Practical Insight in selecting stepper motors for your build -Old Version
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- Опубликовано: 12 янв 2016
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• Practical Insight in s...
This video is an attempt to relay some practical information regarding the selection of stepper motors for your CNC build (or any other need for that matter).
As a post edit note, I will say that I have UNDER estimated the capability of a 400oz NEMA 23. I could have built my entire 4' machine with them and been fine. I would have saved some $ and had a smaller control cabinet. But hay, that experience is what I'm sharing so others have a better chance of getting their design right on. 
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Most of us who are finding 3d printing, CNC etc. interesting will have figured out that steppers come in a variety of sizes and specs. Many of us have NOT come to grips with what motor is needed for a particular application. This is one of the most useful videos I have seen when it comes to attempting to plan a project. Thank you very much! (I look forward to following any videos you post on your machines.)
the hardest part is choosing the motor. Great overview and Thanks.
the handy thing about that nema 23 is that having a shaft on the other end allows for a hand wheel and manual operation as well as cnc, very handy on say a mill or lathe(almost esential) nice video, i'll have a watch of your others to see what more i can learn as i'm still in research mode, pennies are harder to come by at my age and even harder to part with once i decide on a plan. thanks for sharing your hard earned knowledge
The tip relating to ‘round’ steppers was incredibly helpful, as I managed to pick a set of 3 round nema 23’s for pennies that are fantastic! Thanks heaps!
Thanks for the great info, I am just starting into this CNC game, and have been seriously sourcing components, your video clears up questions about motors, thanks again.
Just found your channel, great info. I am just ramping up the design of my own CNC. I purchased Mach3 and plan to convert my small mill as a practice run. Thanks for sharing.
Very helpful spent the past two weeks trying to gauge what size I need, wish I found this video two weeks ago. Thanks
Ryan Marquez Glad it helped. Good luck on your project.
Most helpful video I've seen so far. Thanks
edward kinsella Your very welcome.
Thanks for taking the time to walk thru the detail. It was very helpful!
Hey man - I think I might have said thanks before, but I better do it again. I've come back here a couple of times now to re-educate myself on the NEMA specs... Great video and content.
Your still welcome. ~P
Thank you for taking your time to share this information.
Nice video ! I will try to complement it with a few formulas for those who want to analize different scenarios when designing their cnc. I am a metric guy , so those who are used to imperial will unfortunately have to convert the numbers from metric. I will assume that it is going to be a gantry router travelling for 1,5 m on X (the long axis), ball screws of 25 mm diameter and 5 mm pitch, and that the gantry itself together with the Z axis will weight in 100 kg, milling aluminium, 2,2 kw chinese spindle. The formula for calculating the torque of the needed motor is: (Total torque) T = [ (driving torque at constant speed) Tc + (torque due to preload-should the case be) Tp + (driving torque due to acceleration) Tacc ] x number of pinion’s teeth / number of driven gear’s teeth. I will go into each of them . 1) The torque at constant speed Tc= [(Axial force+ Cutting force)] x pitch / 2 x PI x ball screw efficiency. Now, the numbers: Axial force = coefficient of friction of ball screw (0,003-0,005) x mass (100 kg) x g (9,807 m/s^2) = 4,9 Newtons (I went for the 0,005 coefficient of friction). Cutting force for aluminium on a diy router with a chinese spindle of 2,2 kw depends a lot on the rigidity of the machine/gantry and it will be anything between 0 and 40 Newtons (the gantry of most diy routers is made of an aluminium plate of 20-25 mm thick, which is peanuts because the main force in a gantry is torsion and an aluminium plate pretty much sucks at torsion, but for some reasons many people go this way). If we choose 40 N as cutting force under these circumstances, and knowing that the ball screw efficiency is around 90% (0,9), then torque at constant speed is: Tc = (4,9 + 40 N) x 0,005 (pitch in meters) / 2x3,14x0,9=0,04 Nm (which is peanuts ) .2) Torque due to preload Tp has a more complicated formula, but as a rough guide a ball screw of 32 mm diameter will have a preload torque between 