Making a LINEAR MOTOR for a DIY CNC mini MILL - Part #2 (Step-by-Step)

[@lvb3575]

Man I am really loving this video series so far, super nice to see your progress! For the ripples due to the reluctance 'cogging' force that you have with these types of actuators you can do a measurement of these forces by measuring the EMF induced if you move the coil unit manually. This you can then use in a feed-forward control element to compensate for this position dependent force and increase the position control accuracy. I am not too familiar with your driver board setup but I can imagine that they have some feature build in to include these measurements. I can't wait to see your next video!

[@NeverGetTiredEngineering]

Hi, thank you! I'm glad you liked this video. Sounds good - indeed, I saw a setting to enable feed-forward. I'll dive into that! ;)

[@chrismayer8990]

2nd video and in this quality! Fantastic! Thanks for the insight into the ST software.

[@NeverGetTiredEngineering]

Glad you enjoyed it! :)

[@jonjon3829]

if this projects ends up with an open source drive for ironcore motors I'd consider it a success. Off the shelf ones start at $500

[@davidk.713]

Well well well, look who just posted a nice video again!

[@NeverGetTiredEngineering]

Wunderholunder!

[@corbintrubov]

Came for the engineering, stayed for the best intro music I've ever heard.

[@hadinossanosam4459]

I really like the idea of casting your own magnetics using short wire pieces in resin, like a jankier version of the typical laminated-core construction for transformers! I'm wondering how this affects the magnetic properties, though - I suspect saturation field might be quite low, since the majority of the field will likely go through the small contact areas between the wire pieces. How did you model this in the simulations (3:11)? And did you do any measurements of the coil's performance, are their inductances and saturation currents reasonable? (I'm curious because I'm also working on an electronics project with custom magnetics right now :) Have a first iteration already machined, though, just have to get my control loop to cooperate and stop it from doing a 4:07)

[@NeverGetTiredEngineering]

^^ This is still a work in progress. I'm currently building a small 'test station' to extract all the critical data from the materials. I agree that this core will likely perform worse than a laminated one. In one of my upcoming videos, I plan to compare different core types. The goal of the simulation was to explore various core sizes and different types of stators-simple, Halbach, and Halbach with iron segments (to increase reluctance forces). Performance tests for the coils will be coming soon. :) By the way, may I ask what kind of project you're working on?

[@pwkoert6594]

@@NeverGetTiredEngineering granulates hardly conduct the magnetic field, that is why they use plates that are insulated from each other like the copper wire. Also steel does not realy want to change it magnetic field. So I think your core is more like a dead weight. E plates for linear motors might already be available off-shelf.

[@NeverGetTiredEngineering]

I‘ll try to get my hands on some electrical plates, I’ll also make a side by side comparison with some test samples in one of the upcoming videos

[@Ckpe4]

Great start for the channel. Good luck

[@NeverGetTiredEngineering]

Thank you :D

[@ipadize]

i like how one section of the video timeline is named Blah Blah

[@NeverGetTiredEngineering]

😂😂

[@demon4eg402]

Perfect!

[@JLCPCB]

Well done ! 😍

[@NeverGetTiredEngineering]

Thank you very much 😁

[@lumotroph]

Love the build and video! In the editing / mixing stage could you adjust things to make your voice easier to hear please? I find it quite difficult to parse. Best of luck for the channel and looking forward to the next instalment!

[@NeverGetTiredEngineering]

Thank you 🙏. Yeah next time I’ll dial the music down a little

[@xxportalxx.]

I think your best bet is to look for premade E or U cores for this, but if you really want to make your own I'd suggest using either a powdered iron or iron oxide and premix it with the epoxy. That seems the best way to optimize the core itself to me, you could also use the premixed epoxy with iron pieces like your cut wire. Going further you could try finding an epoxy that could be thinned with a solvent before mixing to get the granules tighter packed.

