Wind Turbine Blades from a 3D Printer

Hi out there,
I am a student and we have a project going on. Our aim is it to print blades for a wind turbine with 2m in diameter and a power of about 200W.
The design starts from scratch and is aimed to hobbyists and people which like to be independent in terms of electrical power supplies.
We have access to a sintering-mashine, but not much people have. In our university (university of Stuttgart, Germany) we have no access to the more "simple" 3d printers.

I look now for volunteers which would print parts for one rotorblade for a second version.
to bring the parts to the right form I need to know the printing dimensions.

It would be good if there is someone near stuttgart, which would it make easier to pick up the parts.

If it is possible, We`d like to print in stronger material than PLA, like ABS ore others.

We should find rather strong to each other, because we would like to test the stability of the Blades in the beginning of december.


We need your help, maybe the project can help later many more people.


Greets

Willdmo

There aren't many 3D printers out that have a 1m build volume.
A spinning blade is a safety problem that may need special manufacturing?
I don't think you would want to make blade in pieces?

Perhaps a bunch of sections on a steel rod

Perhaps a graphite-epoxy lay up may be better?

Do you have drawings? Requirements? Plans?

You must think differently to build a blade that is easy to produce and does the job?

Have you thought about a vertical wind turbine?

Good luck testing blades in December? Are there blade vending machines in Germany?

there is a company close to where i live who makes blades for windturbines, and they are all epoxy type things,
and are very strong.
i don't think that printing one is very good idea.
what you maybe could do is print it, and the cover it with something like kevlar.

since your project requires lots of printing time (weeks) you will probably be cheapest with building your own printer,
and then printing the parts yourself.

Some of the most efficient designs are actually incredibly slow in RPM.. using FFF may not be in issue if the design is for a slow rpm

There are quite a few wind turbine things on Thingiverse. Don't know how well they work, however.

Here's a few:
Lenz2 Helical Turbine XL
Complete Downloadable Kilowatt Wind Turbine

Hi,
The stability-issues are well known and we are heavily calculating on the power it must stand.
The plan is with sintering mashine, to make blades with one m length in 6 pieces, 3 for each half (upper and under half). inside the blade will be a laminated rod. In first calulations it would work fine everything. The problems for the "open DIY market" is the sintering-centered production process. To make it real available, it should be printable on a largely available printer, which doesn't cost a couple of 100.000€ (print area is about 30x30x20cm). If the material is stronger than PLA, it might be possible to reduce the complexity of the rod and so make it easier to copy it
the turbine is calculated for the weakest wind-class, but with a lot of safety. To smoothen and optimate the surface of the blades is planned already.

We search someone who is able to print our parts, to compare it to the sintered ones and to make the process easier to copy.

The wind turbine will bring in the and about 200W
it is a horizontal turbine
RPM is limited to 300rpm
nominal wind speed is 6m/s
the blades will be out of 6 pieces (devided in upper and lower blade, largest with about 20cm, pieces of about 30cm length each)
If the parts are too big for printing, the lenght of pieces can be at 25cm too, which will lead to 8 parts for each blade.

What is the problem with using ABS, Nylon, Polycarb pieces?
Why must they be sintered?

Low RPM doesn't matter --- centrifical force put on blade,
energy in blade ---- at what speed will it rip through buildings and bodies?

Why do you need "instant" blades?

Unreasonable development time?

A 3d printer is too small for this... fiberglass coated foam board sounds the best. You just need to get the right shape. There is a new kind of plastic for airplane skin that replaces the old canvas/varnish. I would look into that for light weight.

Perhaps a 3d printer for the spars? Would probably take a long bed, or make them in two pieces each.

Jeff.

Edited 1 time(s). Last edit at 11/25/2013 07:38PM by jeffegg2.

Hi,
We are developing the blades. PLA cant handle the load on the root of the blade caused by thrust. centrifical force is not the main problem here, forces caused by thrust are much higher.
We know that there are "better" materials and that it could be more easily done.

Our task is it to make printed blades. Since we can not achieve the stability only from printed parts (especially the root of the blades will be too weak), the aerodynamic form will be printed, while the stability to stand the thrust comes from the rod.

We have no 3D printer like REPRAP nearby and know nobody who has one.
we have for our models a SLS Sintering mashine which works with PLA.

We need help in printing with Printers like Mendel, Reprap, etc, concrete, someone who is willing to print out 6 parts from, for example, ABS
The construction we made is already calculated and needs to be printed with a not SLS 3d-Printer for:
1. Comparison to the SLS version
2. to know if it is possible to print with a DIY printer or one of its relatives
3. to optimize the construction for this kinds of printers.

since the task is not to make the easiest and best wind turbine, but a wind turbine which is 3d printed, something like fiberglass coated foam is not the way we can go, even if we`d like to.

