The other thing you get into with packaged drives like Omron, 
Mitsubishi, Yaskawa, Teco, etc is that they are setup
to use their motors with their drives.   You typically cannot mix 
between brands.    Don't bother calling them asking them how to 
interface brand B motors with Brand A drives...  they won't help you.

Teco is very typical of low cost Asian packaged industrial drives.  Some 
of the Automation Direct cables interchange with these drives.

http://machmotion.com/cnc-products/drives-motors.html?cat=62
I've bought and recommended Teco packaged servos for several machines 
and they have always worked out well.

If you are willing to deal directly with dealers in China and Taiwan I 
am sure you can better prices, but consider the costs of returns or 
defective products...

Some OEM machine makers buy Mitsubishi, Omron, Yaskawa, etc drives at 
very low prices but unless you are buying $50K worth of drives per year, 
you won't get the low prices.   I'm working right now with an OEM that 
buys Mitsubishi servo motors and drives by the pallet load.

Regarding Nema 24 motors..  All of the ones on Ebay are direct from 
China.     So how does it work when you get a bad drive or motor or one 
fails?    If you need to call them, they are typically 12 hours out of 
sync with Eastern Standard Time in the US.  I think shipping between 
China and the US is pretty much a one way ticket.    It can get here 
dirt cheap.   Getting anything to China is expensive.

For a 3 axis machine you are into $1000 for Nema 24 motors and drives 
off Ebay.     I certainly would not send $1000 to China for anything 
unless I knew something about the manufacturer.   Its not like you can 
take them back to Walmart if they are junk.

There is nothing wrong with Steppers.   Just don't expect them to go 
really fast and make any power at speed.    I think the max power you 
can get out of a stepper motor/drive is about 200 watts.

Dave




On 1/24/2017 2:43 PM, Mark Johnsen wrote:
> Actually, there are a lot of servo's like this (w/ step and direction).
> But, cost comparison is the issue.
>
> Omron and Panasonic servo's only accept step and direction (the ones I
> looked at) and you can probably get them off ebay for a decent price.  I
> had once used Omron and was actually complaining they didn't have a +-10Vdc
> interface and only took step and direction.  I think one reason is the
> Omron's are designed to be used w/ a step and direction output from their
> PLC's, that historically didn't do analog servo control, at least from the
> brick versions.  I always wondered why they just didn't add the analog to
> the servo drive, but oh well.
>
> Also, here's a brand that BeachBumPete (from the IRC) used on his
> Cincinnati mill retro that accepts step and direction:
> http://www.dmm-tech.com/
>
> I haven't used them, no affiliation w/ any of these, but the dmm guys also
> have a lower cost servo i just saw,  DYN2 AC Servo Drive is step and
> direction and analog input...
>
> Chinese servo's from Alibaba or a place like salescnc.com  have step and
> direction servos:
> http://salecnc.com/catalog/Delta-Taiwan-Servo-MotorDrive-Set-400W-3000RPM?osCsid=du1blviq6dlbi02nscik0akre1
>
> While that $350 price is high for a stepper solution, it's waaaayyy cheap
> for a servo drive and servo motor combo (with cables).  For Kollmorgen
> servo's you're looking at a couple hundred bucks just for the cables!!!
>
> I think the bottom line is that the servo pricing hasn't come down like the
> bare-bones stepper motor and $50 stepper driver pricing.  If you are cost
> conscious, steppers are the easier route.  In Gene's case, to match the
> cost competitiveness, he would need to shop ebay for the 'right' deal and
> those don't come by everyday.
>
> Good Luck,
> Mark
>
>
> On Tue, Jan 24, 2017 at 11:17 AM, Andrew <pkm...@gmail.com> wrote:
>
>> 2017-01-24 19:37 GMT+02:00 sam sokolik <sa...@empirescreen.com>:
>>
>>> PWM/dir  though the bob.  (these amc drives instead of +/-10v take
>> pwm/dir)
>> Ah, so convenient. We could save a lot on 7i77's if all servo drives were
>> like this )
>>
>> Andrew
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