C&P Ink Disk Surface Worry

I’m working on bringing a C&P 12x18 back into use. The press was shut down 30 years ago with ink left on the disk. That caused serious pitting in the center and toward one side. I tried to polish it out but gave up and took it to a machine shop today. While there we put a straight-edge across and either the disk is seriously warped or it is dished, with the center about 3/16” higer than the outer edge.
Thats my question: Is the disk supposed to be dished, or is it supposed to be flat right across? I’d like to give the shop better direction when they actually put it in the lathe next week. Thanks for any ideas!

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So far as I know, ink disks are supposed to be flat, or nearly so.

Try to make sure that this press doesn’t have a split disk (the center rotates opposite of the outside—there’s a gear ring on the back). For a solid ink disk, I would be a bit surprised to see this much warpage. There may be a limit of how much the machine shop can take out without wrecking the integrity of the casting.

I’ve seen some literature somewhere that mentioned ink disks being finished a touch higher in the center (i believe it was Kluge). But that being said - the disk on my C&P is dead flat & works great (12x18 also).

I actually machined the ink disk on my press too. Mine seemed like it had been bent at some point in its life & had a low spot along the edge that fell off & remained un-inked for a few inches. Anyway, after some inspection and actually chucking it up in a lathe and indicating it in - I determined I was best off just making it flat.

I could possibly see the merit to making the disk a touch higher in the center in that the roller might have less pressure against the disk in its middle (from flexing along its length) and the higher center of the disk may help compensate for that. But to put that in perspective if your rollers flexed that much, it would affect inking in center of your form - which in reality you don’t get.

Oh, and as far as material removal - on mine it was in the neighborhood of .050-.060” total that I took off.


Edit: I was re-reading your post & I agree that 3/16” sounds like quite a bit to remove. Before turning (machining) you might want to do some more inspection to confirm the amount & exactly whats happening with that surface. I’d suggest sweeping it with a dial indicator (like mentioned above, preferably while in the lathe). What you’re looking for is that the total deviation isn’t all showing in the same direction - in other words, that you can get your disk to fully clean up without having to remove that much material.

I think I would look for an ink disk from a press that has been parted out.

Can you post a photo? It sounds like you have a split disc meaning there is a seperate round insert in the center that originally would have rotated the opposite direction from the main part of the disc, supposedly to better distribute the ink on the rollers.

It seems more common today to see these out of use, one or more of the bevel gears that attached underneath having been removed. A problem with the design is that when cleaning the disc after use the thinned ink would get into the groove between the plates and after the solvent evaporated the ink remaining in the gap between the two discs would harden and often lock up the mechanism. That meant that the gear on the bottom of the disc shaft would have to be removed and the two parts of the disc separated for cleaning.

Also, sometmes the center disc is not seated all the way down into the main outer disc. That may be the problem with yours. If you do have a split disc and suspect that is the problem remove the center disc by pushing it out from the bottom. The shaft of the center disc goes through the center of the shaft of the outer disc and extends beyond it for mounting the gear. Remove the center disc and clean both discs thoroughly, then lightly oil the recessed area and the shaft and put the parts back together. It may still be a bit snug but a few light taps with a rubber mallet in the center should seat it. When disassembling or assembling look for burrs caused by dings on the end of the shaft that may make it difficult to take apart or put together. Just file them off.

If you have a single piece disc and its out that far there is a serious problem that I doubt machining will fix.


Front Room Press
Milford, NJ

Thanks for those comments! My disk is the single piece solid type, 18” diameter and 0.300” thick at the edge. It has no crack or visible damage.
When I brought the disk to the machine shop late Friday afternoon I could not get them to put it into the lathe. So I’m waiting for a call this week to run down there when they do. Especially after your comments I like to see how it dials out when chucked by the bearing shaft end. Laying the straight edge across the surface several places had me worried.
Thanks again.


Another option besides milling the surface is to fill the worst areas of pitting. One method I’ve seen involves drilling several small holes into the area to be filled and with the backside of the holes plugged pouring lead, or even better babbitt, into the pitted area, sort of like filling up a lake. After cooling, the lead/babbitt works easily and can be made level with the disc and finally sanded smooth. The lead/babbitt in the drilled holes anchors it to the disc. I’ve also seen Bondo (auto body filler) used.

If you do have the disc milled down, especially quite a bit, you may need to shim it up at the point the shaft goes into the bracket to bring the disc surface back to its original height in relationship to the rollers.


Front Room Press
Milford, NJ

Hey Hugo,

Found that reference to an ink disk that wasn’t completely flat (see pic below). Its not much to go off of & who knows if C&P would have followed suit. The only reason I even bring this up is that if it turns out your disk is indeed a cone/convex shape & the material removal is too great to risk turning it flat - you may just opt to somewhat follow the existing shape while cutting a new surface on it.

Keep in mind that disk is not very rigid to start with (in terms of machining). Thinning it substantially may compound your problem by making it even less rigid & making it tough to achieve a decent surface finish (although if the center is your high point, there should be less concern about affecting the rigidity by removing the bulk of the material here).

I personally turned my own disk & while I’m thrilled with the results, I can honestly say I underestimated what a chore it would be. The lack of rigidity I mentioned will inherently make the disk want to chatter or ‘sing’. It can be controlled with the correct tooling, depth of cut, speed & feed rate, but has to be constantly monitored & adjusted to keep from developing that harmonic. Furthermore, due to tweaking speeds to keep a stable cut I didn’t really get the exact quality of finish I was hoping for & ended up spending a few hours of hand lapping (in the lathe) to get everything looking as good (or better I’d like to think) as the factory finish.

Take that for what you will & don’t let it discourage you, I didn’t exactly have the optimal equipment available for the task at hand, but made due with what I had. Honestly I’d say the best way to finish a disk like this would be grinding - but that’s a whole different can of worms.


image: Kluge Ink Disk.jpg

Kluge Ink Disk.jpg

dont worryabout the disk just make sure the rollers get ink allll the way acrosss, also skip a sheet every other impression this will insure the best coverage on the rollers to the type. todd

Here is the outcome:
Once we got the disk on the lathe and checked things out with a dial indicator it was not near as bad as it looked laying the straight edge across it. (There is something about that light shining through under the straight edge that really amplifies the surface error). The center was high by 0.050”, the runout at the perimeter edge was 0.020”. That’s what made it look so bad when laying the straight edge across it, on the far side that would project to more than 0.1”. Chucking the disk by the center bearing stud alone was insufficient for machining. The disk was just screaming with vibration when starting to make a cut, and applying chucks at the machined ratchet periphery was the solution. The disk is a fair bit thicker in the center and taking material off there is not so bad. To get decent tool action we had to cut at least 0.010” off the lowest parts at the periphery. So now the disk is mostly 0.270” thick at the periphery instead of the original 0.300”, and it is straight across. It does not feel like the disk is fragile. At about half of the outside edge about 10% material was removed.

Thanks for all of your input!


image: PressInkDiskMach.jpg


Nicely done,

Your experience sounds pretty much on par with how things went for me. Those Jack-screws around the outside are the ticket - the diameter I could support on mine was limited by my chuck size & therefore constantly on the cusp of chattering at the disks extent (like mentioned above, limited by the equipment available).

I had a suspicion things would look better measured up in the machine - glad to see that’s how it played out. Anyway, nice work restoring some former glory - it looks great.


image: 2009-11-18 21.36.05.jpg

2009-11-18 21.36.05.jpg