Leadshine AM822 drivers purchased!

[Agathon]

Thanks for all the advice from members of this forum. Finally bought 3 AM822s - http://www.ebay.co.uk/itm/330782929553 - worked out at about £62 each including UPS shipping (one week) and VAT etc.

Very pleased with these except that they're not driving the direct coupled Astrosyn Nema 34 4.8Nm (8 wire series connected) motors above about 500mm/min terribly well. Plenty of torque at low speeds but losing steps at anything over 500mm/min on the X-axis. This is a very high quality Swiss made mill-drill with 4mm pitch ball-screws and coated cast iron dovetail slides - the coordinate table weighs in at around 100kg. The machine specs state that the maximum rapid traverse was 4000 mm/min. The original motors were massive Superior Electric 11A 2.1Nm jobs, so the Astrorsyns should be up to the job.

The motors have a nameplate current of 2.8A. The best match to that on the driver is 2.57A. They do perform better at the next setting (3.29A), but they get too hot to touch (just warm at the lower setting).

I've got the micro-steps set to 32/6400 and Mach3 set to 1600 steps/rev which seems to give reasonable smoothness.

I'm using a 36v 9.6A switch mode power supply to power all three drivers. I suspect that this is the weak point and that 60 or 72v supply would improve higher speed performance.

Any observations welcome.

[Ger21]

Wire them bipolar parallel, with double the current.
And yes, double the voltage.
Also try 1/8 or 1/16 microstepping.

Note that with the Protuner Software, you can set the current to any value you want, and are not limited to the default settings.

[Neale]

I would certainly agree with Gerry - run the drivers at 68-70V, and go to parallel connection. Series connection is fine but is more suited to lower-speed operation. One of the important things about steppers and speed is to look for low inductance. In effect, this is a kind of electrical inertia that slows the rate at which current can build up through the motor windings and as it's current that gives driving torque, current and fast change of current is what you want. Series connection adds the coil inductances together; parallel connection halves the inductance. Much better!

I'm a bit surprised as well that you are using NEMA 34. Given that the original motors were 2Nm or so (were they steppers or servos?) I would have guessed that you could get away with NEMA23 4Nm. Smaller, lower inertia, lower inductance. If the NEMA23 has enough grunt, it will typically give better performance than a NEMA34, which is contrary to expectation but it can be true. Max useful speed is about 900-1000RPM, which would give close to your nominal 4000mm/min with those ballscrews.

I would have slight reservations about a SMPS as well. These can current-limit under peak load conditions, just when you need the current most. A simple linear power supply with big capacitors on the output can cope much better with peak loads in this situation. People use SMPS quite happily, but they need to be well-specced to make sure.

I'm a little confused about your microstep settings. Again, Gerry has given the usual advice - 8 to 16 microsteps is generally a good compromise between resolution, smoothness and torque. So, x8 gives 1600 microsteps/rev. That's 4mm of movement, so Mach3 should be set to 400 steps per mm.

[Agathon]

Many thanks for your replies Gerry and Neale.

I have three Astrosyn motors on the machine two L709s (x&y) with an inductance of 7.7mH and one L259RE (z) with 3.5mH - both physically the same and both with the same torque (2.8 and 4.3 amps respectively). I've used Nema34 motors as that's what the original stepper motors were and these bolt straight on with no modification.

I've changed over to parallel connection and set the driver to 5.86A rms and it's much, much better. Motor heating much lower too.

I had the drivers set to 32 microsteps since this seems to give the best compromise between speed and smoothness. Just to address Neale's point about steps - the feedscrew is 4mm pitch. 200 steps = one rev/4mm travel. At x32 = 6400. 6400/4 = 1600 = 1/4 rev or 1mm travel.

Having it set at 32 microsteps means that I can't go faster than around 1000mm/min which is a bit slow for rapids, but I can live with it. I've just knocked the drivers down to 8 mcstps and set the travel at 1800mm/min and this works well except that the "sensorless stall" protection trips from time to time. I'm guessing this is down to the power supply not being up to it.

Any recommendations for a source of an unregulated power supply?

