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Messages - stirling

1151
General Mach Discussion / Re: Steppers are too slow
« on: December 01, 2011, 05:23:22 AM »
Today I disconnected all drivers from the BOB and connected each one individually one at a time. As I reconnected them, each one still ran slow and the microstep switches still have no effect on speed or torque levels. The motors don't even make a different sound with each selection.
IMHO your not going to be able to detect visible or audio changes with different microstep settings. Though technically microstepping does have subtle effects on torque I really doubt you'll be able to see or hear any difference. Maybe between NO microstepping and (say) 10 but other than that I doubt it very much so I'd not get too bogged down in that. As I said - set them as near 10 as you can and leave them there.


Also I went into Mach 3 and changed the kernel speed through the range of 100 hz to 75000 hz with absolutely no effect.
To calculate the CORRECT kernel speed multiply your steps per unit by your max velocity (in motor tuning) and divide by 60. Do this for each axis and choose the LARGEST figure. That gives you the max steps per sec you'll ever use. Then pick the LOWEST kernel speed above that figure. Any kernel speed above that is not only pointless but may cause other problems. Post your figures so we can check.

The computer is about 8 years old and is a Pentium 4, 3.2 Ghz processor wit a 2.75 Gb of Ram. I had a fairly new hard drive completely formatted and windows reloaded to be used for this purpose when I first started to set up for this project. the steppers are running off the parallel port on the motherboard but it does have another parallel port PCI card installed. Do you think it is worthwhile trying to use this other parallel port, or maybe removing the card in case it is having any effect on the output pulse rate?
I very much doubt this will make any difference.

I do have some doubt about the BOB as I still can't get 2 of the output pins to work on any of the stepper drivers but they will work if connected to the other available pins. My next thought is to replace the breakout board with a different type. Do you have any suggestions?
You may or may not have a couple of pins out on either your parallel card or your BOB but if all four of your axis are working on other pins I very much doubt this is the cause of your speed problem.

I appreciate this might not be the best matched system, but the attached You tube URL has the identical components on a friends machine and it can be seen how fast it operates. There is no way these steppers are running this fast.
Well if you say it's identical fair enough - but are you absolutely sure?

Exactly the same power supply, drivers, motors, AND GEARING? EXACTLY? The reason I'm checking is if you look at this link (http://www.wantmotor.com/ProductsListB.asp?id=88&Pid=75) the systems APPEAR to be similar to yours but if so, they seem to "randomly" include different power supplies. For example the THREE axis kit has a 24V 350W ps but the FOUR axis system has TWO 36V supplies. It's not clear to me if that's TWO 350W or TWO in parallel give 350W.

IF for example you had TWO 24V 350W supplies you could series them and get 48V at 14.5A which would double the stall speed of your system. (incidentally this is why I say random supplies - 14.5A is waaaaaaaay more than those 4 motors need, so with that supply, the voltage is way too low and the amperage capabilites way higher than neccessary)

Ian

EDIT: didn't see Tweakies post when I posted but FWIW with a supply of 14.5A (if that is indeed what you have)  I doubt very much you'll get a voltage drop. Just a thought.

1152
General Mach Discussion / Re: Mach test problems
« on: November 30, 2011, 12:00:54 PM »
Hi Kart - welcome to the forum

try adding in these two lines at the end of the program


M30 (program end and rewind)
% (comment to make sure there's a carriage return terminitor at the end of file)


Ian

1153
General Mach Discussion / Re: Steppers are too slow
« on: November 30, 2011, 09:14:45 AM »
Tweakie - well I suppose, but ultimately we'd be guessing wouldn't we?

We know that typically a doubling of voltage will double the stall speed so with the 24V as opposed to 96V we can generally expect a quarter of potential. Is 200RPM still slower than we'd expect then I suppose maybe yes but it's a hard call at this distance. Stuart has stated that they run smooth so I'm thinking the drives and Mach are OK. I'd stick the microstepping as close to 10 as possible for starters but after that - like I say from this distance it's hard to tell what other issues (if any) may be at play.

