Need Some Advice on the Base choice

Hello everyone,

I’ve been lurking these forums for a while now and have learned great many things from just reading. However, now I’ve decided to make a dive into letterpress, so need an advice.

Short backstory: my company is considering buying a Heidelberg Cylinder SBG since we have a customer who’d like to do some letterpress books on mould-made 100% cotton paper (Hahnemuhle or Amatruda, still TBD).

After doing some research, we located a machine, made some photopolymer plates (polyester based, 0,95mm thickness) and went to test the machine before buying it. Unfortunately, the current owner did not have a base big enough to test it out (paper format is 500x700mm), so he used multiple smaller bases, which made printouts uneven, but at least we saw that the machine works.

Now I want to order a big enough base for a proper test so I can be sure that it was not a problem with the cylinder as well. Considering that it is an European Heidelberg, I know that the bed height is 23,56mm, so that minus the 0,95mm of the photopolymer plate brings me down to 22,61mm for the base. However, the owner is telling me that I should order a 22,60 or even 22,56 because you can always “add something below the base”, but if the base turns out to be too high, it will be a huge problem to adjust it after the fact. I always read here that I should order the base exactly high enough, so wanted to check what you all think?

Also, would it make sense to get a base that’s half of the needed size and then focus on printing the left, then the right side of the signature? I know it’s double the amount of work, but I was thinking that maybe that way it would be easier to get a good quality print on each side. The current owner is telling that is not a good idea because it could make the cylinder uneven over time, so wanted to check that, too.

I’d really appreciate any advice on this topic. Thanks!

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On any press, you want to try to “Center the Pressure”. I would think you would want to print the complete form in one pass, as printing off to one side, this cause the cylinder to tip a bit. This would affect your pressure side to side. The cylinder is spring loaded and will only offer so much pressure. We had a problem with this in a “converted to foil stamping” cylinder press.

Get a base that is the full size. If you want to try printing one page at a time, buy two pp-plates and print each smaller page on the full-size base.

That way you won’t need to buy a larger base when you want to try printing a lighter form that is larger! And chances are, you will want that right away :p

Also, re: the results of your large-plate-smaller-bases test, chances are that unless the differences in height is significant, they would have printed smaller, individual plates just fine. But when you press a flexible plate over two smaller bases, you get issues.

Thank you both!

So the big base is the way to go, that’s good to know. Oh, if you have any recommendations for where to make the base in Europe, that’d be great. Especially with the grid on it for easier plate alignment, since we couldn’t find a good option for that :)

Also, can anyone confirm that the Heidelberg cylinder bed height is 23,56mm? The current owner of the machine has a roller setting gauge of 23,6mm. I know it’s supposed to be .928” for European Heidelbergs, but converting that turns out to be 23,5712, so a bit confused on that part.

But that still leaves me with the question of whether we should get the base that is exactly the right height considering the 0,95mm or should I leave that little bit of leeway as the current owner of the machine suggested?

Finally, since we will have a full size base, would it make sense to have two smaller plates that cover the left and the right side of the signature, or better if I have one big plate that covers the whole thing? We’re thinking of getting the photopolymer making equipment so we could make our own (we can use them for our other work and can even outsource that service), but there is a pretty steep difference in price between the necessary equipment for making a one full-sized plate and two smaller ones that could be used at the same time, but would need some careful alignment. I have no problem buying the bigger one if it will mean better quality in the end, but was just wondering what would be the smart thing to do :)


I can’t speak to the Heidelberg’s specs so I’ll leave that for others.

I print on a Vandercook, and I do not use packing under the base, I pack the cylinder instead to account for paper weights etc. I’m not sure if that is proper procedure for the Heidelberg. You definitely need there to be space between the cylinder and plate, but if you just talk to your base-vendor and explain what press you have, they will know what to give you.

When it comes to gridded bases, here are my thoughts: I bought a gridded base intended for adhesive-backed photopolymer because they were cheaper. I then found a set of magnetic bases of the same size, and since then I have not used my gridded bases once.

Magnetic bases are more expensive and they do not have a grid. However, I can pretty much guarantee that you will not be able to remove and reposition a large adhesive-backed plate without damaging it. With a steel-backed plate on a mag-base, it is no problem at all. It has saved me tons of money by buying smaller plates and positioning them instead of making giant plates full of empty space.

