Re: [CAD_CAM_EDM_DRO] Basic questions

On 1/2/2012 4:16 PM, Jack McKie wrote:

> Ron,
> Â
> Those zenbots are interesting and pretty reasonably priced.   I
> haven't had any experience with belt driven machines.   How do
> they compare with ball screws in terms of function/accuracy/repeatability?
> Â
> Jack

I can't say about the Zenbot, specifically, but my homemade router is
belt drive. I have no issues with profiling or 3d cutting of MDF. My
belt drive is wicked fast.
Screws are slow. Ball screws with a high pitch are faster, but also more
expensive. Overkill for a router, IMO.
I use XL belts on the X and Y axes and a rack and pinion on the Z. If I
were to build another, I'd either use a screw or a geared stepper on the
rack and pinion. As it is, with no power the head drops. I countered
this with a rubber tarp strap tensioned to all it to go to mid height
when power is off.
I am very happy with the belts on the X and Y. I have two motors on the
X driving two belts. This way I am assured of no racking. A center drive
can rack.
I built my router to make foundry patterns and sized it accordingly. My
working envelope is 12" x 12" x 6". My actual z travel is 12", but a 6"
tool takes half that.
I started with a harbor freight trim router. It died pretty fast. I have
a full sized Craftsman router for a spindle, now.
I have large motors, 425 oz in if bipolar, but I am driving them with a
unipolar driver, so they are somewhat weaker. The HobbyCNC pro board
works OK and was only $100. but if it dies I plan to replace it with a
Gecko G-540.
I have one on a Taig mill and I love it.
Don't forget dust collection. You will want that pretty fast.

--


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

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