Finally, I'm keen to use the Protuner software, but my computer doesn't have an RS232 serial port - any advice on how to connect?

Thanks again David

[Ger21]

I bought the Leadshine RS232 cable, and a USB to RS232 adapter cable, and run Protuner on my laptop. It works fine.

With ProTuner, I set my current reduction to 30%, to keep my motors even cooler.

[Agathon]

I bought the Leadshine RS232 cable, and a USB to RS232 adapter cable, and run Protuner on my laptop. It works fine.

With ProTuner, I set my current reduction to 30%, to keep my motors even cooler.

Many thanks Gerry - is there anything special about the Leadshine cable? I wonder if a standard RJ11 plug to USB adapter would work.

[Ger21]

Not sure. I posted the pinout info in another thread. http://www.mycncuk.com/threads/10842-PDMX-126-with-AM822-drivers-and-relays?p=91052#post91052

[Agathon]

Not sure. I posted the pinout info in another thread. http://www.mycncuk.com/threads/10842-PDMX-126-with-AM822-drivers-and-relays?p=91052#post91052

Thanks Gerry, that helps. If I can find the pinouts from the RS232 to USB then I'll knock-up a cable.

Best regards David

[Clive S]

Many thanks Gerry - is there anything special about the Leadshine cable? I wonder if a standard RJ11 plug to USB adapter would work.There is no problem making your own if I remember correctly there is only 4 wires. I am away at this time but I seem to think the pin out was on the website leadshine


Edit https://oceancontrols.com.au/LSK-001.html

[Agathon]

There is no problem making your own if I remember correctly there is only 4 wires. I am away at this time but I seem to think the pin out was on the website leadshine

Thanks Clive, I'll take a look.

BR David

[Clive S]

Thanks Clive, I'll take a look.

BR David

I have added link 3 wires try 2 and 3 both ways

[Agathon]

I have added link 3 wires try 2 and 3 both ways

Thanks again, much appreciated.

[Ger21]

Thanks Gerry, that helps. If I can find the pinouts from the RS232 to USB then I'll knock-up a cable.

Best regards David

A USB to RS232 adapter is not just a wiring adapter. It has a chip and other electronics, and requires a Windows driver. So while you can make your own RS232 to RJ11 cable, you'll still need to purchase a USB to RS232 adapter.

[Agathon]

A USB to RS232 adapter is not just a wiring adapter. It has a chip and other electronics, and requires a Windows driver. So while you can make your own RS232 to RJ11 cable, you'll still need to purchase a USB to RS232 adapter.

Ah, OK - just wasted the last hour knocking up an adapter! Back to the drawing board.

[Clive S]

Ah, OK - just wasted the last hour knocking up an adapter! Back to the drawing board.You need something like this https://www.amazon.co.uk/USB-RS232-Converter-Cable/dp/B00077DJIQ or one from Maplin some of these don't work well with 64 bit systems.
The pin outs on the cable are directed at the DB9 plug not the usb plug.
Also you just might have a serial header on the mother board of the pc. in this case you won't need the adapter.

[Ger21]

I think I'm using this one, which works fine in Windows 10Pro x64.
https://www.amazon.com/C2G-Cables-26886-Serial-Adapter/dp/B000067RVJ/ref=sr_1_38?ie=UTF8&qid=1497715544&sr=8-38&keywords=usb+to+rs232

[Agathon]

I've bought a USB to RS232 converter, installed the software and my machine says it's working as it should. However, when I go to the Leadshine software it won't connect to the port at which the device is located.

I've also noted that in the hardware profile for my machine that 2 serial ports are listed (although they physically don't exist) and they are both working as they should (whatever that means). They are located at COM1 and 2, but the Leadshine software doesn't recognise them either (which seems reasonable since they don't actually exist!!!).

I had to install a couple of parallel ports when I first got this machine and seem to remember it being quite difficult to get the machine to recognise them. However, this was the system itself not recognising the hardware. In the case of the USB/RS232 it does see it and declares it to be working as it should.

I've tried plugging it to different USB sockets which just gives a different location. However the location still not recognised by the Leadshine software.

