I feel dumb asking this because I know the answer cannot be that hard but for the life of me I have never seen an explanation on how to do anything other than a full, all the way through, cut with Maslow.
From what I can tell there are three different types of cuts a CNC router should make, and I’m sure each of these has a name but I don’t know what they are. Could you help me understand how to do these different types of cuts with Ground Control?
Cut type #1) The regular ole, cut all the way through shape:
These are the cuts we used to build Maslow. The router follows a path and cuts all the way through the material. Leaving a sharp cut all the way through. Obviously I know how to do these since I watched Maslow build itself for a few hours.
Cut type #2 The, I’m going to make a slot in the material by cutting only part way through:
This one is almost as simple as the first example. One tells Ground Control to only cut part way through the material instead of all the way through… seems easy enough, right? Well, what if the material is 1" thick and I would like one line to be cut 1/2" (.5") deep, and another only 1/4" (.25") deep, then go around the outside of the whole part and cut a full 1" deep? How do I get the router to cut different paths to different final depths?
Cut type #3 The, I’d like to shave off some material in the middle:
This one really confuses me. Let’s say I have a 1" thick piece of plywood and I’d like cut out a box in the middle to a depth of 1/2" (.5"). So this box in the middle would be 1/2" and everything else is 1" thick. I’d have a sort of hollowed out section in the middle of the board. How the heck do I do that on Maslow? Would I have to somehow create a tool path that would zigzag back and forth, shaving off material in the middle? Or is there a way to automate that?
Anyway, these are the things I wonder about and ponder. Thanks for any help you can provide.
Great question! Also, awesome illustrations!
These things are handled in the CAM program. I use MakerCAM (http://www.makercam.com/) for this.
The trick is to use different cut types of cutting operations to achieve what you want.
MakerCAM offers four operations.
The profile operation which you are familiar with cuts around the outside of the selected piece. You can adjust how deep you want the cut to be and how many passes to make. This is the type #1 cut
The follow path operation will cut along a line to a depth that you specify. The center of the bit will follow the line, so the slot created will be 1 bit width. This is the type #2 cut
The pocket operation will generate a pattern where the bit zig-zags back and forth (or more commonly spirals out to the edge) to create a carved out shape. You can set the depth to which this is cut. This is the type #3 cut.
The drill operation gives you one more option which is useful if you need to drill a bunch of holes. It will simply move the bit into and back out of the wood in the specified locations.
I hope that helps!
@MeticulousMaynard is right that a slot can also be created with a pocked operation if you need the slot to be wider than the bit
Hah! i just took that post down cause I thought your answer was much clearer than mine!
there are a number of ways to do it, it depends on your software.
Keep in mind that the sled needs to be enough larger than the pocket so that it doesn’t fall in.
Very good point! If we don’t already have a wiki on this it seems like it could be a good addition. I’d be happy to help work on that as I learn how to do it myself.
when I say it depends on the software you are using, if you are using something like onshape or fusion360, you create a 3D model of your part and then it gets cut out, you don’t think in terms of pocket actions, etc, you just create the part to whatever shape you want.
@bar, thanks for the explanation! I do use MakerCAM so that’s very helpful. Unfortunately, I’m also using Sketchup for my design software (I’m pretty proficient in it, but realize it’s not the best option… I’m trying to learn Fusion 360… My head is just not wrapping around how it functions). Because of Sketchup’s limitations I don’t know if I can export the correct shapes to load into MakerCAM. I’ll need to do research on this…
You may find this youtube video about SketchUp helpful
So the file exported can be dropped into MakerCAM and it will understand how to sort out the different cut depths, and pockets? Or is there still going to be programming/settings on the MakerCAM end?
@bar I’ve watched that video many times. It is very helpful but it only shows how to cut a path all the way through. I’m not sure how to drop a design into MakerCAM that has a combination of profiles, paths, and pockets. (by the way, thanks for the explanation on various profile operations! Now I know what the different cuts are called.
Now that I know these different cuts are programmed in the CAM software I can start learning. Look what I found! Here’s a video that sheds some light on how to program MakerCAM to cut out various parts: https://www.youtube.com/watch?v=sNmamQuPic8
Things are starting to make sense now. Thanks for the help!
Fusion360 handles the programming. It’s not quite as simple as take shape, make code, but it certainly isn’t as convoluted as a program like MasterCAM ($$$$ pro program).
In Fusion, I like to design with CNC machining in mind. I will make sketches and lay out features in a way that helps the CAM module make the G-code. Once you have modeled your shapes, you pick out your type of operation (profile, pocket, drill, engrave, etc) and select the geometry you want it applied to. You will need to specify certain parameters such as depth of cut, step over, finish passes, climb/conventional to help it make the G-Code. This is a good video to go from concept to design to g-code: https://www.youtube.com/watch?v=VZU_Jpyyc5M&t=1s
“Unfortunately, I’m also using Sketchup for my design software (I’m pretty proficient in it, but realize it’s not the best option… I’m trying to learn Fusion 360… My head is just not wrapping around how it functions). Because of Sketchup’s limitations I don’t know if I can export the correct shapes to load into MakerCAM. I’ll need to do research on this…”
Sketchup? It is an excellent piece of software for the price. I use it all the time for designing things I cut with my CNC (just a little one, my Maslow should be here in a couple weeks though) or print with my 3D Printer. I have no issues getting dxf files imported into my CAM package (I purchased EstlCam). The key is using a plugin for sketchup that allows the export of a .dxf file and knowing the units you’re working in. As far as the dxf export plugin? I use this one: https://www.guitar-list.com/download-software/convert-sketchup-skp-files-dxf-or-stl
Units? I draw in whatever I need to work in, inches, feet, cm, mm, whatever, but I always export my dxfs and generate my gcode in mm. Whether I am 3D printing or running the CNC, it is always done in mm. All my machines are configured and operate in mm.
I’m also trying to learn Fusion360, but I keep coming back to Sketchup to handle the quick drawings or simple projects, usually because I need a result quickly.
no, you skip makerCM entirely, onshape or fusion360 output the g-code directly.
seethe video I posted the link to earlier this week about doing CAM in onshape.
I honestly did not know other apps could export g-code. That’s pretty cool.
Now, I’ve heard there are different “versions” of g-code, are there any concerns with what version it exports to?
That’s handled by the post-processor. Here is an example list from Fusion:
Machine all “speak” different dialects of G-Code for one reason or another. Sometimes machine will also use proprietary file types. Luckily, this is an open source machine, so the Maslow just uses generic G-Code. If you do go the Fusion route, make sure you use the Grbl post.
If you see ‘grbl’ in the list, that should work.
The Fusion360 grbl post processor generates the following. Ground control fails on many of the commands and there seems to be lots of extra z moves. (The non useable codes are bold.)
Are there ways to limit the post output to Maslow useable items?
Is there a simple screening program to strip out the lines that Maslow can’t use?
Are there Fusion settings that can be adjusted to generate clean Maslow gcode?
(T1 D=10 CR=0 - ZMIN=-1 - flat end mill)
G28 G91 Z0
G0 X93.6 Y-1
G1 Z1 F30
G18 G2 X94.6 Z-1 I1
G1 X95.6 F2328
G17 G3 X96.6 Y0 J1
X95.6 Y1 I-1
G18 G3 X93.6 Z0 K1
G1 Z1 F30
I’m not familiar with Fusion 360 so maybe someone else can answer the Fusion 360 specific questions. However I know that Makercam.com you select the parts in individual depths and create separate paths for them. Your file will then perform the cuts and even prompt you if you selected different tool sizes when to switch them out. it might be worth a try running it through Makercam.