Roller core?

This is a bit of an odd question but here goes…

We’ve recently had a forme roller re-covered for our proof press. The roller ‘sags’ in the middle and thus doesn’t contact evenly with the distributor roller above it. So all in all, it’s useless.

Previously the roller had been covered with wood which was in a really bad way - cracked, uneven and falling off. It could have been like this for many many years as the press is 100+ years old. We don’t know the exact specifics because information on the press is vague.

I think it’s a fair assumption that the sag is caused by the weight of the rubber covering. The core/shaft cannot support it enough, and as it’s the forme roller it has nothing below it to provide constant support.

My thinking is the original wood covering was used because it was light weight which would then have a rubber covering applied to this to the correct diameter.

I should also add that the core length is 42”

The length of the roller is 34”

Quite big really.

So my thinking is to re-create a larger ‘core’ on the roller shaft out of metal, but it would either need to be very lightweight and/or hollow.

Has anyone ever seen anything like this? Any recommendations? Or should I just ditch this before it gets really scary?

Thanks in advance.

[EDIT] - just had a thought - maybe I could use a type of roller bearer…?

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What are the core and roller diameters right now? Larger diameter hollow tubing is stronger and lighter.

You might want to check out this discussion:

The company which replaced the roller covering should have tested it to determine that the roller is concentric. They should not have covered a roller shaft which would not carry the weight ot the rubber. I would call them and ask what they are willing to do for you.

Modernman - core dimensions aren’t to hand at present (my guess is approximately 20mm) but roller diameter is 79mm.

Jhenry - absolutely, I’m on the case.

Messed about with roller bearers last night - no dice.

That still leaves plenty of room for rubber. Not sure what the minimum recommended covering would be, but a 40mm core with 20mm of rubber seems like it should print fine.

Sounds interesting Modernman - thanks for the input.

Roller company are on the case - will post updates if anyone is interested. It might add some weight (no pun intended) to the discussion you highlighted earlier in this thread