11 ms·

Motors for Makers: A Guide to Steppers, Servos, and Other Electrical Machines (2015)

262 points by teleforce 4y ago

piotrrojek 4y ago
Am I missing something? It doesn't seem like this book is available online to read, just TOS and link to Amazon to buy paperback version.
- unwind 4y ago
  Also it seems to be from 2015, which makes it almost more strange to post (especially without tagging the year). Perhaps it is just being ackowledged as a time-less epic classic, I don't know.
  - pca006132 4y ago
    Doesn't seem so, classics will probably not have dedicated chapters for showing how to control motors with Arduino and such. I think it is nice to know the differences between different motors, but I would rather read an article about this instead of buying a book.
- qwertox 4y ago
  Felt like an ad, even though I could imagine that someone would want to post this out of normal interest.
pitched 4y ago
The second Google result for this book is a chapter preview from the publisher: https://ptgmedia.pearsoncmg.com/images/9780134032832/samplepages/9780134032832.pdf https://ptgmedia.pearsoncmg.com/images/9780134032832/samplep... The first result is entire PDF though. I remember back in the old days being a poor student trying to save money spending hours trying to find scans of texts (or making scans in the library). Now it’s the first result in Google! Here’s hoping none of us need to make money through writing…
- boredemployee 4y ago
  man back in my college days (2006-2012), it was a pain in the ass to have books (materials science) and find stuff online. anyway, i was known as "the king of pdfs". because i always knew how to search things. but now the game is in a whole another level and my fame would fall into oblivion!
  - mbustamanter 4y ago
    My trick was searching +"index of" on Google or something like that, I could find all sorts of books that way. What were your tricks?
    - cpach 4y ago
      filetype:pdf These days, Libgen is much more convenient. With that said, I personally prefer buying an official book if available, so that the author can get their royalties. Many publishers even offer DRM-free ebooks.
      - dsfyu404ed 4y ago
        When I can't find a pdf I like buying old editions on eBay for $10 or whatever. I find that having to browse through more info to actually find what I'm trying to reference leads to better ancillary knowledge and understanding than CTRL+Fing a pdf.
- sugarkjube 4y ago
  > Here’s hoping none of us need to make money through writing… i'd assume pretty soon hardly anybody can still make money through writing as it's easy to ask chatgpt "write me a book titled Motors for makers: A Guide to Steppers, Servos, and Other Electrical Machines". or maybe i lack vision, maybe soon chatgpt can answer "should i use a stepper or a servo for my robot arm", or "how do i wire up stepper xyz on CNC machine ABC", or even "design a 3d printer with parts <$100 on ali express".
  - 4y ago
deleted 4y ago
[deleted]
TheRealWatson 4y ago
Another good resource is Jeremy Fielding's YT channel.
- asddubs 4y ago
  I was going to post this too! He's got a great series on motors
- schaefer 4y ago
  I agree, I had a custom controller board for a pair of huge electric motors go bad. I was able to bring the machine back to life using only what I learned form Jeremy Fielding's channel.
CubsFan1060 4y ago
For someone wanting to get into "making",is there a good set of starter resources like this? Software I'm comfortable with, but I'm not really familiar with all of the physical components or how to put them together, when you might use each, etc...
- fellowmartian 4y ago
  IMO buying a hackable 3D printer is the best way to get practical experience with kinematics, motors, stepper controllers, etc. The standard recommendation is to buy an Ender 3, but it’s very slow by today’s standards. I’d recommend Flsun V400, it prints almost as fast as the state of the art, but has no proprietary components, and comes (almost) pre-assembled.
- bartlettD 4y ago
  EE is my day job so I may be biased towards more formal resources. Sparkfun, Adafruit, etc have some good stuff to get you off the ground and building projects almost right away. I think they're great "taster" in how circuits work and what some of the components are for. Khan Academy has a course for EE, I haven't used it but I've used the site for other stuff like brushing up of my math. Manufacturers actually make some really nice training materials, if you like analogue stuff, TI's Precision Labs series is a great resource for that. Analog Devices has an intro to electronics wiki series too. https://wiki.analog.com/university/courses/electronics/text/electronics-toc https://wiki.analog.com/university/courses/electronics/text/... For a deeper look, an undergraduate electronics textbook will hold your hand from the very basics through to more advanced concepts. You can ignore some of the more advanced stuff like AC analysis and non-linear components for the most part (Unless they interest you!) I learned from this book (https://www.pearson.com/en-gb/subject-catalog/p/electronics-a-systems-approach/P200000005502/9781292133416 https://www.pearson.com/en-gb/subject-catalog/p/electronics-...) and found it quite approachable in how it laid out the basics before contextualising them as systems. Theres also the famous Art of Electronics which is a good book but personally feels a bit dated (even with the new edition) and really analogue heavy. A good reference manual though.
