Any real world experience with Camsoft & Steppers

[mbam]

Is there anyone who has actually done a retrofit using Camsoft with steppers? I have a Series II Bridgeport that I have been struggling with for a year.


Thanks in advance

[Al_The_Man]

Marc, What are the issues you are having a problem with? Detail some specifics, some of us may be able to help.
Al

[Bob Pierre]

Hello Marc,

Where are you in the country? I may be able to help you. I have helped my customer set up a stepper machine before. It's much different than the servos I have used with CamSoft. It turned out okay and almost have to say it was easier.

Bridgeports should be nothing special with CamSoft. They showed me a Bridgeport clone running. The man told me it runs much better now with the PC control. I am not sure I can help but I will try.

Bob

[mbam]

I sure appreciate the responses.

Bob, we are just north of Ft Lauderdale FL. Sure, there is no reason that just because it’s a Bridgeport there should be any problem.

I had the machine running OK, although there were some unresolved issues that I had put aside till later. I won’t go into the reasons just now, but I replaced the 3 stepper boards with new drives. The new drives are losing steps (well I assume they are losing steps, the machine is losing position). Here is what I know:

Opto isolated inputs, require 5 v @ 7ma
The Gallil motion card supplies 5V , up to 30ma

The manufacturer of the drives has been very helpful, but we can’t find the problem.

A scope confirms that there is a pretty clean 5v square wave from the card. We are talking feed rates of 1 IPM are a problem, so it’s not speed related.

Separate issue, now that I have a scope on it I see there is a problem with the implementation of ramp up/down on the step pulses while using the handwheel for incremental jogging.

The second issue is minor, as we are dead in the water because of the first.

[HuFlungDung]

Hi Marc,

So you know you can redefine the acc/dec ramps whenever you need to, right? That is to say, you're not permanently stuck with the settings that you made in the setup page. Although I haven't played with any handwheel logic yet, I can imagine that there would be a special balance to be achieved, if you don't use decelstop in the handwheel logic. I'm not saying that you'd want to use it except when you exit handwheel mode, but in the same vein, more conservative (or more aggressive) acc/dec settings might be required (with or without DECELSTOP) whle in handwheel mode, just to prevent drive faults. In a servo system, you might get drive faults, in a stepper system without feedback, I suppose you'd just lose steps.

[mbam]

Hi Hu,

Ok, here is what I know about the handwheel, and steppers in general.

Am I correct when I say that all start/finish of movement on a stepper requires a ramp up/down of the pulse train to avoid losing steps, unless a very low speed is involved

If OK2STOP is enabled, accell/decell is applied at the beginning and end of the travel. But the motor decels as soon as you stop turning the handwheel, so you cannot jog a specific distance

Without OK2STOP each clcik represents a certain movement

Here is the problem, the acell is only applied to the first movement, if you click again there is no ramp
Well actually it depends on how fast you click again, I have the ramps set to be very long so I can observe them, and what happens is that the ramp up starts on the first click, and if the second click is soon enough it will still be ramping up, takes over where the previous click stopped. Am I making sense?

I think this is a problem

[HillBilly]

Marc,

When you changed the drives did you go to microstepping. The stock drives ran full step (1000 counts=1" or 1 count=.001").

Darek

[mbam]

Hi Darek, yes I am microstepping.

[HuFlungDung]

Marc,

Have you tried a normal short Accel and a longer Decel? I would suspect that this could be where there could be a bottleneck in what is going out to the motor. Using a long Decel ramp might allow a smoother overlap between clicks.

[mbam]

Yes, looking at the scope i see the ramps are just not applied

[HillBilly]

Marc,

You may be suffering a loss of torque due to microstepping. The original motors required 8+ amps in fullstep, I do not know what the microstep amps should be.

I see you said it is a series II that means originaly 2000 counts=1" or 1 count=.0005"

You will probably have to reduce your RAPIDSPEED setting to a speed your stepper can start at for handwheel operation.

Darek

[mbam]

Darek, I see,

I will try it without the micro stepping, and see what happens.