Is Z-axis perfectly vertical?

I just finished a milling project with aluminum that required fairly deep milling (about 1-1/2"). The project looks OK, but I’m not sure my Z-Axis is perfectly vertical in relation to my starting material. How do I go about measuring/adjusting the Z-Axis to be sure it is vertical?

I have a 1/4" diameter piece of tool steel that I can chuck and then use 1-2-3 blocks to check the vertical on 4 sides.


Make sure everything is square (like the Z-Rail) with a carpenters square. Then build a rig to set tram. Here is mine. It is a 1x2 with two holes drilled in it. and a cut in each end so a bolt can tighten the bits I used. It doesnt have to be perfectly square either.

I used pieces of belt to shim my router in the mount.

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These are all great suggestions…thanks! I went at it a little this afternoon and did the following. I used a piece of 1"x3"x12" aluminum and got it perfectly level on the wasteboard with a bubble level (X and Y directions). I then placed a carpenter’s square (that was checked against a framing square) on top of the piece of aluminum (see photo below).

When I did this I found that the Z-axis was off by about 2mm. I loosened the screws attached to the T-slot nuts on the back of the Z-Axis and adjusted them. Check out this step in the assembly instructions for pictures:

This worked for the X direction. However, when I checked in the Y direction I found the spindle mount was a little off. I put a couple of washers on the V-wheel shafts to bring the mount vertical in the Y direction. I guess the true test will be to carve something out as suggested by others and assess the results.

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Right. But I figured if I started with a level benchmark the rest of the horizontal and vertical checks would be easier. and I could use my existing tools for measuring parallel and perpendicular surfaces.

Yeah, right…thanks!

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I’m feeling more confident that the X-Y plane is OK. If not, I know I can skim the waste board or some other surface to support my work. My concern is making sure the Z-axis (and the spindle shaft) is absolutely perpendicular to that plane. The tramming technique mentioned earlier has interested me.

OK…I understand how to use the 3/4" bit and will give that a try. I definitely need to make some adjustments since I can feel tiny ridges on my most recent project (milling a putter from aluminum) and that was with a 1/4" end mill to finish the face of the putter head.

I will definitely try the tramming and skimming techniques suggested earlier. In preparation for that I was able to get the spindle mount vertical in both the X and Y directions. I used the set-up shown in the photo below:

The aluminum bar is shimmed so it’s level based on the bubble level. I then use the side of the mount to measure the vertical. The picture shows this for the Y (front-back) direction. I then turn the aluminum bar 90 degrees and set it level and test the vertical again for the X direction (left-right). Next, will be to test all this out with a skimming run and a tramming tool.

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Think of it as if there was no up or down, it only matters in relation to each other. you can cut with the machine completely out of level skewed in any direction you like, but if the X-Y axis are square to the Z axis then the cut will be true. I would quit trying to use a bubble level (works in relation to the earth) and only concentrate on the “level” relationship of the axis to each other.

I understand this only gets the spindle vertical to the shimmed aluminum bar, but, at least, it’s vertical to something. I need to go buy a 3/4" bit so I can do the skim cut you recommended.

I agree. What I THINK I have now is a Z-axis that is pretty close to vertical in the X and Y directions. I’ll follow earlier suggestions to run a skim cut on the waste board to get that parallel and to test the vertical adjustments I just made.

This method has already failed. If you have to shim the aluminum bar then your “waste board” and/or support structure is not level and/or not flat.

That spindle can be perfectly vertical with any tolerance you pick and your machine will still not produce good results.

Even if I didn’t need to do all the leveling and squaring I learned a lot about the X-Carve and how it goes together. Since assembling it I’d forgotten how all the parts fit together. I hope it’s close now and when I do the skim cut any needed adjustments will be minor.

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Right. Stopping with only these adjustments is a mistake. I now need to run a skim cut to make the work surface parallel to the horizontal movements of the spindle. By using a large (e.g. 3/4") bit I’ll be able to detect any ridges that will indicate a non-vertical Z-axis. That’ll happen after I buy an appropriate bit.

It would help you to think about this a little differently. Since you have done a lot of work to get your spindle vertical that is not the problem anymore. Now you need to get your work surface perpendicular to the vertical spindle that you have already.

There are several ways to do that, but skimming the waste board is one way. Just keep in mind that wood changes dimensions with humidity so you may have to do the skim periodically to keep things lined up.

what I was trying to explain was that using a bubble level really has no meaning, in relationship to level to earth has no bearing on the cut. it only matters if all axis are square to each other. this would include the waste board. sorry that was not clear, I will stop trying to explain this now.

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Right. I’ve done the skimming procedure before and noticed changes. For some jobs a little change isn’t a big deal, but for the aluminum milling I’d like more consistency. I’m thinking of attaching a piece of 1/4" aluminum screwed to the wasteboard and skimming it. I’ll then place the piece to be milled on that.

The washers will assure that your Z will never be trammed correctly, if the Z maker slide is not also perfectly parallel to the mount, IMO.

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Right. I’ve removed those.