Cutting parameters - chip load right

LowRider CNC Advice
1

Hey,

I used the FSWizard to determine the feed rate and spindle speed.

I set the speed to 30% (FSWizard Override) so that the feed rate would be within the limits of the Lowrider 4.

Then I ran everything through Gemini again to verify.

It flagged the spindle speed as incorrect – according to Gemini, it should be between 7,500 and 10,000 rpm for a better chip load – I want to cut 6.5mm birch plywood.

So, which is correct: the values ​​from the FSWizard or Gemini’s suggestion? According to my research on the optimal chip load, Gemini is right, but even when I adjust the speed in the FSWizard, the chip load doesn’t change.

Did I configure something incorrectly in FSWizard?

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2

I would not rely on AI. I can’t see in the wizard where you input the number of flutes in the tool you’re using though i assume you can specify the diameter.

I’d go by the designer of the machine’s advice:

For The Impatient

If you just want to get the machine dirty here is the generic recipe. This should work in every material softer than metal; you can optimize later.

  • Single flute ⅛″ upcut bit.
  • 8mm/s Feed Rate (The speed at which you move through the material).
  • 3mm/s Plunge Rate (The speed at which you move vertically into the material).
  • 1mm Depth of Cut (The thickness of material your bit will be removing per pass).
  • 45% Step Over (The percentage of bit diameter that should be in contact with the material)
  • Use the Peel pocketing strategy.
  • Always use a finishing pass of ≈10% of your tools diameter. The denser the material the smaller the finishing pass.

At this point you should be in HD foam, if that works out you can try some soft wood like pine.

If that works at this point the only variable you should be changing is the depth of cut. You can vary this and it will increase the load on your machine in trade for more material removed per pass or decrease the load by taking shallower bites.

Peel, Is usually the best pocketing strategy.

Start there and work your speeds up a little at a time. Remember plywood has alternating grain and hidden knots.

3

Hey,

Thanks for your reply. I need to clarify: milling in plywood is working well now; I’ve already put 20 hours of milling into it with the LowRider.

My current concern is the tool life of the end mill.

The cut quality and the milling noise (not the spindle noise) are fine at both 10,000 and 18,000 RPM, at least in my opinion.

I’ve entered my 3mm end mill with two flutes into the FSWizard.

Everything seems to be correct in the FSWizard, except the chip load (mm/th) doesn’t quite match what I’ve determined, which would indicate insufficient cooling.

I based my calculations on this, among other things:

4

Fair enough, although wood will be different to metal the chips will still carry away heat and you don’t want to ‘rub’ the material.

If you don’t have an IR thermometer or thermal camera you could just check how hot the tool is after a cut to get an idea of whether it’s getting too hot and losing its temper.

As I’m sure you know every tool is consumable even with perfect settings. It can be fun to min/max your settings though. I generally go with what sounds and looks fine and when a tool starts to produce worse cuts I change it out.

Assuming it survives that long and I haven’t run it into a hold down brad nail or screw and broke it by then :smiley: