I just finished reprinting my braces and core after I found some inaccuracy issues with my gantry. (A combination of warped braces and slightly bent tubes). I am going through the docs for setup and calibration and I’m currently on the Z Leveling section. I am working from a previously surfaced surface and my z is off by 2mm on opposite sides with both limit switches at their upper most positions. I understand that I could adjust the offset to account for that in FluidNC.
My question is, is there any point in changing the offset now before surfacing? Let’s say I surface a total of 3mm, wouldn’t this remove an extra 1mm and then leave with a surface that is now parallel?
At this point you really don’t know if surface is truly level from before, because of the bowed tubes and warping. I do not have a LW 4, but I do find that generally it is best to get your mechanical adjustments as close as you can. So surface first. Then you can fine tune with software. If possible I would try to check that the tubes are parallel to the table. Then add the waste board .
Then you check a least 9 points.
First we need to create a reference point. Move your router to min Y/min X. Lower Z slowly and using a piece of paper or your touch plate touch the waste board. Make this Home and zero X,Y,Z.
Now we dont know yet where the low and high spots are, so lift the Z 10mm. So every time you move lift the Z 5mm. To prevent dragging the bit. As you move from point to point you may find you don’t need to raise it so much
So Start with Y min/X min. Check Z. Then check Y min / Xmax/2 . Check Z and note. Now move to Y min/X max,again check Z and note.
Now move to Ymax/2 and repeat the X moves. Then move to Y max and do it again.
These measurements will tell you how much material you need to remove to surface.
This is the question i have as well. It’s the last calibration I need to do, and have been putting it off. I’ll watch this thread to see how the experts respond.
Level Z first. The reason is that surfacing doesn’t make the spoilboard “flat” in some absolute sense, it makes it parallel to whatever plane the gantry is travelling in at that moment. If the beam is 2 mm low on one side when you surface, the board ends up matching that tilt. Then when you fix the offset afterwards, your nice fresh surface is suddenly 2 mm out across X again and you’re surfacing twice.
There’s a second reason too: a tilted beam means the router isn’t quite square to the table in X. A wide surfacing bit will leave small steps between passes instead of a smooth finish.
So set the offset, check both ends at the same Y with the same bit or touch plate, then surface. You’ll probably get away with taking off less than 3 mm.