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Printing with a Platen Press

Will a Boxcar Base work with a platen press (also known as a clamshell press)?

The short answer: yes, yes and yes. In fact, we manufacture a Deep Relief Boxcar Base specifically with platen press users in mind. The Deep Relief bases are a thinner base to keep the inking rollers from inking the base and plate backing while adjusting roller height.  These bases got their name because they are paired with a thicker relief plate . Read more about choosing your base.

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I own both a Vandercook and a platen press – do you suggest that I buy two separate bases, the Deep Relief Base for the platen press, and the Standard Grid base for the Vandercook?

We suggest purchasing one type of base for both presses, so that your presses will be able to share the same plate. It really comes down to your experience: if you’re a new printer, go with the Deep Relief base. Setting roller height can be a longer adjustment process on platen presses and this base will be more forgiving as you work through this. If you can use a roller gauge in your sleep, and you have experience expertly adjusting your inking rollers on your C&P, go with the Standard Base. The Standard Base’s plates are less expensive per square inch as they are slightly thinner but all plates, when paired with the correct base, equal type high (.918) and that is the most critical factor.

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If I have a 10 x 15 chase on my press, why can’t I use a 10 x 15 base?

We totally understand that you want to get the most use and space out of your press. However, knowing about some of the challenges you will face can help you make decisions about the correct size.

First, keep in mind that every press, like every person, has a limit to its strength. A press with a 10 x 15 chase will never be able to hammer a 10 x 15 block of text. You’ll be able to get a good impression using about 60-70% of your chase, depending on your form. Secondly, your base needs to stay put in your chase with a good lockup.  To secure your base in your chase, you need to make room for the quoins plus furniture for distributing the weight of the base, and gauge pins. Gauge pins fit in the space outside the base and over the furniture.

We recommend checking out our Base Selection Chart which recommends the ideal size base for your chase. With a 10×15 chase, we would recommend a 9×12 base, for instance.

If you really want to max out the base size, keep in mind your base should be at least 1 inch, preferably 1.5 inches, smaller than your chase.  If you use a lot of paper that is precut, it is most likely smaller than your base. This can make it challenging to place your gauge pins and still hold the paper and not hit the base. One safety note, the larger the base in your platen press, the further you have to reach into the press to place your paper.  This is very important with a larger press with a motor, so take into consideration your comfortable reach, the speed of the press, and your fingers when locking up a larger base.

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How do I prevent my gauge pins and grippers from smashing into my base? In other words, what do I have to worry about most when printing with a Boxcar Base on a platen press?

When using any kind of polymer printing base with your platen press, it’s vital to keep the gauge pins and the grippers from smashing into—and denting!— your base. When the press goes to impression, make doubly sure – no, make triply sure – that the gauge pins and grippers will not impact the Boxcar Base’s surface. Here’s how to do this.

You must carefully place your gauge pins on the platen to avoid hitting the base. Place the gauge pins below and beyond where the base will sit in the chase. In addition, place the grippers to the left and right of where the base sits in the chase. This will keep the grippers and gauge pins from contacting the base when the press closes for impression. If you need to use the grippers, keep them outside the base but construct a paper (or tape or string) frisket between them to hold the paper.

You might find it easier to position gauge pins if you print on sheets larger than the final trim size, especially if you have a quarter inch margin or less on either of your feed edges. This will move the gauge pins farther from the printing area and from the base – reducing the likelihood of a gauge pin/base collision. Print on the largest possible sheets and trim them down after printing.

You might also want to consider using Henry gage pins for certain print jobs. These cushiony paper holders may be just the thing and won’t damage your base or require cuts in your tympan paper.

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What will I need to do to my platen press before printing with polymer and a Boxcar Base (especially if my printing is blobby and/or has a “halo”)? i.e. how do I add tape to my rails?

Every platen or lever press has wear on the rails and needs tape on the rails to raise the rollers to the right height. This is whether you use lead type or polymer—although the problem surfaces more frequently on polymer if the roller rails aren’t set correctly. You have to build up the rails that the roller trucks travel on so that the rollers just graze the surface of the form. The best way to do this is to add equal layers of masking or strapping tape to each rail. Keep building up the rails in this fashion until whatever you’re printing doesn’t ink up at all (i.e. bring the rollers up just past the point where the rollers ink the plate). Then take off one layer of tape so that the rollers drop down with minimum contact to the plate. This will keep ink from getting on the backing of the plate and the base, and it will also help make your printing crisper. It’s not uncommon to have to add as much as a 1/16″—or sometimes 1/8″—in tape in order to get the rails to the right height. These presses are often 100 years old and have 100 years of wear that you have to overcome. We do not recommend that you adjust your trucks or printing plate/base for this problem. Better printing results from type-high rollers. After you add tape to your rails, we recommend using a roller gauge to perfect the height of your rollers.

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What are roller gauges and why do I need them?

Roller gauges are especially indispensable with a platen press. Letterpress rollers need to be positioned just right in order to deposit a thin film of ink onto the surface of the form, without squeezing ink over the edges. A roller gauge will help you accurately measure the height of your rollers so you can produce the crispest printing that your press is capable of. We sell roller gauges, precision ground to type high, which are also very fashionable.

When your rollers are positioned correctly, your printing will look beautifully crisp. But if your rollers aren’t positioned at the right height, your printing will have a halo effect: dark around the edges and/or chunkier/blotchier than it should be. If you ever notice ink on the back of your polymer plate or on your base — it’s a roller gauge emergency! Adjust your rollers now! We have a great video on setting roller gauge height in our Boxcar Training Videos and step by steps are listed here.

Step 1. While your press is inked up, remove the chase (on platen presses) or the base (on a Vandercook).

Step 2. We recommend checking the roller height in the four corners of the press bed. We’ll start in the upper right hand corner. Engage the form rollers and position them over the upper right corner of the bed.

Step 3. You will be pulling a stripe of ink on the round surface of the roller gauge. Pull the gauge underneath the form rollers so that a stripe of ink is transferred to the rounded surface of the gauge’s cylinder. Measure the stripe of the ink: you want your ink stripe to measure 3/32”. If the strip of ink is less than 1/16”, you’ll have difficulty consistently inking your plate (some areas will appear too light, and some areas will appear too dark). If your strip of ink is wider than 3/32”, your rollers put too much pressure on your plate and cause your printing to be chunky/blurry.

Step 4: On a platen press, to adjust the height of your form rollers: add tape to the rails that the roller trucks ride on. You may have to add several layers of tape. Strapping tape or plumber’s silver tape is frequently used for this. If you’re using a press other than a platen press, consult your manual as to how to raise your form rollers.

Step 5: Repeat steps three and four in each corner of your press bed.

Step 6: When your rollers are positioned correctly, you should pull identical 3/32” stripes of ink from the four corners of the press bed, and your printing should be both crisp and beautiful!

If you continue to notice inconsistencies in your inking after adjusting your roller height correctly, you may need to purchase new rollers and, if using a platen press, roller trucks as well.

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