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  #91  
Old Fri 09 August 2013, 11:55
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
The voltage that I am suggesting, in my experience, have the drives run cold and the motors below the manufacturer's allowed limits. No "laws of physics" are being broken. No "maximum voltages" are stated by the motor manufacturers. Most people out there are happy with the 20 to 25 times rule. You are alone in pushing your concept of maximum voltage - - - - unless you can prove that Thomas still exists and has found his own PC by now
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  #92  
Old Sat 10 August 2013, 00:59
KenC
Just call me: Ken
 
Klang
Malaysia
Actually, I'd seen a few stepper motor torque curve by the manufacturer having the Voltage way over 30x.... but never seen one with current exceeding their rated current.

Last edited by KenC; Sat 10 August 2013 at 01:10..
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  #93  
Old Sat 10 August 2013, 02:36
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Correct, the manufacturers of stepper motors set two absolute limits: temperature and current. And I would always stay within these limits and recommend everyone else does the same.

The motor manufacturers have never set a limit for the supply voltage to the drives. They know that what comes out of the drive and feeds their motor could be at any voltage . . . . as long as one does not exceed the current and temperature.

One lone drive manufacturer, Geckodrive, has recommended a max drive supply voltage based on the inductance of the motors. It is a useful guide, but experience shows that for a Mechmate application that voltage can be upped by 20% to give better performance (higher loads before losing steps) and still stay within the current and temp. limits set by the motor manufacturers.

It is absolutely important to us to get the highest possible motor load before we loose steps on an expensive job, still without exceeding temps or currents (we have not burnt a motor or person yet, and we have many hours of experience with 4 machines and 4+ staff members).

If Mike would stop spamming us from the sidelines, having not yet built his own CNC, we could realise that way too many hours/days have been spent on this subject, and making potential builders reluctant to take decisions and start building machines. This subject is really a very simple one, not needing much thought to select a voltage. He keeps on throwing in little factoids, which appear plausible, but don't stand scrutiny. Heck, he even posted under another name to support himself! It was at that point that I decided enough is enough and that he is a spammer.

Last edited by Gerald D; Sat 10 August 2013 at 03:12..
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  #94  
Old Sat 10 August 2013, 05:17
KenC
Just call me: Ken
 
Klang
Malaysia
Honestly, I'm looking at optimizing the motor, improving acceleration, inertia matching amongst others. NEMA23 motor (with lower holding torque) + belt reduction configuration is amongts them.
I know there is one MM running with this configuration.
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  #95  
Old Sat 10 August 2013, 07:54
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Well then Ken, the last thing you want is to feel constrained by a mythical voltage limit. Go for it!
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  #96  
Old Sat 10 August 2013, 10:44
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
The personal attacks are overshadowing the data. Does anyone really think that the electrical engineers at Oriental Motor and Mariss Freimanis of Geckodrive are artificially limiting the usefulness of the products that they sell because those electrical engineers just don't understand electricity?

Oriental Motor sells the CSD2140T stepper driver for use with the PK296-03AA stepper motor (which is electrically identical to the PK296A2A-SG.72 motor). Oriental Motor limits voltage with that stepper driver to 24VDC. The spec. page shows a 36VDC setting, but the manual shows that 36VDC is limited to smaller stepper drivers. Why would the Ph.d's at Oriental Motor limit that stepper driver to 24VDC? Do they know the electrical characteristics of the components that they use in the drive? Have they tested that drive to see how it performs?

When I attended training at Oriental Motor's plant in California, the electrical engineers explained how various stepper drivers work and how they differ. Those electrical engineers seemed to know what they were talking about. The manuals that they distributed to those of us who attended that training session seem to follow established rules.

Mariss Freimanis designed the Geckodrive stepper drivers. He sells thousands of stepper drivers every month. He's posted osilloscope screenshots on the geckodrive group (found on Yahoo.com) showing how his newer model stepper drivers work. He's inserted into every manual that he ships with his newer stepper drivers, the equation: SRQT(Inductance) X 32 = Power supply voltage. Why did he do that? Is it possible that he wanted his customers to get the best possible performance from his stepper drivers without damaging the stepper driver or the motor?

Anyone can choose to accept the recommendations published by the manufacturers of the products that they use, or they can choose to ignore those recommendations. Anyone building an electronic control box (which I have done many times for many different projects) is responsible for his own design. Those who are not electrical engineers usually rely on information published by electrical engineers when they select the components that they use in their control box.

