SP-20 roller bearer

I seem to be having an issue with one of the bearers (is that even the right term?) on the rear form roller on my SP-20. I can’t lower the roller height to type-high on that side. I can on the user side, but not on the opposite end. No problem with the front roller. In the video you’ll see the assembly is loose while the others are not. Any ideas?

(I’m taking Paul’s maintenance workshop at the end of April, so hopefully I’ll get my terms down then!)

Attached video: SP20_rollers

Subscribe
Notify of
7 Comments
Newest
Oldest Most Voted
Inline Feedbacks
View all comments
Fritz Klinke
Admin
12 years ago

I think Paul has the problem diagnosed correctly. The bearing is held in the ring by 2 methods. Locktite was specified by Vandercook to glue the bearing into the ring, or “staking,” a commond machine practice, was used. A cold chisel is used to put a nick in the outer ring on opposite sides of the bearing and that will hold the bearing in place. A roller undersize by 1/10th of an inch is a lot and may indicate an older roller that has shruken, or was possibly over ground when made. We sometimes see an attitude of “well, it’s just for letterpress” from some roller makers who think all we do is use numbering machines, so finishes and tolerences are unimportant to them when it is actually just as critical as in making an offset roller.

Paul Moxon, Moderator
Admin
12 years ago

The roller can’t be lowered any more because the gear teeth are seated at the bottom of the gear rack, 0.10 of an inch is significant. You have to recover the rubber on the cores.

Paul Moxon, Moderator
Admin
12 years ago

“Quick Change” form rollers used on Universal and SP series presses allow the diameter to be undersized to a greater extent than on older models where both rollers are bracketed in a frame, e.g. the No. 4.

The other factor in determining whether rollers need to be recovered is their hardness called durometer. I’ll have my gauge to measure this with me in workshop.

It’s a common failure of the Universal and SP20 roller adjustment assembly for the bearing to slip out of the ring. Your shims won’t effect the height adjustment, but telfon plumbers’ tape make for a more snug and uniform fit. Replacement assemblies are available from NA Graphics. http://order.nagraph.com

Paul Moxon, Moderator
Admin
12 years ago

Jonathan, I fixed the link in your post.

This is a common problem: the diameter of the rubber is undersized. If you take a pair of calipers, I trust you would find it to be substantially less that 3″. What’s happening is that the gear is bottoming out against the gear rack. The looseness demonstrated in your video is a result of having turned the adjusting knob, left to lower, beyond its effectiveness.

Copyright © 2024 vandercookpress.infoTheme by SiteOrigin
Scroll to top
7
0
Would love your thoughts, please comment.x
()
x