RE: [CAD_CAM_EDM_DRO] Mill Conversion questions

As I posted on the Sherline CNC list (you will find that there is a lot
of people on both lists so the answers are not going to be much
different) the Gecko's are major overkill for a Sherline. They will work
great and put a big dent in your wallet compared to using something like
a Xylotex and will not perform substantially better. But if you have the
money to spend and don't care if you will not find any performance
difference, than by all means use the Gecko's.

You do not have to unplug the motors to turn the cranks by hand. Yes
they act like generators, but you will not be cranking fast enough to
generate much in the way of a current.

Once again, using Gecko with these motors will put you at such a low
amperage (they are 2 amp motors) that you will not even need a heat
sink. There is no need at all to build a cooling tower that would be
suitable for running the drives at the full 7 amps. If you read the
G201/G210 manual you will see that heat sinks are not required until you
go over 3 amps. At 2 amps they will not get much more than barely warm.
I have run the G210's at full amperage using only a CPU heatsink and fan
to cool them and they stay very cool. At 2 amps you can do just about
anything but pack them in insulation and they will not get too hot.

Don't lose site of the size of the machine and what it requires. A
Sherline is a small machine and it does not gain you anything to build
the drive system as if it was going onto a Bridgeport. This is not to
say that there is anything wrong with a Sherline. I own one myself and
use it regularly. But, it does not require or benefit from using much
more than a 2 - 2.5 amp drive and cooling is not much of an issue.

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

> -----Original Message-----

I'm in the process of convertimg my Sherline Mill to CNC. I'm

> thinking (at the moment) about running Sanyo Denki 232-180-DB
> motors with Gecko 210 drives.
>
> If I mount the handwheels on the rear motor shafts so I can
> run the mill by hand when I want to, I end up generating
> voltage when I move the handwheels, assuming that the motors
> act like generators in this case.
>
> Are the 210 drivers sensitive to this voltage, particularly
> when the system is otherwise unpowered? Do I need to
> disconnect the drive motor cables, either directly or with a
> relay, when I use the mill manually? If so, do all of the
> motor leads need to be disconnected? (That's not a problem if
> you just unplug it, but would be a design detail if you were
> going to use a switch or relay)
>
> Is there a recommended heatsink for the 210? (I've seen one
> at the Camtronics site that mounts 4 drivers) I was thinking
> about using a variation on a heatsink system I once saw on a
> high power stereo amplifier. The drivers would be mounted
> vertically on individual heatsinks to form a chimney with
> fans top and bottom. My idea is to get really good airflow
> for efficient cooling, putting the air where it it really
> needed. (In fact, if I used the Camtronics heat sink I would
> be really tempted to box the back side for the same reason.
>
> I asked a question like this on the SherlineCNC group and got
> some good answers, but not everything I was looking for so I
> figured I should ask here.
> Thanks,
> Chris
>