Z axis precision

LowRider CNC Troubleshooting
1

Hello.

I have built the LR4 a few moths ago and this is my first CNC machine so I might be missing some basic concepts.

I use a draknife to cut a 1.2 mm plastic sheet. I use a 3D printed vacuum table that I put on top of my spoilboard. I have surfaced both the spoilboard and the vacuum table. I am still facing precision issues on the z axis with differences up to 0.5 mm. This is more pronounced on the x axis than the y axis. Do you thing I should adjust the z axis by tweaking the homing distance? Isn’t the surfacing supposed to take care of this issue?

Thanks in advance for your help

2

Are you sure there’s no debris on the rails that the core is having to roll over? That could explain the varience.

3

all rails look pretty clean. I am working on a 2000x150 piece and the difference is pretty consistent with x max direction being the lower as well as being more pronounced towards the center of the y axis then the extremities.

4

I’m running a Primo, not a LowRider, so that pretty much exhausts my suggestions. I expect someone else will have some additional suggestions soon.

1 Like
5

We might need to see some pictures.

I’d start troubleshooting this by bistecting problems. First question is to compare the surfaces of the table and spoil board to be sure they’re actually flat. For me, when I do this I get a metal straight edge (I like to use a metal level for this). I sweep the straight edge over the table surfaces with a light behind it and look for gaps to show me whether or not it’s truly level (planar, really as it’s a 2D surface)

There’s a bunch of ways that you could have surfaced something and it ends up not fully planar.

Let’s get that data then we’ll talk about using your system to probe / map the Z to understand what’s out of whack.