Happy 60th birthday! Have a great one!

 

I was using 48V on the Ox….just before the controller started to smoke. It was running extremely smooth on 1/8 micro stepping and looking at the moves more powerful too.

I think that I fried the controller because the separate power supply for that one (12V) was not connected to earth (AC side) while all DC common are grounded. I assume there must have been some kind of power feedback into that one resulting in an overload of the board, hence the smoking… Which of course is not the fault of the controller but me, not being thoroughly in the works.

I was thinking about using 2x 36V 10A PS's, each one feeding 2 steppers. The ones I have are the previous model of OB Nema 23's, 170 oz-in, max 2.8A, inductance 2.5mH. They would run optimal at 50.6V but I guess the drivers with a max of 50V would probably get fried. At 36V and RMS of 2.03A I should get on average 73 Watt out of them with possible peak of 101 Watt. Hopefully not too much to rip the OX apart.

These are the stepper drivers http://www.wantmotor.com/ProductsView.asp?id=257&pid=82

 

Well guys and gals here is an update of me building my very first cnc machine. I had to go wider for what i'm going to do with it, so now i have to order more parts which they probably won't have. I hope you can see them and give me your thoughts. hehehe. o and motors are on way to !!

 

If any of you are looking for some nice affordable power supplies for your builds, I purchased 4x of each 5v, 12v, 24v and 36v DIN Rail Mount power supplies from this US located company on ebay. They also have 48v versions but I haven't purchased any yet. They were pretty generous and accepted low offers that I didn't expect them to. Then again I was buying quite a few. But they are nice power supplies, no issues with any of them for the past 6 months I've had them. The fact they're DIN Rail Mountable and generally the form factor makes them nice because you can mount them on the backs, sides or inside machines/enclosures fairly easily. I use DIN power supplies and DIN terminal blocks for connections where I can. DIN circuit breakers, fused connections....etc...look around on ebay and amazon and you can find good deals. Each power supply came nicely packaged and I was really impressed with the quality for the money. Yeah there are cheaper alternatives but these are amazingly cheap for what you're getting IMO.

http://www.ebay.com/sch/galco-industrial-electronics/m.html?_nkw=&_armrs=1&_ipg=&_from=

If that link doesn't work try this one or search for the seller/user

http://www.ebay.com/usr/galco-industrial-electronics


Another note, Circuit Specialists is in the US too and have several stepper motor drivers. Most appear to be 32bit DSP based. I have not tried any. Does anyone have any experience with their drivers or this company? I read good reviews on some other forums. They have fairly good prices on stepper motors too. They list their torque ratings in kg-cm so use the torque conversion calculator listed below to see the oz rating or do other conversions.

http://www.circuitspecialists.com/stepper-motor-drivers

http://www.circuitspecialists.com/stepper-motor

http://www.numberfactory.com/nf torque.htm

 

That link to the power supplies is not working.

 

Try the new link? Search for power supply to see all of them

 

Nope, returns nothing!

 

That's strange because I just opened it up on Internet Explorer, which I never use so no login or any info is saved and it loads right up for me. I tested all links before posting.

I posted another link in my first post, directly to the seller.

 

I clicked everywhere, no results. Maybe only for US eBay users?

 

Say's they ship to United States, Canada, United Kingdom, Australia, South Africa, Ireland, Mexico, New Zealand, Singapore, United Arab Emirates, Malaysia and to contact them for other countries.

 

Try using teleport.to to browse from another location. Here is the link it generated for me. There are sites that allow you to browse geo-locked websites. Out of curiosity, where are you located?

http://www.ebay.com.prx.us.teleport...lectronics/m.html?_nkw=&_armrs=1&_ipg=&_from=

 

I don't think you're looking at the right power supplies, here's the ratings for the ones I purchased

5v 4.4amp - Plenty of amperage since 5v is usually logic power

12v 6amp - They have 5amp and 8amp versions

24v 10amp - 10amps can run all the motors of a lot of machines

36v 13.3amp- Again more amps than most people need

They have 48v 10amp versions, which is a lot of power for most applications. You must have only seen the lower amperage versions. Look through their products, search their store for "power supply"

I spent a total of $305 shipped, got them in two days. Here's what I got for that money...again I made them offers and they accepted them for much lower than what they were asking.

