How to make a gripper bar for Star job press?

(The photos above are just from an example I found on line that seems to have the bar with the S curve — leterpress commons — not mine.)

My only guess about the S-curve is that when fully open, it will no longer be in contact with the stud and the spring will rotate it such that the grippers raise up, but when closing it hits the stud, slides over it, and that is what pushes them closed?? Still really unsure about how it works?? Any ideas? I can just get some kind of flexible wire and start experimenting.

It looks in your first photo like the curved rod is held against the stud or stud by a coiled spring attached at its other end to a point on the arch of the frame of the press. As the platen closes that s-shaped rod slides along the stud and as the platen closes it reaches the point where the motion closes the grippers onto the platen. But as the platen continues to close to contact the type, it looks as though the mechanism would pull the grippers against the bed or the lockup in the chase. And the s-shaped rod sliding on the stud would wear badly very quickly even if well greased. It is not a logical mechanism. Does your press have that curved rod as part of the gripper arm “axle” shaft as pictured? Or is the shaft on which the grippers are mounted different from the picture? Or do you not have the gripper assembly? The image of the press has some inconsistencies that make the mechanism impossible to function as needed. Can you post a photo of that portion of your Star for comparison?

Another solution, if you are not trying to stay true to the image (which may not be accurate either! :-) is to make the bar for the grippers with a straight bar across the end in place of the “S” bent piece, with a bar about 1/4” thick, 1/2” wide, and about 4-6” long, with a set-screw in the 1/4” edge bearing on and perpendicular to the rod on which the grippers are, across the end. At the top left corner (viewed face on) drill a small hole, into which put a short length of stout steel wire bent at a right angle, and on the other end bend a hook. Get a small coiled spring with hooks on both ends, that you can attach down a ways on the feed table support arm with a loop of wire around the arm, and hook the stout wire link to the spring and to hole in the arm on the gripper rod. The arm on the gripper rod may need an added weight on its end to counterbalance the gripper arms.

When the platen is open, the weighted arm should hold the grippers open. As the platen closes, the link at the arm’s top to the spring below will pull the grippers closed on the press sheet while the impression it made, and as the platen opens the spring will release them so gravity opens them again.

Grippers and gripper bar are missing entirely from my press, so I have to make one (I have gripper “fingers” off another press). The stud.on the frame of my press does have a noticable groove worn into the top surface.

Here is what my press has. (I had the rough looking eyelet for the gripper bar added to replace a broken one but it lines up with the other one)

PXL_20260131_135849117_exported_1769868131082.jpg

I wouldn’t be surprised if the Star has an unusual mechanism this, the rest of it is a bit odd too (but works pretty well!)

This is a possible solution based upon the images you posted and an examination of the gripper assembly on my 5x8 Kelsey.

KelseyStarGripper.png

Cool, thanks! That’s pretty much what I also envision to replicate the original. Maybe the curve is only to avoid the rollers? (Though shouldn’t be a problem just eyeballing it). In which case it doesn’t have to be some precise shape that affects the operation of the gripper? I’ll do a bit of prototyping with some soft bendable metal and see what happens. Thanks.