Please recommend me stepper motor and controllers

I'm getting started on a project where i want to build a CNC machine to solder paste on PCBs, if everything goes good next thing i will be doing is to place some components, it will be a custom machine for my own use and limited functionality don't consider that i'm going to build some robust solution.

I have planet CNC controller that supports 4 axis, (I can consider using some alternate controller that you think my reduce my efforts but i can't spend a lot)

now looking for stepper motor controllers and stepper motors, I'm using 20x20 aluminum rails about 550mm long

here is the link for stepper motor that I'm considering

https://www.aliexpress.com/item/33007927749.html
https://www.aliexpress.com/item/4000148639109.html ( will consider this one if it better suits)

Stepper motor controller like below
https://www.aliexpress.com/item/33052797367.html

I need suggestion, i want to buy from aliexpress if could share the link of recommended motor/controller that would be great

So Aliexpress steppers. I used to pick and weave trying to find the best for the best price. And just about all of the ones I have bought have been fine.

Search out a Nema 17 kit. Check out the feedback. Go for it. What do you have to lose? They look nice and non expensive.

Stepperonline are ok.

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Hi,
most first time buyer select steppers with the most torque for the least money....mistake. Those steppers have high inductance and so while they are great at low
speed torque but rubbish at producing torque at higher speeds. Manufacturers make and sell them just to catch those buyers who don't know any better......
you don't want to be in that group.

In 23 size steppers look for 1-2mH, 1mH preferred and reject anything over 2mH.
In 34 size steppers look for 2-4mH, 2mH preferred and reject anything over 4mH.

Look for the highest possible voltage drivers, at the current time the max is about 80V. Don't settle for less and run them at 80V., don't shag around with low voltages
or your machine will be as slow as a wet week.

Craig

Not sure if OP is looking for speed and torque?

Regardless. I would love to see the final build. A CNC soldering and board component placing machine sounds very cool indeed.

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Hi,

Torque is proportional to acceleration.

Highest acceleration results in the best possible toolpath following.

How many posts are there on this forum where hapless newcomers buy high torque (but comensurately high inductance) steppers only to find
they start to miss steps and/or stall at 50ipm?

To OP, the trick to buying cheap is to buy the right parts, not necessarily the cheapest, so you only have to buy once. Buying the cheapest will
almost always result in having to go back and buy again.

Craig

It has become very tricky to buy these day, good brands are too expensive that buying right item after two or three wrong buying still we save money. Amazon, eBay and Aliexpress have almost same inventory.
I'm new to CNC world and learning about many possible issues that i may have, one of then is missing steps, i want to learn how can i avoid missing steps, does aluminum rails also play a role?
I bought 20x20 square rails but sounds like aluminum rods gives better smooth motion

If you don't get the mechanical parts of your machine working smoothly, steps are quite likely to be missed. Aluminum rails might work initially, but they won't last long in service. I'm not sure what you mean by square rails, but if they're not precision ground, they're unlikely to work either. If you post images of what you're thinking about purchasing, someone here might be able to tell you if they're going to work before you buy the wrong things again.

Hi,
I have given you a means of working out which stepper may be preferred over another.

Steppers with the highest torque are often not the best overall. The best overall are commonly steppers with good torque, say 1/2-2/3 of the
'high torque wonders' but low inductance. They are no more expensive than others, just better for CNC use.

For a machine, ANY machine, to be accurate it MUST be rigid. What's the point of having fast, powerful axis motors capable of high resolution
then bolting them into a machine that flexes all over the place at the slightest force?.

It is a very misunderstood concept among newcomers....strong DOES NOT necessarily mean stiff. Very seldom do any of our hobbyist
machines ever get to the point of breaking structural elements, they never achieve the force necessary to break a rail say, they will however
flex or spring with much lower forces. Spring and flex are to be avoided at all costs.

Your 20mm square rails are vastly stiffer (and therefore preferred) than any round rail (think spagetti) will ever be.

