Closed Loop

[motomitch1]

I’m not trying to build a peacock, I could also buy a CNC Machine shop with state of the art, climate, dust and humidity control, using precision calibrated 5 axis machining centers to perform ultra precision machining of components. But all I have now is my little HF X=8.250 Y=4.250 Z=8.000 2900 RPM $400.00

Manual mill converted into a cnc with 3 201 Gecko’s 200 oz steppers and Thomson ball screws and nuts that runs great and I have some free encoders that I got from my work off some old burned out fadel 6 brush servos.



I was thanking if all I had to do was run some more wires to the pc to have a closed loop cnc mill would make it a little nicer incase it skipped some steps and I didn’t see or hear it and Im cutting for hours and hours .050 out of location and

I wouldn’t have to tram for location of fixtures or parts if it were to skip witch would be kind of nice.

[turmite]

Motomitch I think what Mariss is trying to say is the steppers will not lose position unless you simply apply too much of a load. If they don't lose or gain steps there is no reason for a closed loop system. I have run an open loop system since 1990 on a Digital Tool machine running full/half step software. The machine has served me well and I have just now updated to Mach2 controller and Gecko 201 micro drives. I wish I had known about all this good stuff back in 90, because I would have built my own machine and saved that $19,000. Repeatability is what I am amazed at with my open loop system. I made thousands of wood parts that fit exactly each time, and that was fitted to metal parts that were made on $250,000 vmc's. I personally think the best way to look at this is to look at your needs first. How accurate do you really need your parts?

turmite