Uni III – Gripper Problem at End of Bed

Hi – I have my (early) Universal III up and running and it’s printing very well and all is great except for the paper release/gripper problem at the end of the bed. I posted on this awhile ago and have been tinkering with the problem on and off ever since and still no luck. I have to yank the paper out of the grippers. Here’s what I’ve done so far:

– cleaned and lubricated the gripper bar assembly. The grippers work fine when lifted with the pedal.

– removed, cleaned and re-attached the trip lever – it seems like it’s in good shape (photo) 

– lubricated the push rod

– rotated the cams

– placed a thin shim behind the gripper cam (photo)

I can see movement of the trip lever and push rod when the cylinder moves to the end of the bed, so I know the trip lever roller is moving up onto the gripper cam. But it’s simply not enough to push the gripper pins far enough to raise the grippers. I have pulled on the top of the trip lever to see if more pressure would get the grippers to lift, but I can’t get any additional movement.

I took measurements on how far the push rod goes in at two locations. At the feedboard, using the pedal, the rod pushes in about 1/2″ more than at the end of the bed.

I’m hesitant to add another shim behind the wedge without further advice.

Hoping for some suggestions. Thank you!

 

 

    

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Jeffrey Lay
4 months ago

Ellie, Not sure if this is resolved but I had a very similar problem at the beginning of summer with my late model Uni III, not sure my experience will be helpful, here goes:

In my case the problem was A) excessive wear due to the sharp angle that the MR-68 Roller was meeting the opener cam. B) the looseness of the cam itself because of the slugs I had put behind it, plus Accu-Shim steel tape I put on the front of the cam. C) Lack of proper lubrication and adjustment of the gripper stems played a role too.

Slo-mo videos of the follower engaging with the cam revealed that, in my case, I was damaging my cam follower/roller, bending the pin it rotates on slightly, possibly because of the repeated hard impact on the forward corner of the cam. This was also making the gouge on the surface of the cam much worse. The roller itself had worn well out of spec particularly the edge, so:

I re-adjusted the fulcrum (WD-40 Specialist Rust Penetrant was liquid gold here, the nut had seized) so that the face of the roller and not the bottom edge would meet the cam.

I had a machine shop fill the gouge in the cam, as suggested here. They also straightened out damaged split shanks that hold the cam on so it would sit firmly and stop trying to fall out/rock/wobble. They also removed the roller and flipped over it so that the less-worn edge was contacting the cam.

Removed the steel tape whose edge was cutting into the cam follower, and the slugs-as-shims behind the opener cam.

Removed/cleaned/lubricated the gripper assembly/stems (you wrote you had already done this) In my model the gripper assembly looks like this:
https://vandercookpress.info/universal-iii-gripper-bar-questions/

In the photo figure (B) are nuts/threaded pins that control how high each gripper stands up when the push rod uh, pushes. Mine were too low, and adjusting them seemed to make up for the shims I removed under the cam. However if the pins were adjusted too far up, the grippers wouldn’t close enough to grip thin stock tightly or prevent dust from sneaking under the gripper heads so I adjusted while the assembly was attached so I could test each gripper with scrap of onionskin for a firm grip. This was a pain.

Eric here had a tip to polish the gripper stems with graphite flakes, however I could not access the stems I had to settle for carefully blown in graphite while the assembly was off the press, but it made a difference.

Fritz did not have a replacement for the worn MR-68 so I was prepared to replace the shims if necessary with the understanding that I would likely be exacerbating the problem in the long run but thankfully the grippers open smoothly and high at the end of the stroke now.

Hope something in there is helpful :) good luck.

Jess Snow
4 months ago

Hi Ellie, I’ve been following along since my SP-20 has a similar issue at the end of the bed. If WD-40 isn’t enough to loosen that fulcrum nut, try PB Blaster and let it sit a bit. It smells horrible and is best used in a well-ventilated area, but it really cuts through rust and crud. Penetrating oil also may work on heavily fixed parts. WD40 wasn’t enough when I was working on a heavily rusted press a few years ago. Good luck.

Paul Moxon, Moderator
Admin
4 months ago

Ellie: I agree that it’s absurd. Dan’s suggestion, is one I overlooked. Are you certain that the push rod and spring are inserted into the hole in the cylinder on the operator’s side?

The Arm NYC
4 months ago

Have you tried adjusting the fulcrum point? You will have to remove the X-17151 trip lever and loosen the lock nut in order to turn it. Changing the fulcrum position gives you more or less gripper action. It might take some trial and error to get it right.

Paul Moxon, Moderator
Admin
4 months ago

Re: lock pin. have you checked that the condition of the spring and behind the latch. .

Re: soldering. I doubt that it isn’t original. It’s probably shiny from contact with the cam follower. The parts look to be original as well.

Re: opener cam. If you replace the screw with a longer one you could add more shims.

Re: push rod. Sheet 211 of the manual shows that the gripper lever leans slight outward with the carriage is in the middle of the bed.

Eric Holub
Editor
5 months ago

My old SP-20 came with an aluminum shoe that slid on to the original flange, increasing the width enough to open the grippers fully.

Paul Moxon, Moderator
Admin
5 months ago

Pleased to see your checklist as you work through this problem.

It may be a combination of wear on the outside of the gripper opener cam and wear on the bottom of the gripper pistons. Did you rotate them when you did the gripper cams?

Did you apply a metal-faced adhesive tape to the outer edge of the cam as I suggested in February of 2021: https://vandercookpress.info/knurl-pin-sheered-off/#comments

Another thought: Does this press hav two trip wedges on the end of the press? If so then the cam may be in the wrong position. Please post another pic.

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