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, one of then is missing steps, i want to learn how can i avoid missing steps,

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Missing steps happens when a stepper cannot produce the torque required to overcome the load/acceleration demanded of it. Most hobbyists
use open loop steppers and missing some steps usually wrecks the job you are working on and must be avoided.

I have no doubt you have seen closed loop steppers advertised 'that never miss steps'. Pure BS....they are saying that just to get you to buy them....
and they cost more. I can detail why they do not offer the advantages the manufacturers claim but my advice is don't bother with closed loop
steppers. If you really want closed loop get AC servos not steppers and accept the fact they are way more expensive.

My mini-mill, which I've been using for six plus years has good quality (Vexta) open loop steppers and they have not missed a step in
six years EXCEPT if I do something stupid.

My contention is that open loop steppers will NEVER miss a step IF you use them within their performance envelop.

All steppers lose torque the faster they go....its plain physics and can't be avoided. Inductance is a measure of how bad that torque degradation will be.
For instance a 23 size stepper of 500oz.in but 11mH inductance will have its rated 500oz.in at low or zero rpm but will have 5% or 25oz.in or less at 1000rpm.
Another 23 size stepper of only 300oz.in but 1.5mH will have its rated 300oz.in at low or zero rpm but may retain 40% or 120oz.in at 1000 rpm.
Thus the second stepper is better overall despite being the 'weaker' of the two by virtue of its torque at higher speeds. The first stepper will start missing steps
at moderate speeds where the second one will not.

The absolute classic way to overcome the limitations imposed on stepper performance by inductance is to use the highest possible voltage drivers.
My Vexta steppers for instance, which derive their DC supply direct off the 230VAC input, has a DC voltage of 150VDC. Thus my little steppers
do 2400rpm WITHOUT missing steps, and I have had them going as fast as 3000rpm. They are 5-phase steppers so I would not expect
two-phase (normal) steppers to go that fast....but the point is that the high voltage helps them go fast.

Gecko is the stand-out brand among stepper drivers, very reliable but not cheap. Leadshine also make some very capable 80V drivers at about
half the price.

https://www.ebay.com/itm/Leadshine-D...Cclp%3A2334524

Craig

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Originally Posted by joeavaerage

Hi,

Torque is proportional to acceleration.

Highest acceleration results in the best possible toolpath following.

How many posts are there on this forum where hapless newcomers buy high torque (but comensurately high inductance) steppers only to find
they start to miss steps and/or stall at 50ipm?

To OP, the trick to buying cheap is to buy the right parts, not necessarily the cheapest, so you only have to buy once. Buying the cheapest will
almost always result in having to go back and buy again.

Craig

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Yep. And I'll admit to doing it myself.
Had a few attempts. Gone rubbish big stepper, rubbish 'kit voltage' (36v), high inductance, etc.

My finalized mill setup of 566oz, 3mh ind, nema24 size steppers running on 60v are gorgeous :D Go like rockets and I haven't found their stall point on accelleration yet.

I actually found that one of the worst places for having high inductance steppers was 'Stepperonline' :eek::confused::rolleyes:

I guess I have not really gone for maximum performance instead I run my machine to just before its limitations. If I need more torque or speed I have upgraded. Although I have also taken advice from here prior to purchasing.

Its all been Chinese. Off Aliexpress. Stepperonline a few. Actually the Stepperonline models had "made by..... umm.... either Longs or Leadshine for Stepperonline." I've only been through a few builds.

Tell you what. My best and most awesome piece of kit I bought out of China was a 4.5kw spindle with a 400v 5.5kw HY VFD. Man that changed everything.

Anyway probably a little off topic. OP is not looking for a spindle.





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Stepper online has wide variety but mostly voted against it, I also found few more brands Hong Yi specifications for their motors looks good but who know if those ones are true.