When I use the G203v stepper driver, I fully trust Mariss Freimanis's recommendation. He designed that drive. He knows how it works. It knows its limitations. He is responsible to replace that drive if it fails within the warranty period.

When I use the Oriental Motor's CSK motor/drivers, I fully trusted their electrical engineer's recomendations and I followed those recommendations to the letter.

Everyone is free to follow whatever recommendations they choose.
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  #97  
Old Sat 10 August 2013, 12:20
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Yes, I "really think that the electrical engineers at Oriental Motor and Mariss Freimanis of Geckodrive are artificially limiting the usefulness of the products that they sell" ... because they simply cannot anticipate and analyze every conceivable use of their products. So, those fine engineers take a typical mix of applications, model them to extremes, and then make recommendations that will prevent their products from exceeding the limits under those extreme models.

That's a normal good practice, and it provides useful guidelines. However, getting the most effective performance out of a particular set of products in a particular application may require adjusting those recommendations. That is why they are called "recommendations" and not "absolute limits", or even "normal operating limits".

There appears to be a heap of evidence across 100+ MechMates that the best performance is associated with voltages that are a bit higher than the recommended guidelines, and there are no reports of excessive heating. That is good, useful, application specific data that should not be arbitrarily ignored.

If you ask Oriental Motors, they'll tell you that the gearboxes many of us use are not suitable for this application. There is plenty of real world evidence to the contrary. Do I expect OM to change their recommendation? Of course not. Similarly, I find it completely reasonable to apply application specific knowledge to adjusting the voltage recommendations in this case.

Real world data trumps theory, generic recommendations, and test bench mockups. Arguing for primacy of test bench mockups in cases with real world data points is not rational. Establishing a dialogue that re-integrates those real world data points into a better set of bench tests that models and predicts the real world would be helpful, but thus far that hasn't happened.

The real world data people are ignoring the test bench, and the test bench people are ignoring the real world, and the flame war goes round and round.
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  #98  
Old Sat 10 August 2013, 13:07
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Brad,

You've made a very good point.

What voltage would you suggest for someone using a Leadshine stepper driver and a non-Orientral Motor stepper motor? Many people are not using Geckodrive stepper drivers. Many are not using Oriental Motor stepper motors. Would their system be safe if they set the voltage to 25VDC or 35VDC or 45VDC? How high could they go before encountering problems? Could it safely be assumed that the data sheet on their stepper motor derated that motor's current capacity by 33% (as is the PK296-03AA motor when it is used with the PK296A2A-SG7.2 package)?

If they asked the question, I would assume that they didn't have the experience to know WHY some people had run the PK296A2A-SG7.2 at voltages higher that expected without burning up the motor or the stepper driver.

That's why I will always recommend that those who are just being to use stepper motors and stepper motor controllers stay within the parameters set by the manufacturer. (That's exactly why I told that poster that he should contact Leadshine for their voltage recommendation.)

By the way, do you know why the PK296A2A-SG7.2 motor is rated at 3A and not at 4.5A? (It's so the gearbox won't break prematurely from the greater torque produced if that motor were run at 4.5A.)
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  #99  
Old Sat 10 August 2013, 16:11
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Sigh. Unfortunately, that response can most easily be interpreted as a classic internet troll. Surprising, given the earlier assertion that "personal attacks are overshadowing the data".

I wouldn't answer "a Leadshine stepper driver and a non-Orientral Motor stepper motor" because it isn't a specific set of devices and specifications and cannot be answered. I routinely ignore unanswerable questions.

I am very aware of the exact characteristics of the PK296A2A-SG7.2 Note that I subsequently raised the voltage to 48V by custom winding a new secondary.
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  #100  
Old Sat 10 August 2013, 16:59
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Brad,

If you think that I'm a troll, please contact Mike (Metalhead) and complain. I've told him that if he asked me to leave the forum that I would honor his request. His response was both kind and respectful.

May I suggest you re-read post #58 on this thread that asked the question that I asked you. Fox quoted part of a post that specified using 20% higher voltage than the Gecko formula gave. He asked about using a 86HS9801 motor and a LEADSHINE AM882 driver with the motor wired bipolar parrallel. His specific question was whether it was safe to apply the 20% overvoltage to that motor and driver.

