X Axis not perpendicular to outside Y axis rails

Hi All,

Doing some more tuning and alignment and found the X axis is not square to Y axis rails. About 1/16" to 3/32" checking
about 16" + across. Important ? Not my Grandfathers framing square, machined all around on Fadal vertical machining center. Also, what syncs to two Y axis steppers ? Curious to how it works.
Really not trying to make a missile launcher out of this ! :grin:

As always appreciate the help !

That’s more out of square than we’d like to see, but at the lower end is w/in tolerances for the extrusion cutting.

You can shim it, or best thing to do is remove the extrusions, take them to the Fadal vertical machining center and have them all machined square,

The two Y-axis steppers are driven by two different stepper drivers, but the circuitry on the board is set up so that they counter-rotate.

I bought a new square like your’s at HF and it was farther out of square than your machine. I’d suggest checking the square to verify it is true before you go to extents adjusting your machine. Just my opinion. Jude

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Tighten your belts!!!
Mine was out 3/16ths out, tightened my belts (tight) now it’s a thing of beauty.

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Thanks for the reply. I’ve already machine the ends of the side rails as they were out of square. Made sure the were the exactly the same length also.

See a note below about belt tension.


Thanks ! Will look at that also.


Okay, if the extrusions are square and the same length for the Y-axis, then it’s an uneven bend in the end plates — figure out which is straightest, make that the one at the front, at the back, make sure if there’s a gap that it’s on the left side (so that the homing switch contacts first reliably). If you’re inclined, put a pair of large crescent wrenches on where the extrusions attach and bend into being flat / square / plumb.


" Not my Grandfathers framing square, machined all around on Fadal vertical machining center." It is square.

Appreciate the reply !


FWIW, in the future, rather than removing material from the square, you can square it up by hammering on the square at the angle, near inside corner to make obtuse, outside to make acute.

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I will check on that tomorrow.

As always , I appreciate the help !


Very correct ! Most don’t know that. But, when I had my shop going and owned the Fadal I could not resist machining it !

Brian :wink:

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I have not done extensive testing with this, but what little investigation I have done is that squareness is relative. It’s easy to nudge one side or the other of the gantry (without power) such that it is out of square, and after jogging that “out of squareness” is maintained. Now I understand there are a number of compounding variables here, but I wanted to convey what I had found during my calibration exercises.

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Hi Jim,

Yes, found that to be true without power to motors. I also did a test under power and jogging to see how much the squareness changed. I would say it maintained the squareness I adjusted for. I suppose the sync between the y axis motors and belt tension plays a part.
It was so far off it was affecting the relation to the hold down holes in my base. That’s how the whole squareness thing came about. Relative to the hole machine it is good enough now.


The machine endures a lot of stresses during a cut file with gantry moving and the router spinning and all the cutting forces, is there a concern that it can work itself out of square? Being a kit, i figure “seasonal” squareness checks are required because of that, but is there anything reasonable that could be added to the frame to strengthen the squareness of the machine? Reasonable refers to non-machinist applications (I guess). Thanks

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Hi Jude,

Being new to this machine I think keeping the fasteners tight and looks like belt tension checks would be good.
From my experience so far I think it is pretty solid being a kit. I’ve gotten better at knowing when to stop fussing with something. It is what it is. There is only so much that’s reasonable to try and make into something beyond its design.
Till I know more I tend to keep feed rates probably slower than I should. May give the machine less stress ?



Babying a cut doesn’t help as much as one would wish — the endmill rubs, galls, and overheats and doesn’t cut as well There are a couple of articles on this at CNC Cookbook.