Jon Elson wrote:
> Roger Swift wrote:
>> Jon,
>> The mill is larger than a Bridgeport. Its a 7,000# Tree Journeyman 300 with a
>> 12X26X6 envelope and a 500# part capacity. The motors, reduction (about 
>> 2.5:1),
>> ball screws and encoder counts were not changed in the conversion to Mach3. 
>> The
>> original amps, servo dynamics, were rated for 20 amps continuous and 45 amps
>> surge. The machine works OK with Gecko's but is dreadfully slow. Mach3 has an
>> excellent CV algorithm that almost entirely eliminates corner rounding even 
>> for
>> slow axis and acceleration.
>>
>>   
> OK, so your problem is not acceleration but speed.  Let's do some simple 
> arithmetic to see what is going on.
> Assuming a 5 TPI ballscrew and 2.5:1 reduction, then you would need 1250 
> motor RPM for each 100 IPM of movement.
> What speeds are you being limited to?  You might be limited by the step 
> pulse rate your computer can produce, not the motor/drive/power supply 
> combination.  What is the volt/RPM rating of the motors?

Here's some more arithmetic - 80V maximum rated voltage of the Geckos
divided by nominal 160V rating of the motors means they'll be limited to
at best 1/2 of the design speed.  Probably worse than that - I bet Roger
isn't running exactly 80V into the Geckos.

Regards,

John Kasunich

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