HowTo: WinDIY – Build hub including mechanics

I've probably already mentioned at one point or another that it was important to me to be able to control WinDIY safely and also limit its speed in an emergency.

To do this, I developed a mechanism that makes it possible to adjust the angle of attack of the wings. This allows the blades to be adjusted to the current wind and rotation speed. They can also be turned out of the wind in strong winds.

This allows you to control the speed and load of WinDIY.

I have written down some additional information about this here:

In the following article you will find instructions for replicating the mechanics for adjusting the wing angle of attack.

Safety instructions

I know the following notes are always kind of annoying and seem unnecessary. Unfortunately, many people who knew "better" have lost eyes, fingers or other things due to carelessness or injured themselves. Data loss is almost negligible in comparison, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Because even the coolest project is not worth injury or other trouble.

Affiliate links/advertising links

The links to online shops listed here are so-called affiliate links. If you click on such an affiliate link and make a purchase via this link, will receive a commission from the relevant online shop or provider. The price does not change for you. If you make your purchases via these links, you support in being able to offer other useful projects in the future. 🙂 


Required tool:

Hot glue gun
3D Printer
Allen wrench
Open-end wrench
Cordless drill
3mm drill bit

Required material:

In the following list you will find all the parts you need to implement this article.

9x603ZZ ball bearings
8x606ZZ ball bearings
5xM6 self-locking nut
6xM6 mother
3xM3x20 cylinder head screw
3xM3 self-locking nut
15xM3 nut
3xM3x30 countersunk screw
3xM3x16 countersunk head screw
6xM3x40 countersunk screw
3xPrepared wing slot
1xM6 threaded rod 60cm long

Collect required parts

Before you can start building the hub and its mechanics, you must of course first have all the necessary parts together. You can find a complete list of the materials and tools required above in the materials and tools list

In this picture you can see all the components needed to build the hub mechanism.

You can find the required STL files for printing here:

I printed the parts with the following settings.

  • Perimeter: 5
  • Infill: 50%

The screws should preferably be made of stainless steel so that they do not rust due to moisture.

Mount the hub base on the axle

First, the hub base must be connected to the axle. This actually makes further assembly a little more complicated. Unfortunately, this has to happen right at the beginning, as the screw holes used during assembly are difficult to access later.

To do this you will first need the parts shown.

The axle, the hub base, 3x M3 nuts and 3x M3x50 countersunk screws.

In order for the screws to hold the axle, you must first insert an M3 nut into the axle as shown.

Depending on the print quality of your printer, you may have to “force” the nut into the correct position.

Now you can insert the first M3x50 screw through the hole in the hub base.

Another view of the inserted screw.

The inserted screw should then...

... be inserted into the axle as shown and screwed with the previously inserted nut.

Now that you have temporarily fixed the axle with a screw, you can use the other nuts...

...insert into the recesses in the axle.

You can then insert the remaining screws into the hub base and screw them into the axle with the nuts.

The axle should now be screwed to the hub base using three M3x50 countersunk screws.

Install the first wing slot

The wings are not directly connected to the hub. Initially only the slots are connected to the hub. The wings can then be inserted onto it later.

To do this, place the first 606ZZ ball bearing from the outside into the recess in the hub base as shown.

On the opposite inside there is then…

...the second ball bearing inserted.

Now you can insert the first wing slot.

You should have already prepared this wing slot while assembling the wing.

This should look like this.

The first securing of the sash consists of a self-locking M6 nut, which is screwed onto the M6x100 screw of the sash slot.

Once screwed on, it should look like this.

The nut should be so tight that the wing slot can no longer be moved in the direction of the screw. At the same time, of course, it should still be rotatable.

The next ball bearing is now inserted on the inside of the hub.

To do this, push the 606ZZ ball bearing over the M6x100 screw into the recess on the inside of the hub base...

...and secures it again with a (normal) M6 nut.

Another view of the M6 nut screwed onto the M6x100 screw of the wing slot.

