Maybe five years ago we bought our Vandercook SP-15 off eBay. When it got here the one major problem was that the ink drum was quite scratched from the automatic cleaning bar that scraped the ink off it. Lately we’ve been having trouble printing evenly with it and started to deduce that it might be a combination of the colder weather (and colder ink) and the ink drum dropping ink on rather erratically as the press ran.
We’ve wanted to get it milled for years and finally got around to doing it this week.
I’m not sure what we expected, but we gasped when they brought it out. There is nothing like having the right tool for the right job.
Our studio is a 2,200 square foot space in an industrial park and as it turns out there is a grinding service just down the street called J&A Grinding that we’ve been using to sharpen our cutter blades since we moved in. We asked them if they could mill the surface of our drum smooth and they said, “No problem.”
It cost us $150 as it took at least 7 or 8 passes to get all but one small area that just seemed dangerously deep, but very, very small. I wish I had taken a photo of it before the milling to show you how much damage there was, but above is one of the finished job.
Honestly, we aren’t going to use the auto-cleaning any more. We also might just take all of the other metal rollers and let them take one pass across them all and just have it like new again.
I also think we’ll start adding ink on the rubber rollers instead of hitting the metal ones with an ink knife.
Ray, I have a couple of questions. I’m in the process of getting this done to my drum. This was obviously done in a lathe, right? Was it done merely with sandpaper or with a burin?
If so, have you had a chance to ask them how much they took off, so I can tell my machinist?
Nevermind the sandpaper, I think it’s stone, or a burin. Or both?
Thanks a lot!
That is just absolutely beautiful, and that’s what I plan on doing to my vibrator.
The drum is pushed down by the cylinder (and that is only so the cylinder does not get inked as it passes over the drum), but that is not its position when in contact with the form roller.
The contact can be checked by a stripe test. Set the rollers correctly to .918 with a roller gauge, then let the drum and rollers come to a stop. Lift the rollers and advance the carriage. There should be a stripe along the top of the drum, and normally is is much wider than the stripe on your roller gauge. The extra contact is what drives the rollers.
If your rollers are turning, not to worry.
Eric – I talked with the guys beforehand about how deep the grooves were generally and if they thought I was running a risk. They didn’t think so. The next time I’m over there I’ll ask how much they think they took off. If you look at the thickness on the side,honestly it doesn’t look much if any thinner.
jhenry – The drum has a spring on it that pulls it up. It is actually noticeably higher than the bottom of the first rubber roller. When the cylinder returns it push the ink drum down about 1/4 inch or so. The grooves were essentially reducing the area of the ink drum by about 60% (only 40% was transferring ink). I’m not sure how much it was causing the inking problem we were having, but the first job I ran after that had absolutely no problems at all.
I’d be concerned about how many thousandths the drum surface has now been lowered. The form rollers must be set correctly to type-height, and the slightly higher level of the drum is what allows friction to drive the form rollers when in contact with the drum. A lower drum would lead to less contact with the form roller. Unfortunately there isn’t a way to raise the position of the drum.
That drum looks very nice. It will be interesting to see how your results change with the improvement, I would think the vibrating distributor tends to equalize ink drum faults unless they are extrordinarily deep, but a smooth drum certainly can do no harm.