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Thread: Low Voltage vs High Voltage Stepper motors?

  1. #21
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    Default Re: Low Voltage vs High Voltage Stepper motors?

    Quote Originally Posted by 109jb View Post
    I totally disagree. There is nothing that says you have to run 40V or have a torroidal transformer or any of the other stuff mentioned. Here is my latest machine which breaks all of those rules and yet still works somehow. The machine has dovetail slides for more friction, acme screws with finer pitch than a ballscrew to make things worse, 425 oz-in 6.8mH motors, cheap $8 TB6600 drives and in this video is running from a 24V switching power supply. It milled just fine and was capable in this video of about 25 IPM rapids. It all depends on the performance you want.



    My first machine is in the second video and it had TB6560 drives at 24V, underdriving some 570 oz-in 2.2mH motors. These were 5A motors being driven at 3.5A, so were immediately at 70% power just due to the low amperage, and then were at lower performance due to running at about 1/2 their ideal voltage. The machine did have ballscrews, but had dovetail slides still. Even with all of the supposed no-nos on that machine, I was able to cut aluminum just fine, and actually did some steel cutting too. without problem.



    Bottom line is that what will work depends what performance you are desiring, not what others feel is absolutely necessary.
    The voltage will determine the speed that the steppers will still have enough torque to move the axes, which in essence determines the maximum rapids of the machine. Or in other words, the torque won't drop off as fast with higher voltage.

    The other thing is your federate is determined by the spindle speed; in the case of a typical mill around 4000-5000rpm. The electric spindle the OP is using is capable of 5-6 times that, with the power band of that spindle toward the upper region of its RPM range. This means the machine should be running at a faster federate, likely with less depth of cut, than your mill.

    We don't know exactly what type of machining the OP intends to do with his machine, but a lot of what the machine will do will be determined by the components he purchases and not the other way around.

    Obviously, in your case, you could have bought 380oz-in steppers and ran them at the max current setting of the drive, had better acceleration, and saved a few bucks over purchasing the 570oz-in steppers. But this is why I always stress to prospective builders to make these estimates of what's needed BEFORE beginning a build, or at the very least size the electronics depending on what you need from your machine instead of designing a machine around your steppers.



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    Default Re: Low Voltage vs High Voltage Stepper motors?

    The voltage will determine the speed that the steppers will still have enough torque to move the axes, which in essence determines the maximum rapids of the machine. Or in other words, the torque won't drop off as fast with higher voltage.

    The other thing is your federate is determined by the spindle speed; in the case of a typical mill around 4000-5000rpm. The electric spindle the OP is using is capable of 5-6 times that, with the power band of that spindle toward the upper region of its RPM range. This means the machine should be running at a faster federate, likely with less depth of cut, than your mill.

    We don't know exactly what type of machining the OP intends to do with his machine, but a lot of what the machine will do will be determined by the components he purchases and not the other way around.

    Obviously, in your case, you could have bought 380oz-in steppers and ran them at the max current setting of the drive, had better acceleration, and saved a few bucks over purchasing the 570oz-in steppers. But this is why I always stress to prospective builders to make these estimates of what's needed BEFORE beginning a build, or at the very least size the electronics depending on what you need from your machine instead of designing a machine around your steppers.
    My point is this. I read many times where advice is given as rules. You have to do this, or you have to do that... This is not the case and is dependent on many factors. The post I replied to had several of these type statements

    The power supply must be above 40V, preferably unregulated analogue type (toroidal transformer, rectifier and a very large capacitor).
    The stepper should have VERY low inductance and at least 3A.
    you can't use the crappy Toshiba chip based ones if you have a power supply which is above 36V (or maybe 24V, I don't remember any more).
    All of those statements are only true if the circumstances warrant it. My post was to show that you can still mill aluminum with low voltage power supplies, high inductance steppers, and cheap drives if you are willing to sacrifice performance. The machine itself and the builder's desired performance dictate what is needed, not what someone else thinks is needed.

    As for the 570 oz-in motors on my first machine, I chose those knowing they would not match the drivers I initially used because I planned to upgrade the drivers once funds allowed. I just never got around to it.



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    Default Re: Low Voltage vs High Voltage Stepper motors?

    Quote Originally Posted by 109jb View Post
    My point is this. I read many times where advice is given as rules. You have to do this, or you have to do that... This is not the case and is dependent on many factors. The post I replied to had several of these type statements

    All of those statements are only true if the circumstances warrant it. My post was to show that you can still mill aluminum with low voltage power supplies, high inductance steppers, and cheap drives if you are willing to sacrifice performance. The machine itself and the builder's desired performance dictate what is needed, not what someone else thinks is needed.

