alternative to Ballscrews

[Harvid]

Hi I´m a newbi to cnc and this is may first post
And I´m stuned, to see the amounth off nollege from all you in here

My problem is
Ballscrews are really expensive, and extreemly expensive in danmark (europe)

So I have an idea to use parts from a bicycle these is more avelerble and a lot cheaper
If I´m using a bicycle chaine and the smallest gear (the small guide gear on the back wheel gear shifter)
around the gear its 13,5cm (the green ring on the drawing) and if I use 1/8 microsteping I will have a travel per step at 0,084mm
I think it will be precise enough for me but will it be power full enough to do it this way ?

The electronics is a Stepmasternc controller with 260 oz motors from
http://www.stepmasternc.com/stepmasternc_010.htm
and planning to build “joe” size routher

I have no idea how fast a steper moter is turning around (RPM) and if its posible to ragulate the speed
And if its is poseble to regulade the speed down, will I get more tourgh

How many cm travlinging per second is idiale for cutting mdf
I just saw this wire driven machine, this solution may even be better…
http://video.google.com/videoplay?do...97521879&q=cnc
how is the wire setup build? does any of you have an idea?

Ideas and thoughts will be highly appreciated
Harvid

[jcc3inc]

Harvid,

I like rack and pinion drives. Specifically, either 20 DP or 24 DP rack, 20 degree pressure angle. This approach is simple, easily managed, and very stiff.
It is ideal for steppers and fine for DC servomotors with some gear/belt speed reduction. Cost is low, and it is tolerant of dirty environments. It is easy to shield from the dirt. This type drive is used by almost all commercial manufacturers.

Regards,
Jack C.

[mar999]

Acme lead screws are fairly cheap and when set up properly do a good job hope this helps. Im in the process of building a new machine (almost done) ill post pics soon