If I have a cube of wood, say 3"X3"X3" and I want to make a small box with walls 0.20" thick by cutting out the interior of the cube, thus leaving a box with 0.20" walls, what is the deepest I can cut with the standard cutters that come with the Nomad 883?
At some depth the length of the cutter will not be long enough to clear the top of the side walls as the cutter clears out the interior of the cube. Since the nomad has a cutting area of 3" in the Z axis do the cutters have at least 3" of length form the bottom of the cutter to where it is installed in the holder of the spindle?
If I want to make a full 3" cut straight along a vertical wall do I need different cutters or will the standard ones that come with the Nomad 883 work?
I have not yet received my Nomad 883 and am working on learning Meshcam and Cutviewer. I designed several parts and experimented with different settings in Meshcam then looked at the parts in Cutviewer to see how the different parameters in Meshcam work. I got a tool collision error on one of the projects which is what got me wondering about this topic.
Also in the simulations I am seeing cutting times for this small box to be several hours. I am sure I do not have the correct feed rate and plunge rate for the cutter. What would typical values be for cutting the simple box noted above out of a pine 2X4?
The magic words you’re looking for are “flute length” for cutters—that tells you the maximum depth it can work in cutting into fresh material. Any deeper, and you’re pushing the shank of the tool into a side-wall, which of course is not good as it’s deflecting the material, stressing the motors/betls, and not giving you what you want anyway because it’s not cutting! The caveat to this is if you’re cutting down over the same path area multiple times then the material in front of the shank is already cleared away, so you’re instead limited by the body length of the tool and how much of the tool is gripped by the chuck.
Your cutter doesn’t need to cover the entire Z-machinable height with flute or be that long—it needs to cover the height from the top of your adjacent stock to the bottom of the deepest cut. There is a difference between the “full length” of a tool and the amount that’s actually exposed and doing work. Most cutters that are 1/8" in diameter are ~1.5 to 2" in length overall, but only have a flute length of 1/2" or less. Therefore the deepest purely vertical cut you can make is about ~1 to 1.5" because you’ve got about 1/2" of the tool being held in the collet.
What you want to look into in your case if you really insist on doing it so deep like that instead of making your box out of layers is “long-reach” or “deep-cut” tooling. Here’s an inexpensive surplus stock example from Bits n’ Bits.
I would recommend evaluating your design to determine if 1) straight walls or such substantial depth are really that necessary, and 2) whether it’d be appropriate to make this in parts that you assemble to be more efficient with your materials. To hollow out a 3" cube and leave just .2" vertical walls may not serve you as well as you’d like
Post some pictures of your works in progress or doodles of your ideas, and we’ll try to provide some feedback!
Thanks for the great feedback, I appreciate you sharing this.
I have been designing and making an number of things on my
3D printer over the last two years. I ordered a Nomad 883 so
that I can work with a wider variety of materials than are currently
available in the 3D printing world.
When I designed the box as a test case I was designing as you
do when planning to use a 3D printer. In the case of CNC I see
now that my designs will need to be ‘flatter’ and some 3D structures
will need to be designed to be assembled out of ‘flatter’ cut pieces.
I am trying several different designs and working through the different
settings in Meshcam then looking at the results in Cutviewer to try
and develop a set of basic practices. If you have a few tips for beginners,
or things you wish you knew when you started out, I would love to hear them.
Do you think Cutviewer is something I will want to integrate into my
process long term, or as I gain experience will just looking at the tool
paths in Meshcam be sufficient?
Welcome to CNC, it’s a fun and different world from printing, that’s for sure!
My general advice would be to go through the tutorials first of course, and then start doing relatively simple tool-planning on whatever you are able to crank out of CAD/CAM or find of interest on Thingiverse or elsewhere that you’d like to try to make.
Then, get some cheap polystyrene foam from your local Lowes or Home Depot or whatever, and get familiar with how the tool-paths translate into cuts in the material. As for CutViewer, it’s certainly a good sanity-check follow-up on your paths, but the simulation that comes out of MeshCAM or the CAM in Fusion360, etc… usually does the job. Cutviewer is good if you’re processing NC code provided by other people or trying to modify it without going back to CAM.
The advantage of the foam is that it’s cheap and it’s not going to put much wear on your tooling–it just doesn’t hold much detail at all so it’s good for contouring and doing form studies. You might also want to look at other low-cost and relatively low-wear materials like poplar (since it’s such a soft hard-wood), polyurethane foam boards, and then Renshape (polyurethane tooling board).
You’ll want to dig around and learn about “feeds and speeds” and “climb vs. conventional” cutting, and the different types of tooling available out there. Rob has posted some great links and in particular this write-up is extremely comprehensive. I’ve ordered some bits from Bits n’ Bits, and their surplus offerings are always worth tracking for deals.
