Elevation crank gear slipping

I got my CompuCarve/Carvewright machine a few years ago used. Never really had time to mess around with it until lately. I’m having an issue with the elevation crank. At first I thought it was the ratcheting mechanism, so I disassembled the side panel to get to the crank mechanism. After disassembling and close examination of the ratchet system, I found nothing wrong there. After reinstalling everything and still having issues, I noticed that the problem was actually the two gears slipping. It appears that the top of the vertical shaft is supposed to fit into a brass bushing in the upper plastic housing. Mine does not stick up far enough to go into that bushing, so the gears push the teeth apart when I try to raise or lower the elevation. I have been able to find a reason for that. I have checked the fit of the metal side panel into the top and plastic pieces, and they are fully seated. It appears as if the shaft is about a 1/4” too short. Also, there is an e-clip on top of the gear on the vertical shaft that does nothing. There is no groove for it fit in, and I can lift the gear off the shaft without touching the clip. In fact the clip is still laying on top of the gear when I remove it. I’m wondering if this machine wasnt assembled correctly from the factory, and the original owner never bothered with trying to get it fixed. Has any one else ever ran into this issue? If so, how did you fix it?

Pictures are very helpful..

And now, as Paul Harvey would say, the rest of the story. I decided to measure the height of the vertical screws, just to see if there was any difference between them. Turns out I found about a half inch difference. Upon some closer inspection I noticed that I could easily see the bearing under the right side shaft, but not on the left. So, decided to remove the bottom metal cover. When I did, I found that someone in the past had apparently managed to break out the bearing retainer housing on the left side. Then they tried to repair it with what looks like JB Weld, but of course that failed. So I took a large washer and modified it to make a bottom retainer, then drilled out the old screw holes to fit long 8-32 screws. I then inserted the screws from the bottom thru the modified washer, then the holes in the base, then thru the upper bearing retainer. I then tightened everything down with some nylocks. So far it’s working just fine. The hardest part was getting the two vertical screws back into sync. I have both sides within about 1/32”. It raised fine, but still didn’t go down without ratcheting. So I raised it all the way, sprayed the screws and posts with dry graphite lube, attached my cordless drill to the top of the left screw and ran it up a down a few times. Put the left side cover back on and it now works just fine. I still don’t know what that e-clip/snap ring was for, so I just left it off. See the pics below for my repair. Not pretty, but it did the job!
Attachment 84894Attachment 84895

That is the exact fix I did on one of mine.

Wise minds as they say....,

At least I know I am not the only one who had this problem! I still have to wonder what caused it tho. Did yours break on the left side as well?

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Originally Posted by IndianaJohn

At least I know I am not the only one who had this problem! I still have to wonder what caused it tho. Did yours break on the left side as well?

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yes on both machines. I remember now I had to fix the second one as soon as I got it.

Must be somehow loading that left shaft much more than the right one. I'm guessing that it may be caused by the mechanism getting tight, and the extra force needed on the crank gear causes the gear on top of the left shaft to push downward on the shaft with enough force to break that bottom plastic out. So I guess that the take-away here is to always keep the posts, screw shafts, and the rest of the mechanism clean and lubed.

I have had the very same problem over the years. Great work fixing it.

AL