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Can anyone tell me the difference between the Leadshine easy servo drives on the current Leadshine website (ES-M22430 motor with ES-D808 drive) and the similar spec Leadshine combo I see on eBay (60HS30-EC-1000 motor with HBS86 drive)?
Leadshine website - http://www.leadshine.com/productdeta...odel=ES-M22430
eBay - http://www.ebay.com/itm/Leadshine-3N.../191633860794?
I think hey are the same and are not real servo drives as such. It's a stepper motor with closed loop control. Servo motors are usually 3 phase AC driven, or brushed DC motors.
Any idea why the numbers for the parts are different?
In terms of electronics a servo is just a closed loop system, i.e. it has negative feedback, so whether the motors are steppers, DC or AC, brushed or brushless the servo is the feedback component of the system.
Yes the HBS are the early version of the drive and superceded by the ES-D. Pretty much the same drive just with updated software.Quote:
Originally Posted by Tenson
It's a like the EM806 superceded the AM882 which are basicly same electronics with updated software. Slight improvement in smoothness with the EM compared to AM but nothing to get excited about or a pay lot extra for.
Similiar with the ES-D over the HBS thou I do think there as been lot more tweaks and some performance gains compared to the AM/EM range.
The Easy Servo works exactly like a Servo system it just use's a stepper motor so can't spin has fast or has the linear torque like servo motor offers.
In terms of accurecy then servo's resolution is usually higher with higher count encoders but at this lower level with lower grade ballscrews etc then stepper system if sized and tuned correctly will give them a good close run chase on accurecy.!
Now let me just say this which may make you look again at why you want this closed loop or any Servo system for that matter.?
Closed loop just means it will closely follow the path it's be told to follow and if outside of it's set parameters it will fault.
If it strays from the path slightly the electronics will bring it back on path.! . .. BUT the fact still remains it's lost it's way along the path and the damage is done. It's cutaway material that can't be put back.?
Yes when it finishes the Job it won't have lost it's starting position and will go back to exactly the same place. BUT still the fact remains it strayed and cut material it shouldn't have so job is wrong.!
Like saying that's nice straight edge but whats this squigly bit then goes straight again .? Oh the servo got lost for fraction of second but it's ok it remembered where it was and carried on ok.!!! . . . . No the thing is still fubar because it shouldn't have squigle in it.!
Steppers if sized and tuned correctly are perfectly fine. For larger machines or machines that need rapid movement then servos rule but at lower level then steppers are not far behind servos and IME servos offer nothing other than extra power and slightly smoother if tuned correctly. The Closed loop means nothing really, lost is still lost be that a little or lot still means the job is wrong.:cower:
Surely one advantage with closed loop is that if the following error is set to a very small figure, the machine will just stop, and not perform any squiggles, rather than continue after a machining error? G.
Yes geoffrey that is true upto a point and actually how servos work. Lots people don't realise that a servo never actually is truely on the path but instead is continually off course and making tiny tiny course adjustments TRYING to get back on the path. Obviously these adjustments are so small they are not seen in normal use.Quote:
Originally Posted by GEOFFREY
But if you set the parameters too high then you will be open to faults all the time. It's essentially a balance between accurecy and reliabilty.
Also it only faults AFTER it's got lost so still some damage is done, yes with high falling error setting you have limited it but still material you didn't want to lose has gone.!
Now don't get me wrong I'm not saying Servo's are Rubbish or not better than Steppers because they are in several ways. BUT not always in the ways people think and they certainly often put too much focus on the closed loop aspect when in real terms it offers very little over a properly Sized and setup stepper system. Esp at DIY level to Low end industrial use.
One reason I like the idea of servo steppers is because I find the machine sometimes loose steps when pocketing circles. When it goes to the centre it needs to change direction really fast to keep constant velocity. It then loses position slightly. My current solution is to slow the feed part way through the operation as it nears the centre, but at the moment that means manual g-code edit for me. I might also want to machine a whole sheet of detailed nested parts and then finish off with the through cuts so vacuum is maintained until the final cuts, but doing so much work across the sheet and then eventually coming back to the first part I find I may be out of position very slightly.
