diy solar

diy solar

Building the sickest ® VAWT ever. Brilliant minds unite please!!

thx guys for the suggestions thus far.

I know no one with a routing table. Sure we have commercial shops nearby but at 450 euro excluding tax for a full disk at 80 cm diameter (I asked back in the days when the mag disk was still 84 cm diam) It would not be much less for 63cm diam I am afraid.
The makerspaces / fablabs nearby seem all out of operation so that also is of no help.

Perhaps I can rent a cutting torch and hook it up ;)
 
Torch is something to buy. Cheap brand or used? I bought gas bottles, cheaper in the medium to long run than renting.

Torch only for steel; the carbon in it supports burning with O2.

Consider building a jig with 1 axis travel for whatever cutting device. Rotating disk is second axis. (Radial coordinates.) But the non-parallel cuts of long sides will be a bit of a problem. Offset axis of rotation. Have two holes for it, or flip disk.

Waterjet cutting as a service is a thing. Shipping is what will get you. See if any University shops nearby can do it.

www.xometry.com

Online Waterjet Cutting Service

Instant Quotes and Cost-effective, On-demand Fabrication | Free Standard Shipping on All US Orders
www.xometry.com


The radial cuts could be made by plunging with metal cutting circular saw. Axial cuts more difficult. Plunging with a horizontal mill cutter could do both, would leave curve on ends.

1663342402977.png
 
In the stator with windings, yes, aluminum would be a shorted turn. If so shaped.
In the rotor with permanent magnets, I expect relatively little moving magnetic field. But there is probably a bit.

Here is the flywheel of a CB77 Superhawk like mine.
That has aluminum structure, also steel and permanent magnets.
I think aluminum would be fine. Steel, have to shape it to duct the magnetic field where desired, not short it out.


1663345922696.png
 
Hedges said:
In the stator with windings, yes, aluminum would be a shorted turn. If so shaped.
In the rotor with permanent magnets, I expect relatively little moving magnetic field. But there is probably a bit.

Here is the flywheel of a CB77 Superhawk like mine.
That has aluminum structure, also steel and permanent magnets.
I think aluminum would be fine. Steel, have to shape it to duct the magnetic field where desired, not short it out.


View attachment 112122
Click to expand...
Yes, you are quite right.
I was not terribly clear about where the aluminium was going.
 
I would definitely go for a plasma cutter rather than an acetylene torch. Modern plasma cutters will handle aluminum just fine. It is also easy enough to build a CNC table for them since the head has low mass and the cut has no drag.
 
I have seen a few video's about torches and plasma cutters in the meantime. I'll be honest. they frighten me a bit. If wielded by someone like me houses, no whole neighborhoods, are guaranteed to be burned down ;( This and the sheer cost of aluminium plates at 5mm thickness makes me postpone this idea until my next plan fails.

I do have a dremel with a flexible extension shaft. this shaft weighs next to nothing and I found a mount for it for an ender 3 3d printer.
If plexiglass is strong enough and does not melt or soften while in operation then I guess that is worth a try.

In the meantime I've almost figured out a way of how to configure the slicer software to be used for cnc milling operations. It is rather easy except the layer steps have to be done after each single run with manual gcode instructions so steps can be done in 0.1mm increments.

Basically I configure the printer to print only the countours of a 0.1mm height object at 5mm / s with a single wall line and a flow rate of 0.001% (to stop the extruder from moving and no filament comes out).
I've also removed all the gcode start instructions so that the "print" starts where ever I set the "print nozzle (which will become the dremel rotary extension)" in the meantime. All, I need now is some gcode that moves to the center of the build plate without using the z axis and then move to the start of the print.
If someone knows please let me know.
 
ohh yeah @justgary. not being able to have square inside corners is a good thing in this context btw. it will decrease tension stress on the piece.

I've read instructions of a laser cutting service for plexiglass (rather expensive at 250 euro for a whole disk including tax and material.) and they mention to have rounded corners in the model. Since we are routing it no need to model rounded corners ;)

@Hedges warned about this ages ago and in the model for the 10mm reppeled magnets version of the disk I have modeled rounded corners with flower like petal edges at the top for ease of magnet insertion.
 
I've got some sad news.

nothing happens, even with good wind ;(

1663403314311.png

I could try making the blades taller than 1m. I could try making the chord length (the width) of the blades smaller. I could try a different airfoil.