- conductr 4y ago
  I’ve been diving in the past few years. You end up having to learn a lot of things. And need a lot of tools. Id compare it to woodworking. You can’t really “just start” woodworking one day without buying some tooling and supplies. I’ve amassed a big little workshop over the last few years. I find the best way to get started is to have an idea of something you want to make, then just buy what is needed for that. Pick a microcontroller first. Arduino is popular and well documented. Raspberry Pi is overkill in my opinion. I find I like the NodeMCU. The mini D1 specifically as it as an ESP8266 for Wi-Fi support. If you need Bluetooth or whatever look for the ones you need. And use the Arduino IDE to program and code it. From there, most motors need a motor drive and there’s a million of those and it’s typically a separate board (breakout board). You want to stock up on breadboarding supplies. Openbuilds.com store is great if you have the need and budget for this type of items. You can get anything to build most any type of contraption and generally know it’s going to fit together if you plan correctly. YouTube is your best resource. I like reading text when it comes to software but reading electrical diagrams is hard for me and it’s so much easier if I can watch someone else. They often tell you the little gotchas too. Amazon is good for almost everything else. If you’re like me you’ll end up placing 50 orders in the first 2 months. The hardest part is no retail store, even hobby shops, stock these types of items. I will say I don’t find kits particularly helpful. They can be fun, but at the end of it you’ve just followed the directions and didn’t really learn anything. It’s like putting an ikea dresser together, if you’re trying to learn how to build furniture it’s not very helpful.
frowin 4y ago
in case the author is reading this: I would suggest to add an affiliate tag to the Amazon link. I once heard that authors make more from the affiliate program than from the book itself. Maybe a modern anecdote but yeah... costs you nothing. As you don't get rich by the book itself, atleast you get some few dollars through the link!
frankus 4y ago
VESC (vesc-project.org) is worth checking out if you need (low) triple digit watts and a PMSM/BLDC motor is suitable. You can interface via UART and CAN and a bunch of other analog/digital options as well
- mvidal01 4y ago
  The url is https://vesc-project.com/ https://vesc-project.com/ I think. vesc-project.org didnt work.
rq1 4y ago
Does anybody have an address where to shop servos and gearboxes online? Or at least find references through filtering for specific torque/rpm/power/driver resolution... etc.? I hardly can find something worth looking at outside of ebay. A lot of websites don't have public price lists but ask you to fill forms and receive quotes, but I don't want to order thousands of these (yet?)...
- abakker 4y ago
  If you are doing servos and not well versed in these things, I highly recommend clearpath servos from teknic. The wiring is easy and their tuning support is very good (if the auto tune doesn’t work). If you need more power, or AC servos, I suggest DMM Dyn4 drives and servos. Finally, if you need gearboxes, stepper online has good ones that have held up well for me. Source: have built/converted several CNCs.
  - jbay808 4y ago
    I'll second DMM. Unlike most servo companies, they post their pricelist, making it easy to figure out which tradeoffs you need to make to stay on budget: https://dmm-tech.com/pricing.html https://dmm-tech.com/pricing.html
    - abakker 4y ago
      Another thing as a hobbyist: AC servos can save you money vs high performance DC power supplies. they also simplify some kinds of wiring. in a typical 3 axis mill with 3 motors of hobby scale, you might buy a teknic IPC5 power supply and a a power hub and a bundle of cables and a backup 24v din rail supply for about $370 after tax/shipping. for a DMM DYN 4 setup, you just run AC power to drives with standard wire and terminals. If your control box is tight, it can also pay to use AC servos because then you don't have the power supplies in your box. They may be more expensive / motor but can be way easier to deal with later.
- slicktux 4y ago
  Try servocity…
WJW 4y ago
One of my projects for this year will be getting a slightly bigger AC motor (say a 0.5-1 HP asynchronous motor) and integrating that into a more well-finished project. I have a decent grasp of the software parts and have done some projects with servos and steppers, but using bigger motors has eluded me so far.
_spduchamp 4y ago
If you are looking for a super easy way to put a motor with closed loop motion control, I highly recommend Vertiq (https://www.vertiq.co/ https://www.vertiq.co/) modules. They have a built-in position sensor and microcontroller. They have firmware based anti-cogging for smooth motion. I use them in making computer controlled musical instruments by just hooking up the serial interface to an ESP32 and using the Vertiq API to handle all the hard stuff of controlling motors. They really lowered the barrier to working with motors for me. Just be sure you get the right Kv for your project and use voltage limiting for an extra layer of safety.
- dekhn 4y ago
