SP-20 roller height problem

I’m having trouble with inconsistent roller height on my SP-20. I’ve set them to type high using my gauge. When I move the cylinder a few more inches down the bed, the rollers are now above height and no longer contact the gauge. When I roll it back towards the dead bar, the return to type high. Do I need my carriage bearings adjusted? What’s causing this and how can I fix it? I’m mid-job, of course…

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Paul Moxon, Moderator
Admin
10 years ago

You’re in excellent hands with Perry. Meanwhile, you can read Gerald Lange’s article on carriage bearing adjustment: https://vandercookpress.info/vanderblog/literature/articles/lange-adj/

kyle van horn
10 years ago

ALSO! Check that the threads on the roller bearing-blocks aren’t caught on the leading edge of the metal tabs they are supposed to rest on – they can be easily mis-aligned when cleaning, and once they’re caught wrong in the press, they can shift all over with the torque of the press and cause a variety of problems. Even having one of the four screws caught may wreak havoc.

kyle van horn
10 years ago

Oof, that’s a tricky one.

Is there any rocking fore and aft on the carriage (like a teeter-totter front to back)? It acts like you’ve got bearings that are mis-aligned, and it’s reacting to which direction it’s being turned. You could perhaps prove this by holding the front side of the carriage down as you roll forward, the rollers *should* keep contact with your type. Logic should dictate that it would be more likely to keep roller contact on the downward push and lift on the return, but that’s my best guess.

Other things to look at: Are your form roller bearings square to your cores? You can tell by lifting them in place and spinning them freely by hand – if they’re square, the bearings should be rock steady as the rollers spin. If they wobble back and forth, then you have bent cores (or screws, or bearings) and you’ll get stripes of ink as the rollers traverse the bed. Also (and less likely) you have a bed plate on this press. Be sure it hasn’t slipped or shifted. Be sure also that you’re not checking type-high at the front edge of the press – that section of the press bed is WAY below type-high.

Good luck!

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