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/diy/ - Do It Yourself


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File: 51 KB, 707x768, Electric Motor.jpg [View same] [iqdb] [saucenao] [google]
1560187 No.1560187 [Reply] [Original]

We have all built small electric motors before, but does anyone have any tips for building a larger electric motor, perhaps one that can run a small vehicle? Any tips for building such a device?

>> No.1560192

>we have all built small motors

I haven't. Give me a quick essentials

>> No.1560198

The amount of time spent, the cost of materials and the knowledge needed would far exceed the cost of buying one that would be refined and way more efficient from the get go.

>> No.1560272

>tips
Fuck OP and all OPs like you who always ask for shortcuts and tips. Stop asking for “tips” on complicated industrial assemblies with dozens of variables.
>just optimize the lamination thickness bro then the rest is cake

>> No.1560280

>>1560198
Pretty much this.
Even if you build a working one (which is fairly easy) building a decent one would be near impossible without money, machinery and knowledge.
There is a reason why nobody uses home made motors.
Also they're cheap as fuck you nigger, if you can't even afford that you better put aside your electric dream because batteries will have you bankrupt, and the savings on your shitty motor will be GREATLY surpassed by the extra money spent on more batteries to have the same operating time.

>> No.1560286

It's really not worth it to build a totally DIY motor. Motors are so common, you can find them at dumps and junkyards, for cheap or for free.
Quit thinking about building a motor from scratch, and start thinking about rebuilding old motors.

>> No.1560289

>>1560187
https://www.youtube.com/watch?v=NFvMC3l3fGY

>> No.1560291

>>1560289
That's cool.

>>1560187
I want to try and retrofit an old forklift motor into a much better motor at some point, you can get those really cheap. A lot of people rewind the coils on those things anyway and you get the worst parts to machine already built, so I'm with >>1560286

>> No.1560715

>>1560289
i wanted to post that yesterday, but then didnt
problem with this design is the Armature not being made of laminated steel.
The great scott did a test of printed armature with Ferromagnetic Filament and the induction was still shit
Those Engines are absolute Torquelets

>> No.1560720

>>1560715
>problem with this design is the Armature not being made of laminated steel.

Which is why his stator is wound with the coils parallel to the radial direction while normal stators are wound perpendicular to project the magnetic field into the metal fins. In the way he has done it is almost like three toroidal coils sitting within each other and just like a coil in free space it should have a fairly uniform magnetic field close to the outside surface.

>> No.1560721

>>1560192
This is not a slight or a put down, but look around for highschool teaching material. Building a simple 9v electric motor is a classic highschool physics prac. You probably have all the materials lying around (which is why broke-ass schools like it).

>> No.1560726
File: 139 KB, 1186x662, stator.jpg [View same] [iqdb] [saucenao] [google]
1560726

>>1560720
He's also using a hallbach array to get the most out of the permanent magnets. He's actually using engineering principles to make due with the limitations of his materials instead of just dismissing an idea because it doesn't look like everything that came before. That's what cargo cults and brainlets do.

>> No.1560727

>>1560721
>look around for highschool teaching material. Building a simple 9v electric motor is a classic highschool physics prac

I googled and all I see are the little joke motors that spin but are worthless as a motor. We have this thread every so often, and nobody has ever built a home made motor except for that video up there which is pretty awesome, but anything involving laminations is not going to be home made, and there's a reason that every electric motor in production uses laminations.

>> No.1560738

>>1560727
oh fuck off the guy I'm replying to is after basics and that's what I directed him to

>> No.1560741

>>1560720
>Which is why his stator is wound with the coils parallel to the radial direction while normal stators are wound perpendicular to project the magnetic field into the metal fins.

You have no idea what you are saying. In his design and every other conventional electric motor with a permanent magnet rotor the only part of the stator coil that matters is the part that is in the slots and in every case the slots run along the axial direction (sometimes skewed for advanced reasons I won't get into) so that when the rotor rotates the magnetic field "cuts" across the conductors. That's what creates back emf when you spin the rotor without powering the coils, and that's what creates torque when there is current in the windings.

>> No.1560744

>>1560738

I wasn't trying to make you look stupid; I actually am curious as to what sort of motors they build in high school physics classes. My physics class did almost zero hands-on work like that. If they make the little spinning coils, then fine, but I thought you were referring to something useful as a motor and not a demonstration toy.

>> No.1560749

>>1560727
>but anything involving laminations is not going to be home made
I was going to comment above, they're actually not that difficult to diy.

>> No.1560751

>>1560187
build a shitty BLDC

https://www.youtube.com/watch?v=vnjCrLTMGxQ

>> No.1560760

>>1560751
Thanks, I have epilepsy now.