4x - 5v 4.4amp
6x - 12v 6amp(didn't have 8amp version at that time)
4x - 24v 10amp
2x - 36v 13.3amp

 

you can also get 12a supplies, on the basis that its not very likely in cnc routing that you demand a high current from all of your drivers at the same time you can actually get away with a slightly lower amperage psu than all your drivers etc rated induction combined.

just be aware if you start adding things like 24 or 48v fans, etc also that a 12a psu is close to 13a single phase current limit of your wall sockets, in the uk at least. so having an alternate mains feed for spindle is essential.

 

The norm here is in the US is 115v @ 15amps, but with the correct hardware you can run 115v @ 20 amp. wall service. It requires 12ga. wire, correctly rated outlets and 20 amp circuit breakers, of course. You don't want to have an electrical fire and the inspectors find 14ga wire and 15 outlets on a 20 amp breaker! They can cause your insurance claim to be canceled.

I discovered the seriousness of the problem when I had a barn burn to the ground. About half of it was used for my woodworking shop and a corner for my photographic darkroom. Since it was Filled with high end cameras and 30 years of my tool addiction, the claim was expensive. The fire inspector pulled every outlet that was still existing apart checking wire size and data plates on the outlets to make sure I'd used all the right stuff. I had and my insurance paid up - but they weren't happy.

 

To run 4x 2.5a stepper motors at 24/36vDC, you only really need about a 6a power supply. The math has been done on some other forums explaining why. I mean it's good to have extra room and if you're running other electronics off the same psu that's another thing. That 2.5a rating on stepper motors is the max rating. Rarely if ever is a stepper motor pulling it's full load and normally only a couple stepper motors will be active at any given time. Unless you're doing some pretty serious work, I think most people need a lot less power than they think. That's also assuming you have a PSU that's putting out it's rated amperage. However, I'm of the mindset that I'd rather have it and not need it, than need it and not have it.

 

No. Watts is amps times volts. AC, DC or pink monkey gas - you don't get free energy and you can't use more than you start with. No 115% unless you are talking about those "gentlemen" "!" conning people on YouTube with "free energy devices" and "Perceptual motion machines" that have half of the machine covered up!

 

Yeah I just re-did some math Coming up with the same amperage.

 

It's exactly the same thing. 120v @ 1 amp = 120watts and 12v @ 1amp = 12 watts. In working with AC in LC circuits you deal with hysteresis losses due to the effect of the magnetic field building and collapsing in the coil, but these are ONLY called losses in the most general form of speech. In reality you can measure and quantify these losses in the heat generated, the magnetic field interactions on other ferrous metal around the coil, etc. But the point is that these are generally accepted factors that are ignored at the levels we are discussing.

If you have 4 steppers that have are described as using 5 amps @ 5v. and you add up the use of all the other goodies in your router and come up with 5 amps @ 5v - you had best use a power supply that will give you 25 amps @ 5v or 2.25 amps @ 10v or 1.125 amps @ 20v. Now, I'm using very even numbers here to show the relationship, and I hope you can see what I'm talking about. If you add up all your electrical power "needs" and use a PS that half that rating just because you won't need that much power all the time, you will not be happy and you might as well order a bigger PS now.

Keep in mind that electrical motors can do funny things and still carry a low amperage rating. In reality a AC motor can require 30% more power at startup than it's rated needs are. This is due to that magnetic field I was talking about not being built up to it's full level and being able to allow more amps to pass than it will when in operation. It's called "inrush current" and causes grief for those not knowing about it. And it is the cause of blown fuses or tripped breakers in circuits that are operated near their maximum capacity.