I would buy a magnetic base 10/10 times unless on a tight budget.

That sounds like a great idea, I’ll ask the vendor for recommendations. I found one in Germany, but if anyone here knows other they might recommend, I’ll contact them too.

Interesting about the steel-backed plates, I was under the impression that they are inferior because they could “drift” slightly on long runs. Granted, most of that was from Boxcar’s website (link:, but thought it made sense. Now I’ll have to reconsider, I guess. Funny enough, I wasn’t looking into non-magnetic base to cut costs, but simply because I was led to believe using the grid and adhesive was a superior method.

How do you position smaller plates precisely on a magnetic base? Asking because what you said has got me thinking that maybe printing a large sheet is wasteful and printing 8 smaller ones for a full signature might make more sense. I actually thought about it before, but I was concerned with precise alignment, but what you said has got me rethinking the whole thing.


The magnetic base still has a pattern so you can position things roughly based on that, pull a proof, measure and adjust. Alternatively I also keep a gridded, transparent ruler handy.

Like this one:

If I’m concerned about alignment and making sure things are very square (like if I have lines of text of different colors on the same page), I’ve ordered plates with registration-marks, then carefully trimmed them post-alignment (using tin-shears) by carefully lifting a corner at a time. I’m sure there are more professional ways of doing this, but for someone on a budget, you just have to be creative :)

I don’t know about plates drifting, I suppose it is possible. But if your plate is 1/2 or 1/4 of the bed, I doubt it would.

When magnetic bases were introduced, a long time before Boxcar, pin-mounting of plates was the favored method. It allows exact location, perfect register across forms and prevents drift. Arion Press did this with Bunting bases and a 5mm pin system; I do it with PatMags and 1/16” brads sunk in Elrod high-base. Digital files can include marks for locating the holes.
I would not recommend printing right and left halves as separate runs. You could waste a lot of expensive stock trying to get even inking. You might get a ductor roller that is only covered on one half and turn it around to suit the half being inked (that way ink will not be fed into the ink train on that side), but if you have to play with ink fountain keys for every turn, consistency will suffer.

I guess there are methods to align everything even when the plate is not transparent :) The biggest issue for me was the adamant claim that the polyester-backed plates are superior to steel-backed, hence why I was not even considering the steel ones. I guess if we were going down that route, 2 1/2s or 4 1/4s would save some waste in the long run. Time to rethink everything, I suppose!

Pin mounting sounds interesting, haven’t heard of it, I must admit. Don’t know if there is a way to obtain such a base in Europe though.

As for printing left and right hals as separate runs, yeah, I agree. The more I think about it, the less viable it seems. I’m sticking to ordering one big base and then either making one big PP plate (a lot of potential waste though) or making 2-4 smaller plates to cover the whole signature (a lot of minute adjustments to get it right). Still not sure whether the steel-backed or polyester-backed is better for an edition run (i.e. 400-500 copies per signature), so I’m hoping to hear more first-hand experiences here :)

Hi, a slightly different take on polymer plate mounting. I am UK based and have a letterpress background. At present I have a 10 x 15 Heidelberg platen and use honeycomb mount for polymer plates. I mount the .95 plates on either lead or aluminum shim and adjust for height under the shim and position on the honeycomb mount using the appropriate clips. This certainly makes it easier to position.
I have used this method in the past for Heidelberg cylinders and bigger presses for up to 32 pages to view. I know where to find a Heidelberg mount for .918 , but clips might be an issue these days. The other option is Stevenson Blake dowel mount if you could find enough high mount. I also have access to Monotype woodfilled High Quads for pinning plates to but these are very rare I would imagine these days.