  Do you know if this would be appropriate in, for example, a microscope stage? I use steppers (open loop) to move a stage on bearings, and I would prefer to have closed-loop with position sensing (not movement- actual position- because a single dropped step will ruin an acquisition). I already work with ESP32 and have done closed-loop DC motor stuff before, so I'm just curious if this is something I could drop in and be happy with.
  - iancmceachern 4y ago
    Yes it would
  - _spduchamp 4y ago
    I primarily use the Vertiq line because I'm dealing with speed of spinning a rotary magnetic bow, and timing a robotic drumming. I don't think Veriq is the right fit for a microscope stage. They have a new line of closed loop steppers that would be better suited for that type of motion control. https://www.crowdsupply.com/iq-motion-control/iq-fortiq-bls42 https://www.crowdsupply.com/iq-motion-control/iq-fortiq-bls4... These should provide very smooth and precise position control. These units haven't shipped yet but will be soon.
- iancmceachern 4y ago
  Another product in this vein, Teknik motors. They're fully integrated, give them power and Connect to them via USB amd program it. Once you program it you can just use the gpio pins on the motor to wire up switches or other types of control. Super easy
opwieurposiu 4y ago
One thing to note about steppers, If you take them apart they will loose half their torque. In the factory they magnetize them after assembly. If you take them apart the lower permeability of air causes the rotor to somehow lose much of it's magnetic field. Physicists please chime in, IDK why this happens. We discovered this after machining some stepper backshells to accept optical encoders.
- oakwhiz 4y ago
  This is fascinating, I hope someone knows the answer. Is it possible that they magnetized the teeth of the rotor as a Halbach array?
  - adrian_b 4y ago
    Any permanent magnet demagnetizes partially whenever it is taken out of a closed magnetic circuit. If the magnet is made from a material with very high coercivity, the demagnetization may be negligible, but it is always recommended to store permanent magnets only with a piece of soft iron in contact with their N and S poles. To reach the maximum remanence possible for a given material, a permanent magnet must always be magnetized after being assembled in the final magnetic circuit.
    - GeorgeTirebiter 4y ago
      What about, say, Neodymium magnets? https://www.kjmagnetics.com/neomaginfo.asp https://www.kjmagnetics.com/neomaginfo.asp What I'm asking is: are Neodymium magnets NOT used in these applications?
      - jbay808 4y ago
        They are used in these applications, typically very high grade, unless you're buying a legacy product line. In, say, a hybrid stepper the magnet is usually a wide thin round disc, sandwiched between two steel rotor lamination stacks. With the link below you can examine the BH curve and load line for a Ø20 mm N52 disc magnet, 2mm thick, at 20 degrees C. (It's not exact because this assumes a magnet in free space and neglects the steel of the rotor - but it's an illustration). https://www.kjmagnetics.com/bhcurves.asp https://www.kjmagnetics.com/bhcurves.asp You'll notice that the load line (which assumes the magnet is in free air) is already landing within the "knee" where the intrinsic magnetization starts dropping rapidly. That's working too far along the hysteresis curve, where the poles are already starting to flip and demagnetize. However, if that magnet were surrounded by the steel of the stator, the high permeability of the magnetic circuit would put the load line at a steeper angle, where the magnetic field through the magnet would be much higher. Small changes in permeability around that point would not damage the magnet, but allowing it to fall all the way down below the knee-point would. It would not be completely demagnetized by that, but it would lose some of its original strength.
FatActor 4y ago
One problem I always run into with rotary motion: gearing. Finding gears of the right diameter, thickness, and thread pitch is always such a stumbling block for me. Most sites that sell gears to fit their motors have a small selection, and sites that sell gears are very hard to navigate (only to find out they don't sell in quantities <1,000 units). I end up having them laser cut out of HDPE online. Wish there was an easier solution.
- iancmceachern 4y ago
  The key, if you can, is to choose a NEMA standard motor, there are tons of suppliers you can get a nema gearbox from. They get pretty small, but if it's amaller than the smallest nema size I'd go to a place like stock drive components which stocks thousands of gears. The challenge is that gear tooth geometry is often more than 2d, so laser cutting may not be the best solution for longevity. For a quick and dirty prototype it's certainly fine.
  - convolvatron 4y ago
    standalone gear boxes also seem to be really really expensive what i would really love is a set of compatible gears that work from the same shank and would allow easy construction of 1:2 or 1:4 or 1:8 and i could compose. maybe some 1:1 bevels too
    - iancmceachern 4y ago
      Check automation direct, eBay, Ali express. I recently bought a nema 23 50:1 gearbox for a project for $50
- doctorwho42 4y ago
