Positive lock up bar vs. fixed dead bar

My 215 Positive Lockup Bar has suddenly taken to shifting easily during printing. Since this is a new trend, I’m thinking the bar needs attention, cleaning, adjustment, etc. Any advice on this?

I would also like to have a fixed “dead bar” and I have a machine shop at UAFS (next door to our print shop) who can fabricate one for me.  In this press (same as #4), the bar fits into semi-circular notches on the sides of the press bed. The manual calls this bar a “plate base end stop” but it seems to serve the same purpose as a fixed dead bar. Since I’m not using this as a plate base end stop, I think I may not need the notches on top, nor holes for the bolts. Any advice on this?215 dead bar?

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John and Nancy Johnson
10 years ago

The bar we have measures 1 inch wide, 15 5/16 inches long, and 5/8 inch thick (the thickness of our wood furniture). The rounded ends appear to be 1/2 inch in diameter. With the bar in place on our press one brass pushed in between each rounded end of the bar and the side of the press was tight. There was a 1/16 inch gap between each flat end of the bar and the side of the bed. The two bolts are 1 1/2 inch x 5/16 inch (18 threads per inch) square head bolts. The holes for the bolts are 5 1/8 inches from each end of the bar and are threaded through the entire width of the bar. There are three recess areas in the bar – I am not certain of the purpose of these recess areas. Each recess area is 1/2 inch wide and 3/16 inch deep. One is centered on the bar. The other two are 3 1/2 inches from each end to the center of the recess area. If you are simply wanting a dead bar for the press, I presume you can ignore milling in the recess areas and ignore drilling and tapping the holes for the bolts. I believe these bolts serve the same purpose as the allen screws you find in the chase of a small Kelsey table-top press, namely built-in quoin capability. Attached are a couple of basic photos.

John and Nancy Johnson
10 years ago

Katie, We have a ‘dead bar’ in use on our No. 4. We would be happy to send some drawings/measurements and photos of it if you still need them. John & Nancy Johnson

John Henry
Editor
10 years ago

Katie:

If you can find a piece of rubber dam (thin rubber sheeting), attach it to the ends of the lockup bar which ride against the sides of the bed. You can attach it with p.s. adhesive or contact cement. This will give it a better grip, and will add a slight bit of length to it if indeed the spring has compressed over time.

Making certain that all the contacting surfaces are dry and oil free, would also be a good idea. If you didn’t want to attach anything to the surfaces, roughing them up slightly with fine emery cloth might also help get a better grip, as the surfaces can become polished with use.

John Henry

Eric Holub
Editor
10 years ago

I think these lose presure as the internal spring weakens or breaks. A temporary fix is to insert a washer between the spring and the spring or the extension block, of just enough thickness to compenaste for the gap.
Paul’s question about using quoins is very important. Don’t apply pressure by quoin against the tail of a positive lockup bar.

Paul Moxon, Moderator
Admin
10 years ago

Lockup bar: the quick fix is to insert slips of thick, toothy paper between the lock up bar and the sides of the bed bearers. If this is a student’s problem, might they be using a forward quoin parallel to the lock up bar, that is in fact pushing it back?

The problem with cleaning and lubricating the lock up bar is in removing the center disc bar cam (NR-253) and the long rod in the shaft (B). Ive learned that after removing the handle and clearing the cam rider (NR-255), the bar cam needs to be tapped out with a mallet and wooden dowel that is approximately the same diameter. Then after removing the bar cam, extension block (C) and spring (NRS-23), that the best way to remove a stuck shaft (B) is to saturate the cavity of the bar with a penetrating spray (Liquid Wrench, Kroil or WD-40) then turn the bar downward (L end up) and tap the bar forcefully, several times against a heavy wooden table until shaft (B) and the cam rider slide out (NR-255).

Dead bar: You’re right, Katie, notches are not necessary for the kind of work being done today.

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