0,4-0,8 Nm and a 40 mm ball screw will have a preload torque of 0,8-1,1 Nm; the reason for having an interval is that the nut when travelling along the ball screw will encounter ’’ups and downs’’ which will act like breaks. Ball screws are preloaded with o force of maximum 1/3 of the axial force (2,5-10%of dynamic load) and will only eliminate half of the play in the ball screws. For a 25 mm ball screw -if there is the case of a ball screw preload- it it reasonable to assume a torque preload of 0,5 Nm. I would also add a 0,2 Nm torque due to drag forces created by medium - instead of high- precision when mounting the ball screws and the guideways (lack of parallelism and perpendicularity ). Therefore I will add this imperfection (due to mounting) as a safety factor of 0,2 Nm to the 0,5 Nm of preload torque . 3) Torque due to acceleration Tacc = (moment of inertia of the gantry + moment of inertia of the ballscrew + moment of inertia of the pinion/gear) x angular acceleration of the stepper . I will consider a direct drive of the stepper , so no pinion and driven gear . Moment of inertia of the gantry Jg= mass of the gantry ( kg) x pitch^2 (m) / (2 x PI )^2 = 100 kg x 0,005^2 / 6,28^2= 0,00006339 kgm^2. Moment of inertia of the ballscrew Jb= ½ X mass of the ballscrew (kg) x radius of the ball screw ^ 2 = ½ X 3,14 x 0,0125^2 (m) x 1,5 (m, the distance the gantry travels) x 7850 kg/m^3 (steel density) x 0,0125^2 = 0,0004514 Kgm^2. Therefore the total moment of inertia J = Jg + Jb = 0,0005148 kgm^2. Now, the angular acceleration of the stepper is to be thought of as follows: most steppers lose half of their rated torque before they reach 500 rpm. Note that 500 rpm is basically an angular velocity. We need to come up with some acceleration/deceleration time and 0,5 seconds might be a good start. We have the angular acceleration a=(angular velocity ) v / acceleration time) t. Which we need to transform in radians, therefore a = 2 x PI x rpm/60xt = 2x3,14x500/60x0,5 = 105 rad/sec^2. Now we calculate the torque due to acceleration Tacc= Jx a= 0,0005148 x 105= 0,054 Nm. Lets add them up: Total torque T=(torque at constant speed) 0,04 Nm+ (torque due to preload and due to mounting imperfection) 0,7 Nm + (torque due to acceleration) 0,054 Nm= 0,8 Nm. This is where all manufacturers recomand to multiply this calculated figure by a safety factor of 1,5-2. If we choose the safety factor of 2 the result is that maximum total torque is going to be = 0,8Nm x 2 = 1,6 Nm. Please note that this value is valid for 500 rpm , which translates into feed as follows: 500 rpm al stepper shaft, direct drive, ball screw of 5 mm pitch, means that the feed will be 500 x 5 = 2500 mm/min. Therefore, the stepper needed is that stepper that has a holding torque between 3 and 4 Nm. (the maximum torque of 1,6Nm to be half of the holding (maximum) torque ). It will depend a lot on the driver. For example, a ES-M23440 motor from Leadshine will have 1,6 Nm at about 500 rpm with 48 VDC driver; if the driver is changed to a 68 VDC, at around 500 rpm the motor will develop about 2,4 Nm (www.leadshine.com/UploadFile/Down/ES-Md_V1.3.pdf). I hope it helps.
i'm sorry to be the one to do this but TL:DR..... i do think the world standard in Cad/Cam/CNC should be metric even though i grew up with imprerial.. thats good for wood and what not but machning precice stuff its a dick and a half.
Excellent video, I sort of knew some of the stuff but was nice to see it all together.
Thanks. I appreciate the feedback.
Thank you for this video. Answered a lot of questions I had! The whole NEMA size thing and selecting the coupler sizes was giving me anxiety. My plan is a 1000mm x 1000mm setup. Man the ballscrews are much more expensive than I thought they would be. I thought the most expensive part was going to be the electronics, nope. Great videos. Keep em coming.
Thank you so much for the perfect video. This is just the info I was looking for
Glad it helped.
Thanks for the response and yes please do a video on your machine, I would love to see it in action. I could use more motivation!!!
I am currently fighting with Corel not importing my video clips. When I get that settled I'll put one out.
Such a helpful video. Thank you.
Thank you for the video really enjoyed it
Dude, you deserve way more subs. You'll get them, just keep producing videos.
Thanks. That is nice to hear. I beat myself for not making them faster, but I'm trying. I have a new one almost done now. It is about the spoil board and work holding that I have chosen.
Excellent video , This was very usefull infos
Ty for your video. I'm building a 23 nema unit. Was considering 34.
Very helpful video ! thanks !
