Engines > Your Own Design
1/4 scale Porsche 917 180 degree V12 Build
steamer:
--- Quote from: dieselpilot on April 09, 2025, 06:00:54 PM ---Excuse my ignorance of these machines. Is there reason to believe it should miss steps? I run stepper Emco machines and theyrun all day long without missing a beat. They do have tracking (index pulse monitoring) built in so it knows if you manage to stall an axis. I've only run into it while drilling either due to lack of torque in the spindle or lack of thrust due to drill size.
If you think you'll exceed the machine's ability, calculating cutting forces is quite easy. Various sources have the math and material constants. When I had the Emco Mill 125, I checked every operation when running larger tools for spindle load and drilling thrust also. Once proven, it wasn't a problem. Emco had good documentation for it's abilities where I can't find much about the PCNC440. Spindle power/torque shouldn't be hard to figure out, though.
It's a shame that homing is not repeatable. Emco also has this sorted in their stepper machines with the index pulse.
Quietly (mostly) following along on this great build.
Greg
--- Quote from: steamer on April 07, 2025, 12:53:26 AM ---I get nervous running at 100 in/min the max speed on the 440 as there isn't any encoders so if I make the stepper motors skip I'll never know. Also I've tried to set a start line in MDI on a CAM program and it didn't like it at all. It's fine between diff ops like 3d adaptive and whatever comes next or between toolchanges...
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Hi Greg,
Well. I confirmed what I already knew which the 440 does not have a encoder or home pulse, just a simple stepper drive with large NEMA 34 motors. It should be fine for most situations, but with a 6 hour cycle, I get nervous about pushing it very hard. As it is I'm pushing it to 23 -27 in/min for this job
Rezeroing changed the home position by about .001 in the X and Y direction. Probably in the noise of the indicator, but don't trust the repeatability of the home switches to tenths......so If it goes down for any reason, I re zero.
And again, not encoders or scales......
With 279,000 lines fo code and a 6 hour cycle.....I won't push it too hard Certainly not 110 inches/min
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