Messages

3871

General Mach Discussion / Re: calibration still off? Parts not right size.

« on: December 18, 2011, 07:49:12 PM »

Do the calibration over a larger distance, like 6".

Or just calculate the correct steps per inch and enter that number. For 1/10 microstepping, enter 4000 steps/unit.

3872

General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 03:44:00 PM »

Do you think I'll get my accuracy back with better power & torque?

I honestly can't answer that, but I know those motors are very weak running on 24V. Ideally, they need about 100+Volts for maximum performance.

Your problem could actually be caused by 100 different things. The first thing I would probably try, would be a different PC.

3873

General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 12:15:25 PM »

You went from 8000 steps/inch to 1388 steps/inch, which means you will now need almost 6X the torque to get the same performance!

Ray, most people with ~4x4 machines find that they actually get 2-3x better performance from the same motors when switching from acme to R&P.

You are correct about needing 6 times more power, but I believe that the increased efficiency of r&p and the lower motor rpm can actually give you more power. But you still need to have enough power to do the job

3874

General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 12:10:56 PM »

Yes TP, I have the CNC Router Parts R&P system, which has a 3:1 belt reduction. I'm also using 495oz NEMA 23 motors which should be sufficient.

How did you determine this was sufficient? How much weight are you trying to move? How smoothly does it move. What kind of drives, and what power supply voltage?

Most people use the 381oz motors with a G540, which will usually outperform the 495's by a good margin, due to their lower inductance.

Imo, Nema 23 motors are too small for a 5x10 machine, and I also don't think the 3:1 reduction is enough for a heavier machine.
For the 4x6 router I'm building, I've calculated that I'll need 570oz motors and 4:1 reduction to get the performance I want. (150-200 accel up to 500ipm)

3875

General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 17, 2011, 11:43:45 AM »

IF it seems to lose position, then gain it back, my guess would be something mechanical.

3876

General Mach Discussion / Re: Ref all Home sends X axis running off - indefinaltey

« on: December 17, 2011, 11:41:43 AM »

Sounds like you have an X axis home switch enabled, even though you don't have a switch. If no switches are enabled (pins assigned), then it shouldn't move.

You can use Ref All without switches, and it should zero all the axis at there current position. Before I had home switches, I would jog the axis against hard stops and use Ref All. This gave me a repeatable home position, just like having switches.

3877

General Mach Discussion / Re: trying to improve motor speed

« on: December 17, 2011, 10:04:12 AM »

You'll never get much speed out of that, due to the low voltage and 1/4-20 screws. To get the maximum usable rpm from a stepper usually requires 15-20x the rated voltage of the motor. Speed is proportional to voltage, so you're only spinning the motor about 1/5 of what it's capable of.
The 1/4-20 screws make it even worse. As steppers spin faster, the torque drops off, usually quite rapidly. To get any speed with 1/4-20, you need to spin very fast, which requires very high voltages.

Imo, the software has nothing to do with the slow speeds you're seeing.

On a low powered setup like that, even the slightest amount of friction or binding in the system will seriously reduce speeds.

Using half stepping makes the motors very susceptible to resonance, which can reduce speed. Microstepping drives reduce resonance and provide much smoother motion and higher speeds.
My guess is that even with better drives and 24V, the best you could expect would be maybe 30ipm?

3878

General Mach Discussion / Re: Mach3 4.0 Rev Update

« on: December 17, 2011, 07:42:00 AM »

It's been mentioned before that version 4 probably won't be a free upgrade.

I've purchased plenty of software over the years with "free upgrades for life". Funny that sooner or later, the free upgrades go away. While it works for a few years, at some point you need more revenue to pay for continued development.

3879

General Mach Discussion / Re: Ref all Home sends X axis running off - indefinaltey

« on: December 16, 2011, 06:09:04 PM »

DO you have home switches, and do they work?

3880

Newfangled Solutions Mach3 Wizards / Re: Machine jumps when in program and looking at last wizard

« on: December 16, 2011, 06:07:57 PM »

If you told him a Ford Focus was just as good as a Ferarri, would he look at you funny then. 'Cause it's pretty much the same thing.

I think someone already mentioned that a $10,000 or $20,000 control can't really be compared to mach3, at $159. Even though Mach3 might be able to do 95% of what the more expensive control can do. The difference is that Mach3 is entirely dependent on software, where the expensive ones use expensive hardware to keep everything running smoothly, regardless of what the operator does.

And I mentioned before, when you load a wizard, you are in effect closing Mach3. Everything you see on the screen is discarded, and a new screen (with different controls) is loaded. With some wizards this can take Mach3 several seconds to do, and it just can't keep running smoothly when asked to do another task.

I think the reason that noone is trying it for you, is we know that it will cause problems. We don't need to try it.
Honestly, for the 7 or 8 years I've been reading the Mach3 forums, you're the first person I've heard of who's wanted to open a wizard while the machine is running. You might want to consider removing the wixards, then your operators can't open them. But you'll need to use a CAM program to create your code.