New method for eccentric nut/bolt/V Wheel attachment

So, after having my Z axis fall apart on me mid-job - crashing the spindle and ruining the work piece - I decided to come up with a way to keep those eccentric nuts tight while still adjustable. I didn’t want to use thread lock so I opted for Nylock nuts. It was also a pain in the butt to get an allen wrench inside the X carriage to make adjustments to those eccentric nuts. I wanted to change that too.

So, after having a think about it, I’ve come up with this solution:

To start, thread the eccentric nut all the way down the bolt, get it as tight as you can against the head of the bolt. This essentially gives the bolt head that magical eccentric lobe. Then use the nylock nut on the other end. I added an extra washer to each bearing so there’s a washer on each side of the V wheels where before there was just 1 between the V wheel and the plate.

Now to make adjustments to the eccentric lobe you use a 3mm allen wrench and an 8mm wrench just like before. Loosen the nylock nut while holding the allen key steady. Then move the allen key to adjust the position of the eccentric lobe, then tighten down the nylock nut. I would recommend using a ratcheting wrench for the inside of the X carriage.

I’ve now got about 6-7 hours of cutting time with this setup and have yet to see a loose eccentric nut anywhere.


Yep, for everything but the Z axis. The standard screws aren’t long enough for the thicker bracket that comes with the Dewalt, unless they’ve lengthened them since I ordered mine

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Thanks for the idea and the detailed pictures guys. I will try this method as soon as I get the nuts that I ordered. Im so sick of these things getting lose all the time.

I did this last night, and it’s amazing. i did this on both x and y ($3.30 for the lock nuts). I also did the Z, but I had to buy two 40mm M5 bolts so 80 cents extra there!

So simple I can’t believe I didn’t think of it. My only concern is that the eccentric bolt/spacers scratched and gouged the aluminum surrounding the holes. I’d rather have eccentric spacers that are 10mm or 12mm hex size as opposed to the rather small 8mm that came with the machine. More surface area against the aluminum can’t hurt, I think…

Then i was looking at Open Builds, and it appears that their spacers go a bit deeper and have a washer-like bottom that would indeed catch more surface area. Am I correct that these would work to make this mod more stable? Also, now that I look at it, Inventables has beefed up versions of their spacers as well. I missed this before…

What are people using for this mod?


On my X-Carve, the area around the holes was already pretty boogered up from the eccentric nuts having been adjusted a dozen times prior to doing this mod, so I didn’t really notice if the mod itself had any additional impact.

Since you aren’t using the eccentric nut to tighten anything against the frame, you only have to turn it to adjust the lobe position. Then you apply tension with the lock nut on the other side. This means the eccentric nut shouldn’t gouge against the frame at all.

And, since once you get the lobe position dialed in, you likely will never have to touch it again (1+ year strong on my X-Carve) it means much greater longevity of the holes in the frame.

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Just wondering…normal blue lock tite, or the permanent?
Great job on this btw! I think the concept at least is ten times better!

I use blue 220 or 242.

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Ok thanks. I think I’ll give it a go.

Hello all…I just wanted to say that I switched to this method of attaching the v-wheels, and while I may only have a couple hrs on the machine since I switched; nothing has came loose yet!!! I found this less likely to loosen the nut while adjusting the essentric nut also.
I only did my essentric nuts to see how I liked it, but I’m now gonna switch the rest of them to this method also as it is SOOO much better (at least for me).

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Is this mod needed on the newer 750 xcarve?

Hi Phil,
Question about the 9mm belts you have? What is the difference between G2 and G3? What does the X-carve 750 use? I assume if I use whatever the xcarve uses now then no grbl changes?? Your preference? why?