Thread: stepper motors glitching
did you burn it as an ISO image using 'disc at once' or burn it as a file? If you open the CD on your PC do you see the ISO file, or do you see a collection of files? If the former then you need to find out how to correctly burn an ISO image...
and check the BIOS is set to EPPJohn S -
Looks like I did not create an ISO. Am reading about those so I can try again.
Downloaded the analyser and tried it briefly. The graphical output showed some red pulses, but they were all in a block. I need to play with that a bit more, but my Wife is getting upset with the amount of hours (days!) I'm putting into this.
Started again with a clean install this morning, following the Mach3 windows optimisation steps. Disabled everything on the list (sound, gone back to classic, switched off auto updates etc.etc.). Switched to 'standard PC' in hardware.
In BIOS have disabled: game port, midi port, AC97 audio controller, onboard lan (nvidia), onboard lan (3com) 1394, serial port1, serial port2
Parallel port is set to: 378/IRQ7
Then went through all the parallel port options in BIOS: ECP+EPP DMA3, EPP, ECP DMA1, ECP DMA3, SPP, ECP+EPP.
Then in Mach3 traversed at various speeds (since I noticed that 1500mm/min did not glitch since this fresh install). Noticed that: 50,300,500,700 mm/min all glitched. 1200 mm/minute occasionally glitched. 1500mm/min never glitches, nor does 2500mm/min. 3500mm/minute makes the motor sound unhappy (but not glitching). Cutting at 1500mm/minute is not possible, so this is not a solution but may point to the answer.
I hooked up the scope to the system3 boards whilst it was running, onto pin3 and earth. At 1500mm/min (when there is no glitching), the scope does not give a steady spacing between pulses and is very inconsistant. I can no longer rely on the scope and need to use the motors as a glitch guide.
I'm beginning to think there is a fault with the MB (or parallel port). Even used on ebay this spec of board (ASUS A7N8X) still is quite expensive. What MB are people successfully using Mach3 with?
Thanks for your patience !!
Installed ISO recorder into windows xp, and created a proper boot disc for Ubuntu and EMC2. Installed this onto a reformatted second HDD. I ran the latency test and got max jitter servo thread of 6983, and max jitter base thread of 7541. These are similar to the results in the EMC2 manual, so assume are OK.
I then ran EMC2 using the 'stepper mm' profile. Unfortunately this also glitched the motors!
I then tried the profile which sends the stepper pulses to the speaker (nice feature). This also glitched. I attempted to record this into another computer using 'windows sound recorder', so I could post this and do some analysis on it, but got the windows error about not enough memory. Microsoft say this is a problem on machines with more than 2GB (this other machine has 4GB), but do not offer a fix.
Anyway, later today I switched on the CNC PC and tried Linux again, but system will not get past POST with 'NTLDR is missing' error. Tried lots of things but can't get past this. PC obviously thinks there is a problem with the boot or root directory of the Linux HDD.
Went back to Windows XP and added a PCI parallel port, added the driver, and configured Mach3 to this port. Motor rotated, but still glitched. Glitches are still happening at <900mm/min or so, but not >1500mm/min. This test probably means the built-in parallel port is OK.
So in summary:
Fresh install XP, optimised computer (all drivers updated, standard PC, minimal hardware enabled etc.): this helped and glitches only occur <1500mm/min
Brand new replacement driver system3 board from Roy - glitches
Mach3 using PCI parallel port (Moschip) instead of built in port - glitches
Fresh install on reformatted HDD of Linux and EMC2 - glitches
Linux and EMC2 output to speaker - glitches
This all suggests it is the motherboard (ASUS A7N8X Deluxe Gold), or MB chipset. I would welcome information on successful MB & chipset combinations which work with Mach3 (or EMC2), what are other people using?
Also, been reading about smoothstepper. Since this takes the timing away from the PC, do you think this would help?
I borrowed a function generator from work yesterday and set it up for a square wave TTL output of 8KHz (=1500mm/min on my system). I connected this to pin3 and earth on the driver board and the stepper motor ran smoothly. I then tried different speeds and at low speeds <8KHz the motors glitched. This was the same result as when the PC is connected whereby it glitched at lower speeds. Although this doesn't rule out the PC glitching, it certainly means that the driver board, stepper motors, or power supply are causing part of the problem and need to be resolved before connecting it back to the computer.
The driver board is a brand new replacement since the previous board glitched (but on the X axis only). The power supply is a 33v 10A unit and is the one recommended by Roy at DIY CNC. This power supply provides 33v (I've checked this with a DVM), which goes through a switch and a current display 0-5A. I plan to directly connect the power to the board to elimate the switch and meter. Next is to double check the wiring to the steppers, but I was very careful with this when I wired them up. Might be getting somewhere !!
This morning before work I connected the driver board directly to the power supply, thus eliminating the switch and the current display. Again driving directly from the function generator it still glitched <8KHz (i.e. <1500mm/min).
I then checked the connections to the motor and they are all tight. Checked the coil resistance and they both read about 2.8 ohms. I think I read somewhere that this is OK.
I did notice that if the earth connection from the function generator is not made to the parallel port connector, (i.e. only pin3 square wave input is connected) then the stepper motors will still run. This must be earthing through the mains since the power supply and the function generator both run from the mains.
Therefore since the board can run from 24v - 33v, I'm thinking about running it from 2 small 12v batteries in series, as a test. The function generator can also run from batteries. This might tell me if there is some kind of earth loop problem, although Roy tells me that there should not be. The board is not optically isolated.
Are the other users of the DIYCNC system3 all-in-one board out there? What is your set up like?
Is the glitching at the same frequency? Is there one speed where its worse? I wonder if you're experiencing mid-band resonance where the mechanical and electrical parameters combine to absorb energy to the point where the motor cannot maintain enough torque and therefore loses steps. If you sweep the frequency can you determine a specific point where the glitching is worst? If so, try adding some damping to the motor shaft, e.g. a flywheel or some other angular weighting. Does it still glitch then and has the glitch point moved? If so this would indicate a resonance issue.
The glitching is random, and occurs consistently at any speed lower than 8KHz. There is no bad point, they are all equally glitchy until about 8KHz where it starts to smooth out. Above 8KHz it never glitches.
Note that I'm not actually connected to a cnc machine at the moment to resolve this. There is just the 33v power supply, system3 board, one stepper motor, and the function generator. I've disconnected limits, estops etc. There is no load on the stepper and it is still glitching in the same way as when connected to the machine. By the way it sounds I don't think that this is a resonance issue, more like an electrical spike or interference type problem, but I'm open to try all ideas.
I've got 2off 3Nm motors (Arc Euro) which both glitch in the same way, and have different length wires, and one 1.8Nm motor (DIYCNC) which also glitches in the same way and has different length wires again.
I think the best thing for me to do is try and get a video posted so you can see the set up and hear the results of different speeds. Bare with me, never posted video before!
Thanks for your continued support. Determined to resolve this one . . .
Could i suggest you set it off running and then disconnect your screen plus its power supply. I have a similar issue with a dell and it has bad earthing issues from the screen power supply. The interference from these are notorious, could even be the machines power supply chucking spurious outputs all over the place. Worth a punt?If the nagging gets really bad......Get a bigger shed:naughty:
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