Re: servo board - or steppers to start ?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "george_barr" <
george_barr@y...> wrote:

> The type of CNC machine I want to build is mainly for hobby purposes
> but also will have professional features. I would like to make
> wood/metal projects but don't have the time nor want to do too much
> manual labor to get the projects done. A CNC machine can perform
> much of the manual intensive labor. I just want to create things on
> the CAD (Solidworks) and essentially tell the CNC to build it. I
> can't tell you more specifics since I don't have any experience in
> CNC yet, but I am willing to invest time and money at this hobby.
>
> I found out that the STG requires a relay board and break-out
> boards. This can add much to the finaly cost of purchasing a STG to
> the point that a Pico Systems 8-axis system may cost about the same
> for a STG system. Right now, I am leaning towards the Pico System.
> However, the STG cutomer base is plenty and I am not sure how many
> Pico Systems Servo's have been sold.
>
> Thanks,

<SNIP and trim excess text to be considderate to others>


Hi George,

If I may read into your situtation a little... it appears as though the
engineering part of you wants to lay out every detail before the
entirety of the unit is done.

Many people are extreemly successful with Steppers and others go for
Servos.

Here's a link to the data from Mariss's post on the general differences
between them.

http://www.timgoldstein.com/cad_cam/servotopten.htm

If you are building from scratch, may I suggest you leave enough room
for NEMA43's of whatever motor you choose ? and also enough for a
mouting plate of course.

Also, if you hope to get by with small screws for some reason, (often
cost or availabliity) considder leaving room for much bigger bearings
and screws. Remember, a 1/2 bearing and housing may be 2 in square,
while a 1 inch may be 3.5 square, and the screw height will also
increase.

I built my first machine with steppers and belt drive, primarally for
the super low cost, around $100.00 and axis (can you say scrounge?) and
am using parts that really don't belong in a professional set-up.

My intention was to just use something to see it work or 'proof of
concept' as I like to call it.

It worked so great that I ran it for a year before tearing to dowm for
some upgrades.

I still want to use a servo on one axis, but since the machine is
running and everything works, I will wait until I can get a deal on a 9
foot ballscrew and nut. or decide to try an open ended belt.

Bottom line is that if you want to get there quickly, start building.
The electronics are available and by the time you are sliding the
carrage on it's bearings there may be new and improved stuff.

Dave