RE: [CAD_CAM_EDM_DRO] DenverCNC?

> Derek,
>
> My suggested motor rating comes from being involved with the
> taigtools list for a number of years. A lot of people have
> done there own Taig conversions and those that have used the
> larger motors (~200oz/in) seem to be the happiest. Also the
> fact that Taig supply these motors on their CNC mill gives you a clue.
>
>
> Peter Homann

Peter,

I was also a big proponent of 200 oz/in motors on table top machines.
What I have found is that my experience was based on the then current
state of hobby drives with half step controllers. Now that I have gone
to microstep drives I am amazed at how well the smaller motors are able
to drive the mill. With the new experience I have revised my advise. You
can now get a very solid and reliable CNC setup on a Taig or a Sherline
with a good quality motor just over 100 oz/in if you use a microstep
drive and at least a 10X over voltage on the drive (meaning you are
using a current limiting drive). Now if you have high inductance motors
or are using a 1/4 or half step controller I still agree with the 200
oz/in suggestion. As I have learned I have found that there is far more
to making a solid and reliable system than just specifying a motor
holding torque. Motor inductance, over voltage, microstepping, pulse
stream pacing, and more all enter into the picture. There are also cases
where I have gotten better performance from a smaller motor than a
torquier motor because of the higher inductance of the beefier motor.

Bottom line is that one parameter does not define whether a system will
be reliable or not.

Tim
[Denver, CO]
Sherline & Taig products at Deep Discount
Mach1 & DeskCNC with credit card ordering
www.KTMarketing.com/Sherline
e-mail me at Timg @ KTMarketing.com for items not yet listed