Been a while, Any updates?
should be, all the drivers are missing, but nobody has said anything to me about where they went.
Fireball is undergoing surgery right now. I need a lot of bandages. Sit tight.
Interim ERP area lead
Anything you can specifically point to and say “if I had x, I would be able to y?”
I’m not sure yet. I’m weighing my options with the goal of making the electronics simple and reliable since I have no interest in having to fix it frequently.
So I tested the original stepper driver modules that were used. Only one partially worked; the one that had the SLA7078 replaced, but found the hex inverter faulty, which I suppose explains why there was a bag of replacements (but wrong footprint). These units are not cost effective to fix.
Then there are the A4988 modules that are commonly found on arduino cnc carrier boards that some people intended to use. Using those on the steppers found in the fireball is asking for VBTs™ (Very Bad Things) as they would be picometers away from their death. I would only use these in desperation as a last resort.
What I had been reluctant to use, but am siding towards is the old ShopBot driver board which was stowed in the ERP lab. It is a bit overkill and the driver modules are quite nice, but they’re just about ready to go and would be the least amount of hassle to get the mill running. If the makerspace decides to build some cool CNC thingamabob that requires beefy steppers, I’ll be willing to trade these out for something equivalent to what had been originally used in the fireball (~$15 per unit X3). Until then, in these go unless someone can convince me to do otherwise.
IIRC, we spoke to the manufacturer and found that the original driver modules were no longer available as replacement parts.
If $15 x 3 is all we need, you’ve certainly got that left in the budget.
What’s the current drive required for the steppers? I probably have something on hand I could donate to the cause.
Depending on stepper wiring configuration, it’s a little bit above 2 or 3 amps. But as I said, the old ShopBot drivers and board is just collecting dust at the moment (well, not literally anymore - I cleaned that off) so I’d like to put it to use. I hacked a parallel cable to the board so it should be ready to use. The thing that’s to be determined is if the computer’s parallel port can sink enough current to drive the optocouplers on the drivers. If not, then I’ll need a buffered parallel interface board which is cheap at less than $20.
I also tested the original ~40V power supply which I was told was dead, but it looked operational to me - unfortunately not until after I needlessly desoldered the torroidal transformer leads to check the resistance of the windings.
Curt, so if you do have something that can drive that much current, I might take you up on that offer depending on how this works out. That is, unless you can think of something else cool we can use these beefy drivers on!
How many drivers does it need? I do have a couple integrated options that would work, depending on how many drivers you need.
It’s a 3 axis machine.
I have a Leadshine MX3660 that contains 3 stepper drivers, where each can handle up to 60v/6a.
It’s an integrated set of 3 drivers + I/O, so it’s pretty easy to hook up to a PC with a parallel cable.
That’s a nice unit. A brief look at the datasheet makes it appear that the interface circuitry implements some kind of isolation so that it won’t be prone to ground loops (which I suspect is the cause of the original driver failures). If I thought the old ShopBot board was overkill, that one definitely is. I’ll try to use what I currently have, but if that fails then I just might take you up on your generous offer.
OK, if that’s too fancy for you, I think I also have a cheap 3-axis controller based on TB6560 chip, kind of like this one:
I was looking at similar Toshiba ICs the other day. They’re pretty cool parts. I think those would be a more reasonable solution. I’ll let you know if I need them.