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Vandercook SP20 problem

We are having a problem with the Vandercook SP 20. We are unable to get the rubber rollers to come in contact with the lower chain driven roller. It seems that when the rubber rollers are in place—we think correctly—there is 1/16 to 1/8th inch gap between the main metal roller and the rubber rollers. Is there a way to lower the rubber rollers further, or is there a way to raise the main roller? The two rubber rollers were just referbished. I am attaching a photo to show how we have the rollers set up. We have removed the front rubber roller, and indicated where the gap is. Any help would be appreciated

image: sp20 roller problem.jpg

sp20 roller problem.jpg

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Did you set the rollers with a .918” roller setting gauge? If you used a .968” gauge instead, this is exactly what would happen.
In case you don’t know, the rollers are raised or lowered by turning the black roller adjusting knobs at each end, always with press on impression, in the middle of the bed, and roller brackets lowered. Loosen the small lock screws on the side of the roller bearing block first, and tighten after.

We have done this. Our gauge is .918, and we have adjusted the black knobs and lowered the rollers as far as far as they will go, yet the drum still won’t come in contact with the rollers. Should we/can we raise the drum? or could it be the metal roller bearings are the wrong size?

Sounds like you need to check the rollers again for Diameter correctness.

Put a large type-high form on the bed, place a straight edge on it, and extend it over the drum. The drum should be just slightly above .918”, not sure how much.
Some SPs do have an adjustment for levelling the drum. I’ve only seen it once, but look for small Allen screws going through the shaft.
Is the carriage at the correct rest point with rear roller directly above the top of the drum?
I don’t think it is possible to put the wrong size roller bearings into the assembly.
When SP rollers are undersize, you can’t lower the rear roller far enough to reach the .918 gauge because the roller gear bottoms out in the gear rack. The gear teeth allow a narrow range of adjustment.

Have you measured the diameter of the rollers? The other settings should not have changed since your rollers were re-covered. I believe that Vandercook form rollers are 3” in diameter, any deviation from that would cause problems.

Well another glitch is we know this SP20 was broken for some time, and we don’t know how it was broken. So there could be a number of problems we don’t know about. We will check the roller diameter, but could the drum have gotten out of place? I will check those allen screws and see if we can’t adjust the height. Can you tell from the photo if we have the rubber roller in the proper position?

registercm

Vandercook SP20s are just sort of loaded with problems waiting to happen. I’ve had four of them and had to rebuild them all.

If everything mechanically checks out, everything is in the correct position, etc., I’d suggest, as others have, that your rollers are of the incorrect diameter. Rollers should be purchased from folks who are familiar with the Vandercook specs, not from folks who offer the cheapest price.

I borrowed an SP20 for a job and it had brand new rollers. It didn’t take more than a day to figure out that they were bought on the cheap and wrongly configured. And with everything else that was wrong with it that press soon became an expensive loaner.

Gerald
http://BielerPress.blogspot.com

From the photo, the form looks to be correctly installed.
The roller appears to be about the same diameter as the gear, which is correct. Vandercook rollers are sized to large increment diameters, like 3”, 2.5”, and not to 8ths or 16ths. Even 1/16” undersize could interfere with adjustment, but only on the gear side, and not on the front roller. Even an undersize roller might be adjustable to .918” on the operator side.
There can be problems when the sheet-metal fllanges on which the roller-adjusting mechanisms sit have been bent, but the front flanges in your photo are fine.
I have also seen new rollers that copied the diameters of shrunken or reground rollers. As a temporary solution I removed the shims under the gear rack allowing the gear end of the roller to be lowered.

Is the gear on the form roller meshing with the rack gear?

Another possibility—are the drum springs present? The cylinder is at print height when it passes over the drum. The drum is spring-loaded, with fenders that push against the cylinder (in the margin next to the bearer) and lower it so the packing isn’t inked.
You should be able to push against the drum and feel the springs give.

Thank you everyone for your helpful suggestions, and special thanks to Paul Moxon who gave of his valuable time to walk us through some of the problems. Once we realized the drum moves, we found that one side moved and the other didn’t. Upon closer inspection, we saw the fenders had set screws which adjusted the return height of the drum. On the non-operator side of the press, the set screw was turned down all the way, so the drum only returned a bit of the full height possible. By backing off that set screw, the drum rose up. We leveled the drum, and held our breath as we lowered the rollers, and flipped the switch. Delighted cheers arose as all the rollers were spinning nicely. Think we’re in the home stretch now, and sort of reminds me of “Sling Blade”, when Carl looks at the broken tiller and says, “Ain’t got no gas in it.” In retrospect, it seems so simple.