General Controller Board Chat

The sound of a motor being correctly powered is much quieter isn't it.

Xpros are a bad bet and i will suggest again they are removed as a recommendation from all nema 23 builds.

Not asking people for a debate on the subject, though I'm sure I will get one. But a forum where there is a recommendation for bad hardware ends up being a support forum for said hardware, and gets bit boring reading the same issue again and again in all honesty.

And at the end of the day the Xpro is not that shy cost wise to a mosfet setup with the exception that xpros don't work. And by don't I mean, they are not repeatedly accurate and do not produce smooth enough motion to avoid chatter, both due to power incompatibility with nema 23's.

 

I wish I had that information before I got it. It sure was quite expensive. I think I might put that one on ebay and get something else instead. What do you recommend? It needs to be usb as I don't have a printer port.

 

My opposition to the xpro is always met with claims that they do work, what they actually have is something that appears to work but struggles and the results of which will be substandard, but without a standard I suppose they are not to know. Frankly I have no quarrels saying this now the evidence is clear to see yet again and any opposition to my view on this, I will say that having wasted my fair share of money on rubbish cnc gear, I will and have at times been a voice to disapprove poor quality products and will continue to be so as less people are stung.

Afraid rom you must have not read any of my posts on the subject. uc100 with a bog standard Bob and mosfet drivers such as cw5045 won't let you down.

 

Stay away from the Planet CNC USB solutions. They're also crap. In short, there are no cheap or reasonable priced USB solutions available at the moment, there are cheap promises enough though. I've settled for a Gecko G540 and parallel port solution on an old PC. Works like a dream right now. Lots of power and so silent I can hear the PS fan inside the table (the Kress mill is also extremely silent!). I think you can run it all over USB with the addition of an extra BoB. Look at the work of the guy in Florida, Area 51 CNC Parts F-117 CNC Gear Rack Drive System | OpenBuilds.

 

This is getting more and more pricey. I saw the geckos when I was first starting but at around £300 it is not something I can afford atm. What I might consider is getting the cw5045 (per jonny norris suggestion)
and control with an arduino board. I can get 3 of those for around £60 + £30 for the arduino which would let me control through USB and sort me out until I can afford something more meaty. I have a mac which seems to be a big problem. I can get my hands on an old pc and by old I mean XP, pentium 4 early 00's old. Might work though. What do you think?

 

After fooling around with all kinds of stuff for about a year now, I can only tell you to better save up and get good stuff than waste money on crap and ending up buying the Geckos and other reliable equipment. I've thrown away about $S 300 (a bit more) on Planet CNC crap and some cheap drivers. That money is evaporated with little to learn out of it (besides that it is crap!). So, its "Penny Wise, Pound foolish" or bite the bullet. The CW5045 of Jonny are actually from Wantai and you can get those cheaper with them. Order some extra to be sure you have enough working for your setup. Make a package deal with them (drivers, motors, BoB and power supplies) and you can get the whole load for a very competitive price. (I had 5 drivers, 4 motors, 2 BoB, 2 power supplies 36V for about 235 US$). I didn't use them in real life settings yet, but it looks promising and Wantai has not too bad reviews on their stuff.

That PC could work. Strip it completely of anything not essential. That includes networks, wifi, internet, mail, sound etc. Test it with Mach3 for speed, read the manual for how to set it up.

 

Praux I did a bit of research the cw5045 aka m545d is made by a sister company to wantai, so they do infact come from the same place, just not sold as a wantai. Link >

Changzhou Jinsanshi Mechatronics Co. Ltd.

The cw5045 is a little more powerful in spec then the closest wantai driver hense the extra $10 rrp however they are similar and a ox is a ultra light weight setup so the wantai would be more than surfice.

Jss-motor.com actually do some slightly lower spec drivers also that do seem to match the closest wantai one, and it could indeed be that wantai are rebranding these actually it's pretty obvious with the similarities in part numbers. But the cw5045/m545d has not been rebranded by wantai it seems so not quite the same lol confusing as hell I know.

 

€64 a pop, ouch! seems they have priced it at the same price as a 32bit dsp driver, and the nforce mosfets, dont test as well as the chopper type.

sorry mark, another over priced product from planet cnc

 

And there you have it! Working good at a reasonable price. Planet CNC hard- and software doesn't. Period. The question is, how far did you "push" your Planet CNC stuff? Try starting to use it in a bit more pro way and you'll immediately see where I'm pointing at. Working now with Gecko and Mach3, I can't start to describe how huge the difference is.

