Problem with Z Axis coming loose (Resolved)

I’ve been trying to make small boxes off a 1in thick maple slab with a .250 endmill. I was able to make the lips and the pockets on both top and bottom with no problem but when I got midway through the first cutout, I started to get shatter and the workpiece moved.

I stopped the job, the bottom eccentric wheel was loose. I tightened the wheel and restarted the job. When I got to the same place, the problem reappeared. Again the bottom eccentric wheel came loose. I decided to change the setting and reduce the depth of passes from .125 to .10 and restarted the job I also reduced the speed to 80ipm from 100. The cut went further but again the shatter started and I stopped the job. The eccentric wheel again came loose.

I don’t know if the eccentric wheel comes loose from the shatter or if there is a problem with the wheel itself. Has anyone experienced this? Is this a problem with the wheel or am I too aggressive? Should I put loctite on the wheel?

The best compromise here seems to be removing the bolt, putting a thin bead of threadlock on it, allowing it to dry, then retensioning, being careful to always turn the nut clockwise and turn the bolt in unison by putting a hex key on it.

Thanks, I will try that tomorrow. FYI, I always turn the nut clockwise. One thing I noticed is that it needs to be right at the maximum of the adjustment and of course right after, it is the least so it does not need to move much. Is it worn? Should I get a new one or is there a way of making the wheel have more adjustment?

Depends on how far off-center the hole is drilled — there’s a little variation, but usually the manufacturer is pretty good about putting it properly at the edge.

Replacing the V wheel might be a good idea — let us know at if you continue to have difficulty and we’ll try to help.

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Slight variation on the great advice already given. Put the hex screw through everything except the nut, apply a dot of loctite blue (243/242) directly to the exposed threads being careful to not get any in the bearing(or use a toothpick to apply inside the nut). Why? Reason behind it is blue loctite is anaerobic, meaning it dries in the absence of air (in other words after the nut is tightened). If you let it sit to dry before putting it through the bearing it will not harden completely (and you could push it into the bearing). At work on our assembly line I’ve seen small capfuls of blue loctite sit for months without drying out, assemblers dip bolts as they assemble. After assembly give it time to dry. I would have to look it up, but I recall blue takes a few hours before it reaches “near” full strength (3+ hours) and I think full strength is somewhere in the 24+ hours timeframe. If you’ve done it a different way I doubt you broke anything, just try to avoid repeating.


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Thank you, I was going to do just as you said. I’ve used Loctite for many years and on many machines, it is made to lock the thread and you don’t want to lock anything else. However, I had never seen the time to set, I would have expected it was shorter. I will need to put on my glasses to read the small print on the tube! :wink:

That’s for 243, 242 is pretty much interchangeable from my experience. Some places list “set time” as 10 minutes, but then list “full strength” as 24 hours. The above gives a nice graph for time/temp/% of strength.


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Oh yea almost forgot. I used to to a lot with RC helicopters. Lots of little loctite screws and nuts, lots of tiny bearings. What I would always do during assembly is put a few drops of loctite on some throw away surface(shines paper plate, etc…). Then I’d use a toothpick to apply as needed. Keeps the goo out of the works.



I just sent off an email to this afternoon. I am new and was just cut my wasteboard over the weekend after having issues squaring my machine. I double checked the screws after the alignment and even checked to see if the eccentrics were still snug but not tight. and they were. The wasteboard went like a champ until I lost connection with my computer with about 6 holes to go. I shut it down and finished the last holes by hand.

Today I went back outside to cut the fence for my waste board and about 3/4 of the way through the router started slipping to the left like the bracket holding it on to the z mount was loose. By the time I got the machine shut down the eccentric v wheel at the top left was completely on the outside of the rail as well as the wheel on the top right. I have no idea if it caused any damage to the mount. I am sure the eccentrics and the v-wheels need to be replaced. My 1/4" end mill is toast. Frustrated newbie… :slight_smile:

Serious bummer :confounded:

Were you cutting the holes in the stock wasteboard or onto a supplementary wasteboard on top of the stock? Just wondering if the Z didn’t plunge so far that the bottom wheels came off the rails causing the whole plate to cant to one side knocking the others off? I know you can run the machine beyond it’s boundaries with gcode because I’ve crashed mine into the sides before. If you had a shortish tool, or the router up in the mount I’d bet you could run it off the bottom too? Just a hunch based on theory and guesswork, haha! Hope you get up and running again soon!


Thanks for the input. I will make note of it.
The machine was not drilling holes at the time. It was making the second pass at cutting out the outside edge of the fence. It was no more than 1/4: deep.

Talk to Luke (Mr. Beaver) he manufactures custom eccentric nuts that are far superior to stock. I replaced all 6 with them. Also the suggestion of Loctite 263 helps too. Remember it takes a day or so for the Loctite to set up.

This anaerobic quality is why there’s always so little loctite in the bottle - it needs airspace to stay liquid.

There is a neat, green, fuelproof, “wicking” type - Loctite 290. I’ve only ever seen it in a bottle so big you’ll never use it all. A drop on the edge of a bolt already in a nut will wick into the nut. This only works with that particular type (there are MANY different formulations). This is awesome stuff for sealing around a weeping rivet in an aircraft fuel tank… just sayin’


If it is the same formula, Amazon has a bottle that won’t break the bank
It says Loctite 29031 290 Threadlocker Adhesive (Wicking Grade/High Strength), Green, 50 Ml Bottle

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Thanks, as it turned out, when I got the tube out, I found that I had run out of loctite and since I did not want to wait, I had to purchase locally, the local store only had small tubes of blue (medium) for C$9 for a small tube. I will look at buying some green and blue in larger quantity from a different source.

Super glue works in place of thread locker in a pinch too.

Just an update on this issue. I loosened the screw of the eccentric wheel, put some blue Loctite on the thread then re-tighten the screw. I let it dry overnight. Today I tried to make my boxes from a slab of maple. I’m happy to report that I did not experience shatter, the Z plate stayed in place, the eccentric wheel nut did not come loose. I did however experience my first communication failure between the computer and controller. I removed the dust boot and restarted the job and did not experience any issue except for the wood chips and sawdust flying everywhere. Since my Shapeoko is still in a temporary location until I finish some renovations in my workshop, I have not installed a separate grounding wire yet. I guess that if I want to use the dust boot, I will have to install a temporary grounding wire too.


That’s the one. I think you’re not realizing how much loctite that is…that bottle is the size of your hand, and it’s about 1/4 full. I have one.

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