C&P O.S. Split Disc on a C&P N.S. Press

I have been curious as to how compatible Original Series and New Series parts are between the two press. I recently learned that that the bolts on early New Series presses are still the same as the Original Series, at least up to ‘24. I happened to have an Original Series with a split disc, and a New Series with a solid disc, so I thought I’d give it a shot and take some photos for posterity. I’ll comment them in order so that the assembly makes sense.

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Here is the press as it was, with the solid disk. I’m not getting rid of the disc, because I think it is a rather good one, and I already have shimmed it to the height I want it to be at.

If people want to find shims for these presses, you can get them at McMaster Carr.


image: Solid Ink Disk

Solid Ink Disk

The bolt and gear from the Original Series press fit fine, no issues there. The Ink Disc Bracket had a hole to receive the fastener on this particular press, but I’m not sure if later models removed this.

image: Ink Disc Bracket with Extra Gear

Ink Disc Bracket with Extra Gear

The bolt and gear from the Original Series press fit fine, no issues there. The Ink Disc Bracket had a hole to receive the fastener on this particular press, but I’m not sure if later models removed this.

image: IMG_3909.JPG


Having a look at the back of the discs, it doesn’t seem there is much difference between the two, other than the Original Series disk being much more worn. You can see that the Split Disc has a rod within a rod to facilitate the discs spinning in opposite directions.

If anyone has advice on how to replace the pawl, I’d love to hear that.

image: Solid & Split Ink Discs

Solid & Split Ink Discs

This is the Ink Disk with the inner disc removed. As you can see it’s pretty grimy. This is one of the trouble areas of the split disk, that ink and detritus will build up here and cause the inner disc to raise a little bit. This has been discussed in previous posts on Briar Press.

I spent some time with Acetone cleaning out the built up ink, until it no longer seemed like it would pose an issue.

image: Ink Disk with Inner Disk Removed

Ink Disk with Inner Disk Removed

As you can see here, the inner disc has quite a bit of built up ink around the edge. I took some time to scrape the ink off, and then gave it a once over with Acetone to dissolve the rest of the leftover ink I could get to.

image: Edge of Inner Disc

Edge of Inner Disc

The Split disc fits fine, no issues. The outer shaft for the ink disc is the same diameter as the solid disc, which is 1 3/4 inches. This disc is regrettably not as shiny as my other disc, but I’ll worry about that another day. That is another well discussed topic on Briar Press.

image: Split Disc on Press

Split Disc on Press

Apparently, all that you need now is the lower bevel gear to drive the inner disc. That might possibly be in the same category as Hens’ Teeth; however, I’m sure that there’s one floating around out there somewhere. Oiling the sliding surfaces might be an issue. Interesting presentation, very! Good luck!

Last, I put on the bottom gear, which bolts into the center disc shaft. This fastener needs to be tightened snug, but not too much, otherwise the gears will not rotate properly.

That’s it! No issues, the discs are compatible. I will leave with notes.

My solid disc is in considerably better shape than my split disc, so whatever benefit the split disk may bring might be negated by that.

I can see that the Inner disc is worn, and that the gap at the top of where the two discs meet, on the face, is larger than at the bottom. I’m not sure how much play those discs are supposed to have between each other, but this may cause an issue.

I have read that the discs will eventually not be plane to one another, and that some shimming may be required. If that happens, I will post more photos on this thread.

Hope this helps somebody out there.

image: Split Disc Gears

Split Disc Gears

Frank, you were just ahead of my last reply. I you can see the bottom gear in the photo above, as well as my ad hoc ink fountain clamp. If anyone has a fountain clamp out there, I will gladly buy it. I may just have to make one.

Very cool. I recall that years ago Arie Koelewyn had a batch of the side and bottom gears made up in bronze. I imagine they are long gone.


Nope. I still have a few of both the bottom gear and the center gear. These are rougher castings that need a lot of filing and machining to make them usable, but they’re still available and inexpensive.

I can think of no particular advantage a split ink disk offers, other that it looks very cool during the initial ink distribution. It does require some extra cleaning and maintenance.

