@George_Allen it is so warn here today I decided to play with my pool some. Pools are year round fun, let me tell you.
@Paul_Frederick I have one of the tb6600 chip drivers that I tried to connect to my Z axis today, but I didn’t know how to wire the step/pulse section to the controller board. The labels are different from the other tb6600s. Do you have a photo of how you connected it to the controller? My other tb6600 driver quit in the middle of a job. And, one of the ones on my Y axis has continued to have trouble…very frustrating.
@Paul_Frederick My Chip Drive is an MKS tb6600. All the others are the unbranded type with the black metal covering.
@George_Allen on stepper drives I’ve seen you hook up a logical positive voltage then your step and direction control lines. Now when your control lines go low they become active. This is called sinking logic and it can be somewhat confusing. Because most naturally associate high logic with the active state. I imagine it is done this way to force users to use a more isolated wiring scheme? If it was source or high logic and the constant connection was ground system ground may not be the right potential all of the time to function properly. Glitches could be introduced then. So using the sinking scheme that some kind BS daisy chained ground wiring is automatically disallowed. Which is the kind of nonsense most would try to pull off if they could. But stringing them all together saves me so much wire and trouble Jethro. Mmm hmm Star ground!
I daisy chained the grounds in one stepper motor drive I built once and know what? It didn’t work. It took me a long time to debug that problem too. I couldn’t believe having that one ground strung along was causing all of the problems it did. It was literally the difference of a couple millimeters of wire lead. I was all like no, it couldn’t be. But once I broke that chain and ran a dedicated ground to that one lead it worked. I swear the lead was this — long. Maybe even half that? It still shocks me to this day what a profound difference there was between the two schemes that were electrically equivalent. The same circuit. Except it wasn’t.
@Paul_Frederick the step & pulse wires I have correct,. On my board the top connector is marked ground and not +5v. The other is labeled En (enable) which has been left disconnected. I’m now assuming that what they are calling ground is actually +5v. So, maybe ground here is +5v?
@George_Allen usually step and direction lines are connected to optocouplers on stepper motor drives. If that is the case with your drives then you can measure the current and see which polarity conducts. In the correct polarity you should see a current of between 9-20 milliamps. Just hook it up the “right” way first and measure. If you see nothing then reverse the power and measure. You should use just plus 5V and ground. All an optocoupler is is an LED and a phototransistor packaged together. Your logic lines are connected to the LED. So you’re just powering up an LED. Not being able to see it light up does make it trickier though. But that’s what the man behind the curtain should be in this case. Just an LED in a little box. Which may or may not have a dropping resistor connected to it. You might even be able to use a diode tester on it? But powering it up and reading the current should give what’s going on away. One way you’ll see nothing. That’s the wrong way. The other issue here is setup timing. Every drive has a setup time. The minimum pulse it can read. Too fast a pulse goes by and the drive misses it. Not every drive is as fast on the uptake as others. You configure setup time in your machine controller software. 5000ns is usually a safe slow speed. Then you keep reducing it until you see the drive malfunction and back off to where it works again. Before you do anything you might want to adjust your setup timing speed first. Though long setup times have a negative impact on performance. There’s only so much time so wasting it setting up is a bad thing. Good drives are around 2500ns. To give you a range. Really bad drives might be 10000ns? I know my drives are sensitive to setup time. They won’t go a nanosecond below 5000. They must be union or something.
@Paul_Frederick When I set up the chip driver, I couldn’t make it work. I hooked back up the other drivers and adjusted the DIP switches on the Z axis, and it didn’t stall. A more recent tweak to the speed and acceleration has smoothed the travel further and the sound of the acceleration and decelerations sounds more like what they should be. I have to keep my speed up as too slow of a speed was heating up the bit and burning the wood.
@George_Allen I know I couldn’t leave well enough alone. I’d still want to try to figure out what is going on with your beat drives if they were mine. I have a morbid curiosity at times which causes me to investigate such matters. That is all best pursued off your machine at a test bench though. Which would require you to have some rudimentary gear. Such as a spare power supply and some way of generating step pulses. A spare stepper motor would be needed as well. people into DIY CNC tend to accumulate all of that sort of thing. None of it may be the best but it is still adequate to perform some experiments. I have a short video up on my YouTube channel of me time trialing one of my homebrew stepper drives. In it I am using an astable 555 timer circuit to generate step pulses. So it is fair to say I’ve invested no small amount of time in such pursuits myself. https://www.youtube.com/watch?v=GU2GaSMPxNI
@Paul_Frederick I think I may have most of that, and I think a diagnostic PSU is at the Makerspace. I’ll look into it when I get a chance. Thanks.
@George_Allen fooling around with stuff is where experience comes from. Even if you hook it up and it just blows up you’re bound to learn something. Come to think about it that’s happened to me. I learned a couple things when it did too. One was to not power stuff off mains for the first time at 3 AM. It is pretty embarrassing when something blows up on you at that hour. It is amazing how loud a TO-220 power package is when it blows clean apart. Easy M-80 material. I learned that too. Life lessons can come hot and heavy when you least expect them to.
@Paul_Frederick That is a life lesson! That’s funny. As I see the caption of your YouTube video, I realize that I purchased a set of the chip drivers that you are working with, kinda by mistake. I bought a set (4) of the tb6560 drivers on eBay for $27 before I realized the item stated that they run off motors rated up to 3A, but not for those higher than that. When I tried to cancel the order (5 minutes later) they said it was too late, it had already been shipped! Oh well.
@George_Allen commercial drives made out of TB6560 driver ICs suffer from some inherent problems due to how current sensing works with the chips. Manufacturers took a cop out method of adjusting current on the drives they made. It is a bit boring and complicated to explain. But it is why those drives were generally poor performers for most folks. I studied those chips a lot when I made my drives out of them. Which I actually finished before the commercial drives were on the market. At the time it was the highest performing stepper drives I could make for the cheapest though. Each drive I built cost me $10. I wrote an article about my drives here https://www.instructables.com/id/TB6560-Microstepping-Bipolar-Chopper-Stepper-Motor/
@Paul_Frederick I saw that the current limiting function was cut to 30%. But, I also saw that you could fix that by jumpering two things together.
@George_Allen you have to change out the current sense resistors to get the right current out of a TB6560. On my drives they’re the big white ballast resistors sticking out of them (R5 and R6 on the schematic). The Chinese boards usually have blue power resistors they use. There’s a formula in the datasheet to calculate what value you need for what current and your reference voltage. Using the digital inputs is BS. That was put there for software control of a motor in use not to just adjust the current. Most made TB6560 boards they threw in sense resistors that maxed the boards at 1 amp output no matter how the DIP switch was set. The Chinese you gotta love them. They’re like madcap comedy villains. https://cdn.instructables.com/F94/X50T/GSUSNA34/F94X50TGSUSNA34.LARGE.jpg
