Search found 744 matches

by Buk___
Mar 30 2018 11:18pm
Forum: E-Bike Technical
Topic: Aluminium torque plates: your choice. (Corrected)
Replies: 22
Views: 1309

Re: Aluminium torque plates: your choice.

... the force is distributed across the face of the flat. If your dropout/TP has any clearance -- and all non-pinch-plate type do to some more or less degree -- then the edges of the two flats diametrically opposite each other (red circles) act as fulcrums pushing the crown flats of the threads int...
by Buk___
Mar 30 2018 4:12pm
Forum: E-Bike Technical
Topic: Aluminium torque plates: your choice. (Corrected)
Replies: 22
Views: 1309

Re: Aluminium torque plates: your choice.

To mitigate localized affects, could the slot in an aluminum torque-arm be widened and then lined with two steel flat-bars? Or would the aluminum still form cracks due to the stresses? Sure. The steel would (assuming enough thickness) prevent thread points digging into the Al. (There's the problem ...
by Buk___
Mar 30 2018 2:02pm
Forum: E-Bike Technical
Topic: Aluminium torque plates: your choice. (Corrected)
Replies: 22
Views: 1309

Re: Aluminium torque plates: your choice.

This means the same thing applies to all the aluminum dropouts themselves (front or rear). For normal axles without flats, this particular problem doesn't occur. For hub motors, torque arms/plates are recommended for all but the most minimal powered setups, regardless of the dropout material. Even ...
by Buk___
Mar 30 2018 11:34am
Forum: Items for Sale - New
Topic: Custom Waterjet Cut Parts
Replies: 137
Views: 24663

Re: Custom Waterjet Cut Parts

Perhaps Ron can help us move this discussion to a more appropriate place than Blue Saw's for sale thread. We can move existing posts so the end result will be a clutter free for sale thread with a link to the new discussion, if that is the chosen plan. See https://endless-sphere.com/forums/viewtopi...
by Buk___
Mar 30 2018 11:31am
Forum: E-Bike Technical
Topic: Aluminium torque plates: your choice. (Corrected)
Replies: 22
Views: 1309

Aluminium torque plates: your choice. (Corrected)

Update: Math corrected. I'd made several mistakes, but the upshot is that once corrected, it makes the point even more strongly. ( Why did I my errors earlier? My excuse it that it is the adversarial nature of this place, and certain member's predilection for using pedantry to score cheap 'points' r...
by Buk___
Mar 30 2018 9:03am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Hmm... you sort of lost me with the motor layout but the first one looked like it would do. Magnetic Circuit 1.jpg If you imagine this was a transverse flux motor, then the 'end turns' would be on the sides. Then it would be a matter of comparing the flux in the gap with and without the added iron ...
by Buk___
Mar 30 2018 6:11am
Forum: Items for Sale - New
Topic: Custom Waterjet Cut Parts
Replies: 137
Views: 24663

Re: Custom Waterjet Cut Parts

This is a for sale thread on blue saw's waterjet cut parts. This discussion should probably be moved elsewhere. S'fine. Move it anywhere you like including the bin. I tried to delete it, but it won't let me. (I wish I had a copy of just one of the half dozen reports I've co-authored on aluminium fa...
by Buk___
Mar 30 2018 2:54am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Cool. I wish I had modeling software. FEMM is free and easy to install . The learning curve to producing pretty pictures isn't so steep, though it has its quirks; learning to interpret those pictures is altogether harder. My interpretation is that the extra iron outside isn't making a huge differen...
by Buk___
Mar 29 2018 8:03pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Now if you add a piece of iron to the outside of the coil (and keep in mind this would be extended past the coil and bent down to the main core iron), the flux in that iron will be going the opposite direction and would therefore cancel out some of the flux headed for the gap. This would happen no ...
by Buk___
Mar 29 2018 2:54am
Forum: Items for Sale - New
Topic: Custom Waterjet Cut Parts
Replies: 137
Views: 24663

Re: Custom Waterjet Cut Parts

One advantage of the aluminum torque plates is they will take the damage before the axle does. If you keep a close eye on them and do careful testing, increasing the torque gradually, you should be able to see damage before a failure. Hopefully. The problem with aluminium for this is that it age ha...
by Buk___
Mar 28 2018 11:15pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Mu metal would saturate way, way before you reach 1T. The same stuff used to make the core laminations is about as good as you can get. Something like Metglass might be slightly better. If placing iron around the outside of the coil increased the flux in the pole,... BTW. I tried various different ...
by Buk___
Mar 27 2018 7:38pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