[@NeverGetTiredEngineering]

I also thought about stacking steel sheet with an insulating layer and milling these all at once, but I want to make some test samples and compare some core material

[@Scrogan]

Neat use of wax for your casting. See if you can characterise the permeability and lossiness of different core/yoke materials, by putting a sample of constant dimensions into a solenoid, which you can use to measure inductance. Lossiness would be harder to quantify, but if you use a scope to measure its Q-factor in a tank circuit at a few frequencies, and compare that to what its DC resistance would imply, you should get a value. If you put a lot of turns on it and/or switch a lot of current into it, you can likely see magnetic saturation on your scope too, which would be a handy thing to know. Especially if you plan on water-cooling your yoke. FYI I have similarly sized toroidal cores made of both iron powder and ferrite, and the iron powder is more than an order of magnitude worse than the ferrite. Far less inductance per turns-squared. Modern ferrites are damn good, you can likely crush some toroids in a tough bag with a hammer.

[@NeverGetTiredEngineering]

Thanks for your comment, that’s a great idea before i put more time and effort in a core without knowing how well it performs. I think I will do that and a video about that before I continue this series

[@3.2213]

nice

[@NeverGetTiredEngineering]

Thanks!

[@goosenp]

Awesome project, please keep it going! Where is the part 1 video? I only see 0 and 2 on your channel.

[@Holtylord]

Looking at the playlist, it says "1 unavailable video is hidden". I was wondering that myself. Might've been flagged?

[@NeverGetTiredEngineering]

Thanks :D, I wanted to rename the #0 to #1 and forgot to do that 😅

[@AABB-px8lc]

Maybe try coreless motor and Hallbach array as used in ASML position system. As i understand Iron core have big disadvantage - it "ripple" and tend to make very unwanted unpredicted orthogonal force that ruine precision.

[@NeverGetTiredEngineering]

I‘ll do a comparison core vs. core-less. We would gain in predictability and precision but lose in force. Let’s see ^^

[@lolslim690]

What did you shave and melt in that grey container? Was it to act as a release agent or self inside so nothing leaked out? I use acetone on ABS prints when I want to seal so learning other methods would be helpful, Hopefully I heard back from you!

[@lvb3575]

I believe it is either candle or bee’s wax to prevent the resin from sticking to the mold, if only there were some release angles added :’)

[@lolslim690]

@@lvb3575 I like how the author of the video comments 7 hours later after my comment to one of your comments, but doesn't answer my question, regardless I believe you're right about it being wax. Just curious do you have any recommendations on what can be used as a release agent for resin?

[@NeverGetTiredEngineering]

Hi, sorry about that. I answered a few comments and then I thought I should maybe do something else since I was busy the whole week (work, YT and private live), so please don’t be mad ✌️ And yes it’s wax as a release agent

[@lolslim690]

@@NeverGetTiredEngineering Oh I ain't mad, just little ball busting.

[@georgenovtekov4351]

Next time try using PVA or BOVH filament. Cast in it and than pour in water. PVA gets dissolved and you have your part no matter how impossible for release it is.

[@NeverGetTiredEngineering]

That would have made things a lot easier 😅 thanks for the suggestion!

[@Holtylord]

Somehow I forgot to subscribe after finding the first video, glad that the second one popped up in my feed. I do have a question though, what's the program called that you use to draw/sketch in? I Don't recognise it and I'd like to take a closer look at it.

[@NeverGetTiredEngineering]

I’m using Leonardo drawing app. It’s 40 bugs though but love the design and the infinite drawing area

[@zakariakhamees]

I see you've done what i suggested but instead of powder, you used steel wire which is also great. But i would still recommend iron powder to get more iron in the core. Steel wire pieces are too big which generate Eddie currents. Also, you can pack more iron using powder on the same volume of the cast. BTW are these programs you used free? Good luck

[@Scrogan]

Iron powder might not be as good as ferrite powder, which is non-conductive even at high packing densities. It also doesn’t magnetise permanently, I think. The software is free, at least the STM32CUBE IDE and its programmer are, they’re also platform agnostic.

[@lvb3575]

FEMM 4.2 is also free, nice way to tinker with some iron core geometries (only 2D, but should be more than enough to get you started)

[@Scrogan]

@@lvb3575 doesn’t really help when you don’t know the properties of your magnetic core in the first place.

