ESTLcam feed rates/setting question

Software / Firmware
1

I’m slowly realizing I may not be interpreting the estlcam speed/feed rates correctly from the milling basics page with how I’m using my LR2 in practice.

I very successfully cut a pretty big (38"x52") sheet of 3/4" spruce plywood the other day but it took over 3hrs of cutting time the way I had it setup.

I think I’m babying the depth of cut.

Currently I’ve stuck with the 15mm/s for f(xy) and 3mm/s(z) but I’ve only been nipping at the depth of cut (the stairs)z+ at 1.5mm which I think is one of my main issues. I had to make 13 passes to cut through the 20mm total depth. Worse (the other issue), I’ve also ticked the finishing pass using the same roughing pass (I hope this makes sense) so I end up then doing another 13 passes nipping just 0.6mm off the edges.

Reading all this over again and consulting with the fswizard it seems as though given the 1/8" single flute bit, at 18,000rpm for “wood” I could potentially be taking a 5.5mm DOC/(Z+). This would mean just 4 rough passes. I could/should then also be able to do one single full depth 20mm finishing pass.

I see in the milling basics page Ryan talks about dividing the passes evenly so in my case to make 4 passes at 5mm DOC to get to my total of 20mm depth or 5 passes at 4mm etc. This would significantly reduce my cutting times.

I know the feed rates answer is “it depends”, but I’ve seen Ryan mention the fswizard is a good starting point for cutting rates. FSwizard suggests that with the carbide single flute 1/8" bit I can be around 20mm/s feed with a 5mm DOC at 18,000 rpm. Is that crazy? or reasonable, my table is 4’x6.5".

The bits are inexpensive so I may just end up trying this out but please let me know if I’ve missed something crucial in my reading.

If you’ve made it this far here’s the yes no experts answer section:

  1. At my current 1.5mm DOC(Z+) 15mm/s (XY) for plywood am I being way too cautious?
  2. generally can I use fswizard settings for the LR2 and mostly be okay?
  3. can I safely make a 4-5mm DOC(Z+) at the same 15-20mm/sec in plywood?
  4. for the finishing pass can I make a full depth of cut finishing pass if I'm sticking with the (5-25% tool diameter) 0.6mm finishing tool settings?
  5. if I can do the full depth finishing pass is the correct way to do this by adding a second outside/inside command exclusively for the finishing pass?
Thanks everyone I hope I'm being dumb and have just been doing this wrong all this time, and I can up the bite a little bit more.
2

You really need to experiment with your specific setup. In general start where you are and try deeper and deeper until you start to see issues, then back off a bit. You’ll have to do that with pretty much every different piece type, what works for baltic birch won’t be right for cedar or walnut…

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3

I agree with Bill.

1- I go slower and deeper…plywood is tricky though the glue can be a real buzzkill.

2-The calc is a last resort, and only works when you can base it off know parameters for your machine.

3-pine, sure, plywood-depends on the glue.

4-Full depth for sure, thin to win. I know it sucks but you need to see how your build handles it. If you fast and reckless roughing you will need thicker finishing pass to hide the blemishes. I typically go slow rough (I rather it be slow and work the first time than fast and break a bit) so I do a fast thin finishing pass.

4

Thanks guys. Great info to be armed with for the next phase of testing.

Even if I stick to 15mm/s and just kept trying a little deeper cuts even another 1mm or 2mm on the depth would make a big time savings. The full depth finishing pass seems so obvious now but I don’t know why it didn’t click before.

For the settings I was using it was 13 passes for roughing, then another 13 passes for finishing. With some testing this could be 5-6 roughing passes with a single finishing pass. That’s a huge time savings and hopefully the same great results.

I’ll report back with what I find.

5

I’ll just reiterate, adding depth will definitely make this a lor faster. At some point, you’ll hit the depth limit on 15mm/s and you might find you’ll get even faster with a bit slower and even deeper. You might find that, as an example, you could to 1/2 speed and 2.5x deeper.

That’s why it’s so hard to give much specific advice.

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