Re: Screw Size----Stepper Size?

Hi surfbuilder, I am trying make the same project than you.
A cnc in order to shape flysurf boards.
I have nema 34 250 oz/in and I am going to try timing belt chains,
open mode. Group likes timing belt chain in fixed mode configuration,
but with this config I will go to rack & pinion.

I have a look to Gates Corp. design guides, and I dont see fixed mode
configuration recommendation with its timing belts.
So there are examples with open mode. Open mode config is used in
scanners or printers, I dont know if plotters has the same config.

About problems with open mode, have a look the next link. You get an
idea about problems you are going to face.

http://www.vibrationschool.com/vibeschool/mans/SpecInter/SpecInter15c.
htm

I dont find tutorials about problems with close mode, so I think will
be the same with rack&pinnion but cheaper than rack

Resolution and repetitivelity will be OK with synchronous belts, a
surfboard is not a swiss clock.
You must think that cut foam is similar in forces point of view to
plasma cutter, so nema 42 is very big. With Nema 32 you get plenty of
room from point of view of forces.


Best Regards
Antonio Jimenez







--- In CAD_CAM_EDM_DRO@yahoogroups.com, "surfbuilder2003" <mek0002@a..
.> wrote:

> Hey evryone....I have been having great feedback, thanks to all. I
> have also been looking through the faq page and have been getting
> some good info from there. I am starting to look for screws and
> steppers now. However, I do not want to make any critical mistakes
> and buy the wrong sizes. My table is going to be 10' x 4'. I have
> gotten some suggestions on my large screw. I heard it needs to be

10'

> x 1.5" and I need at least a size 42 stepper motor to turn it. I

want

> to connect all these directly, no belts or chains. I heard they dont
> last as long and make everything run slower and less precise. For my
> y axis I am going to get a 4' x 1" screw but do not know what size
> motor. And my z axis alls I know is I probably want a 2' screw but
> dont know what diameter or size motor. There will not be much
> pressure on the bit as alls I will be cutting is foam. Thanks in
> advance for any help.
>
> Mike