Quote
cozmicray
What is the problem with using ABS, Nylon, Polycarb pieces?
Why must they be sintered?

Low RPM doesn't matter --- centrifical force put on blade,
energy in blade ---- at what speed will it rip through buildings and bodies?

Why do you need "instant" blades?

Unreasonable development time?

there is no Problem with printed ABS, Nylon or Polycarb. Our SLS can only handle PLA and some aluminiomide, which is basically the same in strenth.
The blades are already calculated and should be that strong thet ripping through anything than air will not happen.
the highest loads come from thrust and will be at the root

I suspect that the surface finish of the blades is crucial to their efficiency, given that the operation of an airfoil wholly depends on airflow over the surface.

I assume that a smooth surface is vital (but with luck a rough surface could actually help - kind of a million to one shot). Even SLS creates a quite rough finish. So a printed airfoil would need to be coated or otherwise smoothened in a predictable way to get a consistent efficiency. Regardless of mechanical strength, I would want to thoroughly investigate the requirements for surface finish first. Could be an acetone bath will do it, but I would like to know otherwise the whole idea could be a non-starter.

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Quote
bobc
I suspect that the surface finish of the blades is crucial to their efficiency, given that the operation of an airfoil wholly depends on airflow over the surface.

I assume that a smooth surface is vital (but with luck a rough surface could actually help - kind of a million to one shot). Even SLS creates a quite rough finish. So a printed airfoil would need to be coated or otherwise smoothened in a predictable way to get a consistent efficiency. Regardless of mechanical strength, I would want to thoroughly investigate the requirements for surface finish first. Could be an acetone bath will do it, but I would like to know otherwise the whole idea could be a non-starter.

The surface will be smoothened. It is a fix part of our process. we plan to apply a film, varnish it or coat it with resin and fibers first before varnish it

Quote
bobc
I suspect that the surface finish of the blades is crucial to their efficiency, given that the operation of an airfoil wholly depends on airflow over the surface.

I assume that a smooth surface is vital (but with luck a rough surface could actually help - kind of a million to one shot). Even SLS creates a quite rough finish. So a printed airfoil would need to be coated or otherwise smoothened in a predictable way to get a consistent efficiency. Regardless of mechanical strength, I would want to thoroughly investigate the requirements for surface finish first. Could be an acetone bath will do it, but I would like to know otherwise the whole idea could be a non-starter.

This depends on the Reynolds number, airfoil etc but controlled dimpling can have an effect (golf balls) or at the other end of the scale vortex generators. For stuff like laminar airfoils a 50u bit on the surface will break down the laminar flow but with a windmill you will have insects and dust on the surface so no laminar flow.

With wooden propellors they use a master (which could be printed in sections) and a copy machine (think copy attachment to a wood lathe with a router rather than a chisel and the master turns in sync with the product). The master could be 3d printed in sections and this would be an easy way to try various shapes

could you put a section of your blade on here / thingiverse so one of us can try to print it?

It sounds like quite a large item to print, in terms of time required and also material required - what will the density of the part be? (i.e completely solid, or just a hollow shell)

my printbed area is 340mm wide * 205 deep * 205 tall so i may be able to squeeze something in...
However I'm still a bit of a novice!

Quote
T0mmm
could you put a section of your blade on here / thingiverse so one of us can try to print it?

It sounds like quite a large item to print, in terms of time required and also material required - what will the density of the part be? (i.e completely solid, or just a hollow shell)

my printbed area is 340mm wide * 205 deep * 205 tall so i may be able to squeeze something in...
However I'm still a bit of a novice!

The precalculated "material need per blade is about 600ml. Our steps are now cuting the blade into handleable 3D parts

So thats about 600grams for ABS, at ~£22 per kilo for ABS filament it works out at about £13 material cost per blade

you are in the university of stuttgart and you don't have a reprap there?
there will be at least a few students there who have one. otherwise you really need to invest in a few.

I think the X-Winder concept is way to do this. Think of a lightweight CNC lathe with a stepper driven chuck at one end and a tailstock at the other.
Mount a 1/4" router on the carriage and machine the exact shape of the blade into a foam plastic blank as it slowly turns. Then use the same lathe set up to filament wind over the foam with a fiberglass or carbon fiber and epoxy. for a really smooth surface use an abrasive flap wheel mounted on the carriage to sand the outside once the epoxy has cured. The blades can be extremely strong, light and identical.

If you need to use a 3D printer to make a wing of PLA and ABS then since we already know the material is not strong enough on its own, you will have to use the old style balsa wood model technique of wing construction.

You can make incredibly strong and light wings this way out of relatively weak material.



The process would be to 3D print a lot of ribs, and glue say every 3cm on to a rod spar of carbon fiber or aluminum tube.