If placing iron around the outside of the coil increased the flux in the pole, you would see this done with a lot of motors. Only if the persons designing the core do not consider that all the flux created by the end turns is of no benefit, because it is in the wrong orientation to generate Lorentz...
by Buk___
Mar 27 2018 11:54am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

If there is a high permeability path on the outside of the coil, some of the flux generated in the core would take that path instead of going to the opposing rotor pole. But why? That's what the second big graphic above was trying to show. Flux flows in a loop. One side of that loop is already flow...
by Buk___
Mar 26 2018 9:58pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Somehow I don't totally believe the simulation. Placing high permeability metal outside the coil would tend to shunt some of the flux. The following image shows 5 steps: Nine, 1mm conductors carrying 20A apiece; in free air. Nice circular field lines. . Stick a lump of iron next to it. Familiar car...
by Buk___
Mar 26 2018 8:28pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

fechter wrote:
Mar 26 2018 7:26pm
Somehow I don't totally believe the simulation. Placing high permeability metal outside the coil would tend to shunt some of the flux.
Shunt it from where to where?

(This is magnetism, not electricity. We are providing a preferential path, not a short circuit?)
by Buk___
Mar 26 2018 4:18pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Without resorting to exotic core materials, this is probably about as good as it will get. It's not difficult to see how a couple of end caps, made from something cheap and un-exotic, like Mu metal , could be fashioned to provide a low-reluctance return path for end-turn flux. The sim image in the ...
by Buk___
Mar 26 2018 3:29am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Yeah I guess if you only have 1 end turn per several windings it shouldn't matter, or you can use a different design or accept the uselessness of them if they are useless, They are not useless. Any flux on the outside of the end turn, is just one side of an endless loop of flux around the conductor...
by Buk___
Mar 25 2018 11:26pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Anyone thought of totally reshaping the core to better contain the flux coming off the (end turn) windings like by using something other than laminations of M12 steel like with powdered metal tech which can also reduce Eddy currents in the core? That's kind of where this thread started. If there wa...
by Buk___
Mar 24 2018 5:30pm
Forum: E-Bike Technical
Topic: EBike Toolbox - Bargains! $
Replies: 143
Views: 50339

Re: EBike Toolbox - Bargains! $

Chinese "Stainless Steel" 6\7\8 speed bicycle chain https://i.ebayimg.com/images/g/wU0AAOSwsTxXj4~U/s-l400.jpg Purchased for Snow Beast use in Upstate (salted streets) New York. Attracted to magnet so ... "true SS" to be determined. That is to completely miss the point. Any grade or price of SS can...
by Buk___
Mar 24 2018 10:36am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

major wrote:
Mar 24 2018 9:12am
Ampere's Law applies, universally.
That depends upon whether you are taking Maxwell's correction into account; which you obviously aren't. So you stopped being correct in 1861.
by Buk___
Mar 24 2018 5:11am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

No insult implied here, but your concept of coil "turns" goes back 100 years or more. "Turns" is just a convenience word so students could visualize coils when the physical quantity of current passing thru the closed magnetic path causes the mmf in that path, as expressed by Ampere's Law. In fact, ...
by Buk___
Mar 23 2018 4:03pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Here is a thread from a RC forum that is discussing the same topic: https://www.rcgroups.com/forums/showthread.php?2432496-BLDC-Motors-Short-and-fat-or-tall-and-thin-Case-in-point-1804-vs-1306/page6 In the thread, there was a peer-reviewed research paper that addresses this topic: http://www.aedie....
by Buk___
Mar 23 2018 11:49am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

i think you would not trust them, stop and taking the money :lol: If anyone was offering me me a million dollars for my research, I'd take the money for sure; but that's unlikely as most mathematicians consider my reliance on pictures and words rather than math, makes me little more than a storyboa...
by Buk___
Mar 23 2018 11:38am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

Firstly, let me apologise for not getting back to you earlier. I had part written a reply, when a distance memory of something I had read stirred in my brain. It took me a while to to remember where and what, re-read it -- this time trying to understand it -- and then I had to run a bunch of simulat...
by Buk___
Mar 23 2018 3:27am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 13162

Re: End turns bad?

visualize the flux passing thru the Riemann surface bounded by the coil's turns I will be not replying further as you are too rude I thought I was perfectly polite to you!? (Shame though, I wanted to ask you whether you thought that bounded Riemann was meromorphic with respect to the Stein manifold?)