 

i was going to say, lucky you about the amps but after reading the rest I think, I retract that statement.

 

Yeah, and there we come to what somebody here said not so long ago. That a certain kind of stepper drivers don't deliver the power they should.

When I was measuring and testing my stepper drivers I noticed that I could get maximum about 1.6 ampere out of them (regardless the voltage). As soon I turned them up too high, they shut down. Puzzled I was, but no longer.

The new drivers I ordered from Wantai (due to arrive in about 2 weeks from now) are doing exactly the same! There is something like Peak ampere and RMS. The latter being the average power that the driver delivers (the motor gets). If you set those drivers at Peak 2.84A the RMS is 2.03A. At 2.37A Peak they give RMS 1.69. I guess with the TB6600 drivers the story is most likely not much different. Hence, the lower amps I was reading, since my meter also smoothes the measurements out.

The solution to get more Watts out of your system (and Watt is the measurement of power, not amps) is simply to increase the voltage, of course not exceeding the max voltage the drivers and motors can run on. 2A at 12V gives 24 Watt, at 24V 48 Watt, 36V 72 Watt and at 48V it gives 96 Watt. I believe CNC Cookbook has even some calculator for it.

And there comes another "be careful with the voltage" around the corner. If you put a 48V power supply on your drivers and steppers and that power supply has + and - 10% as a spec it could swing to 48V + 4.8V = 52.8V and that is most of the time more than your drivers can handle (and possibly your motors, too).

Smartly, Wantai advices an input voltage of 45V which will not exceed the 50V spec for the drivers even with a +10% surge.

My steppers have 2.5mH inductance which translates to max voltage input 50.6V. So either tuning up a 36V power supply to the max or tuning down a 48V power supply to around 45V would be the best to do.

 

Maybe build a little spreadsheet or so to have all these calculations made with a couple of input parameters? Might make it easier for those who have trouble getting it all properly together?

 

The frustrating thing is that our standard VOM's won't read RMS. So you are left with using a scope to "see" the power going to the motor, at the motor connectors OR taking it for granted that the manufacturer who built your component says it is going to use. The problem with the latter approach is that you can't know for sure what's going on when you have a problem. Paul's numbers are dead on what I seem to recall from school (about a hundred years ago).

For my money, I pick a PS that can deliver at least 1.5 times as much power (volts times amps) as I need. I'll either have no problem OR finding a failed part is much easier.

 

is that per coil or across both coils?

Could you explain please, little confused as you say you haven't received the wantai drivers yet.

Yes Tb and wantai drivers are both mosfet to have ramped inductuctance, so both output half thier peak current on average, there is then the argument that as each driver has two coils total current would be the same as the peak current on average.

Like you say heat can prevent the TB chips reaching their max current, this sometimes isn't the case with some tb drivers can run at thier max potential without overheating. But still only output half of thier rated current.

My theory is the wantai drivers output half current over two coils totalling the full current, the Tb chips are rated on peak current of both coils totalled.

without getting technical, 4 wantai drivers on a 24v 12a psu powering 3nm 4.5a motors, I found were cooking the motors set at 4.5a and are now turned down to 3.75a.

I only use a 600w 48v psu with its trim pot tuned down to 45 with the wantai drivers on my non ox purely because it also powers 2 45v fans. Otherwise I would be using 24v or 36v. 45 is overkill to be honest.

The video I posted of the effect of current on stepper noise was with the 400w 24v 12a psu.

 

I deleted this post because, as Florian so well showed hereunder, my babbling was one of ignorance and insufficient understanding of the subject.

Whoever read this and thought it made sense, well, it didn't and forget about it!

I sincerely apologize for wasting peoples time.

