Easy Servo Drive?

[Tenson]

Thanks for your replies.

Yes I am using the parallel port of a Sony Vaio Pentium 4 laptop. One thing I notice is that I get an occasional delay when jogging if the wi-fi is active. So I disable it when running.

Motors are 4nm nema 24. One pair for the main gantry (y axis) is driven from 80V and the x axis and z axis are driven from 50V. I thought the lighter weight would need less voltage but I think I probably made a mistake there as I suspect voltage directly affects motor top speed, while current affects torque? In which case my x axis will not be able to reach such a high RPM as the Y axis even though it has less weight to move.

I made a video just now. I must admit there are no problems with it in this case, lol! But I think it shows my point that the direction changes are fast at the center of the circle. This was at 2000mm/min. Circles do seem less round at higher speed and more round at lower speed. In this project I need to cut some 6mm holes and use a 3mm cutter, so the gantry will need to make very small adjustments and fast if the feedrate is high.

Anyway here it is, be gentle!

https://youtu.be/3mmX7BZWEjQ

[JAZZCNC]

Thanks for your replies.

Yes I am using the parallel port of a Sony Vaio Pentium 4 laptop. One thing I notice is that I get an occasional delay when jogging if the wi-fi is active. So I disable it when running.

Ok well for a start you have rotating ballnuts and twin motors so you shouldn't be having any issues with loosing position due to lack of power.
My Gantry is much heavier than yours and I can cut what you where doing twice has fast you where and still not loose position.

I'm 99% sure your problem is coming from the Laptop and parallel port. For starters Mach3 doesn't suppport Laptop with PP for this very reason of it being unreliable with the pulses coming out of it.

If you where running an external Motion controller you wouldn't be having this problem. To be honest at this speed you probably wouldn't with the PP on a decent PC with good PP. But you certainly won't with External Controller. And you'd still be able to use the Laptop.

I'll lend you a USB Smooth stepper if you want to try one.! . . . . Fry it and you bought it thou.
If your going to buy one then buy Ethernet not USB.

[Dragonfly]

I think that one should use a dedicated PC (I do so) for the motion controller - turned off all visual candy staff, no anti virus, no active power saving and screen saver. In two words - everything which might take processing power or interfere with the time critical pulse generation is turned off. Using Win XP, Mach3 special driver is written for it primarily.
Laptops have built into their hardware means to save power, CPU throttling and so on. On top of that if the CPU (Intel processors) heats to a near critical temperature it has an internal protection by skipping clock cycles to cool themselves down. Had a problem with this and took me a lot of time until I discovered that the CPU cooler has detached from the holder on one side and the CPU was getting hot.

[Tenson]

Jazz Thanks so much for the kind offer! Can you link to something that explains what an external motion controller does differently than my current parallel port to break-out-board setup? Looking at the smooth stepper site it basically looks like a USB to parallel port but I assume it must be more than that because such a thing is very cheap and small. Would I still use my break-out-board?

If it means anything I get a 'Time In Int.' on Mach3 sitting at about 4 when idle and jumping between 4 and 11 when running. Does that occasional jump mean something bad?

https://youtu.be/0hVQXoq_eqI

DeagonFly, the laptop is dedicated to CNC and runs WinXP. I chose it because it has a built in parallel port which I assumed would be better than a USB or PCMCIA adaptor.

[JAZZCNC]

Jazz Thanks so much for the kind offer! Can you link to something that explains what an external motion controller does differently than my current parallel port to break-out-board setup? Looking at the smooth stepper site it basically looks like a USB to parallel port but I assume it must be more than that because such a thing is very cheap and small. Would I still use my break-out-board?

No can't link but I can explain it.!!

External Motion controller is a essentially a High spec pulse engine. Basicly it's a parallel port on Super steriods. It just goes between the PC or Laptop and the BOB. You still need the BOB to distribute the signals/wires etc. It just replaces the Parallel port and takes it completly out of the equation.

In practice What it actually does is far more than just replace the PP. It takes all the Hard work of number crunching away from Mach3 just leaving mach to deal with basic tasks and house keeping. So reduces the PC and Mach3's overhead on it. This is why a Lower spec PC or Laptop can be used with External controller without any troubles.

But there's even more to it than that.!! . . .The quality of the pulses are much much higher and clearer. Also the frequency can be set much higher if higher speed are required.
These two factors are what strangle the PP and why you get missed steps when pushing the machine hard like you have been doing. Just fitting an external Motion controller will see you increase performance by minimum 25% and reliablity will be much higher. I've fitted them and seen machines gain 75% in performance using the same drives and voltage.

Connect a Good Motion controller to Good Digital drives and you'll have no troubles with lost steps and with serious performance. Yes over tune and it will like any system but you will be able to tune much higher before being overtuned.!!

Oh and you get 3x Parallel ports worth of I/O for the price.!!

I won't fit anything but Ethernet Motion controllers. To be honest I try to use Cslabs Motion controllers when ever price always has nothing out there touches them for performance to what you get but they are not the cheapest. And the lower Spec isn't ideal for machines with Slave Motors because it doesn't fully support individual switch homing yet.

Think of a Motion controller like a VERY high end Graphics Card and the PP like the Most crappest basic Card on the market.!! The difference is night and day and easy to see and hear.!

[DuffelBuffelWuffel]

I have the ebay version on my machine. The step loss is usually 0-2 after a a bunch of milling.
You can tune the drives via the RS232 adapter cable and their utility.
By default it has an 1000 lines encoder. The driver can actually handle more (4000?), so you could replace the encoder and get (hopefully) more accuracy out of it. I haven't tried that yet.

Edit:
I also haven't done any tuning (508 driver model)

[Tenson]

It certainly sounds worthwhile! I do use individual homing switches on the Y-axis so will that be okay with the ethernet easy stepper?

[DuffelBuffelWuffel]

The "machine" does not know that it is using a hybrid stepper /servo. It just treats it as a normal stepper motor.
So however your homing setup is it should not change.

When you are talking about "tandem" homing (two limit switches on one axis) than it depends on the cnc controller you are using.
I have Eding CNC and it supports tandem homing with a provided script.

[Tenson]

Thanks for your comments. My last post was actually referring to Jazz's post saying Cslabs Motion controllers don't support individual homing switches for slave axis. So I just want to check the Smooth Stepper does.