Another brand is Cloudray want to know if any one has experience of these brands Hong Yi and Cloudray

At the moment i want to avoid speed issues want accuracy at reasonable speed, once i get proof of concept and i am able to see my machine running then i will upgrade it, i believe it makes sense to me to spend more at that time.

Hi,

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At the moment i want to avoid speed issues want accuracy at reasonable speed,

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That's what we a talking about here. All steppers are accurate provided they don't miss steps and low inductance is a key parameter so that a stepper
does not miss steps at reasonable speeds.

If you want genuinely fast....get AC servos and don't mess around with steppers at all.

I don't think the brand matters that much just get low inductance 23 size steppers in the 300-500oz.in range, 80V drivers and you are golden.

Craig

I believe i should have described before that I'm following some existing project that's why I have some limitations.

I will be using AT Mega 2560 shield for driving motors, will be using Marlin open source for controller. I believe this controller allows 12-24V (I also have PlanetCNC controller may be later i will switch to it)
as its not a heavy CNC machine i will be using laser cutting and later i will change it into a Pick and place machine (after learning CNC mechanism)

One thing i do not understand for 90% motors no one describe voltage only amps are mentioned for a few motors i saw 3.3v that is unbelievable.

Hi,

Quote:

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I believe this controller allows 12-24V

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That will be disappointing.

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One thing i do not understand for 90% motors no one describe voltage only amps are mentioned for a few motors i saw 3.3v that is unbelievable.

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The motor is rated for current, lets say 4A. It has a phase resistance of 1 Ohm, Therefore at 4A the voltage over the winding is 4V.
The job of the controller is to apply a much higher voltage, lets say 60V and THEN once the current has built up to 4A it will use PWM to limit
the current to 4A. The only time the full 60V is applied to the winding is when the winding is first switched. The high voltage allows the current
to build up quickly. If you applied only 4V the current would eventually get to 4A but it would take tens of milliseconds, and the motor would be so slow as
to be unusable.

The point of having high voltage drivers is to have the current build up fast so you can run your motors at reasonable speed. Thus you could apply 80V via
an 80V driver to that stepper of 3.3V, but the current will be limited to rated current and no harm will come to it.

Craig

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Originally Posted by sairfan1

I will be using AT Mega 2560 shield for driving motors, will be using Marlin open source for controller. I believe this controller allows 12-24V

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Which stepper drivers will you be getting? Most drivers can be run with more than 24V, even the A4988, which is the most common in the 3D printing world, can be driven with 36V. There is a huge difference between 24V and 36V, one of my printers is on 24V the other is on 36V, so I can clearly see the benefits. The thing with those Mega boards is that some (if not all) directly connect the DC power supply to the stepper drivers, and because the Mega board can not handle more than 24V because of the voltage regulation down to 5V for the electronics, so you can't feed it with more than 24V. But... if you separate the Mega board DC supply and the stepper driver supply then you can connect 36V to the stepper drivers and live happily ever after. Of course, the disadvantage is that you need two PSU, one for the Mega board and one for the stepper drivers.

Quote:

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Originally Posted by sairfan1

One thing i do not understand for 90% motors no one describe voltage only amps are mentioned for a few motors i saw 3.3v that is unbelievable.

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The motor voltage is not important, it is the current you want to know because that is what creates the torque. The voltage is only important for the stepper drivers, and of course, it is important that the stepper driver PSU can deliver the necessary current for your steppers. So if you have 3A motors and have three of them, that means maximum 9A for the motors. Using a 24V PSU you will need MINIMUM 216W + some margin, I would chose minimum 280W. If you go for a 36V supply for the stepper drivers then you will need minimum 324W but optimally 430W. Of course, this makes it more expensive also. Please note that if you are using a separate PSU for the stepper drivers then you only need a tiny wall wart for the Mega board and all the other electronics. You can even use a simple 12V 2A charger supply, so the overall size or price does not have to be very high with that solution.

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