Re: Linear rail & ball screw size suggestions

I can only guess at your cutting forces, but if you are using a roto-
zip tool or similar small comparativly low power unit, your cutting
forces are not very high.

The strongest method is to use a plate and rail that is secured along
the base. These use the open bearings that we talk about often.

Since it appears your long dimminsion it only 18 inches, you could
get by with 1/2 inch dia shaft/rail. An alternative is to buy your
stuff on e-bay for a good discount.

Regarding the lead screw, that depends on your stepper. Some on here
use all-thread and are quite satisfied. It seems that 6 times more
thread than the diameter of the screw offer good results.

Alternatively ACME will offer better deliverd force and lower
friction and ball screws even higher delivered force and even lower
friction, at a higher price. ACME and Ball Screw can be purchsed
whereas the all thread would be something you can make easily.

Search on all-thread to get more data about different styles. I
think a gread 8 or better rolled thread is the starting point.

McMaster Carr has all this, grade 8, ACME and ball screws.

If I remember correctly, a week or so ago, a gentleman on here had a
NEMA23 into a 2:1 timing belt set-up driving a 10 TPI ACME
leadscrew. the 50 in/oz stepper was delivering something like 200
pounds of force to the table. I would assume your Roto-zip would not
handle that kind of force and hold your tolerance.

I havent't seen any discussion on here about linear ball bearings and
accuracy vs. solid bearings. I had a friend who switch out of linear
ball to obtain a smoother cut. But if you reach that point, you are
chasing microns.

Dave

--- In CAD_CAM_EDM_DRO@y..., "J.Critchfield" <js3mc@a...> wrote:
> I appreciate the feed back on the Roto-zip. I share your concern
about the
> plastic housing. My carpenters use them or I should say abuse them
on a
> daily basis and they have held up well so I'm pretty sure there is
enough
> power for what I need. I have one to take apart and see it if a
more robust
> housing could be made.
>
> Now does anyone have any other feedback on linear components and
ballscrews?
>
> Thanks,
>
> Jay