    As for the 570 oz-in motors on my first machine, I chose those knowing they would not match the drivers I initially used because I planned to upgrade the drivers once funds allowed. I just never got around to it.
    I couldn't agree more, for the most part. Then again, the OP had chosen a design that while not complicated, is dependent upon some precision machining and fine tuning and assembly and components. It doesn't make sense to me to then saddle its performance, because it defeats the purpose of purchasing components that were designed for higher speed. But to each his own - I've seen many builds where the expense in materials didn't seem justified to me by the use of a motion system that couldn't take advantage of the components bought, and builds where the motion system far out-powered the machine it was installed on.

    Secondly, again, this is a router, not a mill, and thus there is a difference in how material is removed - and that difference pretty much dictates how the motion components are chosen. We can only guesstimate what is needed based on experience. Actually no one here (maybe even the OP) knows what the circumstances are or what is warranted. We only know that the OP wants to machine aluminum, chose a router-style platform, and is using a high-speed spindle. This dictates that he'll need higher speeds to mill effectively, while still having enough rapids speed that a job won't take unnecessarily long. Since it's a relatively small machine, I don't believe flat-out rapids performance is needed, but running at too slow a feed with a spindle whose power is at higher RPMs is a recipe for not-a-lot-of-fun. What's needed dictates what's needed, not what you or I feel at this particular time.

    That said, in my opinion, I believe the 5mm pitch ballscrews are a better option for this machine. I also believe the 270oz-in steppers, paired with the aforementioned Leadshine DM542A drives and larger (36V) PSU would have paired nicely with the 5mm ballscrews.

    As a comparison, I built a couple machines using 1/2"-8, 2 start (.25" lead) ACME screws, 166oz-in steppers, and 48V PSU with G540 and Mach3, DeWalt trim routers, and used them to machine aluminum with no issues - and still have the machine be capable of over 500ipm rapids. Although at 14" x 8" X-Y travels, this was unnecessary, and I set it at 250ipm rapids on all 3 axes. On my larger 28" x 36" table, I use 425oz-in steppers, with the G540 and 48V PSU, and 1/2"-8, 8-start (1" effective lead) screws, and still have plenty of torque to cut aluminum. And still have enough to rapid at over 700ipm. The same exact screws I used since I built my first wood-framed router almost 8 years ago. Have both builds documented here with plenty of videos to prove it can be done, contrary to what was generally believed at the time.







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    Default Re: Low Voltage vs High Voltage Stepper motors?

    Quote Originally Posted by 109jb View Post
    I totally disagree. There is nothing that says you have to run 40V or have a torroidal transformer or any of the other stuff mentioned. Here is my latest machine which breaks all of those rules and yet still works somehow. The machine has dovetail slides for more friction, acme screws with finer pitch than a ballscrew to make things worse, 425 oz-in 6.8mH motors, cheap $8 TB6600 drives and in this video is running from a 24V switching power supply. It milled just fine and was capable in this video of about 25 IPM rapids. It all depends on the performance you want.



    My first machine is in the second video and it had TB6560 drives at 24V, underdriving some 570 oz-in 2.2mH motors. These were 5A motors being driven at 3.5A, so were immediately at 70% power just due to the low amperage, and then were at lower performance due to running at about 1/2 their ideal voltage. The machine did have ballscrews, but had dovetail slides still. Even with all of the supposed no-nos on that machine, I was able to cut aluminum just fine, and actually did some steel cutting too. without problem.



    Bottom line is that what will work depends what performance you are desiring, not what others feel is absolutely necessary.
    I don't know what you "totally disagree" with. 25ipm is only 635mm/min. Really not a lot, but it depends on the machine as well as your expectations. The higher the voltage and the current the better the performance. My first was also driven with 24V, TB6560 drivers but I was not happy with the performance, especially not with the speed, so I upgraded. Not only the PSU, but also the drivers and the motion controller, as well as the software. With the crappy Toshiba chips there is a serious limit in performance, but sure, if that's enough for you then fine.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: Low Voltage vs High Voltage Stepper motors?

    Quote Originally Posted by louieatienza View Post
    I am a big fan of Leadshine's DM542A; if these are truly a rebranded equivalent then you got a good deal. They're capable of up to 50V.
    Yes, these are the ones I am using as well, though mine are called DQ542MA. They work extremely well and reliable, very quiet, no hissing noise like the Toshiba, very well made (I opened and inspected all the six I have). Very good performance can be had with voltages over 40V and the micro stepping can be set in a huge number of combinations. I am very happy with mine and if I build a new one I will buy the same or maybe the digital version of it.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: Low Voltage vs High Voltage Stepper motors?

