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Offline ger21

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Re: Nmotion Controller
« Reply #10 on: February 09, 2018, 01:56:31 PM »
Missed steps happen when your machine is perfectly capable of running at 100ipm, and you insist on trying to run it at 150ipm.

With closed loop steppers, rather than missed steps, the drive will fault and stop.

They are still steppers, and don't have any reserve power when you try to push them to fast.
Gerry

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Re: Nmotion Controller
« Reply #11 on: February 09, 2018, 02:49:59 PM »
Hi Gerry,
that's my experience also that the only time steppers lose steps is when I'm pushing beyond their limits and closed loop steppers are similarly beyond their
limits. While they may try to 'catch up' by virtue of the closed loop they will fail to do so because of overload.

I'm of the opinion that OP may have been better placed if he'd spent a little less on the closed loop steppers by the simple expedient of getting ordinary open loop
steppers and paid a little more to get 'a known good' external controller.

Craig
My wife left with my best friend...
     and I miss him!
Re: Nmotion Controller
« Reply #12 on: February 10, 2018, 03:48:30 AM »
Hi Gerry,
you have to admit that the manufacturers of hybrid closed loop stepper products 'troll' their bait very very effectively

Had they been more readily available a the time I was designing my machine and accumulating components for it I may have been one of the
customers they caught.

It has taken some considerable time that I can separate the myth from the reality. I've found also that those whom are inclined to believe the hype
about closed loop steppers are very resistant to logic that says that their belief is fallacious.

Whatever may be said about them one has to admire the persuasive message of the people selling and marketing them.

Craig
My wife left with my best friend...
     and I miss him!

Offline ger21

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Re: Nmotion Controller
« Reply #13 on: February 10, 2018, 06:55:03 AM »
It's amazing that so many people think lost steps are a fact of life when using steppers.
Often it's the same people that buy the cheapest components you can buy.
Or those that fall for the "bigger is better" 1600oz Ebay packages, that are easily outperformed by 400oz steppers in a CNC application.

The new fad everone is going to is the Clearpath servos. Clearpaths are great if you are replacing steppers,as they are drop in replacements. But I see people buying them for new machines. AC servos are in many cases cheaper, and can offer 3x the performance.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Nmotion Controller
« Reply #14 on: February 10, 2018, 07:15:14 AM »
Hi Gerry,

Quote
The new fad everone is going to is the Clearpath servos. Clearpaths are great if you are replacing steppers,as they are drop in replacements. But I see people buying them for new machines. AC servos are in many cases cheaper, and can offer 3x the performance

Yes I've encountered some people who are of the opinion that they are the way to go. They attempt to replace their existing 400oz.in stepper with a Clearpath servo of
97 oz.in. The same people point out that the overload torque is much higher, say 300 oz.in without realizing that that overload can be sustained for a few seconds at best
before the drive faults out. I had another chap whom incorrectly assumed that as the speed reduced the torque from the Clearpath servo increased rather like the
stepper he was replacing. He was rather crestfallen when I explained, with the aid of the speed/torque diagram from the manufacturer that it is not the case.

Servos maintain their torque at high speeds and for their size outperform a stepper at high speed. The same stepper is likely to have a great deal more torque
at slow speed than a servo.

If you select a servo that has the same lowspeed torque as a stepper it will be much larger and way way WAY more expensive.

I will admit that it has taken a while for these realities to filter down and displace the myths. It staggering how effective those myths are as a marketing
tool though.

Craig
My wife left with my best friend...
     and I miss him!

Offline ger21

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Re: Nmotion Controller
« Reply #15 on: February 10, 2018, 07:49:24 AM »
The big issue with most of the Clearpaths, is that they have a max rpm in the ±1000rpm range, where an AC servo will be 3000-5000 rpm. Simple belt reduction gives you 3-5x more power. And AC servos have a flat torque curve, where the Clearpaths are very similar to steppers.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Nmotion Controller
« Reply #16 on: February 10, 2018, 09:57:08 PM »
Hi Gerry,
those Clearpaths are so damned expensive.

Until fairly recently I'd never had a chance to experiment with a 'modern' AC servo. I bought a second hand 1.8kW Allen Bradley and drive for a spindle.
Setting it up and programming the EPROM requires software on your PC. I have been absolutely amazed at the breadth and depth of data in the servo
database, the many different modes of control, the vast array of diagnostic tools for tuning and the list goes on.

I have joked that the only thing this servo can't do is 'make me a cup of coffee', as I am still working through all the setup options its not beyond the realms
of possibility that I will find the coffee making instruction! All in all I am extremely impressed by AC servo technology.

I bought 5 phase Vexta steppers with 10:1 low lash (<2 arc min) planetaries and high voltage Vexta drives for my machine some years ago. Despite being second
hand I paid a very hefty premium for them. They have been great and once I got them tuned in they have never missed a step since, unless I am doing
something really dumb.

Had I known at that time just how capable AC servos are I would have bought those instead and given the somewhat esoteric choice of steppers probably
for similar money. I note that there are some very cost effective AC servo units, albeit low power, from some Chinese manufacturers. I suspect they will do well
in the market, no doubt there will be questions over quality but the prices are such that we can afford them which is not the case with American/European/Japanese
brands.

Craig
My wife left with my best friend...
     and I miss him!
Re: Nmotion Controller
« Reply #17 on: March 09, 2018, 01:48:51 AM »
Hey guys with regards to this nMotion controller, I have finally found my original emails from when I made the purchase last Oct 2017.  I purchased this unit from www.amanmachinery.com.  On their Alibaba page... https://wholesaler.alibaba.com/product-detail/HOT-Sale-MACH3-USB-interface-board_60617319093.html?spm=a2700.icbuShop.94.4.609478f2c6Z4cb check out their use of the Artsoft Logo etc.  This is why I had originally suspected that the device was endorsed by Artsoft.  If not then I stand corrected, but I dont know if there is anything that Artsoft can do about it.  Perhaps by registering a dispute with Alibaba, it might stir things up a bit.

At any rate even after this length of time, they still respond to my messages.  If anyone on the forum needs a copy of the manual for this please message me and I will gladly send them a copy.

The good news is that this device has been reduced a bit in price.  I purchased the 6 axis version last year at $172 US and I think it's now down to about $120.

This device seems to be ok, except that you need the 'usbmove.dll' file, and I am currently waiting for an updated copy from them, in the chance it is newer than what I have.  I do have a copy of that file courtesy of the guys on this forum but I havent installed it yet.  You will need a 24 volt power supply for this device, so I am now waiting on delivery of one from China, hence the hold up - aside from procrastination.

If anyone is looking for closed loop stepper kits - with the drivers, I also have some links to reputable Chinese companies.  These complete kits are appox $90 US - $130 US depending on the motor size.  I have 3 motors now in the process of being hooked up.  I'll try to remember to post back with my results.
Re: Nmotion Controller
« Reply #18 on: March 09, 2018, 02:04:23 AM »
Hi,

Quote
The good news is that this device has been reduced a bit in price.  I purchased the 6 axis version last year at $172 US and I think it's now down to about $120.

Don't know about you but even a $10 board that doesn't work is still expensive. I bought an ESS, paid $180 + shipping but it worked right from the start. When I had problems
the Warp9 Tech guy was right onto it and had me running in a couple of days. Warp9 have released six new Mach4 plugin builds in the eighteen months since.  Money
well spent!

Craig
My wife left with my best friend...
     and I miss him!