Help - Current For Stepper Motor Driver AM882 - ProTuner

Good evening all,

I'm using Leadshine's AM882 drivers on 3N.m steppers and am at the point of tuning them all up using Leadshine's ProTuner Software. What I can't understand is the current/phase is stated at 2.1A but can't for the life of me work out if the amp setting in ProTuner is asking me to put in the value per phase or the total value required by both phases combined. I'm running these drivers/steppers at 68v.

I'd be grateful to find out.

This only came to light this evening as it looks like my machine lost some steps somewhere tonight. I've been running the machine without my new dust boot and everything comes out to within 0.05mm but I added my self made dust boot with fairly rigid bristles (rigid compared to a soft paintbrush) to run a program and it definitely caused some loss of position. I suspect the bristles may be causing the issue but at present my drives are set to 2.1A in ProTuner. If it's a lack of amps going to the motors then I can up the amperage but if 2.1A is the correct value to use then I'll have to make a new softer bristle plate for the dust boot. I should mention that I ran the program 4 times, twice with the dust boot on and had geometric errors in the same places then twice without the dust boot both of these were perfect but I was caked in Trespa dust, which I really hate.

Thanks for reading this I really like to know what the score is with this because I can't stand being next to the machine with a hoover hose trying to catch all the dust/chips flying out.


Here's what I mean as an illustration....

Attachment 29533

There has to be something more than just the stiffness of the bristles involved here. Is the frame of the boot catching on something? You'd have noticed that though. Is the boot adding signifficant weight requiring a reduction in acceleration?
I'm fairly confident in saying that currents are always specified per phase where steppers are concerned.

Cheers for the info Kitwn,

The boot is defo causing the shift, it's repeatedly working fine on this part without it and on other parts without it but with it on it was squashed right down and catching edges, plus if my steppers are 'under amped' by 50% it wouldn't surprise me to fail in the same 2 spots. It'll be easier to re-tune (up the amps) the steppers than it will be to make a new bristle skirt, but only if it's the under-amped issue causing the problem. The boot assembly weighs about 400g so no real weight on the system.

My main concern before looking into the bristle issue is the amps being fed to the steppers. I sense they are too low, it's a dual screw axis on X and a single on the Y both use 5mm pitch screws. Before I changed the "PeakCur(A)" value in ProTuner from 4A to 2A it could do 5mm cuts with a 1/4in 2 fluted cutter, now it struggles and sometimes triggers the stall/estop when doing 3mm passes in Trespa (HPL).

The problem was that the motors were getting almost too hot to touch and I wasn't sure if the PeakCur(A) was too high and would burn the motors out. So I lowered it a while back to 2A but now I noticed some missed steps I'm wondering if it should be set to the 2.1A or the 4.2A.

I get that the currents are always specified per phase on motor specs but what about in ProTuner? Does ProTuner's "PeakCur(A)" refer to the current for each phase or to an individual phase?

Currently I'm set on 2A but am wondering if I should really have set the value in ProTuner to 4.2A, or at least to somewhere closer to 4.2A like 3.8A.

Just for the record I'm running all stepper in series configurations, ie 4 wires.

I'll include some pics of the fusion 360 model for sizing and scale but it's a small 2 part dust boot with about a 4-5mm thick layer of bristles glued into a channel on the underside. The drawings won't show the bristles in situ but it's too cold and late for me to go in and take a pic of the actual dust boot at the minute.

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"Almost too hot to touch" is about right for steppers! Particularly if you also use the "half current when stationary" setting, I wouldn't worry too much.

Current sounds low - I think I run my 3Nm steppers at about 3.something amps on the "crank it up until you can't rest your hand on them then wind it back a bit" basis.

Bit worried that you say you are using a series configuration. For best torque, parallel wiring is advised. As long as your PSU can take it (can supply enough current) parallel beats series hands down.

