Re: [CAD_CAM_EDM_DRO] Mini-Mill ball screws/nuts AND CNC Router project

Here is a link to my cnc router which is about the size you mention. I would use a rack and pinion drive.
Here is a link to google video that shows my cnc router/plasma cutter running on G203 step motor drivers and 452 oz in motors

http://video.google.com/videoplay?docid=5437907076855559029&q=cnc+router+plasma&total=27&start=0&num=10&so=0&type=search&plindex=2
If the link doesn't work simply enter the below into google video

CNC router plasma cutter

I would also use the G203 becuase they are essentially burn out proof. The New 251 which I have tested also work nearly as good but don't have the safety features that the G203 has.

The new G251's are not opto isolated but they work well with the newer low voltage pc parallel port. In most cases you will not need additional opto isolated add on boards. The Gecko G251's are so well designed that they seem to be rock solid wihtout it. I have been independently testing them and am really impressed.

Not sure about the Grizzly mini mill and standard ballscrews but I would contact fusioncnc.com and see what they say.


Dan Mauch
economical 3D scanner software and kits
low cost stepper and servo motors.
cases for Gecko drives
kits and assembled 3-4 axis drives
www.camtronics-cnc.com
www.seanet.com/~dmauch

----- Original Message -----
From: Jack Mc Kie
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Monday, June 02, 2008 2:23 PM
Subject: [CAD_CAM_EDM_DRO] Mini-Mill ball screws/nuts AND CNC Router project



Mini-Mill

I converted my Griz Mini-Mill to cnc using Ron Steele's plans (with
minor mods) and Xylotex controller/steppers. The Z axis is a ball
screw/nut but the X/Y are the original screws with modified nuts.
Building the retro was easy except for the Z axis which would have been
easier to make if I had a boring tool. I used the mini-mill in 2 axis
cnc mode to build the Z axis and accuracy wasn't what I would have
liked. Everything was a bit sketchy on how to attach the cog pully to
the ball nut and I had some minor problems with concentricity.
Having a Bridgeport would have been a lot of help!

I'm using Rhino/Rhinocam/Mach3 with this set up and am very pleased with
the results. I think this software combination is the most "bang for
the buck" though I wish I could afford the Rhinocam-pro. The cnc
mini-mill is used to make patterns for spincasting and is saving me many
hours.

All that said, I'm not happy with the conventional screws/nuts on the
X/Y axis. Backlash is the major problem along with the occassional
stall during rapids. The modified nuts are difficult to adjust and, as
expected, wear quickly. Has anyone had experience with "shoe-horning"
McMaster/Carr 5/8" ball screws w/square ball nuts in a mini-mill?
These are such a bargain that I am hoping to use them.

Router

The mini-mill retro has been sucessful enough to prompt me to build a
small cnc router. I am in the process of gathering parts and hope to
build the router in a few weeks. The travel will be - X48" Y16" Z 6".
All the bearings will be linear ball type and the screws will be
McMaster 5/8 ball screw/nut. Steppers will be 425oz + - . The main
purpose of the router will be to carve wood model ship hulls and
wood/plastic patterns for cast parts. I am also wondering if I will be
able to cut brass? Main concerns are being able to level/align
everything.

I need a four axis controller, two of the four will be used for the X
axis with one stepper slaved to the other. I haven't decided what
controller to use but am considering Geckos. I have heard that Gecko is
coming out with a low cost controller and wonder if anyone in the group
knows anything about these? Will I need a opto-isolated breakout board
or are these Geckos opto-isolated?

Any discussion/insight on the above appreciated!

Jack

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