Tips: How to Set Your Origin Point on Your CNC Machine

Hey folks! Have you seen Bucky’s Customs’ latest video yet? In this video, Dana shows us the best and easiest way to find the origin/starting point when using your CNC machine. It is very important to know how to find the origin point correctly, as it ensures the successfulness of your projects and that you are using your CNC effectively.

To learn more about finding the origin point, watch the full video linked below. Make sure to subscribe to Bucky’s Customs’ YouTube channel also linked below for more CNC tips.

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Hi, everyone.
I hope you’ll be patient with me, a newb to CNC, but I’m trying to determine and map out the actual cutting area of my LongMill MK2 30 x 30.
My only goal in woodworking is to build bass guitars. Not for sale, but just for myself.
I purchased the LongMill MK2 with the goal of using it (in conjunction with 2D modeling software, 3D modeling software, MeshCAM, etc.) to accomplish smooth and accurate carves of the “bass of my dreams.”
The issue I’m running into at the moment is: What is the actually cutting area of my LongMill? I mention this because the dimensions of my pieces is right up against the carving area of the machine.
I have basses whose necks (with headstock) extend to 36".
I don’t really need this length, but the specs seem to indicate about 34".
So: is there any g-code or program or method that would allow me to map out, on my washboard, the actual cutting area of my machine?
I ask this because I am working with designs that seem to be pushing the limits of the actual carving area.
I’ve thought of jogging the machine to its “grind point,” and then backing off half a millimeter, then marking the point, then repeating that on all of the X and Y points, just to get a sense.
(I should mention that I’m talking about an area that takes into account the diameter of the bit. Like, how do you factor in the diameter of a 1/4" bit when determining you actual carving area? Do you take the specs and subtract the diameter of the bit?)
Anyhow, would love to hear from anyone who has navigated this problem (if indeed it’s a problem), and would also love to hear from anyone who has any code to “map” out the actual cutting area of the machine.

The only job I’ve done that used the whole machine dimensions was/is surfacing my spoil boards. I did manually map it out for that.

You can use the machine to measure it’s own cutting area like you were thinking. Put the machine in the near left corner. Home there if you have switches or jog there till it grinds and back of 0.5mm. Then set X and Y to zero there. Now jog the the far right and stop before you hit the end, the X number in gSender is now the machine width. If you hit the end and make it grind the numbers will be off. Then do the same jogging to the back and you will have the machine dimensions.

The machine dimensions determined above would be the maximum area reached by the center of the bit. The actual shape that you could cut out would be less by the bit diameter, half on each end/side.

As far as marking your spoil boards, as you can see in this post, I’ve marked up mine with a grid that helps me out. I used a laser but you can use an engraving bit, if it helps you out go for it.

EDIT: In case you haven’t seen these videos that Sienci put out on making a guitar. Building a Guitar on a CNC.

Thanks for the advice! Much appreciated! I’m going to give it a try like you describe and see where it leaves me. (And yes, I have been watching the Sienci guitar build. It’s super informative!)

How good will the mapping be if you’ve forced your machine to lose steps (which is what “grinding” usually means?) Losing steps means that the controller isn’t in sync with the bit any longer.

I’m thinking that if you map in this manner, then at the very least you should re-home the machine after each “grind.” :smiley:

PS. I know this is an ancient thread, but perhaps worth updating.

Your right about that Tex but I think I covered that it my answer. I suggested to only grind in the ‘Home’ position then back of 0.5mm and then set XY zero but to stop short of grinding for the measurement which I think should be OK unless I’m missing something.

EDIT: From reading The_Unkown_Bassist post I assumed, maybe incorrectly, that they do not have limit switches/sensors because they mentioned grinding on all 4 corners.

I got so excited that I missed it! :smiley: There should be max limits stored in the settings (EEPROM?) that could be copied. My machine is not accessible just now, though.

I’m sure that I’m being pedantic. :smiley:

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There are maximum limits but I don’t remember what they defaulted to with the LongMill and I have two sets stored, in backup files, one for with the dust shoe and one without. I don’t think this is a problem with the MK2 but the older machines lose some X travel with the dust shoe.