[pshupe]

Hey guys, I'm new here, somewhat. I just purchased a new CNC machine. It has a water cooled spindle and now I do all my rpms in my software, which is Vectric Vcarve and Cut3d. My current dilemma is rpms & feed rate. I used to just dial my router either high or low depending on the size of bit and how it seemed to cut the material. That is out the window now as I have a new machine. I downloaded a feed and speeds pdf chart with an equation from the manufacturer and basically it says this - RPM = FeedRate/(number of flutes x chip load) and obviously I can solve for other variables. I've just started using this table and find the feed rates to be very very fast. For instance I am usually cutting hardwood so they recommend a chip load of between .019"-.021" - so middle ground of .020" (note this is for a => 1/2" diam bit)

Here is my equation - Feed Rate = 6000 rpm x 2 flutes x 0.020" CL = 240 ipm I think the limit of my machine is around 200 ipm and that even seems quite fast. My spindle can run as low as 2000 rpm, but is that realistic? That would give me a Feed Rate of 80. I think my standard cutting prior would be around 120 ipm which would be 3000 rpm. Does THIS seem more reasonable? Thanks guys. I know this has been done to death but you know what it's like having a new toy and wanting to be sure! ;-)

Cheers Peter.

[waltraud]

Your feedrate seems reasonable, I am surprised that your max is 200 IPM.
I usually train shops on metal cutting machines, but I remember a job teaching in Albany, GA to make bus floorboards, 3/4 inch thick and we were feeding around 300 IPM.
I also remember we used a 1 flute cutter that could drill holes and also mill all contours.
Good luck, Heinz, see mill program examples on doccnc.com

[ger21]

You need a big, heavy, rigid machine and a powerful spindle to use a chipload of .020 in hardwood.

What kind of machine is this?

And big chiploads and low spindle speeds don't work well in wood. Most woods will cut much better at higher rpm's. I'd try to stay above 10,000 rpm.

[pshupe]

It's a CAN CAM Minitron d23m - 24"x36" - 2.2 kW - 3hp spindle. Thanks Gerry I'm not too concerned about the finish of the wood after machining. I'd be more concerned about longevity of the bits. I sand everything that I machine anyway.

Attachment 322306

Here is my setup. I'm just setting up the little water pump and reservoir for my water cooled spindle. I think this will be temporary as I'm just using a tile saw submersible pump in a Tupperware container plugged into a powerbar.

Cheers Peter.