And if you are generating that much drag with the dust shoe, you need to do something about it! I've made mine adjustable by using a series of 1/2" or so plywood plates with small magnets glued in so I can easily adjust height to suit cutter length, etc. I managed to rip the bristle strip off mine recently due to a little accident and as a quick fix staple-gunned overlapping strips of plastic from an old milk bottle round the edge. Crude but effective! Strips are probably around 1.5" long to give flexibility when going over edges of work and so on.

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I'm using Leadshine's AM882 drivers on 3N.m steppers and am at the point of tuning them all up using Leadshine's ProTuner Software. What I can't understand is the current/phase is stated at 2.1A but can't for the life of me work out if the amp setting in ProTuner is asking me to put in the value per phase or the total value required by both phases combined. I'm running these drivers/steppers at 68v.

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Like Neal has said if they are 8 wire steppers then I would use them in a parallel configuration as you will get more torque.
I run AM882 drive on my router at 3. something A with twin screws and 68V PS. Steppers are happy at 60'C and above.

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Originally Posted by PaulP

Just for the record I'm running all stepper in series configurations, ie 4 wires.

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Ok, this bit is a little confusing.? Are you saying the motors only have 4 wires or it's got 8 wires and your only using 4 of them.?

If it's an 8 wire motor then you have it wired wrong which would explain all your problems, in fact, if I'm correct then I'm surprised it even works.

For series or parallel, you still use all 8 wires but connected in a different order. If it's a 4 wire motor then you don't have the option to wire parallel or series because that is already determined by the factory.
Often 4 wire motors are series-wound but you can get them parallel wound but would need to ask the manufacturer to know for sure.

The problem with Series wound motors is that you need twice the amount of volts to get the same speed/torque as a parallel wound motor. For a Mill, series-wound is a good choice because higher torque is produced at lower RPM but it quickly drops away as the RPM rise which isn't good for a router. So if you do have series-wound motors then it's highly likely you don't have enough volts which is why torque is dropping away as the RPM's rise and your getting missed steps

Like Neale says the best way to wire the coils for a router is in parallel. then you would set the current to 4.2a in protune. When setting current always use the peak value.

Whta voltage are you running and what velocity and Acc do you have them tuned at.?

OK lots of food for thought given here, thanks in advance for this help...

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Originally Posted by Neale

"Almost too hot to touch" is about right for steppers! Particularly if you also use the "half current when stationary" setting, I wouldn't worry too much.
Current sounds low - I think I run my 3Nm steppers at about 3.something amps on the "crank it up until you can't rest your hand on them then wind it back a bit" basis.

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Originally they were set to 4A in ProTuner but I could have fried eggs on them as they were almost too hot to touch. I started to worry a bit which is why I reduced the PeakCur to 2A. At 2A they don't get hot which I thought was better but I now think that might be wrong.

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Originally Posted by Neale

Bit worried that you say you are using a series configuration. For best torque, parallel wiring is advised. As long as your PSU can take it (can supply enough current) parallel beats series hands down.

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I've been debating whether or not to switch to parallel as it seems to be what everyone is doing with their routers. I got lazy doing the electronics as I started to get fed up so ended up setting each motor in series. I was mistaken at the time because for some reason I imagined all 8 wires on the motor had to go all the way back to the driver, ie using an 8 core 1.5mm2 cy cable. Each of my motors has a plug with 4 connections going to their respective A+A-/B+B- socket coming from the driver. To go parallel I assume I solder the respective 'spare' wires together on the motor plug. Is that correct?

As for the PSU it's a Leadshine 68v 500W linear PSU from Zapp. Since my machine has 4 motors in total if I changed the wiring to parallel would I need another PSU as I thought 500w/68v = 7.35A and if 2 motors in parallel are set to 3.5A each then my single PSU stated above would only be supplying enough for 2 motors. I'll get another 68v 500w PSU if needs be but wanted to check before shelling out again.