>> No.1560761

>>1560749
>I was going to comment above, they're actually not that difficult to diy.

That is great if you aren't exaggerating. Where do you obtain stock that is highly permeable and has been heat treated so that it is magnetically soft, and how do you create the slots? In normal motor manufacturing you bond the lams together and then you have to grind the OD or the ID to have a decent air gap next to the rotating magnet assembly; I suppose on a crude design you could get by with a larger air gap and weaker performance.

>> No.1560763
File: 69 KB, 1182x664, hallbach.jpg [View same] [iqdb] [saucenao] [google]
1560763

>>1560741
>so that when the rotor rotates the magnetic field "cuts" across the conductors.
>and that's what creates torque when there is current in the windings

Which is why he used a halbach array to try and extend the magnetic field as far out as possible, you can see with the viewing film that the field does indeed cut across the windings. Would it be better with a iron core, of course, no one is denying that, but saying that the motor produces no torque just because it doesn't have an iron core is flat out wrong.

>> No.1560780

There are interesting 3D printed armatures and custom ESCs you can look into.
Printing a winding device at the same time is probably also a good idea.
You can get them fairly large so I'd go with that for something like a heavy lift drone before dropping thousands on commercial parts or heavy ass salvage.

>> No.1560791

>>1560744
we once build a series wound dc motor and my Boomer trade teacher unironically showed us a 3 Phase induction motor using a Monster Endergy Can as Squirrel cache

>> No.1560891

>>1560761
>Where do you obtain stock that is highly permeable and has been heat treated so that it is magnetically soft, and how do you create the slots?
You either buy the right alloy sheet or you can buy premade already laminated parts from China. With sheet you can just do a die press or cut it with something, then you varnish each layer or stick an insulating sheet in, it's similar to https://youtu.be/QGytW_C6hR8?t=297 If you need to resize the ID or OD slightly you can turn it on a lathe, if it's too big a difference then you've designed it wrong. Ime the bigger problem is in getting the permanent magnets in the rotor, dimensions of rare earth magnets can be pretty over the place as can the strength of the magnets. There also tends to be a lot of glue involved which again can cause the magnet to not have its face sitting at the exactly right distance from the centre. AND you're at risk of getting yourself pinched if you're not careful, which isn't pleasant.

You are right tho, it's hard to make an efficient motor. You can hit the efficiencies of most toy/Chinese motors with a little bit of care and if you wanted to go even more efficient you'd either have to up your tooling and metrology stuff a lot or use parts from an existing motor. This is probably better for most people, the barrier isn't really machining imo, it's design. In the west human beings used to build pretty well built electric motors by hand using 50s tooling, but to recognise what you need to make in order to make it easily manufacturable by hand is probably beyond most people.

>> No.1561197
File: 116 KB, 1920x1080, rotor.jpg [View same] [iqdb] [saucenao] [google]
1561197

>>1560891
>With sheet you can just do a die press or cut it with something

If you have dies and presses that can make pic related then you have a lam factory. If you think it's realistic to cut hundreds of these to make a toy motor, then go for it.

And I've worked for motor manufacturers and they don't turn the slotted side on a lathe; you have to grind it. And if you think it's "designed wrong" if you want a close air gap, then you must be referring to junk motors.

>> No.1561373

>>1561197
No, I literally mean you can grind it on a lathe and if you have to do more than that you've seriously fucked up somewhere. You don't want to be clearing mm of material off the OD on one side. You can get an accurate centering and keep the thing round which you can't do so much grinding one side at a time. Again, the problems aren't going to originate from the stator if you're doing bldc or similar, it's much more likely the rotor because one of the permanent magnets is slightly proud for some reason. In that case you want the stator to be ground so that it's barely clearing the proudest permanent magnet. On that point, that's something that you can solve earlier on in design in handmade processes, so that it's less of a problem.

>And I've worked for motor manufacturers and they don't turn the slotted side on a lathe
Most of my motors are Chinese imports one way or another, there's a lot of variation in motor manufacturing in the west and some places are really great, others are terrible. If you have knowledge to pass that's great.

>If you think it's realistic to cut hundreds of these to make a toy motor, then go for it.
It's like 1ish hrs of work roughly when you've set everything up. It's not something to build a business plan around, but it's prefectly doable as a hobby in a garage with fairly basic tools if OP is that way inclined. Listen to a podcast and go zen or whatever. You'll have to treat it like meditation because you also have to build the thing afterwards and wind the coils, all of which are fairly repetitive, long and boring.

I wouldn't bother, personally, unless you feel you'll really learn something or you have some genius new design, or you need a totally bespoke motor and no other motor or motor like shell (so alternators or similar) fits.