Re: CNC an X1 again!

"Tony Jeffree" <tony@xxxxxxxxxxxxx> wrote in message
news:lamnu2tlnt4kumpu4i61rd1ki94nl47fkl@xxxxxxxxxx
On Mon, 05 Mar 2007 00:29:44 +0000, Andy Parker
<andy@xxxxxxxxxxxxxxxx> wrote:

I just can't put this one down! In previous threads I've had great
advice and Tony's excellent write up on the Taig and somebody
mentioned motion controll products ltd.
I am looking at the following:-
57BYGH726 steppers

http://motioncontrolproducts.co.uk/product_info.php/cPath/10_14_32/products
_id/80
MSD325 controllers

http://motioncontrolproducts.co.uk/product_info.php/cPath/1_8_47/products_i
d/78
SP787 power supply
http://motioncontrolproducts.co.uk/product_info.php/products_id/91
and a breakout board.
Am I in the right area here or am I missing something really simple?

Yes I konw I've got to wire it all up, mount the steppers etc etc -
I'm fine with that but just unsure about speccing the kit above.

I think you mean PS487 for the power supply.

Note that this PS generates a higher voltage than the MSD325 is rated
for (max 32V) so this PS is ABSOLUTELY NOT suitable for those drivers
- you will probably blow them up. So if you stick with those drivers
you would need to find a PS that has a max voltage of 30V, preferably
28V.

The motors are a higher current than that driver can deliver (max
2.5A). Yes, you can run the motors in "bipolar series" connection at a
lower current, as the spec *** suggests, but you lose out both ways
by doing this - the relatively low max voltage, coupled with the 4
times inductance that you get running the motors series connected will
have a big impact on the high speed end of operation.

A better combination would be:

57BYGH728 (not 726!) steppers wired bipolar parallel

PS478 power supply

MDS 542 (as John has suggested), set for 3A/phase (yes, the spec ***
says you can up this to 4.2A/phase in parallel, but actually, you gain
very little from doing this and the downside is that the microstepping
"bunches" around the full step positions due to magnetic saturation of
the motor, and the motor doesn't run as smooth). There's also no point
in setting the driver for more than 8 or 10 microsteps by the way -
more than that and a) there isn't any benefit in resolution or
smoothnes, and b) the computer may run out of steam attempting to
generate the pulse rates you need.

Regards,
Tony

Cheers Tony and John, correct bits duly ordered, if the lights go out in
Cumbria it was me!



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