View Full Version : Ballscrew advice requested

04-09-2014, 11:55 AM
I have lurked for years. I have learned much from the members here that share their knowledge and I joined to say Thank You. As for me, I have played with a Grizzly G3103 for 12 years. Not a machinist with 12 years experience, just a rank amateur. Having recognized my machine knowledge limitations I am going to cnc a G0755 so as to broaden my experience.

My work for a living experience has been with developing software and implementation services in the business and government markets until "retired".

My problem at this point is determining the proper Ballscrews for the X, Y, and Z axises. It is possible I have not even posed the question properly!

The specifications for the machine are as follows:

Swing: 20"
Max. distance spindle to table: 18"
Table size: 9-1/2" x 31-1/2"
Table travel (longitudinal): 17"
Table travel (cross): 7-7/8"
Head travel: 13-3/4"

A request to Grizzly both by phone and by email has resulted in zero feedback as to what length, diameter, pitch or source.

Any recommendations would be greatly appreciated.


04-09-2014, 12:24 PM
I suspect that this is a custom application, which means that you'll have to examine the machine and figure out what ball screws you could use. That means considering length and space for the ball nut. The pick the parts and modify to fit. If this is to be for a CNC conversion, pitch won't be all that important.

04-09-2014, 12:27 PM
Grizzly is not going to help you on this. You will just have to buy a machine and convert it. That being said you would be far ahead by buying a cnc mill with a dead control if you have the room.

04-09-2014, 12:53 PM
Seems like a perfect use for Evanuts.


04-09-2014, 03:59 PM

You are right. Evan is the MAN. I believe with the 19 page write up, it is something I can do. I will update the results!

Thank you for the topic reference.


Jaakko Fagerlund
04-09-2014, 11:54 PM
I take it that you are going to take the acetal nut route instead of ball screws then? Ball scrws would have been an easy/fast solution without any extra friction and they are commonly available on eBay in many lengths with the ends premachined for standard ball screw bearing mounts.

Good example, the last C5 grade screw I bought was 370 mm long, pre-machined and together with the fitted nut cost me 35 EUR.

04-11-2014, 01:52 PM
Depending on where in the US you are, you could probably buy an old Bridgeport Boss or other CNC knee mill for about what that thing is going to cost you to convert, and a lot less time, and end up with a much more capable machine. You're probably looking at a hundred-plus hours and a lot of mistakes along the way. I've converted or built from scratch five CNC mills/lathes/router tables and last year I bought a Tormach 1100 and said Never Again!

One big issue with that machine is the spindle speed tops out at 1970RPM, which is going to severely limit your feed speeds with smaller cutters. With a .250" 2-flute endmill in 6061 you'd be limited to a feed speed of around 10IPM which is slow as $#@!. At least it's a bed mill rather than a round-column mill-drill so you can get a proper Z axis. Still I suspect you will spend north of $4000 before you're done and that's a lot of money for something that will likely always be a work in progress.