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Originally Posted by Neale

And if you are generating that much drag with the dust shoe, you need to do something about it! I've made mine adjustable by using a series of 1/2" or so plywood plates with small magnets glued in so I can easily adjust height to suit cutter length, etc. I managed to rip the bristle strip off mine recently due to a little accident and as a quick fix staple-gunned overlapping strips of plastic from an old milk bottle round the edge. Crude but effective! Strips are probably around 1.5" long to give flexibility when going over edges of work and so on.

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I like that milk bottle idea for skirting it defo beats the tedium of gluing bristles into a channel. I did see that video on youtube of some german chap making one but he used a small metal tube squashed at one end to help with the fiddlyness of the bristles. Similarly to the milk bottle idea I was thinking of drawing up and printing some strips on the 3d printer. Maybe 2 layers of 0.2mm with a rim with holes for securing it.

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Originally Posted by Clive S

Like Neal has said if they are 8 wire steppers then I would use them in a parallel configuration as you will get more torque.
I run AM882 drive on my router at 3. something A with twin screws and 68V PS. Steppers are happy at 60'C and above.

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Would you recommend another 68v 500w supply for this setup?

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Originally Posted by JAZZCNC

Ok, this bit is a little confusing.? Are you saying the motors only have 4 wires or it's got 8 wires and your only using 4 of them.?

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The motors have 8 wires but only 4 are in use, the other wires are soldered together in their respective pairs. I'll include a sketch but i think the A+A-/B+B- polarities in the sketch might be different as I can't see the motors at the minute.

Attachment 29540

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Originally Posted by JAZZCNC

If it's an 8 wire motor then you have it wired wrong which would explain all your problems, in fact, if I'm correct then I'm surprised it even works.

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They do work but when I fire up their linear power supply you can hear a very slight whistling sound, it's high pitch and really annoying to be honest, when they drivers get the ENA high signal they switch off and go quiet. These motors were bought from zapp some years ago but I can't find them on zapp now so am unable to confirm the drawing is defo for this motor. The motors are labelled as SYS80STH86 - 3008BF. Do you hear any sounds from your AM882 powered motors when they are idle?

Here's the motor pic and what I think is the closest match to the spec sheet for them, the colours are in Hungarian but i translated them manually and they were the same colours. You can see in the pic that the white/coloured wires are paired together to get what you see in the sketch of the wiring.


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Originally Posted by JAZZCNC

Like Neale says the best way to wire the coils for a router is in parallel. then you would set the current to 4.2a in protune. When setting current always use the peak value.

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So does the PeakCur box in ProTuner refer to the total amperage the driver supplies to each coil or to the motor? If a spec sheet says 2.5A or 4.0A per phase do I double that figure in ProTuner's PeakCur box? This is what I find hard to understand, If Leadshine stated that the figure was for each phase or if it was for each motor in total it would make it much less confusing.

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Originally Posted by JAZZCNC

What voltage are you running and what velocity and Acc do you have them tuned at.?

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I'm running 4x AM882 drivers with a 68v/500W PSU (Leadshine) to 4x SYS80STH86 - 3008BF currently wired in series. As for vel/acc I'm running OK at 6000mm/min with 1200mm/s2 without stalling.


Thanks again chaps, I can see my soldering station coming out again soon but before I do that will I need another 68v linear power supply to deal with the extra amps required for parallel? I read many posts from those that went from series to parallel and have had better results but it was either laziness or amperage concerns that pointed me to wire them in series.

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Quote Originally Posted by Clive S View Post
Like Neal has said if they are 8 wire steppers then I would use them in a parallel configuration as you will get more torque.
I run AM882 drive on my router at 3. something A with twin screws and 68V PS. Steppers are happy at 60'C and above.

Would you recommend another 68v 500w supply for this setup?

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I only have a 500Va toroidal running 68v DC with no problems

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Originally Posted by Clive S

I only have a 500Va toroidal running 68v DC with no problems

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Is that PSU of yours running 4 off 3nm stepper motors from that or 3.

