Roller Height Variance (10x15 C&P)

I’m having a problem with roller height variance at different points on the bed and was curious how others have solved this problem.

Things to know: My 3 rollers are brand new and my trucks are nylon and all have the same diameter. My rails are in good shape. My bed looks to be flat and free from debris. I have a 10x15 old style Chandler and Price.

For example, I can get my rails taped neatly and evenly and pull a perfect 3/32” ink strip on my roller gauge in the center of the bed, but when moving out toward the edges of the rollers, it quickly goes to a 1/8” +. This also happens if I pull a measurement toward the very top or bottom as well. Initially, I was going for a 3/32” measurement in all four corners of the bed, but then I had no roller contact with the form at all… I could pull no ink on the gauge in the center of the press.

I’ve attached a little diagram of my measurements at different points on the bed. Again, these measurements are the size of the strip of ink I pull on my roller gauge.

My initial solution to this problem was to place paper strategically behind the chase - sort of like makeready for the bed. I’m curious if others have had this problem and what solutions you’ve come up with. Thanks!

image: 10x15_bed.png


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What kind of rollers?

Check your bed and rollers for flatness and cylindricity with a straight-edge and a flashlight, it sounds like your bed has a low spot.

Sounds to me like the bed is somewhat dished in the center. Not really surprising considering the age and use an OS press is likely to have had in its existence.

A paper underlay for the form can’t really hurt, but it isn’t a permanent solution.

Very simple test for starters, just to eliminate *bowed bed* syndrome:-
Lock up best possible full out form, Type Matter, Blocks, Cuts, Mounting base, W.H.Y.? Locked up as normal, (no need for powerful lock up!) but planed down carefully on a piece of onion skin, bible paper, air mail etc???
It will be virtually impossible to get NO CONTACT marks over the entire sheet, with a view to using the form as a proving block, with Engineers blue, (or even standard printing ink)
Either one, (the blue) rolled over the back of the form at microns thickness? a fairly accurate guide can be seen from the coverage as in a normal proof!!
The form and chase slid in and down as per normal, clipped in /locked in and then removed straight away.
Crude initial test will give reasonable guide as to how serious (or otherwise) the problem may be.

Contact or non contact will show on the Blue??

In essence this method is precisely that which Engineers used to employ to *Scrape* surfaces accurately.