 

HI

All coils needet to rotate eiter cw or ccw.
There is information out there how they work - so no need for asumptions about "one coil per direction".
Search for "how a stepper works"..... eventhough it is less fun to read -there is more than forums or wikipedia out there.
In short and not to technical:
The current going through the " next" coil makes the rotor "jump" towards this (full step -max power-magnetic fields overlap 100% -thus max force). Then there is north and south (jump to and away) so one can make the rotor jump in between two coils (half step - and of course only 1:1.44 power - sine wave).
Full and Half Step -these are the only "exact modi " for a stepper. All further microstepping is pure interpolation and partial power to each coil - thus there is no real balance (magnetic) and thus no exact position. Also the power gets less and less as the magnetic fields do not exactly match and so the forces only "grip" partially. Think of the rotor swinging betweeen the partial fields.

Btw. the holding power at say 24 and 36 Volts hardly differes.

Example graphhere:

http://de.nanotec.com/produkte/497-st5918-schrittmotor-nema-23/#

It is more pronounced for motors build for less currents but on the ones for max current there is no difference to speak of.

What changes though is is the power at higher rotation (speed).
In reality one hardly needs the holding power of a nema23 for cutting (especially wood) but as the power drops off so fast one could hardly run the machine at any speed. Thus a stepper has to be quite oversiced.
I do cut regualary aluminium up to 20mm on my tiny mill using 1,3NM nema23 . These easylie have enough power at the speeds i cut the alu (23000rpm, 4mm onetooth, about 0,8mm depth, 800mm/min , 800w hf spindle-no ox and on ballscrews).

On top,there are steppers for different volt vs amps (just like your avg. rc-plane/car motors) so buying them on e-bay doesn`t make them comparable with what otheres use. One stepper(motor) preferes more volts but less amps while another likes the opposite.
Use quality motors like the mentioned nanotec in the link above and you get specs to work with.

greets

flo

 

Thanks Florian, that makes sense to me. I did know how they worked, then got confused and apparently forgot about it, but now the knowledge is refreshed!

Question about your Nema's 23; what micro stepping do you use on them for cutting aluminium?

 

wantai have metric micro step settings !! I use 1/10 on the ox with the 400w 24v psu 3nm 4.5a motors and still get the feeling they could pull the ox apart

 

Yeah, so do Leadshines and many others. Question is though, do you need 3NM 4.5A motors? If the motors are too much oversized, it's still of no use. With 48V on my Nema 170 oz-in steppers I also got the feeling they could pull the OX apart. But feelings and mathematics are two different things.

 

No you don't is the answer to that, if I were to jam the axis the pinion will slip which is clear evidence. Motors are only as powerful as the belts are effective.

What I'm saying is, try not get caught up in all the mathematics, you now have the wantai drivers on thier way, as long as you have a 400wpsu 24v 10a or larger you have nothing to worry about. They will run all nema 23's upto 4.6a to the point of cooking if you wanted them to. And the psu will run 4 drivers no problem.

with the 48v psu you will need to be cautious, trim the pot right down and put a multimeter over it, before you wire the drivers up. make sure it's only outputting 45v, if it will go down to 40v use 40v. To be honest if you haven't yet bought the 48v, don't, you won't find any noticeable improvement over 36v, the wantai drivers at 24v already exceeds the effectiveness of the belts with most nema 23's so you don't gain anything.

Running 45v is ruthless really. Especially on an ox which is ultra light weight in the scale of what nema 23's are capable of. You have no allowance for surges so your putting a lot of faith in your psu being stable.

 

Hi,
i use 1/4 step which is still enough power at up to 900-1000 mm/min if cutting wood. Aluminium dedicates slower anyway as i only use a 800w HF spindle. If one uses a 2kw spindle, like most out there, it would be wise to "up" the stepperpower somewhat to make use of the now possible cutting speeds.
Btw my mill still runs on a 12v setup.
At about 1200 i start loosing steps.
But i use Ballscrews- so there is a difference in our setups anyway.

greets

PS: After rereading my post i have the nagging feel that it does sound a little rude. That was not my intention.
I am no native english speaker so pls. forgive me the way i express myself sometimes...

greets

flo