Introduction: How to Run a Desktop CNC Mill

Picture of How to Run a Desktop CNC Mill

This instructable is a quick guide to desktop CNC milling with an Othermill, a common small-scale machine that's mainly used for making PCB circuit boards. This machine can do everything a larger machine can, it just has a smaller build platform.

I have another instructable up on how to make the CAM setup for this particular model: 3D-Milling-CAM-Setup-Fusion-360

Step 1: Tool Change + Homing

Like every other CNC mill, the Othermill uses collets and collet nuts to attach the end mill to the spindle. It's important to insert shaft to the proper depth as described in the graphic below.

To insert a tool, insert the collet into the nut, then insert the shaft so that the flutes are exposed while keeping the shaft in the collet at the maximum possible depth. Use a pair of wrenches to tighten the collet. Don't tighten with too much strength though- this can strip the threads.

Home Axes

With the tool in place, you will need to home the X, Y, and Z axes. Homing tells the machine where the zero points are on each axis. The Othermill has proximity (prox) switches for the X and Y (horizontal) axes, so this can be done automatically. The Locate button in the Configure menu will allow you to automatically home the X and Y axes.

The Z axis cannot be homed with a prox switch because the depth of this axis depends on the length of the tool inserted into the spindle. The Othermill has a conductive platform that will automatically set the proper Z zero height when the end mill touches the plate.

To set this height, click on Change under the Configure menu, select the type of tool from the list (1/8" ball nose end mill in our case), then move the X and Y axes as necessary to locate the tool over an empty spot on the bed. Click Locate Tool, and the machine will move the spindle down until the end mill touches the plate. This will automatically locate the proper Z axis.

If your CNC mill doesn't have a conductive Z function, just put a piece of paper between the bed and the end mill, then nudge it down until you can move the paper with a little bit of resistance.

This process will depend on the CNC mill you're working with, but the concepts are more or less universal.

Step 2: Fixturing Stock

In order for a CNC mill to cut out a tool path, the stock must be properly fixtured to the bed. There are lots of different ways to do this which include vices, clamps, hot glue, and many other methods. Since our part is so small (3" X 3" X 3/4"), double-sided tape is sufficient for a firm hold on the bed.

Be sure to properly align the stock with the bed on of the corners. I'm choosing the bottom left corner of the bed which is X=0 / Y=0. Also, be sure to account for the thickness of the tape and add it to the thickness of your stock when you're setting up your cut.

Step 3: Running Machine / Cleanup

With the stock fixtured and the machine homed, you can run the gCode you created in Fusion 360. To run a file, just click Open Files in the Othermill dialog box and select the G-Code you exported from Fusion 360 in post processing.

Note that the Othermill control software lets you specify which corner the material is in ("at left of spoilboard origin"). My piece of wood is .76" thick, but I've changed it to .77" to account for the double-sided tape on the bottom of the wood.

For the Othermill and most other desktop CNC machines, a computer must remain plugged in to run the tool path via USB. You can pause the job, meaning it will resume where it left off if you click the Play button, or you can stop the job by clicking Stop. This will reset the spindle position and won't let you restart from where you left off. This toolpath takes about 1.5 hours as indicated in the progress bar.

Step 4: Finished Product

With the toolpath settings we created, the piece comes out kind of like a topographical map. With a smaller stepdown value, the layers would be less pronounced.


gatiel made it! (author)2017-04-04


JON-A-TRON (author)gatiel2017-04-05

Nice work! You might want to try filling the relief with tinted resin, that can yield some good results.

gatiel (author)JON-A-TRON2017-04-05


gatiel (author)JON-A-TRON2017-04-05


kkistler made it! (author)2017-03-22


JON-A-TRON (author)kkistler2017-03-27

Good start! Plywood is great for this kind of thing because the layers show up with the cut.

JodyCochran made it! (author)2017-01-30

Carved the handle grips for a Han Solo prop I 3D printed.

JON-A-TRON (author)JodyCochran2017-01-31

Nice work! The CNC is so help fun for that scalloping effect on the grip- one of those things that would be a huge pain if you had to carve it by hand.

julawrey made it! (author)2017-01-05

The oahu map I cnc milled in the previous lesson

JON-A-TRON (author)julawrey2017-01-10

Really nice work. Well done.

linmag made it! (author)2016-12-12

I made it.

Made a hand drawn picture of a flower with a grayscale, took a picture, and CNC milled it from some scrap wood.

JON-A-TRON (author)linmag2016-12-13

That's awesome! Hand drawing is a great idea because you get to control the depth by picking how dark the parts are.

Renauld made it! (author)2016-12-12

Lousy CNC machine build on a Laser engraver.

The bottom carving is from lesson 4 (with a lot of mistakes)

The top in black I replaced the drill with a pen. It works.

JON-A-TRON (author)Renauld2016-12-13

So cool that you're figuring this out. I'm sure a lot of people would love to see an instructable of your machine.

MyatCharm made it! (author)2016-11-30

That's my country

JON-A-TRON (author)MyatCharm2016-12-05

Myanmar? Very nice.

MyatCharm (author)JON-A-TRON2016-12-05

Yes, I'm from Myanmar

adam37 made it! (author)2016-11-30

still can't get the image you used to open in fusion 360, but I was able to make the moonscape image work. Do you know if that extra material is from the feeds and speeds or is it the bit?

JON-A-TRON (author)adam372016-12-05

It's probably a combination of both. A straight profile end mill (router bit) is more likely to leave the hairy edges like that- a downcut spiral will most likely prevent it from happening. Lowering the feedrates might also solve this problem.

Of course, there's always sandpaper!

jlwilliams03 made it! (author)2016-11-28

I learned something! I can't wait to run this on my inbound FR4 Machine Shield (See

JON-A-TRON (author)jlwilliams032016-11-29

5-axis! That's an awesome machine. Fusion just announced that they're going to release 5-axis machining functionality. I can't wait to play with that.

jlwilliams03 (author)JON-A-TRON2016-11-29

Actually, the FR4 is a three axis "starter" machine, offered by the PocketNC folks. It too was a Kickstarter offering that is 1/10th the pricetag of the 5-axis PocketNC. The PocketNC is a Tesla; the FR4 is a Vespa :)

ablank made it! (author)2016-11-18

followed the example

JON-A-TRON (author)ablank2016-11-29

This is a good example of how you can have an object oriented any way you want in Fusion and create a machining setup with the orientation you want.

squared59 made it! (author)2016-11-16

Here is my finished project. Took a lot longer to do than I had planned. I have an old Isel Techno Davinci mill and it took a lot of searching to make it work with Fusion. Mostly finding the right post processor.

I just did a test run with some end grain balsa wood. It seems to machine nicely and is easy on the tools.

JON-A-TRON (author)squared592016-11-28

Looks really good! Yeah, post processing can be kind of a pain, but there's almost always a solution since everything basically runs on G-Code anyway.

This is the same depth-map image Hans used to write the script, incidentally.

ShawnW66 made it! (author)2016-11-18

Took a lot longer than I thought it would but was messmerizing to watch!

JON-A-TRON (author)ShawnW662016-11-28

Very nice! You can make the stepover distances smaller to get a smoother surface if you want. Personally, I like the topo map effect on this one.

brucesdad13 made it! (author)2016-11-18


About This Instructable




Bio: I'm a full-time Designer at the Instructables Design Studio (best job ever). My background is in residential architecture, film set design, film animatronics, media ... More »
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