Our Uni 1’s back form roller gear is spinning out on the starting teeth of the rack. I’ve changed the roller height, made sure the end screws on the roller core are tight, made sure the spring beneath the starting teeth is free of debris (it depresses with finger pressure). I’ve had this issue on other presses before and it’s usually remedied by changing the roller height. I’m stumped and appreciate any advice you can offer. I’ve included photos of the rack and gear.
The proper spring is important. I did once get this particular spring from NA that was correct diameter and length, but their supplier had used a slightly thicker wire than original spec, and after a struggle to install, the starting tooth could not be depressed because there was no open area left. I had to remove a few coils from the spring, and then it worked.
Be prepared to modify and improvise when it is actually necessary, but only when absolutely sure. You can’t put back what you cut or file off.
The starting tooth spring is not the X-11022 specified by Vandercook and appears to be some wimpy hardware store spring. When properly installed, the spring pushes upward to keep the impression cylinder in place at the start position, and should be hard to depress when starting to move the cylinder. A weak spring may be causing the chatter. They need occasional replacing, and I suggest getting two springs to have a spare on hand. Also, make sure the press is level, front to back and side to side, and use a decent level, like a carpenter’s two or three foot long level. The part that needs to be level is the bed of the press, all else follows suit.
Thank you for all of the suggestions. After resetting the roller gear so it aligns with the rack, and checking that none of the shims under the rack had been removed/changed, the sound has stopped. I printed an entire run yesterday and the press seems to be fixed. I appreciate all of the help!
Can you check how much the rack is shimmed? If the shim stock beneath the rack that engages the roller gear is too low, this will happen.
It is perplexing. The roller bearings appear to be seated in the brackets on the carriage side plates.
You could try stretching the spring under the starting tooth.
I was able to remove the gear and there isn’t a woodruff key. I will purchase one, but in the meantime reassembled the press, tightened all of the set screws, lowered the rollers all of the way down, and am still having the same sound/issue. Is it possible that the starting teeth are just too low, causing the gear to graze the tops of the teeth? I’m not sure how it could have suddenly become too low but that’s the only thing I can think of right now.
With the form roller bearings removed you should be able to see if there’s a key in the keyway. In any event, the gear is tight on the core. However, using a piece of wood and a hammer, you should be able to tap and rotate the gear either off the core or toward the rubber to align with the rack.
Thank you for the diagram. I removed the shaft and gear assembly but can’t seem to remove the gear in order to access the woodruff. Is there a trick to removing that gear? I appreciate your help!
The gear is set slightly too far to the right
The roller height may be set slightly too high.
The gear can take a Woodruff key. You can see the keyway in the image below.
Here’s a video showing the exact issue.
Here’s a photo of the end of the roller. I don’t believe there is a woodruff key with this type of core/gear connection, is there? I tightened the set screw on the gear hub. This seemed to start after a student mistakenly took off the form roller to clean it. I don’t understand how that could’ve caused this issue but it wasn’t doing this before she cleaned.
Is there a woodruff key connecting the gear and the core? Is the set screw on the gear hub tight?