Shapeoko 3 xxl X / Y Axis

[Nexus77241 (Dave Tepper)]

Hi y’all,

I just built a new stand for my Shapeoko. When I was moving it on, I moved the x axis all the way forward and found that the gantry does not touch the front on both sides. Here is a shot of the left side.

And here is a shot of the right.

It’s about 3/16 off. This might also have been contributing to my previous accuracy issues. Anyone know how I can fix this?

Thanks!!!

[WillAdams (William Adams (Carbide 3D))]

Check the opposite extreme of movement, there are three possibilities:

• the Y-axis rails are unequal in length and this is caused by that (early machines had rail ends cut by the extruder, normally this is quite square/even/equal, but not always — this is why we now have a CNC machine large enough to machine both ends of a rail)
• the Y-axis rails are equal in length and the rails/end plates are shaped as a parallelogram
• both the Y-axis rails are unequal in length and the rails are not square

In my experience, the best approach is to work from large → small:

• level the table (optional, put a sheet of foam in-between the table and the machine, dampens noise/vibrations, makes leveling easier, addresses sag on larger machines)
• ensure that the end-plates are level
• Y-axis rails level and parallel to each other and plumb/vertical
• gantry level, square to the Y-axis rails and plumb
• carriage level and plumb
• Z-axis level and plumb

Shim as necessary to get things to line up.

[ScottsdaleSteve (Steve)]

Shimming in the correct spots will fix this. Here is my post from a few years ago that shows how…

Yet another xxl squaring issue

I had the exact same issue on my XL, though only a 1/4" gap in the same places (back left/front right). I don’t think you’re shimming in the correct spots. You need to shim the X rail in the places indicated (back of the left end; front of the right end). I used a stack of 3 slivers of aluminum from a Coke can in each spot and it closed the gap exactly. If you look closely, you can see the shim in the second picture. Coke can wall thickness is ~ .004" thick, so with 3 layers my total shim wa…

[Nexus77241 (Dave Tepper)]

Thanks so much guys! I’ll try all this next week when I’m back in town.

[Nexus77241 (Dave Tepper)]

I’ll try shimming in the spots.

I got the gap down to between 1/8 and 1/16. I used a feeler guage to shim but didn’t do it in the spots listed above. I’ll shim again.

Do they need to be same on each side?

I have plenty of foil… gotta love Costco.

[WillAdams (William Adams (Carbide 3D))]

Shims should be placed/sized so as to result in the machine being square — they would only be the same on each side if the rail was cut as an even parallelogram (which is possible, even likely).

[ScottsdaleSteve (Steve)]

Aluminum foil is kinda thin and deformable/crushable. For that reason I didn’t use aluminum foil - I used aluminum from a Coke can, which is .004" thick. Three layers of .004" closed my 1/4" gaps exactly. My two gaps (back left/front right) were both 1/4", so both spots got three stacked shims.

I’m sure any aluminum beer or soft drink can would work.

[Nexus77241 (Dave Tepper)]

That makes sense! Definitely don’t want anything that will deform. Since I’m off close to 1/8, I’ll need two can pieces….

Really dumb question. How do you keep them from moving when you put your x gantry back? Like how do you get it to stay when you make the front of the x gantry perpendicular to the bed?

[ScottsdaleSteve (Steve)]

I don’t recall how I did it - they’re slippery little devils. Maybe a sliver of scotch tape to hold them while you bolt things up?

[Nexus77241 (Dave Tepper)]

Tried the soda can shims. It actually made it worse. Took them out and I’m back to how it was.

This is a picture of the gap as of an hour ago.