Luban CNC Parameters

Snapmaker Artisan
1

Using Luban 4.13.0 engraving some flat expensive material, I don’t want to get the parameters wrong. SO:
I find the description of the Luban parameters are not obvious.

  1. I believe the “Target Depth” means the total thickness of the material.
  2. What does “Allowance” represent? Is that the thickness of the background after engraving but not the material where no engraving at all takes place?
  3. Step Down apparently means the depth of the engraving. But how does this relate to “Allowance”?
  4. I believe “Step Over” means the distance between one engraved line and the next.
  5. I believe “Separate from Boundry” means to engrave the background between the foreground perimeter and the boundary box, while “Connected to Boundry” means to only engrave within the perimeter boundary. And which parameter controls the depth of this background outside the perimeter of the engraved design?

I’m sure this confusion is only the result of different languages, but could someone please clarify these paramaters to an English speaking old guy.

Lew Palmer

2

Target depth is how deep you want it to cut. i.e. if you have a 10mm thick piece of wood, and want the engrave or whatever 5mm deep, you would set target depth to 5mm. If you wanted to cut all the way through, you would set at 10mm.

Allowance is to leave stock, such as for a roughing pass. You would set an allowance of say, 1mm and run a flat endmill to quickly rough out and take away material, then 0 allowance to follow up with an engraving bit to clean up the rest.

Step down is how much it will take off in each pass. i.e. if you needed to make the above 5mm depth, you can’t realistically do that in one go. Set the step down to 0.5mm or 1mm, and it will take several passes only cutting your set depth each time i.e. 1mm stepdown with a target depth of 5mm, it will make 5 passes to get there.

Step over is how much the bit moves over as it goes. It can kind of be relatable to the ‘resolution’ of your cut. The smaller your stepover, the better your finish, but the longer it will take. For roughing with a 3mm bit, a stepover of say 2mm will make it quick, but have scallop lines, but for a final pass with a V bit, your stepover would only be 0.1-0.2mm to make a smoother finish.
It’s particularly important when using a bullnose, tapered ball endmill, or other finishing bit
Example of large to small stepover;

3805×1121 433 KB

I’m not familiar with the separate from boundry, but I assume it’s likely similar to the machining boundry in Fusion360
image
image498×693 101 KB

Where 'separate from boundary likely would be a silhouette, and connected to boundary would be like the bounding box in the above image. (basically just your engrave vs clearing out the entire square bounding box)

EDIT: Or a better example would be in the stepover example above; Silhouette would JUST cut the dome part, whereas bounding box would cut the entire square AND the dome, flattening out the entire area in the bounding square.

1 Like
3

I don’t have any particular CNC experience, but I have screwed up a lot of projects.

I suggest making a bunch of test runs on some less expensive material. Use some MDF or Acrylic, and observe. It’s not the same hardness or stickyness as your expensive material, but you can probably extrapolate a bit. Like if your material is particularly hard, say ceramic tile, you might see some roughing passes that work on acrylic, but seem too aggressive. Or if the material is sticky, say brass, maybe you need to be more aggressive. I would suggest trying to get a cheap material that’s as close as possible. Aluminum instead of brass, terracotta instead of glazed tile, etc.

When you’re finally ready to use the real material, use the roughing passes to validate your earlier tests. While you’re still roughing, you can abort, adjust, and restart.

And if you don’t mind sharing the type of material, there is a lot of experience on the forum with different material.

4

Thank you both for your responses. It may take me a bit of experimentation and thinking about your answers. I have been playing around with some 3mm plywood but my experiences don’t seem to agree on a couple of points.
When I have tested with plywood and set the Target Depth, I have set it to the material thickness and used the Step Down parameter to set the depth of the engraving.
The problem I see with that is that the background of the design is cut to the same depth as the background OUTSIDE the design but within the bounding box. So I may have to experiment with different settings.
I understand the Step Over parameter, but some diagram of a few projects along with the parameter settings for each would help my old brain to see it more clearly.
So I’m still a little confused.

Regards,
LewPalmer

5

Oh, two other questions:

  1. What effect does the “Allowance” parameter have on your examples?
  2. What then is the difference between “Target Depth” and “Step Down”?

Lew

6

Unfortunately i cant find the setting in Luban right now so here my thoughts:
Allowance is the part of the material which is not carved (left over). For example, if i have a target depth of 3mm and a allowance of 0.1mm it would carve only 2.9mm.
Allowance is made for toolchanges but if you want to use this for toolchange you need to use advance cnc cam software.
The other reason of using could be for additional grinding

Step down is the depth per step, i set it normaly to 1mm.
Target depth is the absolute depth which has to be carved, for example 3mm.
This means the software generates (Target depth / Step down = Number of passes) three passes a 1mm to reach the target depth of 3mm.

7

OK, thanks.

Lew