Exactly the info I was looking for. Thanks for doing this video. Gonna subscribe so I can check out more of your work.
Glad you appreciate it. I am painfully slow at getting new videos out, so hang in there.
Thanks for very useful info....
Thank you for making this video
I really dig how you DIDNT go with the upside-down-field-goal style gantry… To me this looks much more solid… I have been thinking about building mine this way, because I can easily add another set of linear rods at the bottom of the Y Axis…. I think this design adds a whole lot more stability to all the axis when compared to the typical gantrys that just flap in the wind, causing more jitter at higher speeds, and or harder materials. Thumbs Up!
It's actually less solid, at least in terms of compound flex. All three axes being in a line from (Workpiece > Frame > X > Y > Z > Endmill) introduces a little movement from every axis between the endmill and the workpiece. A fixed gantry is different in that the most solid part of the structure sites in the middle (Workpiece < X < Frame > Y > Z > Endmill) which is better for chatter reduction, resonances, etc. Both topologies have their advantages and disadvantages, but for most it's difficult to know how to leverage those advantages to your benefit.
Nema 34's are total overkill for a 4x4 router table unless you are building an all steel industrial table that you intend to run a 4hp or more spindle on. I have a commercially built 4x4 gantry style table built with 4"x4" extrusions. It came with Nema 23 275oz motors (one per axis), and it works quite well even with a 2.5hp router. Mine is rack and pinion drive on linear rails, so it probably has more drag then ball screw drive. In my opinion people get caught up in overpowering mainly due to a mistaken belief that they need super fast rapids (I've seen guys boast of 1100 ipm rapids). The reality is you will never be cutting anywhere remotely close to that. Most of my routing on pine or MDF is in the 40 ipm to 90 ipm range and my machine can also be adapted to plasma cutting which I typically do at 150 ipm. My machine's max speed is approx. 200 ipm rapids. I have never felt that I needed more. Overbuilding results in a LOT more cost due to needing higher grade stepper drivers and sometimes separate power supplies for each motor (not to mention the higher cost of the motors themselves). When building your own table, I would recommend looking at similarly designed commercially available tables and noting what size motors, power supplies, and drivers they are using. Some professional engineer designed those systems, and if they are being sold commercially, then they work just fine.
what a great help thanks for your video
Man, can't tell you how bad I needed this video... Thank you!
Your welcome. I really enjoy all the positive comments people have made about this content. Make sure you read the full video description comments too.
So do you think the nema 17's could drive a 20x20in cnc for cuting aluminum?
If they are not direct dive and the axes are on a precision slide. Yes. The feed rate will be very slow for cutting aluminum on something that small so speed is not an issue. You will want to have zero backlash so I would go with ball screws. That setup, yes. Keep in mind that the 17,23,34 sizes are frame size and can have different torque ratings
lol man, I may be getting in over my head. I'll go with 23's to be able to upgrade table size once I build my shop (I have a lot of work to do) and have a little more room. I still would like to go with linear bearings and acme rods for control (I actually plan on building it boxed instead of gantry for the small build and enclosing it.
However, I keep reading about this backlash, but no real explanation of it. Could you explain a little more what it is? Or, possible future video for you to monetize.
lol nvm, I looked it up and realized I just didn't know that was what the action was called for the 'wobble' between engagement of gears.
I guess I should also mention I'm fairly educated in the mechanical field (been working on cars most of my adult life and was a crew chief [mechanic] on F-15's)
Would e-mail be a better form of communication? I ask because I intend to pick your brain on this subject as I have full intentions of building my own.
Thank you, lots of info. Planning on a 5' x 10' plasma table.
Good luck. Plasma table is my next build. My first was planned to be 'convertible' from a spindle to plasma, but my design turned out to be too heavy to make it feasible. In additions, because all my motor controls are portable, all I need to do is build the machine and add motors. P.
Thanks, still settling on designs. At the moment, It looks like a water table. Doing gantry research.
Thank you. It was a little hard to hear you, but this was a much better approach to what I am trying to do than trying to master calculations. I wonder if you would be able to answer a question or two, as I am looking at steppers instead of conventional motors mainly because of weights, and then the ability to maintain constant speed. My machine looks very similar to yours, and was originally designed as a router table. It was partially converted to run tapping heads. I am trying to replace the motors that drive the tap heads, and conventional motors seem just to heavy by today's standards. To drive a 1/4-20 tap through 1/2" of steel (through hole), based on the information I have found, I need about 1/3 hp at a speed of 800 rpm. This is the largest tap size I would use, and most likely the fasted it would need to go. The stepper would run continuous throughout the cycle, and would only need to run in one direction. Again, the main reason I am looking at steppers is the lighter weight and constant speed between 400-800 rpm, as compared to a dc motor and gearbox.
rockford-ettco.com/DownloadBroch/Etctvr%206_(Pg%2046).pdf
Thanks for sharing!