If anyone has more suggestions on what to try to get it to spin I am all ears. Until such time I will be crying a bit alone in shame ;(
 
i think I know. the central column is not really touching the bearings. they only serve to keep the column from falling over.

the bearings have a 50 mm diam opening. the column is 49mm diam.
I had ordered a 48mm column so that i could use 1mm spacers to snuggly connect the column to the bearings. but they gave me a 49mm diam column and I don't have the correct spacers. I'll measure how much force it takes to rotate the turbine at a bit over 2m distance.

I will design an adapter to make sure the column is being held by the bottom bearing at least and not toouching the osb.
 
Last edited:
only 150 grams of force is needed to rotate the turbine. I measured using a suit case weight measuring tool. I am rather disappointed that these blades can't generate that much force.

anyway let's see how much is needed once the adapter is ready and installed
 
I am also getting a bit nervous regarding my wind speed measurements. the weather station on the roof reports 6.2 m/s yet my hand held anemometer indicates 3.3 m/s as measured near the turbine.

I do know that with this wind things better be rotating otherwise the turbine is crap.
 
ok good. using a column adapter for the bottom bearing and a pipe clamp ring on the top bearing to fit in between the bearing and column did improve things a bit. now still 100 grams needed to rotate the turbine and lo and behold. it does rotate ever so slowly in this wind.

1663410385898.png

I am certainly still not celebrating as I think a sick turbine should be able to provide at least 10KT of force ;) yes I mean 10 killo metric ton ;)

I could replace the bearings for ones that are easy to rotate but that will not solve the sub par force the blades are producing. Nah I hope making the blades 3 meter high rather than the current 1 meter will exponentially increase torque.

does that make sense?
 
At what pitch did you set the blades?

The airfoil you use should be chosen carefully for the wind range you expect. Some foils may be more self starting than others. Does yours continue to spin in low wind if you give it a push start?

Low wind is hopefully not your design point anyway. Anything less than about 5 m/s is not really worth your time.
 
justgary said:
At what pitch did you set the blades?

The airfoil you use should be chosen carefully for the wind range you expect. Some foils may be more self starting than others. Does yours continue to spin in low wind if you give it a push start?

Low wind is hopefully not your design point anyway. Anything less than about 5 m/s is not really worth your time.
Click to expand...
pitch = 0
However the turbine and alternator are being designed modularly. So changing the blade connectors to something with a variable pitch is rather easy to do. No need to make changes to other parts of the turbine. Variable pitch at preparation time that is, I did not mean variable pitch while in operation

I did not choose the airfoil, it was suggested on fieldlines as a better choice than naca 0015 I had planned for my scenario.
In low wind there is no power so I was indeed not aiming for that. We have favorable wind conditions here albeit turbulent.

I prepared the column attachment disks to be able to hold 6 blades. So I could also try adding another 3 blades of 1 meter and see if that helps.
But first I think I will try adding a low cost drag type drum to the central column as I keep reading more and more that lift type blades do not self start all that well.

Today's test showed the turbine auto started though and rotated really slowly continuously. So it can work, just too little force being generated to drive an alternator with.

I'll get there, I am on the case.
 
hold on to your buttocks everyone. I've gotten some new info and from it I gathered that the turbine blades should spin between 4.8 to 7 times faster than the wind speed. Then it will start doing work.

I'll try that tomorrow. can't wait to see if that does the trick. Already dark now.
 
brandnewb said:
I am also getting a bit nervous regarding my wind speed measurements. the weather station on the roof reports 6.2 m/s yet my hand held anemometer indicates 3.3 m/s as measured near the turbine.

I do know that with this wind things better be rotating otherwise the turbine is crap.
Click to expand...

Higher up, more wind speed. Try holding anemometer on a pole.

brandnewb said:
hold on to your buttocks everyone. I've gotten some new info and from it I gathered that the turbine blades should spin between 4.8 to 7 times faster than the wind speed. Then it will start doing work.
Click to expand...

"Lift" is what makes that happen (well, efficiently, I think; just an angled blade would also do that.)
Turbulence kills lift.
There is turbulence near the ground.

VWAT and HWAT will both be subject to that, except for drag devices (e.g. anemometer.)
 
Hedges said:
Higher up, more wind speed. Try holding anemometer on a pole.



"Lift" is what makes that happen (well, efficiently, I think; just an angled blade would also do that.)
Turbulence kills lift.
There is turbulence near the ground.

VWAT and HWAT will both be subject to that, except for drag devices (e.g. anemometer.)
Click to expand...
noted sir!..as for manually starting the turbine I am failing to get it to spin fast enough to start working.

I'll have to consider some more options. One of which is getting better bearings. current ones are really stiff and might hinder manual starting too much.
 
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