#4 worm gear needs an evaluation

The oscillating metal roller on my recently acquired #4 has been having a little bit of trouble making making its way back and forth when I ink up. It was sticking just as it reached it closest position to the operator, when the worm gear was no longer visible, I guess at the point where it makes the transition to go back the other way.
I took apart the roller assembly and the worm gear to give it a good clean, and I noticed that a couple of the points of the worm gear seem to be worn down or chipped so that they are no longer pointy. I suspect that the crescent is catching on these worn areas, rather that gliding past them smoothly.
My question, I guess, is can I just file down the points on the worm gear to make them pointy again, or is this a bad idea. The crescent looks ok, so I don’t suspect it is that. If I can’t make those transistion points smoohter somehow, I may need a new worm gear. Is this pricey? Is it something kept in stock?
Anyone else out there with worm gear issues? Any tips would be much appreciated, thanks.

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Fritz Klinke
Admin
15 years ago

The worm is a lost wax steel casting that is then hardened after machining. I need to place an order for these. The original Vandercook pattern is still at the foundry and thus we can have more made. But I don’t have any new ones in stock.

The points can be sharpened, backing off on the set screw as Eric suggested may help, and if the crescent has worn the holder set screw it sits in such that the crescent wobbles in the holder, that could be part of the problem. The crescent is also hardened steel, again a lost wax casting.

The recommended grease for the crescent stem is graphite grease, and Vaseline for the worm, but as has been mentioned, some of the modern greases that were not made over 30 years ago may work as well or better. The end of the ink drum opposite the worm needs some lubrication as well. It is possible for the worm steel to wear on the softer inside surface of the hole in the end of the ink drum, typically making it out of round. The original tolerences are fairly tight for that fit and it may be necessary to rework the end assembly as the ink drum itself is nothing more than a section of steel tube. I was just working on a vibrator roller for the 219 press and figured out an easy way to remove the old crescent and install a new one and if I can take some photos, I’ll post them.

Eric Holub
Editor
15 years ago

If the mecahnism is damaged to the point that it chatters or stops, sharpening the points of the worm may help (though it is hard metal and needs good files). But if it a matter of the roller rotating at one spot instead of osillating, or oscillating intermittantly, I don’t think filing will solve that problem. Your best bet is to see if Fritz has worms in stock, and replace that along with the crescent and holder.
Note the allen setscrew on the end of the oscillating roller that keeps the crescent-holder from backing out; and that over-tightening the holder will prevent the crescent from swivelling properly. And like the manual says, lubricate with Vaseline, including the post of the crescent.

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