I've had direct contact with Fox on other matters and have always tried to answer his questions as accurately as possible. I've tried to treat him as someone who was fairly new to stepper motors and as someone who deserved a respectful answer. Because I have never used a Leadshine stepper driver, I referred him to Leadshine. I have used a 86HS9801 motor that Mike (Metalhead) sent to me to test; however, I used a G203v stepper driver to test that motor. Just as I stated in a previous example, assuming that one stepper driver has the same characteristics as another brand of stepper driver would be an improper assumption. If I assumed that Oriental Motor's CSD2140T stepper driver had the same characteristics as the Geckodrive G203v stepper driver, I would have destroyed the CSD2140T stepper driver. I made no assumptions when I answered Fox.
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  #101  
Old Sun 11 August 2013, 00:33
KenC
Just call me: Ken
 
Klang
Malaysia
Big G,
I'll in the process, just need more time learning, sieve scientific facts from snake oil voodoo before I start on refining the engineering calculations. My gut feeling is NEMA 23 may be a surgical solution...

Mike,
Electro-mechanical characteristics of the motor isn't all the factors for a linear motion system, even the height of motor mount actually get into the considerations in reality.
You are institutionalizing component selection with electrical characteristics alone.
Honestly, V rating of the motor is limited by the insulating material of the motor coil & lead wires, which are easily 400~500V, any motor re-winder will tell you that with confidence. The physical limitation is the current through the coil wires. Smaller the coil diameter, lesser the I rating, but fat wires can only allow less coil turn of the winding which will reduce the magnet inducing capability which means lower torque which means lower power.

Motors are motors, no rocket science. Today, its common sense that opposing poles of magnet repels, everyone know excessive heat will melt copper, keep the heat at bay & motors will run for a long long time.

Oriental motor don't make their own drivers, Gecko never produce motors. both their data will surely be bias to protect their own interests. Whereas Chinese supplies such as Leadshine, Wantai among others manufactures both, I tend to trust their data more (when they are available).

Stepper motor & drivers ain't rocket science, they are just don't get as much glamorous publicity as smartphone. Don't turn CNC into another Audio snake oil. please.
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  #102  
Old Sun 11 August 2013, 06:00
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
Ok - look - Can you all quit picking at each other please.

We have established we have differing opinions on this subject.

I actually like that fact. It shows our folks building machines that MANY options are available when it comes to power and drive options.

Nothing here is cast in stone when it comes to P=I*E .

You will get power or smoke - your risk, your call.

I have said this before , you can live on the edge and take the chance to smoke your drives, or you can be conservative and stay in specs, or you can be in the middle ... your call your hardware.

Just remember , all electronics run on smoke. How do I know this? Let the smoke out and see if they still work !!

KenC - I would love to see someone push a NEMA 23 belt drive setup to see if it can handle life in a MechMate. I know someone has done it here before, but having a few out there would give us more options to fight about !!!

Are you building a Plasma cutter? With no drag and as well as the MechMate is balanced, I bet NEMA 23 will work fine. I would still go 3:1 or 4:1 belt reduction for power though.
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  #103  
Old Sun 11 August 2013, 20:05
KenC
Just call me: Ken
 
Klang
Malaysia
Mike,
Yes, I am designing a MM inspired plasma table, the X is V-rail on rail, but the gantry will be a single beam Aluminum Extrusion, with fully constrained V-wheel on rail. R&P on all axis of course. I reckon W-wheel on V-rail + R&P is the only configuration which will survive Plasma cutting working environment with minimum maintenance.

I ran into a dead lock in motor choice.

From torque/speed curve, NEMA 23 when coupled with 2:1 belt reduction is suitable, but will draw a lot more current ( above 6A) which will end up with fatter CY cable, tranny, capacitor & parts count... and the cost along with it....
Nema34 direct will guarantee more than enough torque for the job, BUT Plasma doesn't need the extra resolution; I'm lazy & stingy, lower the parts count the better...

BUT NEMA23 with belt reduction looks soooo coool.....

Just can't make up my mind...

Last edited by KenC; Sun 11 August 2013 at 20:12..
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  #104  
Old Tue 13 August 2013, 09:21
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
I will donate four used 23-size Oriental Motor PK268-02A motors to anyone who wants to build a 3:1 to 7.2:1 belt-drive if you pay the shipping costs. The motors are in excellent condition, but they were used in Kodak 5-S printers to advance the paper. I would expect that the motors have years of life left, but they are used, so there is no guarantee of any kind. New PK268-02A motors from Oriental Motor cost $99 each.