Attach lever and adjust correctly

Now comes a somewhat critical step in which you should work as precisely as possible. To be honest, I'm not yet completely satisfied with the mounting of the lever on the M6x100 screw of the wing slot. This is secured by clamping between two nuts on the screw. In theory that should hold. In practice it does that too. However, it would be safer to put a split pin through the M6x100 screw, for example. There is certainly room for future improvements here. 🙂

To adjust the lever correctly, you should now position the hub base a little higher. For example, I put them on two boxes.

The goal is for the back edge of the wing slot to be exactly the same height as the back of the hub base.

Once you have set the wing slot correctly, you can now attach the lever to the axle and to the previously screwed-on M6 nut. The nut should fit as tightly as possible to the ball bearing, but the entire wing slot should still be able to rotate freely.

As soon as the lever is inserted correctly... can temporarily secure its alignment in the hub base with an M3 screw (the screw will be removed again later). (see image)

View of the lever secured and aligned.

Install guide ball bearings

In this step, the ball bearing is installed that allows the push rod to adjust the wing angle of attack. Actually, this step could have been carried out before installing the wing lever.

Use the 606ZZ ball bearing...

...into the recess in the hub base.

The ball bearing is then clamped into the hub base using the clamp shown.

Close-up view.

The screw for clamping the ball bearing is secured in the axle using a nut.

Now repeat this two more times...

Until the ball bearing is jammed over a total of three clamps.

Another view of the jammed ball bearing.

Top view of the jammed ball bearing and a mounted lever.

Mount the remaining two wings on the hub

After the ball bearing for guiding the push rod is installed in the hub base, you can proceed with installing the remaining two wing slots. These are installed using exactly the same procedure as the first wing slot.

As soon as all three wing slots are installed, your current setup should now look like this.

Close-up view of the three mounted wing slots including levers.

Close-up view of the three mounted wing slots including levers.

Close-up view of the three mounted wing slots including levers.

Close-up view of the three mounted wing slots including levers.

Attach the nut lock

As already mentioned above, the levers for adjusting the wing angle of attack are clamped on the M6x100 screw of the respective wing slot. So that the inner nut can no longer loosen (and the lever would no longer have any effect on the rotation of the sash), you should now urgently secure this nut against twisting.

Before you secure the nut, you should make sure that the internal nut is tightened as tightly as possible.

Of course, the setting of the lever should not be changed.

So first check that the angle of the lever to the sash slot is correct and then tighten the nut as tight as possible.

“Tight as possible” here means so tight that you can no longer get it tighter “by hand” using a wrench.

Now you need an M3x20 cylinder head screw, an M3 nut and the 3D printed plastic part to secure the lever.

Now place the fuse over the M6 nut as shown...

...and secures it with the M3x10 screw... screw it to the M3 nut on the back of the lever.

Now repeat this again for all three wing slots.

Close-up view of the levers including attached fuses.

Close-up view of the levers including attached fuses.

Now you can also check that the levers are at the correct angle to the wing slots.

If the wing slots are straight (as shown in the picture)…

—the levers should touch the stops on the hub base. The angle of rotation of the wing slots is therefore limited in one direction.

Other view.

Attach the “lever extender”.

(Btw: Sometimes it's not easy to find suitable names for the individual parts. 🙂 )

This section is about attaching the “lever extender” to the previously installed levers. This is part of the mechanism that later turns the back and forth movements of the push rod into a rotational movement for the wing.

To do this, you first need a 3D printed lever extender, an M3x20 cylinder head screw and a self-locking M3 nut.

Now mount the lever extender on the first lever as shown.

Another view of the assembled lever extender.

Another view of the assembled lever extender.

Once you have installed the first lever extender, you can repeat this for the remaining two levers.

Close-up view of the mounted (and folded) lever extenders on the levers.

Close-up view of the mounted (and unfolded) lever extenders on the levers.

Attach lever plate

Here comes the next important part of the mechanics for adjusting the angle of attack: the “lever plate”.

For this you need the lever plate, three M3 nuts and three M3x30 countersunk screws.

Now mount the lever plate on the first lever extender as shown…

...and fix it by inserting the M3x30 screw into the lever plate from the outside.