  It really comes down to the fact that gear shaping/cutting machines are quite specialized machines. Therefore demand a higher cost to buy (machines cost) and setup (tooling cost). For example a single gear shaper cutter is on average $700-$1000, and that's for a pretty standard and brand new cutter. So without taking into account actual time to set up the machine, program it, and feed it material. You are already having a high overhead. So the only real way to deal with that cost is in volume or cost. But when looking at the hobby market, volume is out of the question (who wants to buy >1000 of one gear for a personal project) and cost is out of the question ( if it's so expensive, I might as well 3D print or laser cut or waterjet some) So it's an odd market to get into.
waynesonfire 4y ago
how does one protect the microprocessor from the back EMF? Do you need an optoisolator?
- gwynplaine 4y ago
  That answer would depend on the type of motor. For a DC motor, they are rarely connected directly to the microcontroller. But you can put a diode across the motor terminals to minimise any back EMF. A stepper would typically have a driver circuit between the microcontroller and the motor. A small servo would usually just need one signal connection to the microcontroller, there's no back EMF via that path. You would of course also need common ground.
deleted 4y ago
[deleted]
fumoto 4y ago
[dead]
gwynplaine 4y ago
I feel like there's a gap in the hobbiest motor market. On the one hand there are stepper motors which can withstand lots of radial load thanks to steel shafts and bearings. They also provide some relative position control and no absolute position feedback (at hobbiest prices). On the other there are servos, which typically have weak components. Plastic gears, shafts and bushings which cannot withstand radial load. But they do allow control of absolute position. For many robotics projects, a hobbiest has to choose between servos which are physically weak, or steppers which can tear the project apart if they don't home correctly. And of course the hobbiest has to roll their own safety/endstop system every time. I'd love something physically like a Nema 14/17 stepper but with a servo interface. However I can't find them anywhere at hobbiest prices. Why are there thousands of good value steppers and thousands of models of servos, but nothing in between, I wonder?
- jbay808 4y ago
  It's worth distinguishing between two completely different types of "servos": RC hobby servos, and industrial-type servos which are robustly built like steppers but significantly more fast, accurate, efficient, and powerful. They are hard to find in Nema 14/17 sizes but not impossible. RC servos typically have an analog or PWM signal interface. That would usually not be accurate enough for an industrial servo in positioning mode. Industrial servos, like steppers, have a digital interface which might be a serial format or STEP/DIR pulse train. Some drives will accept a -10V to +10V analog signal for velocity or torque control mode. Anyway, here are some Nema 14/17-sized industrial servos with online pricing, which might be what you're looking for? https://en.nanotec.com/products/2262-smart-servos-motors-with-controller-drive https://en.nanotec.com/products/2262-smart-servos-motors-wit... https://catalog.orientalmotor.com/viewitems/l-categories-servo-motors-tuning-free-servo-motors/50w-nx-series-servo-motors https://catalog.orientalmotor.com/viewitems/l-categories-ser... Or many companies offer stepper motors with built-in encoders and controllers to prevent missed steps: https://catalog.orientalmotor.com/viewitems/az-series-absolute-encoder-servo-motor/az-series-42mm-absolute-encoder-stepper-motors-ac https://catalog.orientalmotor.com/viewitems/az-series-absolu... https://www.zaber.com/products/stepper-motors/X-NMS-E https://www.zaber.com/products/stepper-motors/X-NMS-E
atonse 4y ago
Wow this is AMAZING! There are a whole set of projects I’ve just not tinkered with because of my lack of knowledge about motors. For example, I want to make my bicycle hook system run on a motor. But winches are too strong. Don’t need something to pull 1500 lbs. just 100 lbs. All I know is that it should probably be low rpm and higher torque. Another is to play with something like curtain opening motors but as long as they are as quiet as possible. Hope this resource helps with the first principles understanding of how to pick motors, etc.
- conductr 4y ago
  > Don’t need something to pull 1500 lbs. just 100 lbs. I suspect with a smart pulley design you could get that down significantly as well
  - atonse 4y ago
    So the problem is that I don't even know where to start... where to buy, where to experiment. Say I want to hoist a 30 lb bicycle to hang on a 10 foot ceiling. The winch just needs to pull the rope (the pulleys are already installed). For that, how to go about finding the smallest motor needed (that's also quiet, I love when motors are generally quiet and don't whine). DC Stepper motors seem like the right solution there.
dTal 4y ago
As an aside that might be of interest to some - if you want to build a machine out of steppers, servos, digital output pins etc, and you want it to operate under tight timing constraints, and you want to avoid getting your hands dirty with finicky embedded programming, the Klipper project - nominally a 3D printer system - is sufficiently modular to be an excellent base. The developer documentation isn't perfect, but it's pretty straightforward to write new modules for it, all in Python, and it performs extremely well.