That's a really useful overview and answered quite a few questions I had since I'm about to embark on my first CNC build. Thanks for sharing!
FANTASTIC
Very helpful
I recently finished converting a 600mm lathe to CNC using NEMA 34/1200 steppers, possibly overkill but no regrets. As well as increased torque, the bigger steppers have higher position holding strength. I suspect that the bigger motors will be less inclined to miss steps also. I found your video to be very interesting and well explained. Thanks.
Thank you John and congratulations on your lathe conversion.
Great video. I'm building a plasma Table 5 x 8. I'm looking at the Nema 23 stepper motor is a 4-wire.439 oz in
24 stepper motor which is an 8 wire 425 oz in. I am confused which one is better one would work for me. Thanks
thx for your information good work
well done. Thank you!
cool man thanks for the info. gonna actually get a nema14 believe it or not. a wee guy. good stuff.
Hello, i have made a cnc frame 40 x 60 cm wide with v slot aluminium profiles, have mounted 16mm rods and bearings and a router trimmer. Wanted to ask: for this cnc frame size and 16mm rods and bearings: 1. what thickness of lead screws should i use and 2. which is the smallest stepper motor that i can use ?
OMG I think I got it! Just using deductive reasoning These
drivers must be constant current devices so when you set the value of current
you desire the voltage starts low and increases until the set current is attained then some type of clipping occurs. You can’t adjust the voltage without changing the current. So
if the resistance is 2.75 ohms and you set the current at 4.2 amps then the
voltage will be something like 11.55 V if you lower the amps then the voltage
goes down. I hope I’m right and if I am I hope this helps.
Thank you very informative
Hi ,I want to make cnc machine with working area 500mm x 500mm , I want engraving depth around 15mm , is it enough to put 200w spindle with nema 23 stepper motor.
And what is your advice about liner rod and screws and coupling.
I really enjoyed this video! Im doing two separate builds at the moment and have been trying to figure out which motors to use! I am building a 4x8 ft plasma cutting table and then a harbor freight table top mill that I have been working on converting. My two big questions would be what size of motors for each project do you recommend and which controller and program? I have been looking at the MASSO and the Centroid Acorn just because you don't need a PC to run them.
Thank you very much for the information. Please raise the sound. .
Did you ever have any problems missing steps? I mean, I use to have that problem till I decide to use Hybrids.... also any chance you could share what would be the conversion from watt /amperes to torque? I have been looking at this hybrids for a while that seem good but I honestly don't see the chart that you showed in your video!
Thanks in advance!
Since you are a DIYer...save money and get an good omni-directional, corded mic and make a simple boom to be overhead and slightly in front of you...or...spend the $$ for a wireless.
Appreciate the videos. Keep up the good work.
@Je Durham - I went 'medium'. I decided that I am putting enough effort into these videos that they deserve better audio. I have ponied up for an ok wireless transmitter and receiver set, along with a lapel mic. Here's to hoping.
Nice, sir
hi
i have rotary table
i like to make it stepper indexing
its 200 kg on bearing shaft
what size of stepper motor for this job
That was really helpful. I want to convert a 9x49 inch Bridgeport clone knee mill. Would you do a video explaining everything between the computer and the motors? I just don't understand the lingo or the parts the lingo is talking about. I know each motor will need a power supply but don't understand what makes it step off or know where it is. I'm gonna subscribe because you laid this out in such an easy way to understand.
Thanks for the info
Your welcome. ~P
Please help me. I need a stepper motor to change the direction/aim of my 0.5hp water pump. It's for my thesis 😭
Thanks for sharing. This is a real help for the hobbyist who just wants to gets started, have a play around, make some mistakes and learn from them. Searching around to get a rough idea of stepper sizes usually ends up in trawling through long forum posts of calculations requiring every spec of your machine that only seems necessary if you want to mill stainless steel to aerospace tolerances.
