Re: Building a small 4th axis

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler"
><eexgs@n...> wrote:
>
> I have been enjoying milling small 3D parts on my Proxxon very much
> and have been thinking about making a 4th axis for it.

Graham,
have a look at
http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/taig%
204th%20axis.jpg

for some idea's.

John S.

>
> I have a 4th axis stepper driver so that is no problem but need a
> small rotary table. For starters and to learn the process I will
> probably try milling some foam or wax mounted with double sided on

a

> simple plate mounted directly to the stepper motor shaft. I will
> only have 400 "degrees" resolution but it will get me going.
>
> Ultimately I want to build a tiny rotary table possibly still

without

> chuck that will give finer angular resolution. I have some Nema17
> and Nema23 steppers that would seem to suit the task on this tiny
> mill but no real ideas for the rotary part.
>
> My questions:
>
> 1. What sort of angular resolution is recommended for general as

well

> as perhaps gear cutting processes?
> 2. How much of an issue is backlash? Can this be avoided by

rotating

> in one direction only?
> 3. Is a simple worm gear ok?
> 4. Are there any gearboxes already available at a low price that

will

> fit the bill?
>
> I think that's all I need to know but any tips appreciated.
>
> Cheers,
>
> Graham
>
> p.s. My mill is much more quiet now :)