262 points by teleforce 4y ago

Am I missing something? It doesn't seem like this book is available online to read, just TOS and link to Amazon to buy paperback version.

unwind 4y ago
Also it seems to be from 2015, which makes it almost more strange to post (especially without tagging the year). Perhaps it is just being ackowledged as a time-less epic classic, I don't know.
- pca006132 4y ago
  Doesn't seem so, classics will probably not have dedicated chapters for showing how to control motors with Arduino and such. I think it is nice to know the differences between different motors, but I would rather read an article about this instead of buying a book.
qwertox 4y ago
Felt like an ad, even though I could imagine that someone would want to post this out of normal interest.

pitched 4y ago

The second Google result for this book is a chapter preview from the publisher: https://ptgmedia.pearsoncmg.com/images/9780134032832/samplepages/9780134032832.pdf https://ptgmedia.pearsoncmg.com/images/9780134032832/samplep... The first result is entire PDF though. I remember back in the old days being a poor student trying to save money spending hours trying to find scans of texts (or making scans in the library). Now it’s the first result in Google! Here’s hoping none of us need to make money through writing…

boredemployee 4y ago
man back in my college days (2006-2012), it was a pain in the ass to have books (materials science) and find stuff online. anyway, i was known as "the king of pdfs". because i always knew how to search things. but now the game is in a whole another level and my fame would fall into oblivion!
- mbustamanter 4y ago
  My trick was searching +"index of" on Google or something like that, I could find all sorts of books that way. What were your tricks?
  - cpach 4y ago
    filetype:pdf These days, Libgen is much more convenient. With that said, I personally prefer buying an official book if available, so that the author can get their royalties. Many publishers even offer DRM-free ebooks.
    - dsfyu404ed 4y ago
      When I can't find a pdf I like buying old editions on eBay for $10 or whatever. I find that having to browse through more info to actually find what I'm trying to reference leads to better ancillary knowledge and understanding than CTRL+Fing a pdf.
sugarkjube 4y ago
> Here’s hoping none of us need to make money through writing… i'd assume pretty soon hardly anybody can still make money through writing as it's easy to ask chatgpt "write me a book titled Motors for makers: A Guide to Steppers, Servos, and Other Electrical Machines". or maybe i lack vision, maybe soon chatgpt can answer "should i use a stepper or a servo for my robot arm", or "how do i wire up stepper xyz on CNC machine ABC", or even "design a 3d printer with parts <$100 on ali express".
- 4y ago

deleted 4y ago

[deleted]

TheRealWatson 4y ago

Another good resource is Jeremy Fielding's YT channel.

asddubs 4y ago
I was going to post this too! He's got a great series on motors
schaefer 4y ago
I agree, I had a custom controller board for a pair of huge electric motors go bad. I was able to bring the machine back to life using only what I learned form Jeremy Fielding's channel.

CubsFan1060 4y ago

For someone wanting to get into "making",is there a good set of starter resources like this? Software I'm comfortable with, but I'm not really familiar with all of the physical components or how to put them together, when you might use each, etc...

