roll your own!

[powercroco]

a good friend built a little wire roll for me.



finest mechanics.....
I can use it from 1mm to 2mm thickness (meassured after rolling the round wire flat)

so it comes out of the roll:





a ready rolled 2x1mm wire.
you can't see any injuries into the enamel.



this method is really good usable for smaller wires!
but just thisone has 2mm lenght into the "wrong" direction now.
as we got known, in bigger wires the flattening builds highways for eddy currents in the copper unfortunally destroys all possible wins by better square area and a round wire of same square performes better.
( www.powerditto.de/flachdraht.html )
at the last coil winding fair some producers just offered sectional insulated round copper wires to prevent skin effects and minimize eddy currents also in copper. may be, this type can bring a next step in increasing motor performance.

[SEBBY]

Is English your first language? Sorry but I can't understand any of what you posted

[powercroco]

of course no.
anyway, also the most "normal" germans cannot understand the content of the last post.
but the experienced motorbuilders here in this section will do.

[Stolla]

nice Ralph, I discussed this with my friends some months ago https://www.helifreak.com/showpost.p...37&postcount=2 but was concerned the coating may be damaged, great news so now I'll build one!

[Vinger]

So Ralph, the flattening of the wire gives NO real advantage then?

[powercroco]

my most loved beginning :

.... depends on.....

here on the resulting wire lenght in hammerstalk direction.
the shown 2mm x1mm flattened has almost the same room for circulating eddy currents in their primary direction as a 2mm round wire. but in smaller wires there can be a real measureable advantage.

in bigger industrial high efficiency motors they use also flat wires, but they use them in 90° turned direction.
these are 2 of such (silver!) turns:





we also are just in a range, where a further increasing of coppersquare will bring almost nothing anymore. the part of ohmical losses in the complete summ of losses became just very low and the other groups have been increased in the proportions.
we found, that more than 1,8mm in typical heli use won't bring an advantage!
especially in the heli typical part loaded use at high frequencies.....
this all must be measured very carefully to know the trues.

I think, only in pure record motors for only(!) use in their max power range and with 100% open controller you will get feelable wins.

for the daily use the main advantage (evidendenced!) of such winding is the "nice to have".

[Vinger]

Thanks for explaining, will stick to round wires then as the flat looks more difficult to wind!

[HeliFX]

Ralph very nice

I'm confused.

based on your experience using flat wire I thought your conclusion was there was no advantage in power increase plus due to the nature of the overlapping flat wire it produced additional heat "skin effects"

Has your opinion changed over time

[powercroco]

it's the same, I said just from the beginning.
"depends on" everytime is the key.

[HeliFX]

based on your photo those rollers make a very consistent and even flat wire.

Any problem keeping all the wire equal in thickness ?

Is the handle / measure device a re-purposed from old micrometer ?

Originally Posted by powercroco

it's the same, I said just from the beginning.
"depends on" everytime is the key.

[powercroco]

no problems so far.
and yes, its an old micrometer.
it isn't used "absolute" but "relative" to add some 1/100mm after measuring the result of the first pass.

important is the quality of rolls (hardened material needed) and the bearings - they also have to resist a very high powerload.

[HeliFX]

Safe to say no problem with nicks or breakdown of insulation coating on the wire ?

I would assume you could weaken the bond of coating on the wire creating hair line cracks that may show up after using in a motor.
I guess it has enough flexibility and can stretch.

Originally Posted by powercroco

no problems so far.
and yes, its an old micrometer.
it isn't used "absolute" but "relative" to add some 1/100mm after measuring the result of the first pass.

important is the quality of rolls (hardened material needed) and the bearings - they also have to resist a very high powerload.

[powercroco]

the wire insulation never was a the problem so far, the real problem is in fact the gotten result.
the flat wire in all measurings seems to be bader than a round wire of same square.

also in round wire in 45xx or 50xx size with more than 1,8mm round diameter you can't win efficiency anymore. the side effects become bigger than the advantage comming from the internal copper resistance.

to reduce this complex issue only to the copper resistance part don't work anymore into these regions!
in fact the part of copper losses is by using a real fat wire just reduced to such a low level, that a further lowering brings no over all win anymore.
the only advantage: you can go higher peaks.
but also this way isn't usable, untill we get much better batteries and also controllers.