And please, don't come with the support forum. If you post there, Andrej is catching it before and might answer you in private. 95% of my postings (questions mainly) didn't make it to the forum. Heard that many others had the same experience when encountering serious issues with the hard/software of Planet CNC. A good way to avoid too much negative feedback, but it doesn't change the reality of stuff that doesn't do the job.

Once, in my wild and stupid years, I was a Microsoft Certified System Engineer (sounds like a lot, means actually nothing!). Before I only suspected, but then I knew, Microsoft is the 25% company. Meaning, of all what they promise their software can do, only 25% of that can be achieved. If you start to use any of it in a serious way, it starts crashing and won't stop until you stop trying to do something that it promises but exceeds the 25% threshold.

There are a lot of companies these days copying the Microsoft business model (intended or unintended makes no difference for the customer). Quality has become just another marketing yell, meaningless and belonging to a distant past.

 

Notch-Notch, Wink-Wink, do I need say more?

 

In all fairness Planet cnc are doing something new with that board with its software and firmware opening up a complete new way of calibration with a potentional for many extra options that I've not seen before.

but I can't help but ask why?! It seems they have firmware setting that would otherwise be made in the control software with all sorts of added decay settings and a whole lot of stuff that could improve motion I give it that, but it lacks adaptive pid which takes care of a lot of the issues they are creating work arounds for. And dsp pid does this without getting involved in the mathematics of it all and most importantly of all it adjusts the output current based on motor inductance at any given time so dsp pid will have much better repeatability over the planet cncs constant current driver for that reason alone.

Very confused by this little thing. It has potential, if it had dsp with chopper mosfets instead of the nforce mosfets with its firmware it could be a next generation driver. It may well be that the nature of dsp pid would not allow the customisation they have programmed, so a compromise would be required. But as it is I think they may struggle with that one, do people want hundreds of variables or something that's slightly better and you just plug in and off you go.

 

For hobby work it can be something, but then, it's a bit high priced for that. Tweaking around on cheap stuff as a hobby is one thing, tweaking around on (semi)-pro stuff is another story. For that kind of money one should have a no problem-and-go piece of equipment.

 

yes It does seem orientated towards smooth motion, over accuracy. an alternative to dsp which would suit this approach would be to make it a closed loop stepper servo driver which would allow the settings that dsp would otherwise override.

geckos do seem to be a popular choice though may not be favoured by budget builders with its resonably high retail price over say cncdrives uc100 or uc300 motion controller with there being good quality non motion control type fully isolated bobs out there at around £40 and coupled with uccnc software brings the total to around £140 or £160 with uc300. I have a partner company that uses geckos and I actually find the cncdrive setup to produce slightly smoother motion with the softwares toolpath smoothing though currently doesnt support 4th axis. so a little compromise there, but nether the less a competitive system at around half the cost of the gecko.

 

I paid for my Gecko G540 about US$ 275 (new) and practically received a BoB (included in the drive) and 4 motor drivers for that money. A BoB of good quality does around US$ 50 so that leaves US$ 225 for 4 motor drivers, being US$ 56.25 each. Mach3 is US$ 175 and a parallel cable is US$ 20. Total price for a complete operational set US$ 470, buying a more or less industry standard solution. Mach3 and Gecko have excellent proven support and fora all over the web.

Now we take Planet CNC.

Mark 2/4 board costed me US$113 plus US$79 for the controller license, totalling US$ 192. Proper USB cable another US$ 10 and 4 motor drivers at US$ 26 each. Total price for a complete operational system US$ 306. No industry standard, 1 guy operation from Slovenia. Solution wasn't running smooth at all and extremely slow. After trying for almost 1 year Andrej offered as solution to buy another controller Mk3 because that one was able to run 3D work in a smooth fashion. Bang! another US$ 175 (after a 30% discount of him). So that would bring my price to US$ 481, not even having better drivers and no guarantee things would run smoother with 3 D work.

So conclusion of this; if I would have bought Gecko and Mach3 right from the start, it would have set me back US$ 470, giving smooth runs from the start and not much further tweaking. The Planet CNC option would have set me back US$ 481 to achieve less than the same, lots of tweaking all the way and into the future and still no reliable motor drivers.