Just to confirm when I read 500VA does that mean theoretically it's capable of delivering 500v at 1A and conversely 1V with 500A? So if a 500va psu is set to output 68v then it can deliver (500/68) 7.35A? I know it's quite a generic question but it half confused me back in the days of education.

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Originally Posted by Clive S

I only have a 500Va toroidal running 68v DC with no problems

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Ditto - although the transformer did go pop one day! But that seems to have been some random internal short as before that time it never even got warm. Those current figures are, to be honest, a bit vague. They don't really correspond with anything very much and in practice the load the drivers and motors put on the power supply is much less than your sums suggest. Hence my comments about motor temperature - for most practical purposes it's as good a guide as any! If you can hold the motor in your hand without it being too hot, then it's no more than 60C and that's fine for a stepper. It's what they do!

Your current/voltage sums are correct - power = volts x amps - but in this case, because the loads are pulses, of varying levels, and don't happen at the same time on all motors, then the average is lower than the sums suggest. In addition, using a linear PSU is a great idea as it is able to cope with short duration peak pulse overloads with ease, as long as the average load stays within spec. Translation - you can safely get away with it! Switch-mode supplies are cheaper, smaller, and lighter but do not like even very short duration overloads and go rapidly into sulk mode.

In your wiring diagram, connect A to C, -A to -C (can't replicate the exact terms in your diagram but I'm sure you can see what I mean), and then A/C to A+ on the driver, -A/-C to A- on the driver. Ditto for B&D. I think you know that you only then need four wires back to the driver.

I did have a strip of draught excluder brush with long bristles for my dust shoe but it was a pain to make - getting the groove right was tricky with the balance between too tight/too loose and bending the strip to fit was just a bit fiddly. My cheap and cheerful solution works at least as well and costs nowt into the bargain! That's an engineering solution...

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Is that PSU of yours running 4 off 3nm stepper motors from that or 3.

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Yes twin screws so 4 steppers.

The toroidal does not give out 68 volts . It is about 50V AC out but when rectified it is around 1.4 higher and becomes DC

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Originally Posted by PaulP

They do work but when I fire up their linear power supply you can hear a very slight whistling sound, it's high pitch and really annoying to be honest, when they drivers get the ENA high signal they switch off and go quiet. These motors were bought from zapp some years ago but I can't find them on zapp now so am unable to confirm the drawing is defo for this motor. The motors are labelled as SYS80STH86 - 3008BF. Do you hear any sounds from your AM882 powered motors when they are idle?

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Ok, I understand the 4 wire ref now I just had to ask to eliminate any chance of any silly misunderstanding because series or parallel you are using 4 wires.

The noise you are hearing is normal and if you haven't done the auto-tuning they will even scream/squeal sometimes. The reason why the motors go quiet when ENAble is set is that the motor output in the drive is disabled.

Your motors are Nema 34 so running them in parallel becomes even more important for a router. Large motors like these have a higher inductance than smaller NEMA 23 motors which means you require more volts to get the same rpm. Torque drops away much sooner up the curve with NEMA 34's so if you have them wired in series this compounds this even more which is why higher volts are needed to get high speeds out of nema34s.

What does bother me and makes me wonder if you have an issue is that while they won't spin fast when wired in series they shouldn't easily stall at lower RPM and no way should a few bristles from a dust shoe cause missed steps.? A series wired NEMA 34 with 68V should rip that dust shoe off the machine and not even know it's done it.!

If you wire the motors in parallel and set the current to 4.2a then with 68Vdc you should expect to get approx 900 to 1100rpm before torque starts to drop away at any significant rate. So if you have a 5mm pitch and are getting 6000mm/min without stalling then your about right, but if you have a 10mm pitch then you should be seeing roughly double that.!

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Originally Posted by PaulP

So does the PeakCur box in ProTuner refer to the total amperage the driver supplies to each coil or to the motor? If a spec sheet says 2.5A or 4.0A per phase do I double that figure in ProTuner's PeakCur box? This is what I find hard to understand, If Leadshine stated that the figure was for each phase or if it was for each motor in total it would make it much less confusing.

