Calculations for proper feed rate?

Hi! First post, but i’ve been following for a few months and have constructed a 30" x 4’ mpcnc.

Is it reasonable to just pick depths and speeds that seem comfortable to me? (machine doesn’t bog down, wood doesn’t burn, chips are small but not dust). For a 1/4" 2 flute router bit for instance, i’m at about 1/8" cut depth and 20 mm/s feed rate, ~20,000 RPM.

I went down the rabbit hole of googling proper settings and keep bumping into guides like this: which seem to indicate I am probably destroying any bit I use and that maybe I shouldn’t be trying to cut 1/2" plywood with this thing as it is. I keep coming up with like ~70 - 90 mm/s for the proper feed rate. I don’t think that’s achievable for me and my trusty old rotozip rz20.

I mean it cuts ‘fine’ but I’m a n00b and haven’t gotten to a point where I’ve ever experienced tool dulling or anything.

I am with you on this.

Wood is very forgiving, steel is a nightmare. Everything else is in between. Our 1/8" bits are very inexpensive, I say save the machine and dull the bit. I had to buy plenty of cheepie 1 time use $80 end mills for projects I could see where these things would start to matter. We are using a relativity flexible machine, so things are a bit different. Just know when metal is involved you will get work hardening, other than metal you can really play it by ear. Have fun, don’t worry too much about it. When I set up a cool project I tend to experiment with feeds speeds and depth as I go. You really start to get a feel for it quickly. Plywood was buttery smooth, MDF was a lot tougher to cut, unexpected for me.

Although when you do get chip load correct this is when the machine experiences the lowest loads, and the best cuts (other that tiny slow passes). For us I think spindle speed is the biggest one to play with, we are kind of set in the feedrate.