[dneisler]

I recenty bought a Micro Mill, CNC Fusion Kit, and the Hobby CNC package. I have the mill cleaned up, and the cnc kit installed. I got the electronics working as well. I amaze myself sometimes :-)

Should I run 1/2,1/4,1/8, or 1/16th step mode?

What I need to figure out now is my steps per inch? Can some assist me there?

200 * step mode * X = steps per inch
But what the heck is X?

[drawbar]

X is the pitch of your leadscrew in threads per inch. Say, for your X axis that it is 10 TPI, and that you have your driver set for 1/2 step mode. Then you have:

200 * 2 * 10 = 4000 steps per inch

Brian

[dneisler]

Correct, but what is the TPI on the Micro Mills. I have been told the X & Y is 20 TPI and the Z is ABOUT 1.5mm

[phantomcow2]

congratulations on your purchase.
I have the Micro mill and the HobbyCNC driver board (not package). I made and modified the existing hardware on my own for the CNC hardware as it cost me under 50 bucks for that as opposed to 300 for the CNC fusion. But the Fusion looks like a nice kit.
You pick the step mode by adjusting the jumpers on the board, its based on how much noise and vibration your getting from the motors. I am using 1/8
What is your software? Is it TUrboCNC? If it is, TUrboCNC has a calculator where you enter;
Steps per revolution for the motors
Microsteps
leadscrew TPI (which is 20TPI or it advances .050 per revolution).

The micro mill makes a nice conversion, and be sure to get the Y axis extension kit from Little machine shop sometime, it transforms the machine!

[dneisler]

congratulations on your purchase.
I have the Micro mill and the HobbyCNC driver board (not package). I made and modified the existing hardware on my own for the CNC hardware as it cost me under 50 bucks for that as opposed to 300 for the CNC fusion. But the Fusion looks like a nice kit.
You pick the step mode by adjusting the jumpers on the board, its based on how much noise and vibration your getting from the motors. I am using 1/8
What is your software? Is it TUrboCNC? If it is, TUrboCNC has a calculator where you enter;
Steps per revolution for the motors
Microsteps
leadscrew TPI (which is 20TPI or it advances .050 per revolution).

The micro mill makes a nice conversion, and be sure to get the Y axis extension kit from Little machine shop sometime, it transforms the machine!

So you are saying the leadscrews on a Micro Mill is 20 TPI?

I am using Mach 3 Demo currently. Will purchase soon as I get all the bugs worked out I am thinking.

[phantomcow2]

Well some say they are metric. And its quite possible, all I know is that when i put my dial indicator on the table and test the movement of one revolution, its RIGHT ON .050
This is what 20TPI gives you, so for all practical purposes, its a 20TPI screw

[dneisler]

I was just running my steppers to make sure they moved good, and I am having a issue with the Z axis. Some times it stopers turning with a awful noise from the stepper. I first thought the lovejoy connectors where turning on the shaft as I have not put flats on the yet, but to find out that is not it. The steppers are just not turning.....like not enough power or something. I slowed it down from 200 t0 5 and it still happens. I have 200 Oz steppers from Hobby CNC. The X & Y where doing it to, but I slowed them down, and it stopped there. Is the 200 Oz just to weak for the Z or do I have something wrong.

HELP!!!!!!!!!!!!

[phantomcow2]

First of all, make sure the voltage is set accordingly. YOu need a digital multimeter and refer to the VREF chart that came with the HobbyCNC board. Then if theres taht awful noise, try running 1/4 microstepping

[dneisler]

I already tried 1/4 step, still there. I will double check my vref's. I had them at .54 when built the board, but I will check again.

[NEATman]

You may have your motor acceleration set too high. If you don't allow enough acceleration time, and don't account for the load on the stepper, it will stall before it even gets moving. If this is the problem, you'll have to decrease the acceleration rate in Mach3. It's under the motor parameters or motor set up.

Keith

[ShayArnett]

Are you counterbalancing your head? If not the z axis motor might not have enough force to move the head up. I looked at the fusion kit to check, and didn't see an air spring or any pulley system for counterbalancing, so I am assuming you haven't. You might want to do that before you mess with the steppers too much, may never get the acceleration low enough for it to work properly with that much weight.

[dneisler]

That makes sense......but it will run fine for a few inches then stop. It is only happens on the higher part of the Z axis....I have checked and it turns free by the handles...

I will check that setting and see if it helps any as well.

Thanks

[dneisler]

Link to video of my problem. Small and dirty video.
http://www.donald-neisler.com/mov01676.mpg

[phantomcow2]

Definantly balance the Z axis.
You may have even noticed when the machine was still manual, its probably 50-60% more difficult to lift the head.
Buy a gas strut from McMaster Carr with 20 pounds of force, this balances it out really nicely.

[dneisler]

Happen to have a part #? Maybe some pics on how people are mounting them?

[ShayArnett]

The Yahoo group for this machine has lots of variations for head balancing. At work right now and can't remember the link but just search for micro mill yahoo group or something like that... you'll know when you find it.

Most I have seen make a bracket to use the 2 bolts at the bottom of the column on the right side to hold the lower part of the strut, and then drill and tap a bracket to the head for the top mount. Also you should be able to find a part number for the gas spring on the yahoo group.

[phantomcow2]

The group is called Hf47158toCNC. Search McMaster Carr for gas strut, and look for what suits your fancy. Just make sure you are in the 20-25 pound range.
http://www.dragonworks.info/CAD-CAM-...s/Z%20axis.htm take a look there too.

FOr me, i mounted a piece of angle aluminum on hte head and on the base. ANd selected a gas strut with m8 thread on each end. When i had this thing going manually, it was easier to move the Z up and down than it was to move the x or Y. It makes a big difference!

[dneisler]

tightened gibs = helped a little
turned vref all the way up = help some to

just not quite enough.

[HobbyCNC]

tightened gibs = helped a little
turned vref all the way up = help some to

just not quite enough.

"Turned Vref all the way up"? .54VDC was fine! Any higher and you'll smoke something! Have you tried 1/2 step?

Dave Rigotti
HobbyCNC.com

[phantomcow2]

HobbyCNC beat me to the post....
Please turn down the vref.
THe steppers are simply being overworked. I had the same problem for Z axis when i tried it without a gas strut. Buy a gas strut, they are like around 16 dollars and make such a difference.
Loosening the gibs is sort of a bittersweet fix,, not even a fix at all. YEa it makes the steppers life easier but it adds to chatter which means any chance of accuracy is shot to hell.

My suggestion is that as a temp. fix while your gas strut ships, try a counter weight like shown here:
http://www.balbots.com/images/hf_471...nterweight.jpg
20 pounds should do it