Re: Subject: size of leadscrew question

John,
are you 100% locked into a leadscrew???

you can buy a 6' rack off the shelf, fine tune the
ratio with pinion gear changes (cheaply).

how much accuracy do you think you want/need?
most CNC routers use 500 - 1000 steps /inch.
Gerber for an example uses 800.

The best way to make the gantry stable
is to space the bearings 18-24" (min.)

erie

> Message: 24
> Date: Tue, 12 Mar 2002 11:35:12 -0600
> From: John Thompson <rcav8r@...>
> Subject: size of leadscrew question
>
> I'm wondering what size of leadscrew to use for the X axis on my planned
> router table. I was going to use a 3/4", 5tpi (single start) Acme
> leadscrew, but am having trouble finding wear compensating/ anti
> backlash nuts by themselves to fit this size.
>
> The table I have in mind will have a 48" cutting length X axis, so
> figure 5 to 6' long. Could I substitute a 1/2" leadscrew with 10tpi and
> 2 starts?
>
> Since the gantry will ride on 3/4" shafts on either side to take the
> load, and the anticipated speed wont be more than 40-50 ipm (small, 2-d
> parts), would the 1/2 leadscrew be OK? will it be strong enough?
>
>
> On another subject, what are some good ways to make the gantry stable,
> avoid the posibbility of "rocking" back and forth on the X axis because
> the bearing blocks and the leadscrew nut are in line (on the Y axis), or
> close to it? maybe stagger the nut ahead or behind the bearing blocks?
>
> John
>

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