I'm planning on building my second machine for cutting mainly aluminium. It will be a smallish fixed gantry welded steel frame, likely 2x2" box section with the X moving along the gantry and the table moving along the Y. The working area will only be about 12x12" so it should hopefully be quite rigid. I'm looking at roughly 185oz NEMA 23 steppers, do you think this sounds in the right ball park?
nice presentation. I am in the early stages of my design. My question is the power supply next to your motors what size is it and who makes it.
thanks
the nema 23's I find are 270 oz. in v 3.2 cu 2.8 length 3.1 in.. what is t he designation of the larger 23?
Hi!! thanks for the little video!! I would I would like to ask the link of the rails and coup lings for the nema 34 please. As you sad you had to buy a new set. Thanks!!
Where did you get the long rails and screwlines from? Iam looking for 1300mm long ones.
very informative video. I recently started building a 3d printer, and want to build a bigger one as i underood all the workings of it. except for one part, which brings me to this quesiton: How or where do we put settings, so that the motor knows how much to turn for 1 millimeter movement of the head(nozzle or laser cutter or router etc)? I would really like to find this information. Thanks and great video.
many thanks for the video! It's a bit ironic that to do a proper job adapting the motors (e.g. the plates at 7:35) you needed a heavy duty end mil -- my baby sherline won't handle it. I guess it can be done with a drill press, after centering the holes on the sherilne.
if the stepper are longer, you can have more length of winding and thus, better electromagnet and so more strength
Hi sir how to connect 4 wire stepper motor to 12 dc adapter
Yo, Bill Belichick thanks for the video
hello sir
Please let me know
How can i know the stepper motor torque
-whether if in large amper means torque is also great
-what if the small resistance is big torque
Thank you very much!!!!
Your welcome.
Thanks for nice video. How many Ampers are your nema34 for the CNC and at which voltage you driving it?
I don't wanna use stepper motors as I may miss some steps due to over load , can I use bldc
if my previous question isnt clear, this is what I mean: with a certain size gear on the stepper-motor, it needs to turn a certain steps to move the head for 1 millimeter. If I double the size of the gear, the stepper motor would need to move half way to reach the same position as with the smaller gear. Where or how is this done or set? I assume its some firmware on the "controller board" but I am still a bit unclear.
hello sir. i want to build my cnc machine . i am planing to make it a (4x4feet) and i am thinking to choose the Nema 34 1600oz . do you think that the motor it will be enough for it. and enough for graving steel and aluminum. my machine i made it from steel. and thank you for you video.
I'm looking in to cncing my g0704 mill, now regarding brands, is there a noticeable difference in quality of stepper motors or drivers that I should be aware of? Thanks
The biggest thing about some of the different brands/quality is the customer support and getting documentation in English. From what I have gathered, the cheap one work fine. If you go the cheap route, look and see what other g0704 owners are using and copy them so if you need help, you can lean on them for support.
Hi There,
Thanks for the informative video, I have a few questions if thats okay,.
1) Is the NEMA 17 the smallest of the Stepper Motors?
2) These Stepper Motors, how many diverse stops can you programme them to make within their full 360 spinning cycle?
3) How large is their power source? Does the power source normally come included with a motor?
4) Average price you should be paying for a NEMA 17?
Many Thanks!
hello sir i make 3axies cnc i use SANYO DENKI 103H7121-0415 stepper motor 6 wire this motor Consider only 2A and 1.8 step not Consider power supply
so how much power use this motor and which wire A+ and A- and which wire B+ and B-
This is exactly what I wanted to hear! I am building a 4 X 4 CNC Router Parts Kit machine and went with the 425 oz.in NEMA 23 motors and controller from Xylotex. I'm glad to hear that your machine would have been fine with the NEMA 23s. How did you come to that conclusion? Thanks for the info and I can't wait to get up and running!!!
+payday1963 I came to the conclusion that the machine would run fine on smaller steppers based on my experience with the Z axis. The Z axis with spindle is a very heavy piece of equipment. The force to move that vertical is in my estimation, vastly more than it takes to move any of the horizontal axis. Gravity is a b___h....you know.
Good luck on your parts kit. I keep promising to get a video out about the CNC it self but am failing all of you. P.
Yeah I ran 23s on my CRP4848 (4'x4') metal frame CNC and they ran just fine. 32s definitely work but are really overkill for a lot of nicer DIY CNC setups.