Because those motors have a smaller shaft than the larger PK29x motors, the PK268 can be used with a pulley as small as 10-tooth. You would need to use some "pinch" rollers near the motor to "wrap" the pulley on the motor so that at least three teeth of the pulley would be in contact with the belt.

The PK268-02A motor has six-leads, is rated 1.4A when wired half-coil and has 190 oz*in holding torque. With a 5:1 transmission, it would produce 950 oz*in torque. With a 7.2:1 transmission, it would produce 1,368 oz*in of torque. It has 3.2mH inductance when wired half-coil and draws up to 1.4A of current. I've used it with a 50VDC power supply and a G203v stepper driver. I've also used it at 48VDC with the G540 stepper driver. It runs very smoothly with either driver. Temperature is in the 50-degree C range when I "torture" the motor by using it at maximum load and short moves.

If I were building a machine with the PK268 size motors and used Oriental Motor as the manufactuer, I would use their PK268-E2.0A motors because they are 8-lead motors, meaning that they could be wired bipolar parallel. The PK268-E2.0A motor produces 240 oz*in torque and draws up to 2.8A of current, so it would run much hotter than the PK268-02A motor when connected to the same power supply.

Another choice for motors would be Geckodrive. Mariss sells some excellent 23-size motors. He has one that is rated at 400 oz*in for $59. It has 2.6mH inductance and draws up to 5A of current. Because of the current, it cannot be used with the G540 unless the current is limited to 3A or less, which means that it would produce less torque. Geckodrive sells a smaller 23-size motor that matches the G540 perfectly. It produces 240 oz*in of holding torque. I have not used any of Mariss's motors, but I trust him and his products.

If you're designing a MechMate that would use 23-size motors, email me. I can send you a parts list from McMaster-Carr that would list the XL pulleys and the "pinch" rollers that I would use. (I have built a 7.2:1 belt-drive transmission that used one of those motors and "pinch" rollers to keep the belt in contact with the small pulley. It worked so well that I reconsidered the need to use the larger 34-size motors; however, I no longer have a vertical mill, so I can't build the mounting plates.)

The only two conditions that I have is that you actually build the transmissions and that you report the results on the forum so that others will benefit from your effort.

Last edited by Richards; Tue 13 August 2013 at 09:24..
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  #105  
Old Sat 01 February 2014, 02:57
isladelobos
Just call me: Ros
 
Canary Islands
Spain
Send a message via MSN to isladelobos Send a message via Yahoo to isladelobos
About this discussion:

I go to change the power supply the next days, my actual is one 300VA 42VDC for one 1200VA 63VDC.

I do it for the manufacturer's recommendation, in this case Leadshine. (My drivers)

If we see his catalogue, (motors,drivers, controllers and power supply), can see his toroidal power supply voltages: (36VDC and 68VDC) 36VDC for his Nema 23 and below and 68VDC for his nema 34.
And some of his drivers have a current curve from 20VDC to 68VDC. In his peak this drivers support to 80VDC.

So, in this case, the recommended toroidal power supply for 20VDC to 68VDC drivers, is one 68VDC toroidal power supply, and this drivers are for his Nema 34 motors.

Ok but this is not all, his bigger power supply, 500W is recommended for supply from 1 to 3 motors, when our mechmates have 4 motors or more.

Last edited by isladelobos; Sat 01 February 2014 at 03:05..
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  #106  
Old Mon 03 February 2014, 10:45
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Ros,

I'm not sure what the question is, but perhaps I can suggest a methodology that might help you find an answer.

You'll need some tools on your test bench. You'll need a voltmeter, an oscilloscope, an infrared thermometer and a Variac. You probably have a voltmeter. You can probably borrow or rent an oscilloscope and an infrared thermometer, but you might have trouble finding a Variac. A "Variac" is a variable AC transformer. It is placed in series BEFORE the toroidal transformer so that you can vary the voltage from 0% to 140%.

On my test bench I have a 25-50VAC toroidal transformer. I can wire it to produce 25VAC or 50VAC, depending on the expected voltage desired. Normal DC output is 35VDC when it is wired 25VAC and normal DC output is 70VDC when it is wired 50VAC. The Variac gives me a range of 0VDC to about 50VDC when the toroidal is wired 25VAC and up to 100VDC when wired 50VAC. Of course the drivers that I normally use are limited to 80VDC, so I always keep the output voltage from the toroidal to 80VDC or less.