So that you can now fix the screw, you now have to insert an M3 nut into the recess on the top of the lever plate.

Once it's completely plugged in, you shouldn't be able to see much of the M3 nut anymore.

Now you can screw the M3x30 countersunk screw into the nut.

Repeat this for the remaining two lever extensions.

If you now move the lever plate back and forth, you should notice that the wings can be adjusted according to the distance between the lever plate.

View of the folded lever plate.

Insert ball bearing at anchor point

So far we have used a ball bearing that is intended to guide the push rod.

Now the ball bearing is mounted, via which the thrust movement of the push rod is transmitted to the lever plate.

To do this you need the ball bearing locking plate, a 606ZZ ball bearing, three M3x16 cylinder screws and three M3 nuts.

Now insert the 606Zz ball bearing into the recess in the lever plate.

Close view of the inserted ball bearing.

Now secure the ball bearing in its position by mounting the ball bearing locking plate including the three M3x16 cylinder head screws on the lever plate.

The screws are secured by inserting them into the recesses on the underside of the lever plate.

Other view.

Attach stabilizing ring

In order to give the hub base a little more stability, a stabilization ring is now mounted on the hub base.

To do this you need the 3D printed stabilization ring, six M3 nuts and six M3x40 countersunk screws.

The stabilizing ring is now placed on the hub base from above...

...and screwed into the hub base with the M3x40 countersunk screws as shown.

To do this, screw the M3x40 screws into the nuts, which are inserted into the recesses on the underside of the hub base.

Close view of the inserted M3 nuts.

Close view of the inserted M3 nuts.

Attach push rod

The push rod consists of an M6 threaded rod. It will later transfer the thrust movement generated by the pitch actuator to the mechanics in the hub.

At this point you need the previously prepared hub base including attachments as well as two self-locking M6 nuts and an M6 threaded rod.

Now push the threaded rod through the first and second ball bearings installed in the hub as shown.

Then pull the push rod back a little and screw the first self-locking nut onto the push rod as shown.

Unfortunately, the nut cannot be seen but is located in the socket wrench, which makes assembly much easier.

It is also helpful if you clamp the threaded rod in a cordless screwdriver as shown. This way you can easily turn the threaded rod into the M6 nut.

If everything worked, the M6 nut should sit on the threaded rod as shown.

Now you can insert the threaded rod back into the upper ball bearing.

Close-up view of the inserted threaded rod in the upper ball bearing.

So that the push rod remains in the upper ball bearing, you now have to screw the other M6 nut onto the push rod as shown.

The push rod should now sit firmly in the ball bearing without much play.

Other view.

Other view.

Other view.

Now it's time for a first test.

This video shows how the mechanics should now work. (Don't be put off by the changed design. This is a video I recorded while developing the mechanics.)

Attach cover

Last but not least, the hub now has a cover. On the one hand, this covers the mechanics and should protect them from moisture and rain. On the other hand, it makes the hub a little more aerodynamic.

To do this you need the 3D printed cover, three M3 nuts and three M3x16 countersunk screws.

Close-up view of the parts needed.

Now put the M3 nut back into the recess provided in the hub base...

... and fasten the M3x16 countersunk screw in it.

Now secure the M3 nut again with some hot glue in the frame of the hub base...

... and removes the screw again.

Now you can put the cover on and use the prepared screws...

…screw into the frame of the hub base.

View of the attached and screwed cover.

View of the attached and screwed cover.

View of the attached and screwed cover.

Have fun with the project

I hope everything worked as described for you. If not or you have questions or suggestions please let me know in the comments. I will then add this to the article if necessary.
Ideas for new projects are always welcome. 🙂

PS Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you think it's cool that I share the information with you, I would be happy about a small donation to the coffee fund. 🙂

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  1. A total of 6 pieces of the 606ZZ ball bearings are required. Only 2 pieces are mentioned in the material list.

  2. Small correction. 😀 A total of 8 type 606ZZ ball bearings are required. Two extra for the threaded rod that goes through the axle.

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