Very well done. You once again covered every question, plus more on the NEMA's, even all three sizes. I just viewed the "X axis success video" and saw what controllers you used. The DQ860MA controller seems like the one to get. But I may just play with some home made stuff before doing it the correct way. It's only money right? :)
+King Red Leg Thanks. Glad it helped. That controller seems to be the one of choice for Chinese manufacturers. One advantage is that the larger community has them so there is lots of experience to draw from. Now, my tune may be different if I knew how to make my own, as you do. Good luck.
I am planning to pull 2,5 - 3 kg weight with a belt connected to stepper motor. I think Nema 17 would be enough for that, it is related with the friction but friction will be reduced like icy road. Am I right, or do I need bigger ones?
Thank you
Unless minimal size is in order, I would design for a Nema23. Remember that these are frame sizes and you have some options for torque within the frame size. You could start with a small 23 and if it isn't enough, get a larger torque motor with the same frame size and swap it out.
3kg is 6.6 lbs on this size of the pond. Unless you have some mechanical advantage I think 17 would be small.
TY. Do set ups. You should be making your own motors with your equipment ect.
My home brew 2 by 3 footer using v-rollers running on the edge of 3/4 inch angle iron, 4 on X, 2 on Y and Z. My X ay cad program. nd Y are rotated 90 degrees to the left from the usual setup of the Gantry being X making my gantry the Y. That puts the XY zero point to my belly on the left, just the way you see things in any cad proggy. I work from the side, not off the end due to space reasons. All MDF with the MDF well sealed with 3 coats of the best grade of OIL based paint I could find. A sample was soaked in a bucket of water for a month with no swelling, measured to within say 4 thou. The bed is a torsion box setup capable of holding a bit over 500 pounds in the center with the deflection under 5 thou.
All 3 axis are 1/2 10 Acme thread with anti backlash nuts. X and Y are 5 starts that results in 2 revlitons of the stepper per inch of travel. Z is single start so 10 revs per inch. Using divide by 2 microspeps gives a resolution of .0015 per step on X and Y. Z has no microsteping with the resolution to .0005. As Z is only 6 inches travel speed isnt that big of an issue. ON X and Y 300 IPS is easily possible but I run at 200. Faster IPS requires more ramp up so there is no significant time gain going over 200 IPS. All 3 steppers are 23s at 450/0z inch running on one power 36 volt supply using a trim router.
Using 1/4 shank bits i usually stay within a couple thou. With 1/8 shank bits the bit deflection becomes the real factor in resolution.. They bend easier. Same cut with everything the same the 1/8 shanks usally add a couple thou off what I get with 1/4 shank bits. Typically what I get off ideal in cuts is around 5 thou or so worse case... Close enough for most things..
The big issue with steppers alone of ANY size is the system runs open loop. In other words, the controller just assumes a proper move was made. If you dont push hard enough to loose steps, things work fine. If you hang an encoder on a stepper then the controller will ALWAYS know with absolute precision where things are all the time. If you need closed loop the go with servos. Costs more but you can get far faster moves and more power in the same frame sises. For hobby or small production uses a properly sized stepper will be all you need. Just pay attention to friction and inerta effects of the system and they will work fine.
hell, whats the different between Nema 42 20N.m 2 Phase to Nema 42 20N.m 3Phase 230V ?
Great
Thanks! Good info.
Hi, I have been following all of your CNC build videos and am impressed with your logic and common sense approach. I am also more familiar with imperial and am planning on building a 4'x4' machine as you have. Since I am looking at milling wood, plastic, and aluminum, would you recommend using NEMA 23 with how much torque? (400 - 500?). Have you considered the Clearpath servo motors? Thanks for your videos. Eh!!
Bill, I would say that a 400 nema 23 will be fine for your Z. A little bigger for X and Y if you can. Some of that depends on your design. Going with servos is not something I have entertained. The cost benefit just isn't there for me. I have yet to jam my machine up to the point of skipping steps. Even if I did miss one or 10, the tollerences for wood are not that critical in most cases. Are you aware that @Tormach CNC mills don't have servos? Best of luck. CNC Plasma table videos are coming soon. I'm cutting prototype parts for it with the router. ~P
What are you using to drive the motors?
I am creating an equatorial mount for my 2-3kg Newtonian Scope. The distance to the rotation axis would be around 20cm. Should I use a Nema 17? I am looking for good Holding torque since I am more worried about the static position of the telescope.