All of the stepper drivers that I have used can work at 25VDC, so I set the Variac to produce 25VDC and then run some tests which consists of running the motor in both directions at various speeds with no load on the shaft. At this point, all I want to do is to verify that I have control of the system. After I am certain that the motors turn properly, I let them run at about 750 RPM for about 10 minutes at about 25VDC. Doing that lets the motors warm up. During that warmup period, I read the temperature. Usually the motors stay at 40-degree C or less when they have no load and are driven by about 25VDC. If no heating occurs, then I load the motors by connecting their shafts to something that represents the expected load. Often, they won't run at 750 RPM when under load when driven by 25VDC, so I slowly increase the voltage until the motors run at the desired RPM. If the temperature stays at 60-degrees C or lower, I run some extensive start/stop small movement tests which mimic 3-D cutting. Short moves with little or no "rest time" between moves tend to heat up motors quickly. I always monitor the temperature. Many motors can handle 80-degress C above ambient with 100-degrees C stated as the maximum permissible voltage. I don't like motors to run that hot. At 80-degrees C, you're going to get a serious burn if you grab a motor.

During the tests, I use the oscilloscope to watch the "ripple". A power supply that needs more capacitors will have more than 5% AC ripple. I add capacitors in parallel until the ripple at the load required by all motors is 5% or less. I use the DC voltmeter to monitor the DC voltage of the power supply. A properly sized power supply will NOT droop. It will hold the output voltage under load. There may be slight variations, but if the voltage consistently falls when more motors are turned on, it means than you need a transformer with a higher VA rating.

When I use GECKO stepper drivers and Oriental Motor stepper motors, I've found that the formula published by Geckodrive to find the maximum working voltage is safe to use. It allows the motors to get to about 80-degrees C when they are at speed and under load. That is considered safe by Oriental Motor for the insulation that they use in their motors. I don't know what other manufacturers publish about their motors.

When you've run the tests and logged the data, you'll know how YOUR motors work with YOUR stepper drivers using YOUR power supply, YOUR speeds and YOUR loads. If the temperature is near maximum, I would suggest that you lower the voltage. There will be times when your cutters will be dull or when the material will be harder to cut. Dull cutters or denser material can cause the motors to draw higher current. Drawing higher current increases the heat.

It's necessary to keep in mind that Geckodrive sells the majority of its products to non-CNC users. Stepper motors are used in industry to position parts and pieces repeatedly and reliably. In those circumstances, the motors are run under repeatable conditions where temperature can easily be monitored, and once monitored, the operator can rely on the fact that the temperature will always be very close to that reading because he has complete control of his system. CNC machines require varying loads and varying speeds. I choose to be conservative because I've seen the havoc that can occur when the "unknowns" all pile up at the same time.
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  #107  
Old Mon 03 February 2014, 12:36
KenC
Just call me: Ken
 
Klang
Malaysia
Hi Ros, you can set your max current output to the stepper motors by playing with the dip switches on your Leadshine drivers, just set the current to what your motor specs says & you won't fry anything.
Give it a go, I designed mine for 68Vdc but it came out a little lower which I consider a good thing, with unregulated power a few +/- volt variation is natural thing.
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  #108  
Old Tue 04 February 2014, 17:06
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Let's be careful about recommending things. As far as I have found, Ros did not specify which motors he wants to use. Maybe that information is on another thread, but I didn't see it in his February 1, 2014 post. Some of the motors that I use can be used with 68VDC; most cannot. Some reach 80-degrees C at half that voltage when running 3-D type moves if they're wired bipolar-parallel. That same motor might just get warm to the touch if wired bipolar-series.

Is increasing voltage and then reducing current better than reducing current and increasing voltage? Both are interrelated. Current X Voltage = Watts and Watts = Heat. For instance, an LED drawing 20mA that drops 2V across its junction, would only cause a 150 ohm resistor to produce 0.06W of heat when used with a 5VDC supply, but that same LED, drawing that same amount of current would cause a 1,300 ohm resistor to produce 0.92W of heat when used with a 48VDC power supply. Both setups would cause the LED to glow at the same brightness. To use the same wattage resistor with the 48VDC power supply would require a resistance of about 35,000 ohms. You'd have to hire a bat to tell you whether the LED was lit or not.