Photomechanical work, AKA stripping, has used pin-mounts for a very long time, and Europe was the origin of this precision method in letterpress work. All it takes is a punch and equivalent pins. Bacher in Europe provided the platemaker BASF with the tools, and Alldis and Ternes and others in the US did the same for US litho work. Stripping usually placed images precisely relative to film and plate edges, so holes were punched in film and plates before exposure. For letterpress Bacher also had a crimper to place the pin location in the head of the chase.
At Arion, we started with a 5mm eyeletting punch and had a machinist make a small magnesium strip of equal height to their Bunting bases with two 5mm pins placed at exact positions. One pin base was made for each plate base, and for the first project (Rudolph Koch’s Christian Symbols), each base held one page, if I remember correctly, 8x10”, four bases in a four-page press form (no image ran across a join). We experimented and found a circle in a digital file that would in the photopolymer plate seat exactly into the throat of the punch, so a hole could be placed very close to final position, and a chain saw file could make slight corrections. Pin height was just at plate backing thickness so they did not ink or print.
I use PatMags, and my pins are just bits of 18-point Elrod high-base with a 16-gauge brad driven in and the head cut off, shifted for specific jobs. For metric users 1mm is similar scale. I have a digital circle that on plate, that cab be drilled through the center by hand with a 1/16” drill bit in a pin vise. If the hole is off, filing and peening the steel can correct it.
PatMags are a lot weaker than Bunting bases, and I wouldn’t use them on an auto cylinder press without pin-mounts, not just for location but also to prevent creep. Some like spray glue, I tend to avoid it because it degrades the PatMag surface.
Ganging smaller plates and bases in a run allows for a smaller platemaker too, if you don’t need larger continuous images.

I’m based in Europe as well and have been involved in getting a large Vandercook that the Royal Academy of Art in Amsterdam discovered in a storage space, back in working order. New rubber rollers were made, everything got fixed and the press runs smoothly. The print department did also invest in a large format photopolymer machine and needed a good base. We opted for an aluminium base and found that 25 mm is a standard thickness. We had the block machined down to the desired height. The photopolymer plates are fixed with double sided adhesive. The german brand Tesa has got a range of different adhesives for this purpose.

I’ve used magnetic bases as well on cylinder presses but often experience ‘plate travel’ or ‘creeping plates’. However, they seem to be fine for platen presses.

There is a reason Boxcar settled on two different thicknesses, regular and deep-relief. A thinner and less expensive plate that works on a precise cylinder press or Heidelberg platen may not work on an older floor or tabletop platen with an inexperienced or misinformed operator.
Plate-making is more problematic with thicker plates. I would still want .045” plates if I could find a supplier rather than .052”, but all my former suppliers have gone out of business, as did my service bureau, and to restart the darkroom/process camera/contact frame would be far costlier than any single job would justify. Buying a copper photoengraving would be easiest.

Wow, seems to me I’ll have a lot of googling to do!

We’ve opted for using the 0,037” (0,95mm) plates, similar to those that boxcar recommends, but digital ones. That way we can skip the film and just use the CDI to create the plate. Then it only needs to be washed and it’s ready for use.

Pin-mounting sounds both interesting and smart. Not sure whether we could get everything we need here in Europe. The CDI machines for digital plates that we’re planning to buy are optimised to process either polyester-backed plates (vacuum hold) or steel-backed (magnetic drum option), so I suppose the pin mounting would be best for polyester-backed plates.

@thomas gravemaker
That sounds exciting! I’ll look into Tesa for adhesives, thanks!

I’ve been warned about “plate travel”, but I was thinking, if we’re doing such a big investment, might as well get a magnetic base and an appropriate CDI for the plates. That way I can still do polyester-backed plates on it with adhesive, but can also switch to steel-backed for stuff that has less chance to experience “plate travel”. But that got me thinking—would you say plate travel has a higher chance of occurring with a large plate or with a small plate?

@frank hemmings
I’ll look into clips system, but I think our Heidelberg is of a .928 variant. Haven’t heard about Stevenson Blake dowel mount, will look into it. Thanks!

You’ll probably be able to find the pin-mounting strips and the puncher in Europe. Nearly every offset/litho printshop had them in use, films and plates were all punched with the same machine. Bacher made them, but other companies as well.
Check out this, there are plenty of them:

Ah, I see—great, thanks! Then I just need to order a base with pin-mounting holes in mind?

There is a problem with transferring photo-litho pin-mount systems to photopolymer letterpress.The punches work well with film and thin litho plates, but not steel-backed photopolymer plates, and I’m not sure how well they would work with plastic-backed photopolymer. The film back is no problem, but punching through unexposed photopolymer may gum up the works. That’s why the methods I’ve used make the holes after wash-out.
I have to wipe the blade with a damp rag for every cut of unexposed photopolymer, but that would be worse with the steel-backed, fairly thick plates I use.

Yeah, that makes sense. Thank you for the explanation, it’s much clearer to me now!