fellowmartian 4y ago
IMO buying a hackable 3D printer is the best way to get practical experience with kinematics, motors, stepper controllers, etc. The standard recommendation is to buy an Ender 3, but it’s very slow by today’s standards. I’d recommend Flsun V400, it prints almost as fast as the state of the art, but has no proprietary components, and comes (almost) pre-assembled.
bartlettD 4y ago
EE is my day job so I may be biased towards more formal resources. Sparkfun, Adafruit, etc have some good stuff to get you off the ground and building projects almost right away. I think they're great "taster" in how circuits work and what some of the components are for. Khan Academy has a course for EE, I haven't used it but I've used the site for other stuff like brushing up of my math. Manufacturers actually make some really nice training materials, if you like analogue stuff, TI's Precision Labs series is a great resource for that. Analog Devices has an intro to electronics wiki series too. https://wiki.analog.com/university/courses/electronics/text/electronics-toc https://wiki.analog.com/university/courses/electronics/text/... For a deeper look, an undergraduate electronics textbook will hold your hand from the very basics through to more advanced concepts. You can ignore some of the more advanced stuff like AC analysis and non-linear components for the most part (Unless they interest you!) I learned from this book (https://www.pearson.com/en-gb/subject-catalog/p/electronics-a-systems-approach/P200000005502/9781292133416 https://www.pearson.com/en-gb/subject-catalog/p/electronics-...) and found it quite approachable in how it laid out the basics before contextualising them as systems. Theres also the famous Art of Electronics which is a good book but personally feels a bit dated (even with the new edition) and really analogue heavy. A good reference manual though.
conductr 4y ago
I’ve been diving in the past few years. You end up having to learn a lot of things. And need a lot of tools. Id compare it to woodworking. You can’t really “just start” woodworking one day without buying some tooling and supplies. I’ve amassed a big little workshop over the last few years. I find the best way to get started is to have an idea of something you want to make, then just buy what is needed for that. Pick a microcontroller first. Arduino is popular and well documented. Raspberry Pi is overkill in my opinion. I find I like the NodeMCU. The mini D1 specifically as it as an ESP8266 for Wi-Fi support. If you need Bluetooth or whatever look for the ones you need. And use the Arduino IDE to program and code it. From there, most motors need a motor drive and there’s a million of those and it’s typically a separate board (breakout board). You want to stock up on breadboarding supplies. Openbuilds.com store is great if you have the need and budget for this type of items. You can get anything to build most any type of contraption and generally know it’s going to fit together if you plan correctly. YouTube is your best resource. I like reading text when it comes to software but reading electrical diagrams is hard for me and it’s so much easier if I can watch someone else. They often tell you the little gotchas too. Amazon is good for almost everything else. If you’re like me you’ll end up placing 50 orders in the first 2 months. The hardest part is no retail store, even hobby shops, stock these types of items. I will say I don’t find kits particularly helpful. They can be fun, but at the end of it you’ve just followed the directions and didn’t really learn anything. It’s like putting an ikea dresser together, if you’re trying to learn how to build furniture it’s not very helpful.

frowin 4y ago

in case the author is reading this: I would suggest to add an affiliate tag to the Amazon link. I once heard that authors make more from the affiliate program than from the book itself. Maybe a modern anecdote but yeah... costs you nothing. As you don't get rich by the book itself, atleast you get some few dollars through the link!

frankus 4y ago

VESC (vesc-project.org) is worth checking out if you need (low) triple digit watts and a PMSM/BLDC motor is suitable. You can interface via UART and CAN and a bunch of other analog/digital options as well

mvidal01 4y ago
The url is https://vesc-project.com/ https://vesc-project.com/ I think. vesc-project.org didnt work.

rq1 4y ago

Does anybody have an address where to shop servos and gearboxes online? Or at least find references through filtering for specific torque/rpm/power/driver resolution... etc.? I hardly can find something worth looking at outside of ebay. A lot of websites don't have public price lists but ask you to fill forms and receive quotes, but I don't want to order thousands of these (yet?)...

abakker 4y ago
If you are doing servos and not well versed in these things, I highly recommend clearpath servos from teknic. The wiring is easy and their tuning support is very good (if the auto tune doesn’t work). If you need more power, or AC servos, I suggest DMM Dyn4 drives and servos. Finally, if you need gearboxes, stepper online has good ones that have held up well for me. Source: have built/converted several CNCs.
- jbay808 4y ago
  I'll second DMM. Unlike most servo companies, they post their pricelist, making it easy to figure out which tradeoffs you need to make to stay on budget: https://dmm-tech.com/pricing.html https://dmm-tech.com/pricing.html
  - abakker 4y ago
    Another thing as a hobbyist: AC servos can save you money vs high performance DC power supplies. they also simplify some kinds of wiring. in a typical 3 axis mill with 3 motors of hobby scale, you might buy a teknic IPC5 power supply and a a power hub and a bundle of cables and a backup 24v din rail supply for about $370 after tax/shipping. for a DMM DYN 4 setup, you just run AC power to drives with standard wire and terminals. If your control box is tight, it can also pay to use AC servos because then you don't have the power supplies in your box. They may be more expensive / motor but can be way easier to deal with later.
slicktux 4y ago
Try servocity…

WJW 4y ago

One of my projects for this year will be getting a slightly bigger AC motor (say a 0.5-1 HP asynchronous motor) and integrating that into a more well-finished project. I have a decent grasp of the software parts and have done some projects with servos and steppers, but using bigger motors has eluded me so far.