Stepper drivers are versatile. They can often be used with more than a single size motor by varying the voltage and/or current, but there is a very definite relationship between voltage, current, how the motor is wired and how the motor is used when you're trying to build a safe and reliable controller.
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  #109  
Old Thu 04 September 2014, 11:36
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
This thread subscribes to several approaches for choosing power supplies. Make sure you review the entire thread and understand the approaches to choosing your power supply. Many combos have been used and tested, so read the build threads to help you decide on your approach.
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  #110  
Old Mon 15 June 2015, 23:39
Bazza
Just call me: Bazza
 
South West Rocks
Australia
Hi People
I knocked up a spreadsheet to learn more about Stepper motor wiring configurations so I could match up corresponding Toroidal Power supplies

From Richards post #17 "Calculate the Voltage and VA size of the DC power supply for stepper motors/geckos", I borrowed the use of 80 (v). (I think its been used to match the maximum stepper driver voltage??)
My spreadsheet allows the following options:
4 wiring Configurations, U, H, S and P
6 models of frequently used 34 series stepper motors
1-9 motors (for the hell of it)
Some sample results are (assuming 4 motors being used):

KL34H280-45-8A wired (S), 719VA delivering 56.6VAC @ 8.4 amps
34HS9801 wired (U), 733VA, 45.8VAC @ 10.56 amps
PK296-F4.5A wired (P), 705VA, 27.7VAC @16.8amps
PK299-01AA wired (U), 214VA, 26.8VAC @ 5.28 amps
KL34H260-60-4A wired (H), 500VA, 29.5VAC @ 11.2 amps


Do the numbers look right?
Can I use a better method to get Maximum Voltage or is Richards method a goer?
If the numbers are right Iím happy to offer it to the forum
Cheers
Bazza
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  #111  
Old Tue 16 June 2015, 07:51
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Yes, 80 VDC matches the max stepper driver voltage of the Geckos, and many others. Of course, you should use whatever the max voltage is on the driver you choose.

Using data from http://www.automationtechnologiesinc...kl34h280-45-8a or http://www.kelinginc.net/KL34H280-45-8A.pdf that says 4.5a / 2.2 mH (U), 6.3a / 2.2 mH (P), 3.2a / 8.8 mH (S):

KL34H280-45-8A (S) Inductance of 8.8 mH. 32 x √8.8 = 94 Volts (Yuck! Forget that!)

KL34H280-45-8A (U,P, or H) Inductance of 2.2 mH. 32 x √2.2 * 1.2 = 57 Volts (DC)
57 VDC / √2 = 40 VAC
So U or H = 40v * 4.5a * 4 motors * 2/3 = 600VA
and P = 40v * 6.3a * 4 motors * 2/3 = 672VA

I didn't check any of the other examples.

(32 x √mH is the Maris Freimanis formula, 1.2 is 20% more as determined by collective experiences of MM builders, and 2/3 accounts for not all motors demanding full power simultaneously, also determined by collective experience. See post #1).

Last edited by bradm; Tue 16 June 2015 at 07:53.. Reason: Add second url.
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  #112  
Old Tue 16 June 2015, 18:27
Bazza
Just call me: Bazza
 
South West Rocks
Australia
Hi Brad
I got rid of the 80v Driver bench mark and added 120% (already have the rest in my equation) to get my new VAC, however my value for KL34H280-45-8A (U) comes in @ 480VA ?

The motor I'm leaning toward is the MotionKing 34HS9801
I want to wire them bipolar parallel and incorporate a 3:1 belt drive running a 30T Pinion
My spreadsheet with the modified inputs give (P) 829VA, 55VAC @10.6 amps

From this Antek's PS-8N56 - 800W 56V Power Supply looks like a close match (but out of stock)
Thanks for your help
Bazza
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  #113  
Old Tue 16 June 2015, 19:04
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
34HS9801 running with 63VDC work for me reliably at 1000 rpm driving a ballscrew on one machine.

34HS9802 running on 48VDC with AM882 spin at 1800 rpm until they loose torque

don't know where down the road 32 x √inductance became add 20% ? Lowering the current if over heating will derate the holding torque of a stepper while voltage only affects maximum rpm as the voltage on the drives input does not applies to the motors.

