Re: [CAD_CAM_EDM_DRO] Re: Tormach stepper motors

John Stevenson wrote:

> The problem with the old BOSS machines is they big 42 motors are not
> suited to the Gecko drives.
> They are just too big and require too much power, typically 9 amps to
> be reliable.
>

Yes, I have heard this, and even that some people have Gecko
drives burn up when driving these big motors.

> Most were only 850 to 900 oz/in and with time probably a lot less than
> that. The modern 34's can use less power, have faster acceleration and
> be far more reliable.
>
> As you say early to mid release Gecko's are the worse. I can get these
> to run reliably with the Chinese drives from Keeling but not Gecko's.
>
> I have had a Divisionmaster indexer driving a big Hoffman dividing
> head via a 201 Gecko and it has been loosing steps for a while.
> Last week I needed some accurate splines so tested the head by setting
> to 10 divisions and doing 5 rotations. At the end of the 5 rotations I
> was 1/2 a hole [ 5mm ] off the mark.
>
> Just swapping the driver to the Chinese 7.9 amp one and retesting gave
> me no visable error at 10 rotations.

Well, that sounds pretty convincing, but I still wonder if it is
a drive-motor issue or a software-drive issue. If you put a
small stepper motor on the Gecko and it worked perfectly, then
I'd agree with you. But, you are changing your drives to fix
your problem, and saying that Nate will fix his problem by
changing his motors.

If Nate was having obvious stalls, loud grinding of motors, etc.
then I would be ready to believe his motors are not following
the Gecko drive's output, and better motors would fix it. But,
he may have a different problem, he hasn't given enough data to
be sure. I believe, reading between the lines of his original
post, that he is losing position in very small increments, and
this builds up over repeated runs of the program. If this is
true, it is a lot less likely to be the motor, and may be the
problem of the step to direction change timing causing the drive
to misinterpret which direction one or more steps should be made
in. I'd hate to see Nate go and buy $500 worth of motors and
still have the same problem!

Jon