_spduchamp 4y ago

If you are looking for a super easy way to put a motor with closed loop motion control, I highly recommend Vertiq (https://www.vertiq.co/ https://www.vertiq.co/) modules. They have a built-in position sensor and microcontroller. They have firmware based anti-cogging for smooth motion. I use them in making computer controlled musical instruments by just hooking up the serial interface to an ESP32 and using the Vertiq API to handle all the hard stuff of controlling motors. They really lowered the barrier to working with motors for me. Just be sure you get the right Kv for your project and use voltage limiting for an extra layer of safety.

dekhn 4y ago
Do you know if this would be appropriate in, for example, a microscope stage? I use steppers (open loop) to move a stage on bearings, and I would prefer to have closed-loop with position sensing (not movement- actual position- because a single dropped step will ruin an acquisition). I already work with ESP32 and have done closed-loop DC motor stuff before, so I'm just curious if this is something I could drop in and be happy with.
- iancmceachern 4y ago
  Yes it would
- _spduchamp 4y ago
  I primarily use the Vertiq line because I'm dealing with speed of spinning a rotary magnetic bow, and timing a robotic drumming. I don't think Veriq is the right fit for a microscope stage. They have a new line of closed loop steppers that would be better suited for that type of motion control. https://www.crowdsupply.com/iq-motion-control/iq-fortiq-bls42 https://www.crowdsupply.com/iq-motion-control/iq-fortiq-bls4... These should provide very smooth and precise position control. These units haven't shipped yet but will be soon.
iancmceachern 4y ago
Another product in this vein, Teknik motors. They're fully integrated, give them power and Connect to them via USB amd program it. Once you program it you can just use the gpio pins on the motor to wire up switches or other types of control. Super easy

opwieurposiu 4y ago

One thing to note about steppers, If you take them apart they will loose half their torque. In the factory they magnetize them after assembly. If you take them apart the lower permeability of air causes the rotor to somehow lose much of it's magnetic field. Physicists please chime in, IDK why this happens. We discovered this after machining some stepper backshells to accept optical encoders.

oakwhiz 4y ago
This is fascinating, I hope someone knows the answer. Is it possible that they magnetized the teeth of the rotor as a Halbach array?
- adrian_b 4y ago
  Any permanent magnet demagnetizes partially whenever it is taken out of a closed magnetic circuit. If the magnet is made from a material with very high coercivity, the demagnetization may be negligible, but it is always recommended to store permanent magnets only with a piece of soft iron in contact with their N and S poles. To reach the maximum remanence possible for a given material, a permanent magnet must always be magnetized after being assembled in the final magnetic circuit.
  - GeorgeTirebiter 4y ago
    What about, say, Neodymium magnets? https://www.kjmagnetics.com/neomaginfo.asp https://www.kjmagnetics.com/neomaginfo.asp What I'm asking is: are Neodymium magnets NOT used in these applications?
    - jbay808 4y ago
      They are used in these applications, typically very high grade, unless you're buying a legacy product line. In, say, a hybrid stepper the magnet is usually a wide thin round disc, sandwiched between two steel rotor lamination stacks. With the link below you can examine the BH curve and load line for a Ø20 mm N52 disc magnet, 2mm thick, at 20 degrees C. (It's not exact because this assumes a magnet in free space and neglects the steel of the rotor - but it's an illustration). https://www.kjmagnetics.com/bhcurves.asp https://www.kjmagnetics.com/bhcurves.asp You'll notice that the load line (which assumes the magnet is in free air) is already landing within the "knee" where the intrinsic magnetization starts dropping rapidly. That's working too far along the hysteresis curve, where the poles are already starting to flip and demagnetize. However, if that magnet were surrounded by the steel of the stator, the high permeability of the magnetic circuit would put the load line at a steeper angle, where the magnetic field through the magnet would be much higher. Small changes in permeability around that point would not damage the magnet, but allowing it to fall all the way down below the knee-point would. It would not be completely demagnetized by that, but it would lose some of its original strength.

FatActor 4y ago

One problem I always run into with rotary motion: gearing. Finding gears of the right diameter, thickness, and thread pitch is always such a stumbling block for me. Most sites that sell gears to fit their motors have a small selection, and sites that sell gears are very hard to navigate (only to find out they don't sell in quantities <1,000 units). I end up having them laser cut out of HDPE online. Wish there was an easier solution.

iancmceachern 4y ago
The key, if you can, is to choose a NEMA standard motor, there are tons of suppliers you can get a nema gearbox from. They get pretty small, but if it's amaller than the smallest nema size I'd go to a place like stock drive components which stocks thousands of gears. The challenge is that gear tooth geometry is often more than 2d, so laser cutting may not be the best solution for longevity. For a quick and dirty prototype it's certainly fine.
- convolvatron 4y ago
  standalone gear boxes also seem to be really really expensive what i would really love is a set of compatible gears that work from the same shank and would allow easy construction of 1:2 or 1:4 or 1:8 and i could compose. maybe some 1:1 bevels too
  - iancmceachern 4y ago
    Check automation direct, eBay, Ali express. I recently bought a nema 23 50:1 gearbox for a project for $50
doctorwho42 4y ago
It really comes down to the fact that gear shaping/cutting machines are quite specialized machines. Therefore demand a higher cost to buy (machines cost) and setup (tooling cost). For example a single gear shaper cutter is on average $700-$1000, and that's for a pretty standard and brand new cutter. So without taking into account actual time to set up the machine, program it, and feed it material. You are already having a high overhead. So the only real way to deal with that cost is in volume or cost. But when looking at the hobby market, volume is out of the question (who wants to buy >1000 of one gear for a personal project) and cost is out of the question ( if it's so expensive, I might as well 3D print or laser cut or waterjet some) So it's an odd market to get into.

