Member postings for Steve Pavey

Two things that I find mildly annoying - posts that ask questions but the final solution is never posted, and idiots who can’t admit when they’ve been really stupid.
So in order not to be guilty of both at once, and very red-faced, I think it’s confession time. I have some 4 pin plugs and sockets connecting the steppers back to the control cabinet. I had made such a neat job of these connections - all with heat shrink and numbered labels etc - that I left these alone yesterday when I did the rewiring. It turns out that one of the conductors wasn’t actually soldered onto the terminal, instead the tinned end of the wire had stabbed itself into the plastic and missed the terminal by about half a millimetre. Having melted itself into the plastic it survived my normal tug test, and once covered with heat shrink was out of sight.

A quick test once it was soldered up correctly and it works perfectly.

So, my sincere apologies for wasting everyone’s time - the only silver lining is that it was actually everyone’s responses that forced my brain to eventually work out where the problem might lie - ie that one of the coils wasn’t getting a signal. Actually, another silver lining is that I have at last used the little oscilloscope that I bought as a bit of an impulse purchase a couple of months ago.

Many thanks for everyone’s help.

This is proving to be a bit of a learning curve - I bought a little ds212 oscilloscope a few months ago which I haven’t used, until today that is. I hooked it up to the DIR and +5v terminals on the output of the controller, 5en used the controller keypad to run the X stepper left and right. The DIR signal is absolutely consistent - high in one direction and low in the other, irrespective of which way the stepper decides to turn**. I also looked at the PULSE signal and it displays a reasonably good square wave. I’m afraid I am not good enough with an oscilloscope to actually measure the voltage, but it’s clearly enough to run the stepper.

the other thing I wanted to do was to hook both up at the same time to see what the time relationship of the PUL and DIR signals was, but something didn’t like me doing that as the stepper didn’t run with both channels connected - maybe something to do with the internal resistance of the oscilloscope?? (Way out of my depth here, so I just disconnected it). I tested the DIR output with a multimeter and it was 4.8v which seems ok. I don’t think I would get a meaningful result doing the same on the PUL output.

I have tried setting both leading and trailing edge active in the controller software, without any difference to the random behaviour, so I’m not that much further forward, except I’m a bit happier that the controller is not at fault.

** To me this suggests that the stepper motor coils are not connected correctly, though I have checked many times that the wiring conforms to the supplied datasheet - https://cnc4you.co.uk/resources/Stepper%20Motor%20Nema%2023%2057HS82-3008B%202.2Nm.pdf

The Ruida user manual is at https://variometrum.hu/pdf/rdc6442g.pdf, though it’s a bit light on details related to configuration.

A small bit of progress - in a fit of frustration at my own inability (!) I decided to remove the wiring to the steppers and drivers completely and start from scratch. The result is now three steppers that run smoothly and don’t seem to get hot. I have no idea what I rectified by rewiring which is slightly annoying, but I’m pretty sure it was a daft mistake on my part.

But I still have problems with the X axis motor not knowing which way to turn, and it hasn’t been solved by substituting a different stepper motor. I have checked the jumpers in the driver - actually no jumpers are fitted to the pins, so it is set to Pul/Dir and active on leading edge. I configured the Ruida controller with these same settings.

I did wonder if the datasheet for the motor has incorrect colours described for the 8 wires, although when I substituted a four wire stepper it exhibited the same behaviour. Another possibility might be some sort of electrical interference, although the cable to the this stepper is the only one that is shielded.

John - thanks, I will have a look at the jumpers. I recall seeing a setting on the Ruida setup menu to change from Pul/dir to cw/ccw mode, and also to change from leading to trailing edge. I assume that these controller settings have to match the jumper settings?

I’m still a bit puzzled by the talk of changing the voltage - I can’t see how this is done without changing the power supply (mines a 24v Meanwell model).

Only the Y axis is connected up at the moment (and that’s the one that’s working fine). Being a laser cnc there is very little load on the motors though, even with all the pulleys and toothed belts fitted.

Edited By Steve Pavey on 24/07/2021 20:58:25

John - I’ve just digested your post. I set the current as suggested on the datasheet. Maybe I need to have another go at trying lower current settings. I have also been wondering about the polarity of each of the four windings, and whether the datasheet shows the correct colour codes. I’m not sure how I can test for this.

I’ve had another play about this afternoon. First I removed the Z stepper (the one that was overheating) - I’ll sort it out later.
next to the X axis, and I tried Keith’s suggestion of just wiring one coil from each pair, but it made no difference - still the same vibration on starting and stopping, and still the random choice of direction at each start. I then swopped to a 4 wire Nema17 motor, (same as on the working Y axis) and the vibration problem is still there. Then a swop of the X and Y motor leads, and the problem is transferred from the X to the Y motor, so it looks to me as though the problem lies with the motor driver.
I can’t see the reply now, but yesterday the first response suggested that the DM542 was not the best - maybe the next step is to buy a new driver for the problem axis.

Re the overheating Z motor, there is no provision for adjusting voltage. The dip switch settings adjust the current and the microstepping, except for sw4 as mentioned. Clearly it’s overheating because the holding current is too high, but changing the current setting either results in a motor that doesn’t spin, or doesn’t affect the overheating. Maybe two new drivers are needed.