    Quote Originally Posted by 109jb View Post
    My point is this. I read many times where advice is given as rules. You have to do this, or you have to do that... This is not the case and is dependent on many factors. The post I replied to had several of these type statements





    All of those statements are only true if the circumstances warrant it. My post was to show that you can still mill aluminum with low voltage power supplies, high inductance steppers, and cheap drives if you are willing to sacrifice performance. The machine itself and the builder's desired performance dictate what is needed, not what someone else thinks is needed.

    As for the 570 oz-in motors on my first machine, I chose those knowing they would not match the drivers I initially used because I planned to upgrade the drivers once funds allowed. I just never got around to it.
    EVERYTHING on Internet must be taken with a grain of salt... That includes your posts as well as mine. Of course you can mill aluminium with things which are CONSIDERABLY different and weaker than what I wrote in that post. I milled aluminium with a slow and weak 400W DC motor as spindle, and also with a weak little Dremel, and in fact also with a simple bench drill machine. Would I recommend anyone to do it? No, except if nothing else is available, and even in that case only temporarily. Would I recommend anyone to buy the Toshiba based drivers? NEVER. Why? Because I have experience with them, several of them. I even have a few unused, brand new chips (original from Toshiba) but I guess those will never be used. Can the 6560 based drivers be used? Sure, but that's a different thing from recommending them.

    When I give advice I do it from my own experience and knowledge and my starting point is: why not advice about what I believe in and not about what can be made to work? Many things can be made to work, but if I would start over again and had the same experience I have today I's skip quite a few stages, like the 24V switching PSU and the TB6560 drivers. But of course they work also... just not that well...

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: Low Voltage vs High Voltage Stepper motors?

    Quote Originally Posted by A_Camera View Post
    Yes, these are the ones I am using as well, though mine are called DQ542MA. They work extremely well and reliable, very quiet, no hissing noise like the Toshiba, very well made (I opened and inspected all the six I have). Very good performance can be had with voltages over 40V and the micro stepping can be set in a huge number of combinations. I am very happy with mine and if I build a new one I will buy the same or maybe the digital version of it.
    Leadshines latest versiin is the DM542E, doesn't have the big cooling fins of the other drives but I don't think from ezperience they were necessary. Selling for $40 each from AMT....



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    Default Re: Low Voltage vs High Voltage Stepper motors?

    Quote Originally Posted by louieatienza View Post
    Leadshines latest versiin is the DM542E, doesn't have the big cooling fins of the other drives but I don't think from ezperience they were necessary. Selling for $40 each from AMT....
    Thanks. I'll remember it in case I'll buy more. Right now I have two spares as well, apart from the four I have installed.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: Low Voltage vs High Voltage Stepper motors?

    To the original poster: your expectations dictate machine design!! Until that is quantified it is very hard to give good advice.

    Some key points already hit upon.
    1. Current is directly related to torque in a motor.
    2. Voltage impacts rotational velocity.
    3. Steppers are not motors per say as velocity is a bit more compłex to understand. Velocity depends upon how quickly the electronics switches the coils Voltage impacts how fast the electronics can actually switch those coils. This takes a bit to grasp but voltage impacts how fast the inductance of the stepper coils can be over come.
    4. Modern stepper drives manage the current through the motor coils. In general you want the best torque possible out of a motor so you buy a drive that can be set to the steppers rated current. The voltage to the drive impacts your ultimate velocities.
    5. Depending upon the work load and machine size, achievable acceleration can often be more important that max rapids.
    6. Going too small with components is a bigger problem than going to large. However either way from optimal creates its own set of issues.
    7. While motors and electrics are easy to upgrade you can end up paying a lot for an incremental upgrade. Frankly it makes no sense at all to install one set of steppers at the first build with the idea that you will upgrade to larger steppers / better drives, in the future.
    8. An upgrade from steppers to servos is a different story. Even here though you need to make sure you will get your money's worth. In either the case of 7 or 8 here id rather see one implement the right solution for their machine with the initial build. In the end you waste money and spend too much time screwing around.
    9, When you make a statement like "i will machine aluminum" it really doesn't mean a lot as it isn't very specific. There is such a wide range of possibilities here that people cant really say if the machine will work well for you. Using a high speed router spindle though does imply a machine capable of higher feed rates. If your drive motors and electronics cant keep up you will end up with tooling issues. If you go this route you need to engineer you axises to feed at the proper rates reliably.
    10. Probably the most important - nothing in this world is perfect. Most of the home built machines you see in these forums are compromises. This usually due to shallow pockets Ultimately you have to live with what you built.



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Low Voltage vs High Voltage Stepper motors?

Low Voltage vs High Voltage Stepper motors?