Unfortunately, I don't have any other RS232 equipped devices to test the port.

Any thoughts?

I can just about find my way round a PC, but having had Macs as my main machines for getting on for 20 years I'm neither impressed with PCs nor adept at overcoming their inadequacies!

[m_c]

COM1&2 are most likely for onboard ports that don't have the required headers connected.

If you go to Device manager, and select the properties for your USB-RS232 adapter, it should show the COM port number somewhere within the properties (I would tell you exactly where, but I'm on my laptop and don't have any adapters to hand to try). Does that COM port show up within the Leadshine software?

If it doesn't you may need to close and re-open the Leadshine software so it refreshed the COM port list.

If it does show, it could be a cable problem.

[Agathon]

The rs232 shows in the device manager list at port 6. Thinking about it, I wonder if it's my home made r11 to rs232 cable. Does a driver have to be connected for the Leadshine software to see the port? - I thought it would see the rs232 even if there was nothing connected, or incorrectly connected.

[m_c]

The COM port should be visible in the Leadshine software, as long as the adapter is plugged in.

Might be worth trying to uninstall the Leadshine software, then re-install it with the adapter plugged in. I've just downloaded the AM software and don't see anyway to refresh the COM port list, so I'm wondering if it maybe populates the list when it's installed.

[Agathon]

The COM port should be visible in the Leadshine software, as long as the adapter is plugged in.

Might be worth trying to uninstall the Leadshine software, then re-install it with the adapter plugged in. I've just downloaded the AM software and don't see anyway to refresh the COM port list, so I'm wondering if it maybe populates the list when it's installed.

Thanks, I'll give it a go.

[Ger21]

Yes, I believe you need the AM882 plugged in and powered up for ProTuner to detect anything.

[Agathon]

Yes, I believe you need the AM882 plugged in and powered up for ProTuner to detect anything.

I've tried everything else. So it's probably down to my lead then.

I've used an old ADSL filter and removed all the components except the RJ11 socket. One thing I did notice on the RJ11 cable that I have is that the connections are reversed from end to end.

I'll try reversing the pins.

[Agathon]

Fixed. Reversed the connections between the RJ11 socket and the R232 and all working.

Thanks to all for the help.

[Agathon]

Drivers now powered with 625VA 70v linear power supply and everything working much better. However, I think I'm coming to the following conclusions:

1. The steppers I have have too high an inductance and/or are not powerful enough to perform as the original Superior Electric steppers did (even though their inductance was much higher and their power (on paper at least) was lower.

2. Steppers are probably not going to perform well enough for an industrial machine like this - they're just not going to be smooth enough for the type of fine work this machine is capable of. The latest version of this machine is fitted with servos and I think I'll eventually have to go down this route. Unfortunately, I know less about servos than I do about steppers.

I shall persevere with the set-up I have at the moment, but I think the steppers will find their way onto my 4th/5th axis project that I have planned.

I am very impressed with the Teknic Clearpath servos which look like very good VFM even with Sterling being so weak. However, this decision will require much further research and consultation on this forum.

Many thanks to all those who've advised so far.

[Clive S]

1. The steppers I have have too high an inductance and/or are not powerful enough to perform as the original Superior Electric steppers did (even though their inductance was much higher and their power (on paper at least) was lower.

2. Steppers are probably not going to perform well enough for an industrial machine like this - they're just not going to be smooth enough for the type of fine work this machine is capable of. The latest version of this machine is fitted with servos and I think I'll eventually have to go down this route. Unfortunately, I know less about servos than I do about steppers.
How about a pic of the machine or a link model etc.

[Agathon]

How about a pic of the machine or a link model etc.

I'll take a couple of snaps today - after a tidy-up!

[Agathon]

A few pics - I'll add a video later (probably start a new thread):

22040220392204122042

[Agathon]

I've started a new thread on this machine:

http://www.mycncuk.com/threads/11067-Fehlmann-Picomax-50-CNC-conversion-refurb

This video shows the X-Y table issues:


https://youtu.be/4fkWZsn4Z_w