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The setting is per phase so just set protune to the spec sheet per phase rating ie: 4.2a





I'm running 4x AM882 drivers with a 68v/500W PSU (Leadshine) to 4x SYS80STH86 - 3008BF currently wired in series. As for vel/acc I'm running OK at 6000mm/min with 1200mm/s2 without stalling.


Thanks again chaps, I can see my soldering station coming out again soon but before I do that will I need another 68v linear power supply to deal with the extra amps required for parallel? I read many posts from those that went from series to parallel and have had better results but it was either laziness or amperage concerns that pointed me to wire them in series.[/QUOTE]

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Originally Posted by Neale

In your wiring diagram, connect A to C, -A to -C (can't replicate the exact terms in your diagram but I'm sure you can see what I mean), and then A/C to A+ on the driver, -A/-C to A- on the driver. Ditto for B&D. I think you know that you only then need four wires back to the driver.

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Neale,
Have another look at this please. My assessment of the drawing with it's 'start of winding' marks would suggest connecting A to -C and -A to C to create an in-phase pair of windings. It seems an odd way to label the wires but I think it's correct and agrees with the standard drawing....

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Originally Posted by Kitwn

Neale,
Have another look at this please. My assessment of the drawing with it's 'start of winding' marks would suggest connecting A to -C and -A to C to create an in-phase pair of windings. It seems an odd way to label the wires but I think it's correct and agrees with the standard drawing....

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Absolutely correct - that was a weird way to label the connections! "Start of coil" ends of windings (marked with star) should go together. I confess that I was looking at the lettering and not the "star" marks - and the lettering does not seem to follow a logical convention. Nothing would have blown up my way - but nothing would have gone round either...

Well spotted!

Thanks for the replies gentlemen,

OK so I've been popping on most of the day for short burst to see what's been said but was unable to reply as I hate using my phone to do any forum posts. I've got back to my laptop to read your replies properly without the mither of a sugar loaded 4 year old.

I ran the program twice more this evening with the dust boot on and got the same results in both Trespa (HPL) and MDF. I nipped up the grub screws on the carriages to see if they were causing any issues ran the programs and had exactly the same deviation in the tool path at the same 2 locations. I'm concluding that there are two issues at play here. One I expected the other I didn't. Firstly it's definitely losing steps in both the x and y, the x was out by 0.23mm and the y was out by 0.18mm, I'm now going to change the wiring to parallel. I'll include the wiring diagram that I translated into english, if someone could confirm I got this right I'll try to get start on doing that tomorrow.

The second issue which is a bigger worry is the flexing on the Z axis. Those bristles are 0.6mm diam. the layer of bristles is about 6-7mm thick and when pressing down and sideways when it's machining it's flexing the Z axis at certain points because of the geometry of the part it was cutting. Bristles are easy to bend if the layer is only 2-3mm thick but 2 rows of a 6-7mm channel was enough to cause the z axis to bend enough to show up in the finished part. The bristles are already 15-20mm past the bottom of the cutter and when it's cutting 20mm deep they are forcing the z axis in 3 different directions, plus sometimes they go into the slot and get caught by the cutter. I'm opting for a single 0.6mm layer of skirt printed out in a strip to be fastened on to the rim. This should eliminate the forces acting on the z axis and contain the dust/chip spray when cutting. It's also much easier to make as it's 3 layers of PLA printed rather than cutting bristles off an old draft excluder and glueing them in vertically. We'll see how that goes. I'll include the sketch of what I mean below.

