If you hang around letterpress circles for very long, pretty soon you’ll learn that those rubber rollers that transfer the ink to the type ain’t cheap. After a little research, the best prices we could find on replacement rollers for our (free) Kelsey presses that desperately needed rollers were a slick $100 – $200 if you needed the trucks too. Yeah, no.
Apparently, from what we gleaned from the interwebs, you want urethane, due to some sweet property it has adhering ink and transferring it to type. Also, the hardness of the stuff is pretty critical – it seemed like “Shore A” ratings liked to be around 25-30 – about the consistency of an eraser or maybe as soft as a rubber band.
In the spirit of #makedontbuy, we decided to dive into the fairly intimidating world of casting urethane rollers… with pretty awesome results! Here’s the step-by-step.
This is the stuff we bought, from US Composites. This is the 74-30 rubber, which is rated at Shore-A 30. We also got the mold release spray:
From what our research told us, the rollers want to be very slightly larger in diameter than the trucks – like, maybe about 1/16, so we ordered some stainless tube from McMaster-Carr. Almost any material will probably do fine, but the stainless seemed nice and rigid with a good, clean inside surface, at a good price.
The idea is to use the trucks as end plugs, and mold directly to the shaft. We taped the trucks for a snug fit and drilled a hole in some plywood to stand the rig up:
Before assembling the mold, we sprayed the interior of the tube with the release, and the tops of the trucks.
…then assembled the mold:
The goo you see at the bottom is from a previous pour.
The next step is to mix the stuff up. This gets mixed at a 1:1 ratio. After mixing, you want to let it sit for a few minutes to try to let the inevitable bubbles work their way to the top, shown here:
Make the pour…
…and get it right up to the top of where the truck clip sits – a slight groove:
Place the second truck on top, just inside the tube, and that locates the shaft in the center.
You have about a 20 minute working window with this material, and a 24-hour cure time at room temperature. Pulling it apart is no trick at all – pull the trucks off and give it a start with a press or a hammer, and once it starts sliding you can just pull it right out – we found it helpful to clamp the end of the shaft in a big vise, and give it a nice pull.
Next up – we’ll let it sit for about a week, then try it out!
Cost? The urethane kit was $15, the release spray was $10, the stainless tube was $28 with shipping, so basically you’re looking at about $15 per set of rollers.
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