Rotating Nut

[mhasting2004]

Hi Coop

I'm going to use a ball nut on my Z and if I could afford two 3 meter length ball screws for the Y I would have done that too but am opting for the fixed belt drive option for that due to cost.

I like your design to convert a standard ball nut into a rotating one but I'm sure you are aware that they do make ball nuts that already have all the bearings built in for this type of application.

See BLR type on this page:
http://www.thk.com/eng/products/clas...ballscrew.html

Cheers

Mark

[coop2005]

Hi Mark

Ya i was aware but cost prevailed, my time building is free so i bought the cheapest ballscrews i could find, they were a few hundred bucks i think. If i went with the premade rotating nut it would have cost me a significant amount more for these. And building it is fun, which im sure 99% of the people on this forum would agree.

[mhasting2004]

Hi Coop

I didn't realise the prebuilt jobbies where that much more. I agree with you 100% that the journey is as much fun as the destination and finding ways around the high cost of parts is definetly where a lot of the inovative designs come from. I've got a bit of the reverse problem on my build as I have a few BLR's (free out of decommisioned gear) and need a fixed nut for the X.

Still hoping the Y axis belt drive does the trick otherwise I'll be on the lookout for some very long ball screws and copy your design.

Cheers

Mark

[kb18951452]

Kudos on the great design.

Those parts you fab'd are pretty nice i might add. Good Luck, very innovative.

[coop2005]

Got the ball screw mounted on the y axis and got the gantry moving. Its got plenty of power that is for sure. Just did some quick testing but it seems to do 150 ipm easily with no hope of stopping the gantry with my strength. Going to get the remaining axis running this friday then i can start some real performance testing. Ill add some pictures on the weekend.

[Cartierusm]

What motors are you using stepper or servo and what strength?

[coop2005]

i am using 1200 oz-in steppers from keling with their drivers.

[coop2005]

YouTube- Rotating Nut CNC.MPG

YouTube- Rotating Nut CNC.MPG

its been awhile since i posted on this thread, i have finished up most of this machine and been tuning it in a little. Seems to be running quite well now that i have worked some bugs out. At 25Khz pulsing i have been able to run the axis' quite well at 150ipm. The speed is maxing out due to the pulse rate, i need a better PC to get the rapids up higher but the motors are really not doing a whole lot at 100 ipm (400 RPM)

[kylemp]

Hi,
I havent been on this forum for a while.. been distracted by other projects that are a far cry from CNC stuff, but the rotating ballnut idea was the last place I left off and the first place I am going to start on my next build, probably a 4x8 or 4x4 table. I agree 100% with the ballnut idea over belt drives, rotating screws or rack and pinion.
My plan is quite similar, I will start posting when I get it all worked out, but I am VERY happy to see someone else got this system up and running and is having success with it.. makes me even more excited to get started on it!
Good job!

Kyle