I didn't know it until tonight but I zero'd the tool to the work piece on both the x and y sides and pushed the neck of the spindle and on the side of the spindle to see what was going on. When I could see light passing between the workpiece and the tool I knew what was up. It was evident in both the x and the y but more so the y. This was disappointing but at least I know what was causing the movement. I'll measure the flex tomorrow/today but I'd estimate it's about 0.3mm in the Y and a little less in X. I should say that this machine is built from 20mm thick Trespa TopLab and uses supported 20mm rails. I was never meant to be a brute of a machine and was only for light materials such as MDF, foam, balsa and any other material used in pattern making. It is pretty tough though it cuts ali pretty nicely but you can't go too deep with it. The gantry design does allow me to lower it for more rigidity but I'm unsure if the flexing is the gantry upright plates or the combination of the Y carriage plate and Z axis assembly. For now I'll be using it for light machining and drilling ops for the MK2 version which will be a totally different design, mainly ali frame and components.

Without the dust boot it does cut MDF, Trespa and Ali to within 0.02mm to 0.04mm so I'm happy about the fact I can make the parts for the next machine on it. Hopefully with the wires in parallel and the printed skirt it should do what it needs to do without any more cock ups.

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Originally Posted by Neale

In your wiring diagram, connect A to C, -A to -C (can't replicate the exact terms in your diagram but I'm sure you can see what I mean), and then A/C to A+ on the driver, -A/-C to A- on the driver. Ditto for B&D. I think you know that you only then need four wires back to the driver.

I did have a strip of draught excluder brush with long bristles for my dust shoe but it was a pain to make - getting the groove right was tricky with the balance between too tight/too loose and bending the strip to fit was just a bit fiddly. My cheap and cheerful solution works at least as well and costs nowt into the bargain! That's an engineering solution...

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My bristles came from a draft excluder but your milk bottle idea made me think of the printed skirt idea, it's hands off and much less tedious to do. As for the wiring I think Kitwn confirmed what I thought when I read that so below is the schematic I'll follow when I rewire my motors...

The printed skirt...

Attachment 29544


The wiring schematic...

Attachment 29545

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Originally Posted by Clive S

Yes twin screws so 4 steppers.

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That's good news as I'm now reassured that there's enough power there.

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Originally Posted by JAZZCNC

The noise you are hearing is normal and if you haven't done the auto-tuning they will even scream/squeal sometimes.

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I did the tuning but wasn't too sure what I was doing or what the Kp and Ki settings were about but found a decent guide in a Leadshine ProTuner manual, out of curiosity I'll try it again before I go parallel. They do squeal a bit which is noticeable when the ENA is not active (as in powered down) but I'll try them again when I'm back on the machine.

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Originally Posted by JAZZCNC

Your motors are Nema 34 so running them in parallel becomes even more important for a router. Large motors like these have a higher inductance than smaller NEMA 23 motors which means you require more volts to get the same rpm. Torque drops away much sooner up the curve with NEMA 34's so if you have them wired in series this compounds this even more which is why higher volts are needed to get high speeds out of nema34s.

What does bother me and makes me wonder if you have an issue is that while they won't spin fast when wired in series they shouldn't easily stall at lower RPM and no way should a few bristles from a dust shoe cause missed steps.? A series wired NEMA 34 with 68V should rip that dust shoe off the machine and not even know it's done it.!

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These motors are NEMA 23, I got them from Zapp a few years back but either they've discontinued them or for some reason, I may be wrong they seem to be listed as NEMA 24. Either way the frame size is defo 23. I might have used the wrong diagram but I wasn't brave enough at the time of buying to get the 34s. I bought all the electronics before I'd designed the machine. I was 10 years younger back then and didn't know exactly what I was doing or getting into.

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Originally Posted by JAZZCNC

If you wire the motors in parallel and set the current to 4.2a then with 68Vdc you should expect to get approx 900 to 1100rpm before torque starts to drop away at any significant rate. So if you have a 5mm pitch and are getting 6000mm/min without stalling then your about right, but if you have a 10mm pitch then you should be seeing roughly double that.!