Well you have under powered steppers or are overtuned if loosing steps or position.(or some mechanical issue) The closed loop system won't help in this case all it will do is fault rather than carry on out of position. Under powered or Overtuned it will be just same closed loop or not and Only way around this is correctly sized steppers or tune motors correctly.Quote:
Originally Posted by Tenson
My machine cuts Ali for 10hrs + with deep DOC at High feeds and still comes exactly back to where it started.
Like today it did a 4hr job with multiple tool changes and straight after a 2.5hr job with 5 tool changes. The last operation was a Finish pass on some pocket walls with smaller dia tool to clear out the corners etc. If I'd lost just few micro steps this would have shown on the pocket floors. And this was after 6.5hrs straight cutting Ali with at times high feed trochoidal toolpaths with 20mm DOC using 8mm cutter, 15 toolchanges and 200+ drilled holes.
So what I'm saying is Closed loop won't help a badly setup or under powered machine.! Or make it anymore accurate than a correctly setup plain vanilla stepper machine.
You say it will 'fault' you mean it will just stop? I thought the whole point was it will get back to position and carry on.
How do you mill circular pockets? Say you want a 30mm pocket and you set a feedrate of 2000mm/min then it will be rather slow at the outside edge but at the center the direction changes will be super fast and the motors can't keep up.
Yes it will stop if it's outside of it's following error parameter. You are loosing steps for a reason not because steppers are inaccurate. That reason will still be there unless you change something like use larger motors or change the tuning setup. Closed loop system will correct for some error before it reaches the following error threshold but still error happend and if while in the cut material will be lost.!Quote:
Originally Posted by Tenson
In your case with only happening on occasional Rapid moves then Closed loop probably will correct the error rather than fault. But thats an awful expensive route when just buying correct size steppers/drives and/or tuning motors correctly will give you exactly same results.
I think part of the matter is my gantry is super heavy. It's probably good for cutting metal but I mostly cut wood and want fast feeds. Actually fast feeds are not a problem, it's fast changes in direction that get it confused, like zig-zag ramping on a tiny detailed pocket.
I'd probably build a whole new machine to go along with the servo motors, it it will not be the only thing I do to try and improve matters.
The question is why can't the motors keep up.? 2000mm/min isn't fast and to be honest it's often acceleration that is the cause of most lost steps.Quote:
Originally Posted by Tenson
The way I do circular pockets is to enter with spiral entry to full depth then interpolate outwards with small stepover. There are no Centre direction changes, at the finish the tool retracts straight up or arcs out if programmed to do so.
So the problem is the wrong size components not steppers are inaccurate. Wrong sized closed loop steppers will still do the same.!!Quote:
Originally Posted by Tenson
Thou It's more likely you have the accleration set to high. Or like often the case both velocity and Accel set too high.
How much does the gantry weigh.? Do you have any pics of the machine.
What drives and how much voltage are you running them with.?
I should point out I mostly use 3mm dia. cutters so this means my direction changes need to be more frequent and smaller. Maybe I'll make a video tomorrow and show you.
Gantry weight I dunno but the whole back is a massive slab of Ali. I guess 60kg.
I doubt it's heavier than My wide all Ali gantry which is 70Kg and I do everything from fine engraving with tiny cutters to Hogging out lumps of ali and don't have any troubles. To be honest if mechanicly sound then I'd put a small wager on that your problem is overtuned motors and not undersized motors.Quote:
Originally Posted by Tenson
Again same would kind of happen with closed loop.? The difference being they would or could depending on how much error fault because would still be loosing position due to being overtuned and following error will be reached.
Also what are you using to provide the pulses.? If parallel port then this could also be some of the problem.
The secret to a sound relaible machine is balance and each component needs to match and work nice together with others in the system. One weak link and the machine will be compromised in some way.!!
Thanks for your replies.
Yes I am using the parallel port of a Sony Vaio Pentium 4 laptop. One thing I notice is that I get an occasional delay when jogging if the wi-fi is active. So I disable it when running.
Motors are 4nm nema 24. One pair for the main gantry (y axis) is driven from 80V and the x axis and z axis are driven from 50V. I thought the lighter weight would need less voltage but I think I probably made a mistake there as I suspect voltage directly affects motor top speed, while current affects torque? In which case my x axis will not be able to reach such a high RPM as the Y axis even though it has less weight to move.
