Micro Mill CNC Conversion

[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]

Originally Posted by dneisler 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

[dneisler]

I went back to .54, didn't help that much. I am in 1/2 mode now. Still having issues.

Actually all 3 axis is having a stalling problem it appears. I have them set to 20 IPM and it is happening.

[dneisler]

In mach 3 for my x axis I have like 64446 for steps/ inch. Does that sound right?
I can set the DRo in mach 3 to zero, and my cailiper as welll and move about one inch and both DRO's are within .003.

That is currently at 1/16 step mode which I need to change I think to 1/2 step.

Is that right?