Thanks! I was under the impression that Doug’s layout used a 1/4" single flute endmill. I would imagine that would change things a bit. the 1/8" does make sense in keeping the overcut smaller…thoughts?
I can only again recommend the Sorotec App for a rough guideline. It used to be on the higher side, but with the LR4 the values are mostly realistic. 
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One of the most important things to pay attention to for successful CNC cutting is the concept of “feeds and speeds“ …
One reason why it’s not possible to simply give a single feed (forward rate of motion of the machine during a cut) and a single speed (rpm of the bit/router) is that there are some variables — the material being cut, how many flutes there are, what the diameter of the bit is, how sharp the bit is, how deep you are cutting, whether you are cutting in a straight forward, full slot width, versus trochoidal milling, and whether you are doing climb versus conventional as far as the rotation of the bit in relation to the motion of the machine.
As much as it pains us to say it, the answer is, honestly, “it depends.“
There are free spreadsheets out there, and you can get great results with them. I paid a one time fee for a tool that is very good. It’s called Gwizard calculator. I typically use it the first few times I’m getting familiar with a certain combination of “this bit, this material, this depth of cut, for this project.” Once I get it dialed in then I can do that particular cut successfully without having to go back to the calculator tool. But it’s nice because you can put in a proposed speed, a proposed feed, proposed material, and a proposed bit, and it will tell you whether that strikes on the conservative, or the aggressive side, and it also tries to calculate how much deflection you will be at risk for.
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iOS ?
And Android. See if you can download it here: https://app.sorotec.de/. They are one of Germany’s largest retailers of CNC stuff.
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JJ, The $65 is depot for 3/4" ply… Unfortunately when dealing with school build funds, I have to source through a “Board Approved Vendor” it’s a complete joke…
But seriously, for my own purchases, where did you see prices like those in NJ??
I have sheets of 3/4" sanded ply at all 5 of the schools I build sets for, but the 1/2 MDF for the skins and spoil boards will set them back $135/table…
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It makes a difference in your calculation, for which bit diameter you choose, and how many flutes there are on the bit. A 1-flute bit (also called an O-flute bit) has half the blades of a 2-flute bit, but it has a larger channel for evacuating the cut chips. It is particularly helpful when cutting plastics, such as acrylic, and softwoods. It has to be run at a slower faster rotation speed because there is only one blade, not two (or more), and the diameter has to be taken into account. Small diameter blades need to be rotated faster than large diameter blades. A 1/4” bit will eat up more material, and produce more waste, but might be slightly more forgiving if you bind it up (than 1/8” blade). That quarter inch metal is harder to break then 8th inch metal. But if you get the feeds and speeds right, you can cut practically anything with 1/8 inch bit.
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I am not in NJ, so your mileage may vary. But the Home depot price is the same down here. I would just do a google search for any cabinet supply shops in your area and start calling around and seeing what they have to say. I get all my stuff at a local shop here in Pensacola, FL. Great people and great prices for sure!
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I’m only about a year into this CNC journey and on an LR3 yet, but I haven’t cut anything that fast except foam.
I’m a pretty amateur woodworker. I didn’t use a CNC to build my table. Your experience will certainly help you. I’d be willing to bet you can build this faster the traditional way. A bunch of people have done this as a first major CNC project but it is a little bit adventurous. If you get a bit of deflection or don’t do a finishing pass, you can run into issues where the joints don’t fit right.
Yea, there are a bunch of really talented people here with a wide variety of backgrounds.
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My 3D printer barely even went that fast last year…
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I’m pretty sure the last time I cut plywood, it was an 1/8 inch upcut at 15mm/s with like a 3 or 4mm DOC. That’s pretty conservative but still not making that big of a jump.
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My X1C disappoints me…it doesn’t go to Plaid, Just Ludicrous… 
In all seriousness, WHAT I SHOULD HAVE ASKED… is "so, how long should it take to cut the torsion box components using the suggested settings in Doug’s pic… That’s really all i need to know to plan ahead 
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So far all I have cut on the beta/RC3 LR4 is some MDF, Red Oak, and Alder wood. These were a combination of cuts and pocketing. The Red Oak is the hardest of the three. It seemed to be pushing the limits there to cut at 50mm/sec, 10mm depth of cut, and 75% step over. If I get a chance to do it again, I think I’d change the step over to 50%. Again, this was right at the boundary of skipping steps, and not a speed I’d plan to do for a mission critical job. Maybe for plywood I could test at 40-50 mm/sec, 6-8mm depth of cut, and step-over 50-75%. ??? But I have not tested that. With a 1-flute bit, the RPM on router likely to be with knob set at maybe 3.5 to 4. @Tokoloshe gave some speeds and feeds too I think.
Kinda backwards. Single flute can be run faster (our Routers), two flute endmills have a blade come around 2x as fast at the same RPM.
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Thanks for correction! Will edit my post.
Plywood is very tricky. Number of layers and amount of glue. So quality ply has filled not and even glue, crap ply has knots filled with glue. Feeds and speeds area gamble in glued ply.
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Just confirming what you where saying…it is complicated. Test cuts are the easiest way, take notes for your build and each test will teach you mountains of info about your own build.
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I edited it to this:
EDIT: Please disregard the post below, now edited to not share out of context. I guess I had plywood speeds and feeds on the brain.
In another thread, Enrico posted these numbers:
The posts to the Twist Test are not really relevant to that question, also, the answers Rico gave are in contrast to Ryan’s, so I would not just blindly believe those at the moment.
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