New at CNC - What went wrong?

[JPressN]

Hello y’all

I’m enjoying my SM2.0 and trying out the different modules. I’m new to all of them so there is a steep learning curve.

I’ve been working with the CNC for the last couples of days. Designing a project for it that is. I wanted to make something similar to the photo underneath of Stockholm (This is from the site actioncoin.com):

(NOTE: I only want to make this for myself as a fun project! I am NOT trying to copy the designs of others for my own benefit )

So here is what I did:
I glued three pieces of plywood together:

• at bottom 1,5mm blue plywood.
• in the middle 4,0mm walnutt/birch plywood (brown).
• on top 2,0mm birch plywood (light/sand color).

With some help from Qgis, paint.net and photopea.com, I was able to make three files I wanted to use in Luban.

1. A .png file with the name of the city (Silkeborg) and some coordinates.
2. A .svg file with the streets. Actual everything but the streets was black because everything but the streets needed to be carved.
3. A .svg file with the water areas. The water areas needed to be cut through the top and middle layer of plywood. That way the blue 1,5mm plywood at bottom would be visible.

This was the plan. But from there it went kind of down hill
In Luban this is how my project looked after compiling the g-code:

The text was set to be carved 1,00mm.
The roads were set to be carved 2,25mm.
The water areas were set to be carved 6,15mm (the decimal is due the the actual thickness measured with a caliper.)
Around it all I made a square to be carved 7,70mm (carving the entire thing out in the correct dimensions)
Now, as you can see in the pictures bellow multiple things went wrong.

• The text was carved but for some reason it carved down a square first and then carved down the text - Why?
• The CNC have made a diagonal path between the two text areas which is not defined in Luban - Why?
• There are a lot “fibers” from the plywood. These have been caught up in the drill and unfortunately broken the drill. - How can this be avoided.
• I used the flat ended mill which came with the SM2.0 (Shank diameter: 3,175mm). Looking at the details it managed to carve before it broke, I do not think that it was the correct mill to use. Or my settings are way off.

I hope some of you guys and gals can help me in what I have done wrong or maybe you have some nice hints to a new guy
I have attached the screen shots for all the toolpath settings underneath. In the meantime I’m going to figure out where to buy a new flat end mill bit.

Kind regards
Jonas

P.S. I’ll leave a positive picture as well. One of the highway intersections actual looked pretty nice

Settings:

[sdj544]

First of all, they aren’t gluing the plywood together and then cutting it.
They’re cutting out layers and then gluing them together.
They’re probably also not using cnc (at least of the top layer) they’re using laser so that they can get much more detail. (They’re also probably using a more powerful laser with an air assist on a honeycomb bed so that they can go much faster with out scorching it)

Besides that, Luban is really terrible for cnc. It does some strange stuff sometimes and there’s not much control over toolpaths. Fusion 360 is free for hobby use and what you should probably learn (there are alternatives, but most are expensive or have other drawbacks).

When using luban you’re probably trying to go to fast or cut to deep and that’s what’s snapping your bits (and contributing to stringing (although plywood often times just is)) There are also up-cut and down-cut bits. Up better for clearing (lifts shavings away from surface) Down better for finishing and less stringing- presses down against surface.

-S

-S