Mini Mill CNC converting info needed.

[Oldboy]

Hi
Im trying to understand a few things about converting the Harbor Frieght Tools X2 Mini Mill into a CNC Mill.
When selecting a Stepper Motor Driver Board for this Mill.
Do you use FULL STEP,HALF STEP,TWO PHASE STEP,WAVE STEP,MICRO STEP? Whats it all mean?
From what I have found about it all is FULL STEP gives you the most power from the stepper motors. And stops the stepper motor faster.
And as you go to Half to Micro you lose power from your stepper motors.
My plan was to go with a Stepper Motor Belt drive 4 to 1 , 20 TPI BALL SCREWS X,Y,Z set up.
So My qestion is; What Driver Board step system do you use and WHY?

[maxboostbusa]

From what I understand of the different stepping for controllers is say full steps moves 1/2" then half step would be 1/4" and so on. Dont know about the torque though. I think the higher the rpm the more effect it has on torque (higher rpm=less torque). I dont know about if the step has a direct effect on torque besides the rpm or not. My board only has full and half step abilitys and here is what Hoss told me when I asked a question on my controller.

"A 200 step/rev stepper (1.8 degree per step, pretty typical)
A .200 pitch ballscrew (5 revs per inch)

200 x 5 = 1000 steps/inch (full step mode)
1000 x 2 = 2000 steps/inch (1/2 step mode)
1.000 inch divided by 2000 steps = .0005 axis movement per step.
Use a 2 to 1 timing pulley ratio (like on my Z axis) = .00025 per step.
More than enough accuracy for any of these little mills."
Hoss

Full step with this setup no pulleys directly running the ballscrews with the steppers would yield a .001 inch per step rate which would make manual g-code entering easier although it may not be as precise as half or quarter step. As far as controllers I would go with Kelings. Lots of features along with protection built into the controller. They are also single axis controllers so if something does happen you only have to buy 1 and your whole machine isnt down because you got the wire pinched in something and smoked the chip in the board. Just my 2 pennys though.

[Adamj12b]

With a standard 200 step motor per 1 rev you would get:

Full step - 200 steps
Half step - 400 steps
1/4 step - 800 Steps
1/8 step - 1600 steps

So like you said, you are going to be using 20TPI lead screws, with a 4:1 belt reduction, in that case you would multiply the number of steps per rev by 4, because it will take 4 revs of the stepper to out 1 on the other pulley, Then since it takes 20 turns of the lead screw to move the table 1 inch you would multiple that number by 20. Giving you a large number of steps per inch but alot of accuracy.

Full step = 200 x 4 x 20 = 16000 steps to move 1 inch or 0.0000625" per step
Half step = 400 x 4 x 20 = 32000 or 0.00003125" per step

I'm not going to even do the other 2 because it is of no use.

If you didn't use the belt reduction it would be like:

Full step = 200 x 20 = 4000 steps per inch or 0.00025" per step
Half step = 400 x 20 = 8000 or 0.000125" per step
1/4 step = 800 x 20 = 16000 or 0.0000625" per step
1/8 step = 1600 x 20 = 32000 or 0.00003125" per step

Now for the torque aspect of things.

For every smaller micro step you lose torque, but increase accuracy, as you can see. Also with the belt reduction you can use a smaller stepper motor and still have enough torque to drive the system.

Belt reductions are not used very often with the smaller mills like the x2 because stepper motors are powerful enough to work with a direct drive system. I have read on the forums here that a 305oz in stepper is plenty of motor to drive the x2 directly without a reduction system.

Also, you will have faster feed rates without the belt reduction, because the motor will be able to spin the lead screw 4 times faster.

The only axis you might need a gear reduction on is the Z because the spindle is heavy.

So insted of buying the timing belts and pulleys just spend the money on getting bigger stepper motors.

For a driver I would recommend the HobbyCNC board. You have to solder it together yourself but it is a good deal. The have kits with almost all the stuff you need for electronics.

I think I covered everything, if not just say something. Hope this helps you out.

[hoss2006]

I would avoid unipolar boards such as hobbycnc and stepperworld.
you'll get more torque (ex. 305 vs 425 oz/in) by using a bipolar board for the exact same motor.
gecco's are the best but kelinginc has similar boards cheaper (what I use now KL-4030).
The voltage running the board and motors makes a BIG difference in power,speed and torque.
the more the better.
i'm using 40V but you can get boards that handle 80+volts.
also these are single axis boards not all-in-ones like the unipolars and xylotex
If one fries it usually takes them all out.
Half step mode is a good middle ground, you get good torque and decent accuracy.
I use microstepping (1/8) for my 4th axis for increased accuracy. (the KL-4030 goes to 1/64th microstepping)
4:1 pulleys will give you more torque but at a big cost in speed.
I agree that what you'll spend on the pulleys and belts could be better spent on bigger motors, you'll get the same ? torque but not lose any speed.
who wants to rapid at 20IPM? 100 IPM is cooler.
Just my pennies too.
Hoss

[Smitty911]

http://www.cnczone.com/forums/showthread.php?t=36678

My CNC conversion using Geckos and a KDN Tools kit. Works incredably well.

Smitty