Stator Rings

[kitestrings]

There is yet (at least) one other option; do away with the stator rings entirely.  Say what?  Well, if the stator bracket had, had 12- arms, instead of six, the rings might not have been warranted.  I'm not planning a redesign, but it is possible that I could provide metal supports on the downwind side of the bracket.  The supports would bridge between the 6-arms and provide an intermediate anchor point - picture for example another set of 6-coupler-nuts on the downwind-side of the stator bracket.

[mmurray70]

Mcmaster carr lists green G10 as suitable for outdoor use and yellow G10 (stronger) as not suitable.

Seems like the most commonly used plastics for outside use are PVC (conduit, electrical boxes, windows, siding, etc) or PE. These would not be nearly as rigid as g10, not sure if that would be a problem or not, or if you can increase thickness. Delrin is a dream to work with, fairly rigid and can be used outdoors in some cases, might want to do more research on UV resistance before buying it.

Could you do an aluminum ring with small standoffs so the coils dont contact the aluminum?

[kitestrings]

Hmm, I was just looking there yesterday.  Where do you see the outdoor rating info?  I was here:
https://www.mcmaster.com/grade-g-10-garolite

My concern with AL would be eddy currents, at least in this format (rings).  It could be used to fabricate stand-offs on the down-wind side as I described earlier I suspect.

[mmurray70]

Just follow your link and click outdoor use on the bar on the left side. Unfortunately they only sell small sections with outdoor rating, but im sure you can find it somewhere if you look hard enough. I wouldnt be surprised if the larger sections on their website is the same stuff, just not listed for outdoor use.

Regular G10 will probably be fine anyway. All the G-10 spec sheets say its fine in high humidity environments, only issue would be UV possibly breaking down the epoxy. Couple coats of black paint should fix that.

Also, FWIW ive also noticed cracking around holes machined in polycarbonate just like yours did. Even on simple windows for parts that didnt vibrate or flex at all. I read something about stress releiving the plastic after machining, but never ever tried it. 

[MagnetJuice]

KS, check this out, the specs look really good.

Weather-Resistant VHMW Polyethylene

https://www.mcmaster.com/standard-plastic-sheets

$50 for a 24 x 48 sheet ($7 per Sq. Ft.)

https://www.alro.com/dataPDF/Plastics/PlasticsBrochures/Brochure_PE_ComparisonChart.pdf

Ed

[kitestrings]

Hi Ed,

I looked at that...and several others.  A few things I don't like about VHMW.  Coefficient of friction.  We don't really want a slippery material like this or Delrin, or similar.  Ideally we want it to pinch and hold the sectors from movement.  The tensile and flexural modulus are also too low.  See:
https://www.mcmaster.com/about-plastic

https://www.mcmaster.com/grade-g-10-garolite

[kitestrings]

I've purchased the G10/FR4 material.  Increasing the thickness from .1875" to .235" and the ring width from 2" to 2.3125", adding SS spacers/stops on all fastening points, and adding heat-shrink over the fasteners to allow for a bit of dissimilar expansion.  The rings are being CNC cut to shape: