Checking out a machine. Any tips?

[Richard]

Just bought a used gantry router. It's a custome made machine, but appears very well designed and is very chunky. It's basically a 3040 on steriods. (i'll stick some pics up later...)

Now it's in situ, what checks should I do, no make sure its all square and hasn't suffered any issues from transit?

Tramming and retrun to zero in each axis comes to mind.

Is it worth disconnecting the axis drive belts to make sure there are no tight spots?

[Neale]

Flatness across the bed? Measure gap between tip of tool and bed at various points.

Squareness of gantry? Drill four holes at corners of a square, fix pins in, and measure diagonals. I use a box of, say, 4mm drills for this - drill holes with one drill and jam four others in holes by their shanks. Thick bit of MDF works well for this.

Check that tool returns to same position after move - useful check for backlash.

Do, say, 100 there-and-back moves in each axis and check that tool returns to same position. If it slowly drifts, this might indicate an issue with the polarity of the "step" signal on that axis - not an unknown but sometimes difficult to spot issue, easily fixed.

[Richard]

Flatness across the bed? Measure gap between tip of tool and bed at various points.

Squareness of gantry? Drill four holes at corners of a square, fix pins in, and measure diagonals. I use a box of, say, 4mm drills for this - drill holes with one drill and jam four others in holes by their shanks. Thick bit of MDF works well for this.

Check that tool returns to same position after move - useful check for backlash.

Do, say, 100 there-and-back moves in each axis and check that tool returns to same position. If it slowly drifts, this might indicate an issue with the polarity of the "step" signal on that axis - not an unknown but sometimes difficult to spot issue, easily fixed.

Thanks Neale, excellent advice.

[Richard]

Some pics of the beasty.

Hiwin rails and slides all round. 16mm ball screws.

Z axis has moving rails, which is good.

It's made partly from extrusions and partly from plate.

Gantry uprights are quite tall and might be a bit floppy but they are 20mm thick.

Everything feels nice and tight where it needs to be.

Bed is not shown, it's a slab of 15mm cast iron with an ali plate bolted onto that, which has been drilled and tapped in a grid.

Spindle feels smooth and vibration free.

Appears to be set up for spray mist. There's a line running to a valve mounted (or rather strapped on) on the front of the spindle which would take a liquid feed I assume. There's only an air line there at the moment.


2495824957249592496024961

[Clive S]

It looks you have found a very nice cable machine with many good points

[Richard]

It looks you have found a very nice cable machine with many good points

It certainly looks ok, not the biggest capacity, but if that becomes a problem, it wouldn't take much to extend the bed...

Came with laptop and mach3 2.0, collets and a few endmills too.

VFD is a Schnider ATV12 and stepper controllers are CWD556's. The motion controller is a UC100.

[Richard]

I've been checking out the machine some more. Mainly tramming today.

I found that it was out a little.

Adjusting the spindle mount to get it perpendicluar to x axis (left/right) is pretty easy, but is there a prefered method to adjust the other direction?

My tramming arm is 100mm long, so over 200mm I am seeing 0.2mm 'nod' forwards. I was thinking I just need some very thin shim stock under the bottom bolts of the spindle mount?