I have been told the standard Boxcar base is .875” (7/8”) thick.
The ‘regular’ photopolymer plate thickness is .037”
.875 + .037 = .912 which is not type height of .918
Is this very small difference ever a problem? Just make it up with packing behind the tympan?
Log in to reply 11 replies so far
I’ve never had a problem with impression using a Boxcar base and their photopolymer plates. Maybe the adhesive makes up that difference.
The problem isn’t impression; it’s inking.
If you’ll be printing on a platen press, get the (slightly more expensive) deep relief plates. In either case, some tag or oiled tympan behind the base will give you the adjustment you may need for proper inking.
If you adjust your rollers for inking polymer plates, you may lack sufficient contact for good inking of type or photo-engravings.
Once the ink roller height issue is resolved, you can increase impression by adding packing to the tympan, but if inking is your issue, pack behind the base.
We often shim behind the base to avoid having to readjust our ink rollers.
Actually, that little bit of difference is not a problem.
Alan is right: If you put your plate onto your base and it’s a teenie-tiny bit lower that your rails, you can always put a sheet of paper under your base to bring it up.
Don’t get all hung up on the minutia of letterpress. Just shim up your plate/base to rail height, and go for it.
There you go (wink, wink) I second “Don’t get hung up on the minutia of letterpress” (this should be the quote of the week.)
Some of the purists on this forum would be horrified to find out some of the ‘work arounds’ printers have used for years.
“It’s not rocket science; we’re just putting ink on paper….”
Being a newbie, I did not know how important these dimensions are. If it is only a matter of “toss it in the press and built it up with paper” I can work with that.
Well, you might not end up too happy with that, unless, of course, you are easy to please and quite satisfied with whatever you do, yeah know, just because you did it.
But, in regard to your question, my understanding is that the Boxcar Base would be, with the KF95 plate, and its adhesive, only off by .001, plus or minus, and that variance is the closest you can be guaranteed. Even Bunting Magnetics won’t guarantee less than that for its Cerface bases. You will be okay. No need to shove a bunch of this will be fine crap under your base.
i sit here amazed to read about all the problems people have with the higths of bases and tympan thicknesses,if you buy an engineeres micrometer,make sure all your mounts are type high,set your rollers to type high, measure your tympan + printed sheet and use that as a base setting it will save a lot of time & worries
“…i sit here amazed to read about all the problems people have with the higths of bases.”
Um, I did not see anyone post that they were having problems.
My initial question merely asked if those minor differences in total height would CAUSE a problem. I am a newbie at this but not in both wood and metal construction and machining. There are LOTS of places in metalwork where 6 or 8 thousandths would make a difference. I am glad to learn that letterpress is not in that category of precision.
although for good printing
there are LOTS of places where 6 or 8 thousandths would make a difference.
You may be glad to hear that but a thousands of an inch will make a difference in letterpress printing. Oftentimes, make or break. Depending upon what will satisfy you, of course.