Sounds a little small to me. I would consider 23's...or at least the option to switch to a 23. ~P
Felipe Menzella it depends on how you drive it. My ancient eq mount had a worm drive. 17 would be more than enough. The worm reduces a need for holding torque. You can't back drive them. I'd assume the other axis is tooth belt reduction arrangement. Smaller motors and reasonable max slew rates mean longer battery life out in the field. Remember the scope would be balanced so it's mostly friction and inertia not weight to consider.
Do you have some plans of making a video which discusses more on proper selection of steppers base on particular requirements or applications..and explanation on stepper specifications like rotor inertia...load to rotor inertia....current rating against the load
No. It is level level of technicality that I had not use for in my design and is exactly why I did this simple striaght forward comparison with discussion on how it was applied in my situation.
This is a very inter interesting video , I would like to build my diy cnc plama 4'x4' like yours .All information and suggest I can have is important , I take it and what and where buy hardware I need thanks very mutch for all
Here is a link to the ebay collection that has most of the parts I used. I would suggest looking at Nema23 size steppers though. r.ebay.com/YPustw
How much does your os Together with the spindle?
FYI, 425oz/in NEMA23 motors are total overkill on my CNC'd HF mini-mill when directly driving the ball screws. It has no problem moving any axis (although the Z has an airshock assist, never tried it without it). 1200 oz/in motors are definite overkill (especially if you use any kind of gearing to increase the torque). I think that the more important considerations are the driver and it's ability to deliver current and utilize higher voltages. Stepper motors do better with the proper current and the greater voltage they will tolerate translates into decreased ramp-up speeds. The 1/2 current setting on the driver is typically the holding current (which is typically fine at 1/2 current) and it switches to full current when actuating the motor, this will help the motors run cooler typically.
Thanks great vid- question: I’ve got 3 power supplies, and I’m running 2 Nema 34 for the x, and want to use a 23 for my Z. Using a smooth stepper too... do I have to have/use 3 power supplies for this? And should I use a pulley reduction for the z? I have a 5start screw for the z and two v style linear slides for it too (insane expensive at 300 for both -pacific bearing) v quad rails rollers 1400.00modern Linear)- and have 3 640 oz in for the y and z .can I use the old drivers for the 23 for the z? It was a xylotech kit!
Thank you! Great vid !
I am running my Z on direct drive with lots of resolution and no small amount of mass it is moving. I would not expect you to need a step down pulley. As for the power supply, you only need as many as you need to supply the requisite amps at the required volts. I have an individual one for each motor. I could have used one large power supply. ~P
sbirdranch Thank you so much for info, it was really helpful, and that’s what I decided to do. Thanks again.
I just bought 6 nema 42's for a giant project....... We didn't do load calculations. Just going to brute force it, if we can use geared or smaller then we will in the future.
Hi there What exactly project you do? If don’t mind
I want to create a turntable that supports 5 to 10kg weight on 50cm diameter plate. Which one should I choose? Should I have vertical on axis or it is better/more durable outside connecting the axis with a rubber belt?
That depends on how hard it is to turn the table. I would suggest that the biggest thing to overcome is the initial start of the turn so if you are making small steps around the axis, you might consider some mechanical advantage like a step down belt setup. This will also give you the ability to make smaller steps. 5-10kg is 11-22lbs roughly. For a single motor and the cost difference, I'd design for a nema 34.
As for the motor connection....steppers are not designed to carrry a load down their axis. They don't have a trust bearing. So regardless of what you do, direct drive or otherwise, the table has to carry it's own weight.
P.
Thank you.
To answer your question about how "longer" motors have more torque, it's because they have larger coils and larger armatures.
Imagine grabbing the handle of a stubby screw driver vs grabbing the handle of a full sized one. It's kind of like that but with EM fields.
Great description. Thanks Mike.
Thanks for this, I think you just saved me a bunch of money i was going to go with the Nema 34's 1600oz but there pricy, What torque do you think Nema 23's would have to be for a similar build to yours for plasma and mill for all Axis? should i just get the highest i can?
I will be using 400oz Nema 23's on my plasma table.
Audio is fine and more than bearable.
Thanks. I have started using a wireless mic. For videos where I move around it was not acceptable to me. For videos where I'm just talking, the build in mic was ok.
Good to hear, looking forward to more content! Thanks!
I know that most people have a full set of either nema 23s or nema 34s. I was wondering if it it's possible to use a nema 23 for the Z axes and nema 34s for X and Y axes. I'm asking ecause my X and Y could use more torque or power.