Ian

1154
General Mach Discussion / Re: Steppers are too slow
« on: November 30, 2011, 08:09:24 AM »
Stuart - from the info you've given and what I've been able to find...

With inductance of 9mH your "ideal" power supply voltage for your motors to achieve max torque/speed is 96Vdc. Your drivers can only handle a max of 50Vdc and your power supply is only 24Vdc. I'm afraid this is NOT a well matched system if high speed is what you want.

Ian

1155
General Mach Discussion / Re: Steppers are too slow
« on: November 30, 2011, 05:23:09 AM »
Stuart, can I make a plea to you and everyone else that posts similar problems? Without the motor, driver and power supply data sheet/specs and idealy some info about the gearing and drive type of your machine, all anyone can do is guess. By googling "Wantai DQ542MA" and searching the links for a 380oz motor option (the two clues you've given) I could probably spend some time and home in on which motor, driver and PS you might be using but frankly it would be a lot easier to help you if you did that yourself and posted links.

Thanks

Ian

1156
General Mach Discussion / Re: USB Breakout board for Mach3
« on: November 29, 2011, 09:10:25 AM »
NEVER put an LED accross 5Vdc without a current limiting resistor (unless that 5Vdc is a PWM signal carefully designed to match the specs of the LED). You stand a very good chance of either blowing the LED or the output stage of the device supplying the 5V depending on it's current sourcing capabilities.

Ian

1157
General Mach Discussion / Re: TB6560
« on: November 29, 2011, 08:06:58 AM »
at the risk of being ignored again I'll give it one more shot. According to your link your motors are rated at 3.6mH. That means that for max speed/torque combination the optimum voltage is 60V. Your power supply is 24V max - way too low. Plus the blurb on your link states "High voltage will burn up the chips or stepper motors!!!". This is misleading at best. With a decent driver 60V would NOT damage your motors. However with THAT driver it WILL damage the driver and MAY damage the motors. Motor curves will help you to understand this but won't change the facts.

Ian

1158
General Mach Discussion / Re: TB6560
« on: November 29, 2011, 06:32:14 AM »
You haven't given the specs of your present motors but I suspect that your *real* problem is the drivers.

According to the data sheet for the board it is 24v 1.5amp to 3amp.
Doesn't mean much without motor specs.

The motor supplier says
"Yes this driver will work with our steppers, you can use them in series to give you better torque but slower speed or in parallel lower power but higher speed."
Doesn't mean much - but it might get him a sale.

Why wont a bigger motor 566oz against 263oz not produce more power?
Beacuse (very simply put) motors don't *produce* power, they convert electrical *power* into mechanical *power*. If the electrical power isn't there in the first place, *more powerful* motors arn't going to improve anything.

Not a lot to go on but my guess would be you'd be better off replacing your drivers than your motors.

Ian

1159
General Mach Discussion / Re: Confused about Stepper Motors
« on: November 29, 2011, 06:18:30 AM »
Posting the data sheets for your motors and drivers would have been useful but I'm thinking your present 24 Volts is waaaaaaaaaaay to low. If I've looked up the correct motor specs then to get *max* speed/torque combination you should be using around 80V. I can't find a data sheet for your drivers but having looked at other Toshiba drivers I'd hazard a guess that they can't handle this voltage.

Ian

1160
General Mach Discussion / Re: Probe
« on: November 22, 2011, 12:35:19 PM »
Hi Terry - don't think debounce is the issue. Don't want to get too bogged down in this - it's something I've noticed and thought I'd mention. It's NOT really a problem I think if your accel/deccel is decent. Anyway FWIW...

See attached pic.

It's meant to represent a downward probe (i.e. in Z). In both cases the probe trips on the step and then decelerates and comes to a  halt at the position shown (obviously exagerated). In the RIGHT hand case all works as you'd expect. The stored point is where it hit the step. However in the LEFT hand case the recorded point is where the probe stops and NOT where it tripped.

Ian