waynesonfire 4y ago

how does one protect the microprocessor from the back EMF? Do you need an optoisolator?

gwynplaine 4y ago
That answer would depend on the type of motor. For a DC motor, they are rarely connected directly to the microcontroller. But you can put a diode across the motor terminals to minimise any back EMF. A stepper would typically have a driver circuit between the microcontroller and the motor. A small servo would usually just need one signal connection to the microcontroller, there's no back EMF via that path. You would of course also need common ground.

deleted 4y ago

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fumoto 4y ago

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gwynplaine 4y ago

I feel like there's a gap in the hobbiest motor market. On the one hand there are stepper motors which can withstand lots of radial load thanks to steel shafts and bearings. They also provide some relative position control and no absolute position feedback (at hobbiest prices). On the other there are servos, which typically have weak components. Plastic gears, shafts and bushings which cannot withstand radial load. But they do allow control of absolute position. For many robotics projects, a hobbiest has to choose between servos which are physically weak, or steppers which can tear the project apart if they don't home correctly. And of course the hobbiest has to roll their own safety/endstop system every time. I'd love something physically like a Nema 14/17 stepper but with a servo interface. However I can't find them anywhere at hobbiest prices. Why are there thousands of good value steppers and thousands of models of servos, but nothing in between, I wonder?

jbay808 4y ago
It's worth distinguishing between two completely different types of "servos": RC hobby servos, and industrial-type servos which are robustly built like steppers but significantly more fast, accurate, efficient, and powerful. They are hard to find in Nema 14/17 sizes but not impossible. RC servos typically have an analog or PWM signal interface. That would usually not be accurate enough for an industrial servo in positioning mode. Industrial servos, like steppers, have a digital interface which might be a serial format or STEP/DIR pulse train. Some drives will accept a -10V to +10V analog signal for velocity or torque control mode. Anyway, here are some Nema 14/17-sized industrial servos with online pricing, which might be what you're looking for? https://en.nanotec.com/products/2262-smart-servos-motors-with-controller-drive https://en.nanotec.com/products/2262-smart-servos-motors-wit... https://catalog.orientalmotor.com/viewitems/l-categories-servo-motors-tuning-free-servo-motors/50w-nx-series-servo-motors https://catalog.orientalmotor.com/viewitems/l-categories-ser... Or many companies offer stepper motors with built-in encoders and controllers to prevent missed steps: https://catalog.orientalmotor.com/viewitems/az-series-absolute-encoder-servo-motor/az-series-42mm-absolute-encoder-stepper-motors-ac https://catalog.orientalmotor.com/viewitems/az-series-absolu... https://www.zaber.com/products/stepper-motors/X-NMS-E https://www.zaber.com/products/stepper-motors/X-NMS-E

atonse 4y ago

Wow this is AMAZING! There are a whole set of projects I’ve just not tinkered with because of my lack of knowledge about motors. For example, I want to make my bicycle hook system run on a motor. But winches are too strong. Don’t need something to pull 1500 lbs. just 100 lbs. All I know is that it should probably be low rpm and higher torque. Another is to play with something like curtain opening motors but as long as they are as quiet as possible. Hope this resource helps with the first principles understanding of how to pick motors, etc.

conductr 4y ago
> Don’t need something to pull 1500 lbs. just 100 lbs. I suspect with a smart pulley design you could get that down significantly as well
- atonse 4y ago
  So the problem is that I don't even know where to start... where to buy, where to experiment. Say I want to hoist a 30 lb bicycle to hang on a 10 foot ceiling. The winch just needs to pull the rope (the pulleys are already installed). For that, how to go about finding the smallest motor needed (that's also quiet, I love when motors are generally quiet and don't whine). DC Stepper motors seem like the right solution there.

dTal 4y ago

As an aside that might be of interest to some - if you want to build a machine out of steppers, servos, digital output pins etc, and you want it to operate under tight timing constraints, and you want to avoid getting your hands dirty with finicky embedded programming, the Klipper project - nominally a 3D printer system - is sufficiently modular to be an excellent base. The developer documentation isn't perfect, but it's pretty straightforward to write new modules for it, all in Python, and it performs extremely well.