Absolutely. My CNC router is setup that way. I am running separate power supplies as the 24 takes less voltage. Other than that it is no big deal.
@@sbirdranch Cool, thanks for the reply
hi i need a motor to operate a cnc lathe carriage for heavy duty work but i not confirmed which is best kindely help me. which is best servo vs steper according torque and what is steper nema
Steppers have brave torque at low speed and as you ramp up your speed lose the power and "PRETTY OFTEN START TO MISS STEPS" leaving you with a crappy job that you have to repeat..... (But steppers are very cheap) Servos usually the really good quality are ridiculous expensive!! and you can not use servos without Dedicated & Proprietorship software and hardware... I would advice if you have enough money to go with hybrid steppers.. they are some what more affordable and reliable.
@@Migueldeservantes Hi friend, I'm looking into starting a build and i'm looking at the ClearPath servos from Teknic. Do they qualify as a hybrid? I saw a video saying their high torque was wiggling their entire build about 1/8". Would these have the same missed step issues that you mentioned?
Hi sir. I watched all of your videos about this CNC machine and it looks amazing. I would like to build sometrhing about 8'x4'. My first question is: the longer you go, more torque you need?. I see that those 1230 ounce-inch motors are just monsters. they would probably work good on a biger machine. But my second question is: are those 1230 ounce inche motors a bit overpowered? you said that you use them at half they amperage. I know it is a bad idea to use a motor to his full power, but maybe 3/4 of the power may work as well? maybe a 900 ounce-inch would work, and i would not loose to many speed or presicion?
and last but not least. I see that rail sistem and the thread that you are using. I know that the rail wont bend on a long distance because of that platform that goes along all the rail, but what about the thread? is it thick enought to not bend at 8' long? could it work with thinner ( you are working with 50 inch rail and thread right?)
Where to start....First...good for you to start an endeavor like building a CNC. I'm sure you will have success.
Motor size...yes they are big. But I like 8 cylinder motors, not because I need that much torch...However, I have learned that there is a trade off with speed, etc. I haven't studied down that deep to truly understand what I traded off with the size. I can say that I have not missed whatever I gave up. If that helps. As for precision, the number of steps the large motors make is the same as the small motors I show in this video. Nothing lost there.
You are correct to question the ball screw length when considering an 8' machine. At 4' and full RPM they almost want to wobble. I have also never seen 8' ball screws. For an 8' machine, I would use rack and pinion. Then I would use a belt style gear reduction. I didn't do rack and pinion because of the lash that you cannot avoid. Ball screws are what are on a milling machine so I wanted that. There may be other options I haven't explored. I wonder how they keep large production machines tight?
There is a guy on youtube calle frank howarth that have buildt two 8'x4' machines, and in both he uses rack and pinion and that kind of belt reduction that you said, so i guess that is the way to go on a big machine. The reduction is used to maximize the power output of the motor right? puting the rack right on the motor would force too much the motor i guess.This guy uses a lot of 8020 aluminium extrusion, wich i think is WAY very expensive, it may be cool and lightweight, but more than 10 times expensive that regular iron.
It does more than amplify power, it also increases your resolution and ability to make small steps. I can move a fraction of a thousandth because of the thread pitch and motor steps. The motor alone, direct drive, won't give you that.
Frank has done some nice work. I would definitely refer to his designs for ideas on a big machine.
Best of luck in your build.
thank you! you will see my video when i build this big machine! i will start with a little one to test things, and my second build will be a big bad boy
hey chief. got a question. to run a machine that large 4ftx 4ft what bitsize ecm did you run. 8-bit or 32-bit. going to build a 3ftx3ft unit myself. and was wondering if I would over run an 8bit controller.
I'm not sure I understand your question, but based on the last sentence, I think the question is, what size (bit size that is) computer did I select for a controller. I'm using a 32 bit Windows system running Mach3. Does that help?
I am in the process of building my own CNC.
What are your travel speeds with the nema 34's?
35 to 40 inches a minute. That is limited by a vibration in the ball screws if i go faster. It has been suggested that if i had double ended motors with dampers on them, the harmonic causing the vibration would be deminished and i could go faster. Good luck in your build. ~P
@@sbirdranch thank you sir, I am enjoying your videos
Can we use both Nema 17 (DRV8825) and Nema 23 (TB6650) on same Arduino simultaneously?
Yes. The signal is the same. You will have different power supplies and possibly different stepper drivers.