X axis out of square

After some unfortunate issues with my new machine finally have the spindle running. I’m now trying to dial in the machine.

I first leveled the table with my Starrett 98 machinist level so I’m sure that that part is good

I’ve trammed the spindle and have it dialed in pretty well. Left to right is within a thou. Front to back has a little nod that I’ll have to shim out, but is close enough to move on right now.

The Y axis front to back seems to be pretty close with in a .001 front to back for the work envelope.

The issue I’m seeing is left to right I’m seeing .020-.030sweeping the dial indicator from left to right across the work envelope.

I’ve put a height gage and measured the linear rails from the top surface of the table and the left side of the rails are .020 higher on the left both rails are the same so they are parallel so that’s good. I double checked the Saunders fixture plates on the surface plate and they are good so it appears the gantry is sloping down to the right.

Before I start loosening bolts on the gantry, is there enough slop in the holes to take .020 out?

Has anyone else noticed this amount of slope in their gantry on the HDM?

Yes, I couldn’t get it zeroed out. I flattened my waste board and got some ridges.
However, they are “in plane” for 99.9% of the bits I use.
When I pocket a large area, I have minute tool marks.
If and when I 3D something, I may worry about a “dead nuts” tram and re-flatten!

I belive @davidgjohnson had this issue as well. Look up some videos on youtube of machine axis tramming. There is many ways to go about fixing this. You need to verify your using all of the mounting bolts for the fixture plates as that is how they are milled. After that lay a flat edge across the plates and verify they are flat to one another. If they are flat then you need to shim your x axis positive on the negative side the difference your measuring. If the plates are not flat but your using all of your mounting bolts then you need a verified flat you can run across laying ontop of all three fixture plates to normalize their heights. Then do a sweep. I am not sure of the flatness of the stock aluminum extusions that go across the x axis floor so I wouldnt trust measuring off of those. Keep in mind, this is across the entire work volume. Your difference in endmill height across a a single cut straight contour with a 3/8 end mill is gonna be less then 0.0004 (pretty sure, whipped up a quick sketch in fusion to see). Will increase with larger pockets like mrchips has happen. I need to head to sleep soon and cant find a video of a cnc specific shimming but here is one with the basic concepts you need to know to get it done.

While it is important to be trammed up, dont let it ruin your experience by spending ages chasing zeros. Get her close to where she needs to be and dont dwell on needing perfection.


Yeah all the plates are planar with each other. There is no jump from plate to plate. I’ll be able to either shim it out if the adjustment of the gantry bolts won’t do it, but as it stands it currently would be .0044 across 6 inches so that is pretty huge in machining terms. I think you moved a decimal in your calc.

Worst case is I’ll machine some tapered shims to lay across the aluminum base extrusion

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