How to do multi-tool cuts?

No Judgement
1

I am VERY new to CNC and Maslow… I have assembled my frame, and I am working on cutting out my “final sled” but I wanted to one-up myself by cutting the sled, and then doubling back with a round off bit. However, I realize now as a noob, this is way more difficult than I had originally anticipated. It is a skill I’d like to learn (if possible) for future projects.

Tools:

The Plan:

Using the 1/4" Up Spiral bit, I will cut the outside profile (of the actual sled), then cut two more inside profile cuts on the outside of the sled, giving me a wide enough channel to set the rounding over bit with bearing down into the channel. Then I would execute a cut using outside profile using a 1.7mm offset from the first outside profile cut. In theory, this will give me a nice rounded off sled without having to get router table, or sand, etc.

The Problem:

Here is where I am having trouble, in general actually. So I took the SVG for the original sled, and load it into MakeCam, export the Gcode for the first set of cuts, and all that goes well. Then I load the SVG a second time and trim out everything but the final rounding bit cut. Export the Gcode.

I open GroundControl, and load the first set of cuts, and run the cuts and all goes well. Once the cuts are done, I hit the home button (the little house) and the bit is drawn up, moves to the home position. I stop the motor, slip the motor out off the sled, switch bits. I do a Z-axis adjustment. Then I load the new Gcode (for the rounding bit). The image is way off the screen. I hit “define home” to bring it back to where I am cutting. Then I hit play. However, it appears that the home may have repositioned, or my math is off, because the rounding bit doens’t line up as expected.

Do I have the order of operations correct?

  • Start GroundControl
  • load Gcode (for first cuts)
  • Move sled to preferred starting position
  • Hit “define home”
  • Run the cuts
  • When cuts end click “Home” button
  • Stop motor, replace bit
  • Adjust Z-axis
  • Clear Gcode
  • Load Gcode (for second cut)
  • Hit “home” button
  • Hit “define home” button
  • Run the cuts

Is there a write up I just haven’t found that explains how to do this type of work better?

Am I expecting too much from the Maslow system?

I want to add how very impressed I am with the CNC, and all my neighbors keep coming walking by in awe of the machine. Good work guys!

2

don’t redefine home for the second cut, just load the bit and the new g-code and
go.

it’s also normal to remove the bearing from these bits when using them on a CNC,
you aren’t pushing against the material like you are by hand.

David Lang

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3

When I load the new Gcode, it always sends it WAY off the view. Is that something I am doing wrong?

4

I don’t know makercam, but I guess you have similar functionalities as fusion.
In fusion you can add an additional route with alternative bit. Generate one g-code and ground control will pauze automatically telling you to change bits. Then resume cut.

5

Seems like if you make the rounding path in the same place as the primary cut line, then the rounding path will land in the same spot when you load it. Don’s use MackerCam, but have seen discussions about setting the home spot, so I know you will get an answer. When you set up MakerCam, is the workspace the same as Ground Control (96” x 48”, or the metric equivalent)? If so, it seems that the cut file should land in the same spot in GC.

Welcome to the Forum, and good luck!

6

OK,

So this would be an advanced topic. I’ll try to explain. However the answer here is cut out the sled and use the round over bit by hand.

To use this bit you will need to remove the bearing and probably grind the bit down - not ideal, and not suggested unless you have skill making edged tools and knives.

Then you need to figure out the geometry of the tool, divide it in half and use it as an offset from your original line. The other issue here is it is designed to engage 1 edge. The way you will be using it you will be trying to do a plunge cut on both sides of the profile you originally made. Looking at the bit it is not designed to enter a 1/4 negative space. It needs more clearance. The Plunge will likely stall due to all the forementioned issues.

You could spend hours or days working out how to get the CNC to do an operation you will likely do 1 time ever and could have done by hand in 3 minutes.

Work efficiently. Take the lesson forward for something you will do many times, Create a jig, work holding and a workflow. Make a million of them.

Thank you

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