Again: One could go for the Planet CNC option if being a true hobbyist and with seas of time to tweak and play around. But having that time and attitude there are lots of cheaper solutions available, just as good or even better and also on USB. But if you want to have your machine to do some serious cutting and carving, stay away from it. Mach3 and Gecko does work surprisingly well and way more reliable.

On an extra note about Planet CNC stuff.
When I wanted to switch the router on and off with the software and using the Planet CNC controller for that, it turned out I needed extra hardware and boards to make that happen. Bringing the cost of ownership even further up. The same solution in Mach3/Gecko G540 costed me not more than a couple of $ for a simple relay and some wire to make it happen. Lots of extras can be added to Mach3/Gecko for very little money, where Planet CNC will keep adding considerable amounts for the same. So, even for some serious playing and tweaking I would 1st go for the Mach3/Gecko solution which in the longer run turns out to be cheaper and more reliable.

Choosing for Mach3/Gecko over Planet CNC is a logical and sound decision. I wish I would have had that information when I started more than a year ago and save me lots of trouble and money. Hope it will help others that starting now or looking for better solutions.

 

This sounds good for a basic nema 23 CNC build:
UNO + CNC SHIELD BRD.V3 + 4PCS DRV8825 DRIVER with HT-SINKS, GRBL DIY 3D printer

 

That's a fair point you make. However, it is often possible to get an old computer and monitor for free or nearly free if you look around a bit. Lots of them lying around with people almost forgetting about them. So I would say, make a provision for it in your budget but try to get a freebie.

 

I think one has to look through the first impression of things being more expensive than others. In this case, more expensive turns out to be cheaper on the longer run with added reliability as a bonus and as an other extra, cheaper ways of extending the functionality of your machine (camera, laser pointer, mist, pressure valve, relays for switching on/off peripheral extra tools etc.). Having a limited hobby budget, my choice would be clear.

 

For a printer it might, I don't think it will work out good with an Ox.

 

Why?

 

It's fine - there is a more current version of the CNC Shield that you can get from the original designer - he also sells on eBay under Protoneer. This is the main site with good info on the board: Arduino CNC Shield – 100% GRBL Compatable | Protoneer.co.nz

Check out some of the latest posts in the Ooznest thread - latest build is using that exact set up. The DRV8825s can drive 2.5a, so probably good for smaller (< 270 oz or so) NEMA 23s. I think a couple of other Ox builds are also using the CNC Shield.

-- John

 

That's my build; to be honest I think the DRV8825's are only borderline capable of driving NEMA 23s. While they can theoretically drive 2.5a, the thermal design of the modules is not good, you'll note I have mine adjusted to 1.5a. They can be made to work, I am after all using them, but it's too easy to stray beyond their limits. Having been into electronics for a long time, I fortunately have the test gear to monitor what's happening when they didn't work well straight out of the box.

The biggest problem is a long (non adjustable) blanking time on the pwm current regulation, that when paired with a low impedance motor like the NEMA 23, makes it difficult for the module to regulate the small currents used in microstepping.

 

That's a great point - drivers do need to be matched appropriately with motors. The data sheet for the DRV8825 recommends heat sinking for 2.5A operation, but I think thats pretty standard with a lot of drivers. The Pololu sticks (and the xPro) are set to use mixed decay mode, which works pretty well in most scenarios. On the xPro, there is a solder jumper that you can use to set fast decay like the mod you did with your drivers. Biggest problem I see is that people tend to use the "default" grbl settings, which are not optimal. Right now I am using 233oz. motors that are rated at 2.5a, and they run very smoothly. Automation Technologies has a beast of a NEMA 23 that is rated at 425oz. and only draws 2.8a. People tend to overpower the Ox design, and use much larger motors than necessary. The DRV8825 and A4988 are used in a lot of smaller CNC designs (Shapeoko, Carvey, Xcarve, original Ox, C-Beam Plate maker, etc.) and are probably the standard for grbl based control. The TinyG uses similarly capable drivers with good results for a lot of designs as well. One of the cool things about the CNC Motor Shield is that you can use it with an Arduino Due running G2 to get a good look at difference in motion control between grbl and TinyG.

All that being said, if I was going to build a larger machine, and use rack and pinion or long screw drives, I would probably head towards a G540 or similar design. Currently starting to experiment with Beaglebone/LinuxCNC/TB6600 drivers.