Cuts not repeatable, losing steps(FIXED) but will continue thread

[TCandee]

I am designing a DMM system for a lathe and came across this thread and thought I would share some info that may be helpful. If you need to convert your step and dir signals to differential, CNC4PC offers a solution. C86ACORN (1 for each acorn board), C34DYN4 (one for each DYN4), and C74 (one for each DYN4). I have not used these but will be. Marty has a video on the C86Acorn and DYN2 which is essentially the same thing using the relevant parts for DYN2. I do not belive the differential input is available for the DYN2 board.

Hope this helps someone.

[ShawnM]

I am designing a DMM system for a lathe and came across this thread and thought I would share some info that may be helpful. If you need to convert your step and dir signals to differential, CNC4PC offers a solution. C86ACORN (1 for each acorn board), C34DYN4 (one for each DYN4), and C74 (one for each DYN4). I have not used these but will be. Marty has a video on the C86Acorn and DYN2 which is essentially the same thing using the relevant parts for DYN2. I do not belive the differential input is available for the DYN2 board.

Hope this helps someone.

Why not just wire the DYN4 drives to the DB25 and go make some chips? No extra parts needed.

[gawinaa]

I contacted CNC4PC.com, & they suggested that a likely root cause of the EMI is due to here in Australia we have 240v A/C.

I also don't have a line reactor installed, it makes sense why would be having problems on my machine while those in North America don't.

CNC4PC has a C86ACORN board, though it does not address the EMI issues, "main reason for using these boards to easily integrate not just the step and direction signals, but also the fault and enable signals into an interlocking system...cnc4pc".

They do have a differential converter C74, though they believe it unnecessary. "C74 is intended to use if you need to send very fast pulse rates, but the ACORN is not fast. I would not worry about it.... cnc4pc".

I think I'll fix up the voltage regulation & provide a bit of extra shielding to the a/c lines & see what happens.

[cnckeith]

Acorn is not fast? hmmm.... Acorn can output pulses up to 1 meg hz step freq.
its the drive that is the limitation not Acorn.
most stepper drives can't handle more than 100,000 step freq. some can do 200,000 others say then can do 200,000 but in reality not.

high quality servo drives like yaskawa and delta can run with Acorn up to 600,000 to 800,000 reliably but, usually that is unnecessary anyways so the recommended rate for AC servos is 400,000 steps per second for typical applications.

from eng199, "Acorn is not necessarily limited to 400kHz. The open collector outputs will limit speed. The limit will also depend on external circuitry and cable length. The logic level outputs can go faster, depending on what they interface with and if 5V levels are an option for the drive. The rate setting is (1.2MHz / (parameter 968)). This gives a theoretical limit of 1.2MHz, which is not practical for any step and direction drive interface.

On the typical machine, there is no difference. The maximum speed, axis ratios, machine mechanical accuracy, and other factors would have to be considered to determine if there will be a real difference in a particular configuration. Accuracy comes into play as well as precision/resolution. For example, 20 bit encoders used on motors aren't accurate to 1 /1048576 of a revolution. The resolution is there, but not accuracy. Usually the overall goal is to make accurate parts. Resolution greatly in excess of accuracy is not a benefit in the overall picture."

[ShawnM]

I contacted CNC4PC.com, & they suggested that a likely root cause of the EMI is due to here in Australia we have 240v A/C.

I also don't have a line reactor installed, it makes sense why would be having problems on my machine while those in North America don't.

CNC4PC has a C86ACORN board, though it does not address the EMI issues, "main reason for using these boards to easily integrate not just the step and direction signals, but also the fault and enable signals into an interlocking system...cnc4pc".

They do have a differential converter C74, though they believe it unnecessary. "C74 is intended to use if you need to send very fast pulse rates, but the ACORN is not fast. I would not worry about it.... cnc4pc".

I think I'll fix up the voltage regulation & provide a bit of extra shielding to the a/c lines & see what happens.

Are you using shielded wires for all signal paths? Is the shield grounded properly? Do you have a SINGLE ground point in the cabinet? Can you share a link to your Google photo album so we can see how things are wired and installed in your cabinet? Just so you know, we do have EMI here in the states as EMI knows no boarders.

As Keith stated, Acorn is FAST, faster than most drives can handle.