What's your fastest feed rate for your mill/parallel port.

[mikep_95133]

The problem with that drive is you have to avoid the 127 count error limit and where you are wanting to run is right there.

Darek

Have you owned one? Tell me more.

Mike

[HillBilly]

"One  area that my controller falls short of the more expensive control boards is it only has an 8 bit counter, compared to 24 or 32 bits of an expensive servo  board. This has the effect of only being able to control position error up to +/- 127 encoder or computer pulses. When pushed past these limits the motor  slips like a stepper motor does when under load except instead of 1.8 deg. slip there will be a slip in multiples of 127 encoder pulses. This means that the amount the motor slips, or cogs, is a bit bigger step than a stepper depending  on the resolution of the encoder mounted on the motor. This motor slipping I  speak of is no problem under normal operating conditions, this is because the  error should never get close to being that big. If it does it means you are asking to much from the system and need to get bigger motors and amps or slow  the thing down. Although my servo controller is not as sophisticated as a full blown motion control card, it is more than the average hobbyist needs, and cost only as much as a stepper system that has no position feedback, if you take into account the fact that stepper motors will cost more."

This is from the website

[mikep_95133]

So when the system hits the 127 count limit, it just slips instead of flagging an error. OK.

Mike

[stevehuck]

Thanks Rich. Understood. Has anyone ever hit 200ipm for example??

Hello Mike!

I have a 1.8G machine with a BOB and Gecko. When I first setup I wrote a piece of Gcode to move around for a dozen or so moves and then return to a spot where I had 2 indicators setup. I would keep increasing the speed to see where I would start to miss steps. I got to 350ipm and the table zipped around in the pattern and returned to the indicators and zeroed them right out never losing a tenth. I finally backed the setting down to 200 and that's where it is today. I would have to check the setup but I think I'm at 35Khz kernel and 10,000 Steps per inch. Can't remember

Home built mill
12" X
7" Y
570oz steppers
Gecko @ 51 Volt
$5 breakout board

[mikep_95133]

Hi SteveHuck,

That is an amazing feed rate! Thanks for letting me know!

Mike