[@lvb3575]

⁠​⁠​⁠@@Scrogan you can be conservative with the properties you test with, and also see the effect of different properties. For a custom core like this with no properties measured it is indeed difficult to match the simulation with reality, but if you use laminated sheets with a laser cutter for example you can get pretty good results. Or core-less actuators, my personal favorite

[@Scrogan]

@@lvb3575 core-less? Wouldn’t those have much less force?

[@slevinshafel9395]

finally someone thnk like me. i was wondering why are not more linear motors and why are they so expensive. i dont finde the point where this have to be expensive. let see the video boy(or girl), ok creator hahaha.

[@NeverGetTiredEngineering]

Both have advantages and disadvantages. But quality rotary motors can get expensive too ^^

[@creadorestijuana3411]

A German with a mustache making the old in and out with adventurous beautiful women nopor from the 90's. So obviously I stayed till the end.

[@NeverGetTiredEngineering]

Ah, a true man of culture! Love that comment 😂

[@jamescarter9147]

Do you have an OEM Linear Motor to compare your results against?

[@NeverGetTiredEngineering]

Sadly I have no conventional linear motor…

[@АлексейЕ-ц5ж]

А что за марка стали идёт в наполнение ( из чего пруток сделан )? для сердечника.

[@NeverGetTiredEngineering]

It’s from the hardware store so it’s unknown. Took it just for experimenting. Final one will have proper electrical sheets 😁

[@Leo.Wolf.the.Engineer]

Did you measure how much force this produces? Also just add a second linear rail on the other side of the magnets to keep it from cantilevering around. Thicker printed parts and sandwiching the alu profiles between a plate on the top and bottom should solve all those problems.

[@NeverGetTiredEngineering]

I ran a quick test and as it is it produced min. ~16N at 2A (without any further optimizations). Yeah that would be an easy fix ^^

[@Leo.Wolf.the.Engineer]

@@NeverGetTiredEngineering not bad! Should get much higher once you can reduce the air gap right?

[@NeverGetTiredEngineering]

yes, will be higher, and then i can also use the hallbach array :D. I try to get my hands on some laminated sheets like permenorm or vacoflux to have a better core material

[@aarondcmedia9585]

Turn the music off. It's unnecessary and is almost as loud as your voice over.

[@NeverGetTiredEngineering]

Noted. I’ll turn it down a little next time 👍

[@bencohen9624]

I for sure second this

[@tonyhill8300]

Rubbish it was fine

[@leonardoaugusto5491]

You should have used iron powder for the yoke in my opnion.

[@kelna2]

Or both small pieces and iron powder mixed with resin. Very cool idea though!

[@NeverGetTiredEngineering]

I‘ll make some test samples of core material to compare them

[@heitorgoku]

Fourth 🗣️🔥🔥🔥

[@luca87375]

Real ones are an U shaped stainless piece with neodymium magnets glued to both sides. The coils are inside an T shaped epoxy

[@NeverGetTiredEngineering]

Have seen that on core less motors. Would definitely increase the max force. Sound great for a second version

[@Nayel-Khouatra]

The errors is due to two files you have to delete tho I don’t remember the path to them

[@NeverGetTiredEngineering]

I‘m sure ST will fix it… but it’s no big deal

[@shrawankhatri6083]

Greate work, I wants to make one ,and wants to use for diy cnc. How to do it?

[@NeverGetTiredEngineering]

Hi, how exactly can I help you? I also want to use this for a CNC…

[@shrawankhatri6083]

​@@NeverGetTiredEngineering Do you have any discord channel

[@NeverGetTiredEngineering]

Not yet ^^

[@SilviaCao-k6e]

Hello, I apologize for contacting you here. We think your content is a great fit for our product, are you interested in accepting a business partnership?

[@AshleyLiu-h9g]

Your project is very interesting, and I would like to invite you to explore our newly launched LINEAR MOTOR. I'd be happy to discuss this in more detail with you.😍

[@toma.3d]

2

[@therecon448]

First :D