I made a video just now. I must admit there are no problems with it in this case, lol! But I think it shows my point that the direction changes are fast at the center of the circle. This was at 2000mm/min. Circles do seem less round at higher speed and more round at lower speed. In this project I need to cut some 6mm holes and use a 3mm cutter, so the gantry will need to make very small adjustments and fast if the feedrate is high.
Anyway here it is, be gentle!
https://youtu.be/3mmX7BZWEjQ
Ok well for a start you have rotating ballnuts and twin motors so you shouldn't be having any issues with loosing position due to lack of power.Quote:
Originally Posted by Tenson
My Gantry is much heavier than yours and I can cut what you where doing twice has fast you where and still not loose position.
I'm 99% sure your problem is coming from the Laptop and parallel port. For starters Mach3 doesn't suppport Laptop with PP for this very reason of it being unreliable with the pulses coming out of it.
If you where running an external Motion controller you wouldn't be having this problem. To be honest at this speed you probably wouldn't with the PP on a decent PC with good PP. But you certainly won't with External Controller. And you'd still be able to use the Laptop.
I'll lend you a USB Smooth stepper if you want to try one.! . . . . Fry it and you bought it thou.
If your going to buy one then buy Ethernet not USB.
I think that one should use a dedicated PC (I do so) for the motion controller - turned off all visual candy staff, no anti virus, no active power saving and screen saver. In two words - everything which might take processing power or interfere with the time critical pulse generation is turned off. Using Win XP, Mach3 special driver is written for it primarily.
Laptops have built into their hardware means to save power, CPU throttling and so on. On top of that if the CPU (Intel processors) heats to a near critical temperature it has an internal protection by skipping clock cycles to cool themselves down. Had a problem with this and took me a lot of time until I discovered that the CPU cooler has detached from the holder on one side and the CPU was getting hot.
Jazz Thanks so much for the kind offer! Can you link to something that explains what an external motion controller does differently than my current parallel port to break-out-board setup? Looking at the smooth stepper site it basically looks like a USB to parallel port but I assume it must be more than that because such a thing is very cheap and small. Would I still use my break-out-board?
If it means anything I get a 'Time In Int.' on Mach3 sitting at about 4 when idle and jumping between 4 and 11 when running. Does that occasional jump mean something bad?
https://youtu.be/0hVQXoq_eqI
DeagonFly, the laptop is dedicated to CNC and runs WinXP. I chose it because it has a built in parallel port which I assumed would be better than a USB or PCMCIA adaptor.
No can't link but I can explain it.!!Quote:
Originally Posted by Tenson
External Motion controller is a essentially a High spec pulse engine. Basicly it's a parallel port on Super steriods. It just goes between the PC or Laptop and the BOB. You still need the BOB to distribute the signals/wires etc. It just replaces the Parallel port and takes it completly out of the equation.
In practice What it actually does is far more than just replace the PP. It takes all the Hard work of number crunching away from Mach3 just leaving mach to deal with basic tasks and house keeping. So reduces the PC and Mach3's overhead on it. This is why a Lower spec PC or Laptop can be used with External controller without any troubles.
But there's even more to it than that.!! . . .The quality of the pulses are much much higher and clearer. Also the frequency can be set much higher if higher speed are required.
These two factors are what strangle the PP and why you get missed steps when pushing the machine hard like you have been doing. Just fitting an external Motion controller will see you increase performance by minimum 25% and reliablity will be much higher. I've fitted them and seen machines gain 75% in performance using the same drives and voltage.
Connect a Good Motion controller to Good Digital drives and you'll have no troubles with lost steps and with serious performance. Yes over tune and it will like any system but you will be able to tune much higher before being overtuned.!!
Oh and you get 3x Parallel ports worth of I/O for the price.!!
I won't fit anything but Ethernet Motion controllers. To be honest I try to use Cslabs Motion controllers when ever price always has nothing out there touches them for performance to what you get but they are not the cheapest. And the lower Spec isn't ideal for machines with Slave Motors because it doesn't fully support individual switch homing yet.
Think of a Motion controller like a VERY high end Graphics Card and the PP like the Most crappest basic Card on the market.!! The difference is night and day and easy to see and hear.!
