Hello Guest it is July 19, 2019, 11:41:08 PM

Author Topic: What's your fastest feed rate for your mill/parallel port.  (Read 10524 times)

0 Members and 1 Guest are viewing this topic.

Re: What's your fastest feed rate for your mill/parallel port.
« Reply #20 on: January 12, 2012, 08:52:14 PM »
I'm trying to maximize my feed rates so I can make parts faster.

Be patient Rich. Over time you'll figure out that I have a clue.

Mike

Offline RICH

*
  • *
  •  7,342 7,342
    • View Profile
Re: What's your fastest feed rate for your mill/parallel port.
« Reply #21 on: January 13, 2012, 06:33:46 AM »
Quote
I'm trying to maximize my feed rates so I can make parts faster.

Then you must determine  the required parameters which will optimise the machine and provide
the appropriate components to accomplish the task reliably and within tolerance. The required or desired acceleration, velocity, power are determined FIRST.

Have fun,

RICH
Re: What's your fastest feed rate for your mill/parallel port.
« Reply #22 on: January 13, 2012, 07:13:11 AM »
With some experimentation yesterday I achieved 175ipm up from 135ipm with and acceleration value of 10. Here I come Ian ;) Didn't miss any pulses. Over about 4" of travel is was off by .005". It's usually off by .000".

I better find the rpm limit of the ball screw.

Kernel went from 45khz to 60khz. So at 200ipm, it missed just a few pulses. The 60khz kernel was limited to 200ipm max with my 20,000 pulses per inch. So at 195ipm it was better, just not zero lost pulses. Testing yesterday and in the past showed that I need to get the kernel higher in order to go faster since the velocity slider is now almost pegged at 100%. I hope to see more of what is happening at over 65khz+ with the scope. I'm hoping today is scope day.

Both the step and dir pulses go through the PS2501 opto's. I still have to figure out where the 6n137 opto is in the circuit. There are no schematics.

Mike
Re: What's your fastest feed rate for your mill/parallel port.
« Reply #23 on: January 13, 2012, 09:09:48 AM »
Hi, What servo driver are you using, I just read the thread through and as said previously servo drives dont lose steps or pulses. If the motor cant drive the axis to keep up with the sent pulses it will fault the drive. That said, if the drive does not fault but the position if off a small amount then the drive's PID or tuning needs tweaking to provide a stiffer positional response.

I also found that if I ran a high kernal on the 1.2ghz computer I am using the pulses output on the printer port became less square and erratic when viewed on an oscilloscope which would cause the drives to fault intermittantly.

If you cannot tune the drive to get the accuracy then you need more powerful motors.
Re: What's your fastest feed rate for your mill/parallel port.
« Reply #24 on: January 13, 2012, 09:20:22 AM »
And high speed, without high acceleration, is kinda pointless....
Regards,
Ray L.
Re: What's your fastest feed rate for your mill/parallel port.
« Reply #25 on: January 13, 2012, 09:24:39 AM »
Servolite is the name of the hardware. This hardware can't fault. It's simpler than that. It just slips. But it's done very well for me for 10+ years.

I'm anticipating the same thing you found with a mal formed pulse train. If that's the case I wonder if there is a parallel port card that actually works, but also has a higher rate of throughput. Or maybe I can build a high rate buffer that can clean up the pulse train.

The motors are Ametek Servo 600in-oz on 38v IIRC. At double that voltage the horsepower is quadrupled. So I don't worry about the motors. They keep the repeatability and accuracy up nicely.

Mike



Re: What's your fastest feed rate for your mill/parallel port.
« Reply #26 on: January 13, 2012, 09:27:30 AM »
And high speed, without high acceleration, is kinda pointless....

My experience is different. I've done fine making parts and robots with accel at 1 for 10 years. So far I'm up to 10 and that's more helpful.

Mike
Re: What's your fastest feed rate for your mill/parallel port.
« Reply #27 on: January 13, 2012, 10:16:09 AM »
Ah, Is that Mr Bill's Servolight? I just looked it up on the net, The web page states that tops was 135ipm for the board.

When you get the scope, check the printer port and then do some checking on the driver board. Check part numbers for chips and specs to check the upper limit for pulse through put. It might be that the board just cant run those high freq pulses.

A drive that doesn't fault, not sure I'd be happy with that, I've had a few mishaps knocking into fixtures and have been thankful the drive faulted instead of carrying on regardless.

Re: What's your fastest feed rate for your mill/parallel port.
« Reply #28 on: January 13, 2012, 10:20:44 AM »
Ah, Is that Mr Bill's Servolight? I just looked it up on the net, The web page states that tops was 135ipm for the board.

When you get the scope, check the printer port and then do some checking on the driver board. Check part numbers for chips and specs to check the upper limit for pulse through put. It might be that the board just cant run those high freq pulses.

A drive that doesn't fault, not sure I'd be happy with that, I've had a few mishaps knocking into fixtures and have been thankful the drive faulted instead of carrying on regardless.



The website is mine. I reconstructed it once Bill closed shop. I'm updating it as I gain progress to let the remaining users out there know the hardware is still viable.

I'll scope the entire pulse train path and compare the timing of the step and dir pulses.

A hard enough fault just pops a fuse.

Mike
Re: What's your fastest feed rate for your mill/parallel port.
« Reply #29 on: January 13, 2012, 12:33:39 PM »
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