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1441

General Mach Discussion / Re: how to set A-axis to move continuously,not in steps?

« on: September 17, 2010, 04:25:38 AM »

how many revolutions does your motor turn if you command G0 A360

   if i put "4" in Steps Per it makes 1 turn

Then to summarize - I'm afraid that's it - your system has a resolution of 4 steps per degree and as I've said - there is nothing you can do about it other than gearing.

Ian

1442

General Mach Discussion / Re: How to recover from power interuption?

« on: September 17, 2010, 04:02:31 AM »

OK Lets look at the resolution and expected accuracy. This tells me that he is working on extreme detailed parts. AND the time to run tells me it is an expensive part.

I have never seen a machine cutting a finish cut at that resolution that IF you did a feed hold you would not mar, ding, scratch, gouge a finish cut.

Also With certain Material you cannot interupt a cut and have the bit rub the same spot it creates a hard spot which will never finish cut correctly

NOw as the outage events are random we have to assume the worst case senario, it is in a finish cut mode. Experiance tell us IF you plan on the worst case senario the rest will take care of itself(;-)

Try it and you will see what I mean.

OK I'll ignore all of the above because these are the very reasons for my suggested approach. Did you read it?

The only way out would be to RUN continuously or wait FOR a point in the program that the bit is NOT cutting material.

More or less what I've proposed. Did you read it?

That could be hours into a long program. The only way to be absolutly sure is to STOP in a tool change senario. OR use built in hold routines throughout the program AND the programs may not  HAVE either.

could be? - may not? - try asking the OP before you right things off. I've always found that an analysis of the problem usually precedes the selection or otherwise of possible solutions - just me from years of software engineering 

The only way out would be to RUN The generator is just a replacement for a large battery bank same thing only different name. Still a stored energy source(;-) He mentioned a UPS so they need a battery and it is EASY to add more capacity, add more batteries. LONG outages yep he has the answer UPS and a backup generator

You only know this because I asked - it was only a few posts ago you ASSUMED it was capacitor based and had less than a second of capacity. Like I said - ask some questions of the OP.

Now from past Power company Power Quality Tech experiance

Ah Terry - is there any job you havn't been an expert in?

As to the stop restart part that would very simple to do ONCE you have the machine stopped. We do that all the time in plasma to stop and check the consumables in long cuts. There is a routine to start restart on this forum somewhere that we use to do it.

One minute you're on about the need for extreme accuarcy and the next your quoting me PLASMA?

That is just my experience in outage recovery technics, Your mileage may vary (;-)

There's clearly no limit to your expertise. I'll get back in my box - Over to you Terry for finding the solution for the OP.

1443

General Mach Discussion / Re: how to set A-axis to move continuously,not in steps?

« on: September 16, 2010, 04:28:06 PM »

how many revolutions does your motor turn if you command G0 A360

1444

General Mach Discussion / Re: how to set A-axis to move continuously,not in steps?

« on: September 16, 2010, 02:44:22 PM »

xaco

The only ways I know of to increase a stepper's resolution is by gearing or by microstepping and microstepping for this purpose is not ideal. From what you've said in your OP it looks like you're already using 8 microsteps. 10 is the accepted maximum so it would appear you're left only with gearing.

Ian

1445

General Mach Discussion / Re: How to recover from power interuption?

« on: September 16, 2010, 01:54:32 PM »

Looking at your accuracy requirements the ONLY way to do this is to run a UPS "AND " a very large battery bank. That way there is NO interuption of cut.

With your resolution requirement you cannot even "stop" the program without effecting the finish cut. SO the machine must remain running thru the  power outage.

It would be very hard to create a macro to be to retract the cutting bit in a method that would not cause harm to a finish cut. COULD be done but very complicated.

(;-) TP

I think you're being a bit "absolutist" here Terry. ONE other way - which kinda kills your ONLY way - is to do what Bivouac has said and incorporate a generator with the UPS.

But I would go further and say that with a bit of thought it wouldn't be be that hard to "park" the spindle, shut down and resume without losing position. The advantage of this of course is that you don't have to then expend on a generator.

I suggested a basic scheme earlier on. I'd be interested in why you think that wouldn't be a reasonable starting point.

1446

General Mach Discussion / Re: how to set A-axis to move continuously,not in steps?

« on: September 16, 2010, 10:36:55 AM »

Just wondering but when you ask "how to set A-axis to move continuously,not in steps?" do you really mean "continously" or do you mean you want more resolution. I think maybe there's a misunderstanding going on here - at least that's what I get when I read your second post.

1447

General Mach Discussion / Re: Soft stop at limit switches

« on: September 16, 2010, 09:51:42 AM »

Nicolas - maybe it's a language thing but "load" has nothing to do with this. But if what you mean is in the realms of the rate of change of acceleration i.e. "jerk" or "jolt" then in my view we're getting far too theoretical for the sake of it and I'll try to explain why. If we do what you don't want and just take away the pulse train from a motor, lets say it then skips 8 steps (which in a screw system for example is actually a lot). Now lets say that your deceleration curve can stop it without skipping steps in say 4 steps. That would mean you would have to fit a 3rd order S curve deceleration profile into just 4 steps... bit of a raggedy assed curve don't you think.

1448

General Mach Discussion / Re: Soft stop at limit switches

« on: September 16, 2010, 08:39:23 AM »

Nicolas

Going back to one of your reasons for asking this. i.e. being kinder to the machine.
Do you agree that IF a decceleration curve were able to stop the axis more quickly than simply stopping the pulse train, then the crash/bang/jolt whatever we want to call it, would be increased? I ask again because for whatever reason, you didn't comment the last time I asked.

Ian

1449

General Mach Discussion / Re: rounded corners

« on: September 16, 2010, 05:49:01 AM »

Upgraded and it works now. Yeah!

That's good but what's REALLY strange is it all works fine in MY R3.042.020. This is EXACTLY the problem that used to happen a few years back.

Everything in your testing/results makes perfect sense and is what SHOULD happen EXCEPT for the very last bit "1 pass ccw pass on the square rounded corners." which was your original problem. Don't suppose you could post your test gcode (square and oval) just for interest.

Ian

1450

General Mach Discussion / Re: How to recover from power interuption?

« on: September 16, 2010, 05:15:45 AM »

How do you think using "Feedhold" will help?

Well that was the point of my question really. I think there's quite a bit more to it than JUST doing a feedhold when power outs. "How to recover from power interruption" in my view is the second part of your problem. "What to do when power is first interrupted" is the first part.

a question: How long can your UPS keep the system running i.e. making chips.

I think this is crucial and will determine to some extent your options down the line.

Ian