CNC Micarta scales - feed/speed?

[C_Claycomb]

CNC contouring handles in Micarta, what feed/speed/cutter size & type would be reasonable?

A guy I work with has offered to sell me his elderly but lightly used CNC-Step High-Z S400 router. I have had the chance to borrow it and see if it will do the things I want, which at the moment doesn't run much beyond 3D machining handles, cutting mortises, precision placement of handle holes and profiling scribe patterns. In theory this machine should be able to mill aluminum and perform complex relief carving routines and run up to 100ipm when not cutting. Its got a 1050W spindle running 5000-25000rpm with an 8mm collet. I fitted a 3 flute carbide ballnose cutter. The problem is that if I run faster than 20ipm, even without cutting, the machine jams and loses track of where it is, often to the tune of several inches.

My gut is telling me the machine is faulty, but I am new to this and the only feed data I have been able to find relates to bigger machines routing things like signs. There is a chance that I am asking for too much speed given the size and shape of a knife handle. What do you guys use, what do you think?

Thanks!

Chris

 

[Nathan the Machinist]

Different machines can run a tool path at different rates, it depends on both the physical acceleration capabilities of the machine and the blocks per second data processing. High speed machines have large look ahead and can safely get up to high speeds without gouging, but still have limitations to how fast they can change directions and go around turns.

I program my little minimill at 80 IPM and 7,500 RPM on knife scales. It could do it faster, but smooth motion is important for surface finish and machine tool life so that's as hard as I push it. A new Makino could run the same tool path at 200 IPM. A big old mill might need to surface at 20 IPM. You have to learn a machine's capabilities and set feeds accordingly, then match speeds to those feeds.

 

[C_Claycomb]

Thanks Nathan.

I think that pretty much seals it, that there is something not right with this little router. It's small, all aluminium construction, so pretty light for easier acceleration, the spindle is fast compared to small mills in general, so faster feeds than I am getting make sense. If you could run your mini mill like that, this thing should be able to operate in the same ball park.

Pity, I was really excited at the though of being able to get into CNC with this thing. German made, not used much, and a friendly seller who's let me borrow it for a month to try. Even with an engineering and CAD background learning the CAM stuff is a steep curve and trying to figure out whether errors are the fault of the machine not working to spec or my own rubbish program choices tips it into taking more time than I want to invest. Bummer

Thanks again Nathan!