If the center disk is worn on the inside, it probably needs more oil. The C&P oil chart does not have it marked, but it still needs it. I have run mine for over 20 years without any noticeable wear.

If you’re talking about the short little pawl that engages the bottom gear, it can be replaced, but not in the original position. My machine shop tried, but could not drill out the old one (too hard they said), which had ben mostly ground off when I got it, so they put in a new one 90 degrees from the original.


I was just going to mention that you had said you had a few at the last Monks and Friars meeting.

I also agree that at the moment, I have no reasoning for why the split disc would be an advantage, other than it is indeed very cool. I am going to run a series of tests, that I’ll post another day. Part of that is determining where exactly on the disc is a roller supposed to hit—right on the edge to start, or farther up to use more of the disc?

I think the wear was from it never being separated before. The press person that ran this press before I had it did nothing but numbering, and that was pretty apparent by the red and black ink gunked up in there. I will oil it when I’m back to the shop, although I wonder if the oil will want to work it’s way up to the disc.

I’m talking about the piece of metal that’s supposedly replaceable on the main disc lever pawl. It looks like it’s ready to fall off at the moment. Still works fine, but would like to have something lined up for it.

Gerald F. Schulze

Gerald, I’m curious what your reasoning has been to shim the disk in the past, and how you determined proper height? That isn’t something I had thought of before, but not I’m curious. I want to say my rollers hit my disk about 1.5 inches up from the bottom edge.


Hey Brent,

First, if you have your rails taped, see if your tape is extended past the point where the rollers first touch the disc. If so, that will be some of why your rollers are hitting high.

I have no idea what “proper height” was thought of when the presses were made, that’s another post I’ll put up in the future. However, all discs over time wear down a bit, and a .01” difference will really change where your rollers first hit the disc.

If your rollers are hitting high on the ink disc (I had a press that was hitting about 2.25” high) that means it’s not spreading ink all the way across the disc, and you’re losing some of the discs ability to spread ink evenly. If you shim up, you should be able to get your disc so that the rollers gently meet the edge of the disc as it rolls up, and gets the full inking area.

A friend of mine (thanks Tom) gave me this tip, and said that he likes he measures this by seeing if the rollers can just grab a post it note at the very edge of the disc, which is about .003 thickness.

Now, another friend asked “Well wouldn’t this just keep the rollers from going as high?” Not really. Changing the height of the disc just changes where the rollers first contact the disc. You may lose a few thou at the very top, but thats negligible compared to the 1.5” you’ll get back. When I did this, I had my pony fountain set up on the press, and I did not see any noticable difference in contact at the top.

Get a couple shims and see what happens.

Gerald F. Schulze
Detroit, MI


Have not had any problems with oil rising out of the divide between think disks. I do have to wait for roller wash to evaporate out of the gap, though, between inkings. Not a problem at the speed I work, but if you’re doing multiple colors in a day it could get annoying.

I’m not sure that the rollers hitting the ink disk a bit lower makes all that much difference. The majority of the ink transfer occurs in the center, where the rollers have nearly full length contact for more than a revolution of rollers. The tiny (relatively) area at the lower extreme, where the rollers are in contact for a fraction of the length, aren’t going to add much ink transfer. One more impression cycle will do much more.

I don’t know of any replacements for the “38 disk lever pawl” (from the C&P parts list) other than machining a new one. Usually if it is that badly worn, the teeth cast into the back of the ink disk are also badly worn down and need to be rebuilt. I suppose you could weld/grind new metal there.

Hey Arie,

Thanks for that. I’m running some tests on the split disk today, now that I’ve got a motor temporarily on the press. I suspect I’ll still revert to the solid disc since it is in much better shape.

I agree with your thoughts on the disc, but I have seen a few presses where the gap (like on my 10x15) is quite severe. The shims are more for that than anything, but I do really like to have my presses running as good as I can make them—because it’s fun!

I’ll work on the lever pawl. I saw a post on excelsior about it and I’ll talk to my machinist about what he thinks. It’s working fine for now, but It doesn’t have much life in it. This press (Stan’s 8x12) has a very nice ink disk on it, with very little wear on the teeth. I suspect that this disc is not the original one, and that the wear on the pawl was on another disc.