While there might be some use for upping the voltage don't know how could that possibly be useful to a mechmate already running at 1000 ipm in rapid and cutting up to 400ipm (25 m/min and 10 m/min) Improving the feedrates to near 2000 ipm for test on my mechmate was due to AM882 drives and using a Smoothstepper which eliminates fluctuations in feedrate which cause a stepper stall.

Also someone mentioned that current is proportional to load which can't be true for a stepper motor using bipolar drive which is a constant current device and knows nothing about load applied to it and can't be described with a sentence "works at full load". It only can work part time, but as routers rarely cut straight lines most of the work involves X and Y motors so they work almost full time.
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  #114  
Old Tue 16 June 2015, 20:05
Bazza
Just call me: Bazza
 
South West Rocks
Australia
Hi Danilo
Thanks for your input
I'm in the process of putting my parts list together
Its good to know you are getting good results with 34HS9801 running with 63VDC, how did you wire it?

I'm only new at this and don't know anything about feed rates yet and reckon you're replying to Brad including the addition of 20% to the VDC result.
Gerald recommended (see thread 702 post #1) adding 20% to the VDC figure and mentioned elsewhere he saw no overheating issues on working machines using that method.
Cheers
Bazza
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  #115  
Old Wed 17 June 2015, 01:04
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
Wired bipolar parallel, but recently I order only 4wire versions for simplicity and as any other wiring is no use on a router with this motor.

You can look at 85BYGH450D-008 from Wantai its a same motor, there's lots of them on ebay cheap.
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  #116  
Old Wed 17 June 2015, 02:15
Bazza
Just call me: Bazza
 
South West Rocks
Australia
Hi Danilo
I appreciate your help
I'm going bipolar Parallel too, the torque and speed performance seem best wired that way from my understanding.
Living down under in Australia is great in most ways except acces to affordable delivery costs for quality products, Looking into the motors you suggest now
Thanks again for your input
Bazza
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  #117  
Old Wed 17 June 2015, 07:33
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Bazza, you are correct, not sure where I miscopied, but that formula clearly results in 480 VA, not 600 VA.

Danilo is correct that going too high on the voltage would cause overly hot motors - which is an argument for not going arbitrarily high over the formula's estimate. I think it's important to recognize that the formula is a compromise across a large range of motors - just think of the difference between a NEMA23, NEMA34, and NEMA42 not to mention single, double or triple stack. Very different form factors, percentage of mass of the various components, thermal mass, heat dissipation area. And widely varying use cases.

What I'm asserting (and I think Gerald was asserting back at post #1, but he speaks for himself) is that for the use case of midsize NEMA34 motors on gantry routers with good quality drivers, the 32 x √inductance formula can safely be increased by 20% without undue motor heating.

Now, if you're in a direct drive scenario, this won't help you at all - the machine already has as much speed as it can handle. However, if you're in a heavily gear or belt reduced scenario and your usage patterns involve rapid non-cutting moves (3d comes to mind), that extra voltage translates to extra RPM = shorter overall cutting times.
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  #118  
Old Wed 17 June 2015, 18:59
Bazza
Just call me: Bazza
 
South West Rocks
Australia
Removed Reference Quote

Hi Danilo
I take from your comment that the 4 wired 85BYGH450D-008 is similar to MotionKing 34HS9801 but not suitrable for CNC Routers, is this correct?

Hi Brad
Thanks for the clarification and additional information, I haven't done the numbers on inch per rotation using the 30T pinion on 34HS9801 yet.
I intend to use it initially to make my 3:1 reduction components in MDF, install them and make a permanent version.
I'm trying to get the highest resolution I can afford

Cheers
Bazza
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  #119  
Old Thu 18 June 2015, 01:48
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
I wanted to say that a 4 wire option which is bipolar parallel is suitable and there is no need for any other configuration which would require to have 8 wires.
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  #120  
Old Thu 18 June 2015, 03:43
Bazza
Just call me: Bazza
 
South West Rocks
Australia
Hi Danilo
I didn't know that 4 wire stepper motors were wired bipolar parallel.
From Geralds post on wiring configurations, he stated "With a 4-wire motor there can be no confusion as there are no alternatives:
- BIpolar (similar to "bipolar series") "
I understand that series wired motors generate less maximum speed at full torque.
As I mentioned before I'm gearing it, so speed will be an important consideration.
I looked on eBay and you are absolutely right , they are far cheaper, I'll now look into the inductance, and amp rating. The holding torque is massive!
Thanks again for your input

Cheers
Bazza
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