Universal III Tympan Issues

We have successfully used mylar/acetate tympan on our SP-15s for years, but when we tried one on the Uni III, it keeps slipping. There could be multiple causes: 1. The mechanism for holding the tympan on the Uni II is not suitable for acetate; 2. the acetate is thinner than we usually use ( I suspect our latest purchase is .005) and we need to bump up to a slightly thicker acetate; 3. There is something wrong with the tympan mechanism on our Uni III, although we did not have this issue when there was a paper sheet on top.

Thanks for any advice.

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Eric Holub
7 years ago

Only two inner holes are used to locate the tail of the tympan, the two outer holes are for the long pins that lock the clamp in place. The pinbar should snap in easily; I don’t recall if they snap in from both sides or just one. I would clean the holes with pipe cleaners in case there is now paper waste in them.
Underhand turning of a topsheet tail does not require taping; it is standard on production cylinder presses and just requires correct technique. The change of direction in the bend of tympan down from the tail of the cylinder and then back up around the reel provides tension to hold the tympan in place, something which does not happen with overhand reeling.
For underhand reels, my method is to pull the tail taut under the reel and make the first careful fold to conform to the reel. Then I make successive folds around the reel as I roll it out; it is easy to then reel it back in, square and centered. If you start off-center, you will have loose tympan one one side, but reels usually have some side-play to compensate.

Paul Moxon, Moderator
7 years ago

The Universal I has the round reel rod with the split to feed the drawsheet tail. The Universal III has the more common 3/4″ square reel rod. I have seen overhand (counterclockwise) and underhand (clockwise) reel rod take-up on SPs and No. 4s. Unless you have a clamp bar tape is required for Mylar drawsheets regardless of the direction of the tail winding.

Eric Holub
7 years ago

Does’t the Universal III use a pinbar clamp to hold the tail of a punched tympan? You might be missing the clamp, but check for four holes on the reel.
The SPs tighten underhand and no tricks are needed. The Universals I’ve seen tighten overhand and use either a split reel with the tail threaded through it, or a pinbar reel with matching holes on the tail of the topsheet. Some folk just tape the tail in place so the reel can be tightened with enough tension.

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