams of the complete press

In your last paragraph above, it sounds like you are describing the rocker lock. If your press works the same as a Chandler & Price, then the rocker lock should go in and lock the platen in position during the impression (when the press prints).