The setting is per phase so just set protune to the spec sheet per phase rating ie: 4.2a

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As for speeds I think they stalled when rapiding at 7500mm/min so I brought it back down to 6000mm/min which is pretty quick over the size of bed I'm on, it's 915 in x and 515 in Y so not that far to go but I cut MDF at 4-5000mm/min, Trespa at 3000mm/min but shallow cuts only. I knew when buying the ballscrews that I should go with 10mm pitch but corona had started to go mental this time last year and the ballscrews were a bit of a panic purchase. The next machine is having 10's where needed and changeable pulleys for high res work.

As for the setting per phase or for motor total your last comment has really settled my mind. It's been bugging me for a while now with regards to what it meant. Not just on the router but on any stepper system. Anyway I can rest my mind on that one.

OK I'll see what happens with the new skirt tomorrow or Tuesday. Rewiring motor plugs, checking all the fasteners and re-tuning should see me good for a couple of days, I'll then report back.

Thanks again for your responses, I'd be goosed without this forum.

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Originally Posted by PaulP

Thanks again for your responses, I'd be goosed without this forum.

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You're not the only one mate!

Those motors sound very like the ones I bought from Zapp around 10-11 years ago - described as Nema 24 as the case is just a little larger than '23. To reassure you, mine were used on my mk1 router and are now in use on mk2, still running just cool enough to hold (= almost but not quite too hot to hold!)

Mk1 router was MDF, built in a hurry for a special job. All the structural integrity and stability of cold-rolled cow dung. Mk2 is welded steel. I suspect that your mk1 will also lead to a much-improved mk2!

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OK I'll see what happens with the new skirt tomorrow or Tuesday. Rewiring motor plugs, checking all the fasteners and re-tuning should see me good for a couple of days, I'll then report back.

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I would change the motor wiring one motor at a time (obviously the twin screws will have to be done together )

After some time away from the workshop I have finally got some info to report back with.

OK first off one by one I rewired the motors in parallel and set the amps/phase according to the chart given for the motor after that I tuned them all upto remove the resonanse issues. Now they sit idle and are much quieter and I'm now confident that their torque is much more suited to my setup. I tried a cut at 5mm deep in Trespa (HPL) at 3000mm/min without any problems other than the expected noise from the cutter. It didn't skip a step and the final part was as expected.

As for the dust boot I tried the 3d printed skirts in PLA but if you're thinking of replicating it I'd say don't bother, it didn't work. PLA might be stiff but it's still too brittle, maybe another material might work but mine went into the bin. I work in a business that does plastic fabrication so had a decent offcut of clear flexible PVC sheet, the sort you see hanging on doorways. I ended up using that with 8mm strips cut in to act like the bristles would have done. It works well enough but I'd still say bristles would be better but maybe I'll do that at a later date with some 0.15mm paintbrush bristles.

If anyone is interested the machine allegedly pulls just over 3 amps from the socket which is slightly confusing given the amps being pulled by the spindle on the VFD is showing as 3.3a. All devices were powered from the same socket so that might need a bit of investigating. Without the spindle running it shows 2.3a when all 4 motors are running at rapid speeds.

So all issues are now resolved, for now. There will be more to follow no doubt but until they show up I'd like to thank everyone for their help and assistance on the all of the above.

Getting sensible measurements of current with the sort of pulsed waveforms you find around VFDs and stepper motors is not a simple matter. Many meters are designed to work with either fixed DC or purely sinusoidal AC and will give missleading results with anything else. Have a look at the spec for your VFD and exactly what the displayed current is meant to represent. As long as the numbers are in spec for the device and nothing is getting uncomfortably hot I would suggest not loosing too much sleep over the exact readings and how they relate to each other.

Kit

Hi everyone,

I have been struggling for weeks to build a serial cable to connect my AM882 drives to Protuner.
Would anyone provide the actual pinout of their cable? That would be so appreciated!!
I got the pinouts that are floating in diagrams all over the web but none work.

I had made this cable years ago and all was working, but I have lost that cable.
I am using the same PC which is dedicated to Protuner.

Thank you so much in advance.

Assuming that the current tuning is setting the winding current then the supply current from 68v will be much lower as the drivers in effect are switched mode PSUs.