Martin - I’m pretty sure that I have got sw4 set correctly but I will check to make sure.
Keith - Also worth me checking this again, but I hadn’t thought of just using one set of coils - I’ll try that tomorrow morning. Fortunately it’s connected up with Wago terminals, so very easy to change.

I've spent the last few months putting a laser cnc together and have just got to the stage of testing the stepper motors.

The Y axis (Nema 17, 2 amp) one works perfectly - smooth, quiet and cool - so at least I know I can wire one up correctly.
The Z axis (Nema 23, 3 amp) one is smooth and quiet, but gets pretty hot - too hot to comfortably touch after about ten minutes. If I set the current lower then it doesn't rotate.
The X axis motor (Nema 23, 2.3 amp series, or 4.2 amp parallel) is very noisy, especially when starting and stopping, and it also seems to randomly make its own mind up on which direction it goes in. I have tried every current setting, and, since this one has 8 wires, I have also tried both series and parallel wiring configurations.

The motor drivers are DM542's and the controller is a Ruida 6445G. The testing so far has been with the arrow keys on the controller (not ready for g-code yet, and the laser tube isn't installed).

The Z axis motor is not going to be used much, unlike a cnc router or mill its only used to set the bed height at the start of a job, but it will be sitting there getting hot because of the holding torque, so I'd like to sort it out if possible.
The X axis motor is more of a problem as it will be constantly on the move, so it would be nice if it was reasonably quiet, and important that it moves in the direction its told to!
Any ideas?

Just measured mine and they are a touch over 28mm diameter, so a couple of 1” bars would be perfect.

Yes, Ian’s right, there are multiple ways to connect and configure. This is the first time I’ve heard of an inverter that can use anything other than momentary switches!

If you follow Ian’s example of diagram 5 and macro 10 it might be worth adding that the start button is wired NO and the stop is wired NC

Firstly, to the op, it usually isn’t difficult to find the star point in a three phase motor - the first one I did was a bit daunting, but once you’ve taken the motor apart the worst bit is over.

I’ve got two Huan Yang vfd’s, both from China via eBay. The one on the lathe has been fitted for around five years now, and has always performed perfectly. I have another one on my cnc router running a 2.2kW spindle also works well, though I found out that it is a little susceptible to electrical noise from the controller and had to fit a small capacitor to the analogue speed inputs - total cost about £0.01. I have also found that Huan Yang use an unconventional Modbus standard, which doesn’t affect me at all as I don’t use Modbus.

So yes, I agree with John Fletcher - no reason not to buy a Huan Yang, especially if you just want to run a 3 phase induction motor. And I did actually look at buying something from a U.K. supplier - a 2.2kW model was £230, and apparently comes from Italy, and you can bet it is full of electrical components that come from China.

Looking at the manual, the quick start on page six indicates that you need a latching switch:

”Quick Start – IP20
 Connect a Start / Stop switch between control terminals 1 & 2
o Close the Switch to Start
o Open to Stop”

This seems a bit unusual to me, but I have never used this particular drive.

I use carpet underlay in my (cheap Ikea) drawers.

My Boxford, (when I had it) did much the same. It was fitted with a ½ hp single phase motor and was mothballed for a while. When I finally got round to setting it up it was sluggish to start and ran slowly. It turned out to be old thick grease in the headstock bearings. After stripping it all out and cleaning it ran a lot better, though 1/2hp is really on the border line of inadequate for a Boxford, and it was much better when I fitted a 1hp motor.

Karl - Steve Lawes posted (on page 2, near the top) a link to a Multifix catalogue - I think page 5.jpg has some dimensions which you can compare to your particular model. Failing that, I would imagine that one of the suppliers might help you out - someone has said that the PeWe Guy is very helpful, and I know from experience that emailing Create Tools in China usually gets an answer.

Edited By Steve Pavey on 18/02/2021 21:28:23

I’ve just measured the toolholders for my E set and the pins are 70mm apart, so yours must be the next size up, which is probably the B set.

If you go to this page, select one of the items and click the ‘More’ link it will take you to a drawing. While I can’t find the dimension you mention, there are other dimensions you can use as a guide. I suspect yours is the E size, which has 100mm tool slots, so 80mm between the pins sounds about right. I’ll measure mine later and let you know.

It would help to know the make and model of the vfd in question in case others have the same model and want to compare theirs to see if the same ‘fault’ is present. Having just spent a long time sorting out a small control problem with my own Huanyang vfd, I can confirm that there is a variety of voltages present between various terminals when measured with a DMM. And there is a difference between ground, common and earth terminals.

There should be a valve in the road or pavement outside which you can isolate the supply with.

I have freed off stuck valves before (usually gate valves which are notorious for seizing solid), but only by using the methods you describe - take off the gland nut and squirt plenty of penetrating oil down the shaft, then stick the handle back on and see if you can gently start it moving with some mole grips/water pump pliers or whatever tool you can find. I wouldn’t do this without locating a stop valve further upstream though - if it goes wrong it will ruin your day.