I have the ebay version on my machine. The step loss is usually 0-2 after a a bunch of milling.
You can tune the drives via the RS232 adapter cable and their utility.
By default it has an 1000 lines encoder. The driver can actually handle more (4000?), so you could replace the encoder and get (hopefully) more accuracy out of it. I haven't tried that yet.
Edit:
I also haven't done any tuning (508 driver model)
It certainly sounds worthwhile! I do use individual homing switches on the Y-axis so will that be okay with the ethernet easy stepper?
The "machine" does not know that it is using a hybrid stepper /servo. It just treats it as a normal stepper motor.
So however your homing setup is it should not change.
When you are talking about "tandem" homing (two limit switches on one axis) than it depends on the cnc controller you are using.
I have Eding CNC and it supports tandem homing with a provided script.
Thanks for your comments. My last post was actually referring to Jazz's post saying Cslabs Motion controllers don't support individual homing switches for slave axis. So I just want to check the Smooth Stepper does.
I am pretty certain the E smooth stepper does slaved axisQuote:
Originally Posted by Tenson
As an aside, anybody used one of these wireless pendants? http://www.ebay.co.uk/itm/For-CNC-Ma...item4adb63decf
you wont look back using the smooth stepper , i wish i got one from the start , but then again if i did i probably would appreciate what it does
To be honest I find it hard to believe a computer that can process millions of things a second can't pulse the motors accurately and without loosing count. That said, I do believe the feedback from you chaps so I will certainly get one!
Its down to how the software can access the hardware from the software. Where as a motion controller has a direct link to its hardware. I think i read that cslabs stuff uses a fpga controller which are great for this kind of thing.
I guess the parallel port was never really intended for time critical applications.
I ordered the ethernet easy stepper (ESS) from Amadeal last night and they already shipped it! I can't afford any down time on my machine for some weeks so I will have to try it out later on.
I also bought an 80V driver for the X axis that matches the ones on the Y axis. I'm sure it doesn't make much sense to run Y axis on 80V and X axis on 50V as I currently am.
How big a PSU do you guys usually run for Y and X axis? Currently my Y axis is powered from a 500watt toroid with 10,000uF smoothing caps (no SMPS here!). I wonder if it has enough headroom to power the X axis too, or if I need to get an additional PSU. A basic electricity meter shows my machine draws about 250watts for both Y and X together under normal use, but the meter will not show peaks (then again PSU caps should supply peak current draw).
500W will run all the axis no problem.Quote:
Originally Posted by Tenson
Also the ESS works fine with Slaved axis and homing. The install time is minutes with no rewiring required. Just install plug-in and away you go.
You may want to retune the motors for better performance.
you need +5v to the ESS iirc
Yes, that is correct. Unlike the USB you need to feed the ESS
It's a bit late now I've got the ESS, but what do you think of the PoScope Jazz? Looks like more functionality for a lower price.
http://www.poscope.com/PoKeys57CNC
I've got one and it's ok but not has good as the ESS. Also to get the full functiinality you have to use USB rather than Ethernet which is a let down.Quote:
Originally Posted by Tenson
I'd like to say thanks to Jazz for recommending the smooth stepper to me, even though my original post on the subject was about servo motors!
I've got it installed now and cut a few things. The increase in accuracy is quite noticeable, even running at a higher speed. :)
At the same time as installing the ESS I did also upgrade one of my motor drivers so that will no doubt help, but I've gone from rapids at 6m/s to 10m/s and cutting from 4m/s to 6m/s and still seeing higher accuracy.
Worth every penny.
Thanks and your welcome. It's actually quite hard to get across to people the difference an external motion control card makes. It's more than just the speed and more to do with the whole way the machine performs. Has you found out even the sound of the machine changes.Quote:
Originally Posted by Tenson
Being from the MotorCycle Racing background the best way to describe the parallel port is like comparing the sound and performance of clapped out Honda 90 to Honda RC166.!!. . . . Close your eyes and listen to this 50yr old bike.!!!
https://www.youtube.com/watch?v=2KRBbdyWOJM
How many mm/min does that pull?
Revs nearly has fast as your spindle at 20,000Rpm and does in excess of 402,3360mm/min or 150mph +Quote:
Originally Posted by Tenson