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Smitty911
11-05-2007, 06:18 PM
All,

I just got my mill up and running and am attempting to de-bug it you might say. This is my first Mill and first attempt at CNC, so if the terminology is wrong please correct me.

X-2 Mill, KDN Tools CNC setup with 5 TPI Precision Rolled Screws, preloaded balls, Gecko 302V, MACH 3 mill.

I have a pen in the jacobs chuck and down on paper

Imput MIDI Screen
G0 X5 - DRO X moves to 5, pen draws a line roughly .87 on the paper
G0 X-5 - DRO X moves to -5, pen draws line roughly 1.68 on the paper


G0 y5 - DRO Y moves to 5, pen draws a line roughly .857 on paper
G0 y-5 - DRO Y moves to -5, pen draws a line roughly 1.72 on paper

Now I know a pen on paper is not the most accurate method, but it can tell you something is off. I was thinking the the 5 was 5" and it almost drew a line one inch off. Which means to me my 5 TPI Screws are not being accounted for.

Is that correct?

More questions than answers to follow.

Thanks

Smitty

runchman
11-05-2007, 07:01 PM
Disclaimer: I do not yet have my cnc mill conversion done, I've only messed around with Mach3 with steppers on the bench.

My guess is that your motor tuning is off. Did you set this up in the motor tuning config screen? You have to enter "number of steps per inch" for each axis.

So say you are full-stepping, have 200 steps per revolution, and are direct geared to your screws. Then steps per inch =

200 step/rev * 5 = 1000

The 5 comes from the fact that your screws are 5 tpi - since 1 rev of the screw gives .2 inches travel, it takes 5 revs to move an inch.

If you are microstepping, say doing half steps, it will take twice as many steps to go the same inch, so you'd put in 2000 (for 1/2 steps).

If you are geared to your screws via pulleys, you have to take that into account as well.

- John

ger21
11-05-2007, 07:08 PM
If you meant to say G203V, input 10,000 as your steps per inch. You probably have 2000 in there now.

Smitty911
11-09-2007, 05:57 PM
thanks I reset the steps in the Motor Tuning area and voila, inch is an inch

No one to Homing Switches. I have the switches mounted, these will be "HOME" switches. This tells the machine were it is at correct? I have seen several of the diagrams showing them all wired NC on the same loop. Well if Y triggers first how will it know to stop it there and keep the rest going?


Or should they all be wired discreetly, one for X, one for Y and one for Z?????

Thanks

Smitty

ger21
11-09-2007, 06:04 PM
If you wire them all to one pin, you'll need to home each axis seperately. If you want to do one homing command for all three axis', they'll each need to be wired seperately.