Then 3D Print a thin leading edge skin that goes back ~30% of the wing chord to form a classic "D-Box" section for torsional stability.

Then you could print a trailing edge skin about 1-2 cm wide.

The final step would be to cover the entire wing with a heat shrink plastic ie Monokote etc which will provide even more rigidity.

Optionally you could 3D print the entire skin but I think it would add too much weight and would be better off with the plastic film skin.

This site has several techniques you could consider Wing Construction techniques


Some additional thoughts:

Since 3D printers have limited bed size you could print the skins in sections and have Dovetail patern interlocking edges and CA Glue them together.
You would epoxy the ribs to the Aluminum tube spars and CA glue everything else.

This is a time proven technique using balsa wood which would not even necessarily be as strong as the PLA or ABS materials so it should produce a pretty strong wing
and although a bit heavier than balsa should still be much lighter than other technique builds and result in lower forces having to be dealt with in the design.

Edited 2 time(s). Last edit at 12/05/2013 10:32AM by jb92563.

I always thought the root of the blade, was where it attached to the hub, if so the above design would not help aleviate the problem of PLA not being strong enough to endure the Thrust force at the root.
as it has been said above if there is no one at the university who has an ABS capable RepRap I'd be a little surprised, also you can actually build one yourselves.
or there are firms out there that will print your part for a cost.

you are asking others to print your part for you without offering compensation for thier time, use of their printer or the ABS used, not to mention the time involved in cleaning up your design if it does not slice first go for what software they will be using.

this seems like a silly way to get others to do your work for you.

if the part prints in PLA on your printer, you can make a mold and mold an ABS part, the exact characteristics wont be the same as a printed part but would this be less than the cost of having a firm print your part or building a RepRap yourself?

Quote
Zerker
I always thought the root of the blade, was where it attached to the hub, if so the above design would not help aleviate the problem of PLA not being strong enough to endure the Thrust force at the root.

I propossed that the PLA is for the ribs and skin only, and that the Spar which takes all the loading is a Carbon or Aluminum tube which can handle the loads etc.

The spar is the part that attaches the wing to the hub and with a little inginuity you could even control the wings pitch in that way for feathering the blade and controlling the rpm and resulting forces so it does not fly apart in gale force winds or can be stopped altogether in the case of a malfunction of some part of the system.

PLA is not likely up to the task of being a long spar and handling those loads as you suggested.

In any case the student has a problem to solve and needs to do all the work, design and calculations so the 3D printing part is rather trivial.

Edited 1 time(s). Last edit at 12/06/2013 11:24AM by jb92563.

~1 meter long printed wing
[www.youtube.com]

Cool, I like that this topic showed up on RepRap forums! I'm working on a opensource VAWT project. Just wanted to share where I at, and maybe get some feedback?

This is a lenz2 type VAWT. It was printed in PLA. I haven't tested it in strong winds yet.
I have been working on a couple of weeks developing this project based on Its a derivative from [www.thingiverse.com] design so it can be placed pretty much anywhere on a flat surface. Changed diameter for Wing Span and some mouting elements improvements:


Trying to 100% print printable wind turbine. Took too much time tho, and I had to drop it



Proof of concept making some energy


Some videos:
[www.youtube.com]
[www.youtube.com]

What I would love to have one day:


I'm still struggling to get some decent power from the VAWT and I'm having mainly problems with the motors torque. There has to be very strong wind to get it going but hopefully I can try improving the bearings / motor issues.

Nice work Rapcraft.

Since with vertical windmills are blades are better supported you probably have a better application for 3D Printed foils than the Conventional Propelloer type windmills.

I wonder if a variable pitch mechanism on the blades might help optimize output and help get it started in lower wind speeds.

You could vary the pitch based on RPM.

Willdmo. I don’t think many people are listening.
He wants to investigate if its possible to print the blades on a home printer, not what is the best way to make turbine blades.
I guess you would print the sections so the z axis was along the blade axis. The filament would go around the airfoil shape right? Therefore you need quite a ‘deep’ printer. Did you say 1m in 3 sections, 333mm? Are you having twist along the blade?
Are you planning to hollow out the sections except for the hole the spar tube will slide into like wide aircraft ribs.
Why worry about slight efficiency drops due to roughness, its free wind. Make it 5% bigger to account for it. The roughness may even help, depending on section choice.

I don't know if it's really a matter of not listening. Okay some people did question how feasible the ideas were etc. But I personally had no problems accepting perhaps willdmo did have an idea of what they were doing and had thought of most of the major issues but still wasn't surprised at the responses, or lack thereof. And probably wouldn't have offered to help even if I lived near willdmo and did have a 3D printer.

Probably the main reasons why there were limited offers of help were the requirements were fairly poorly defined (what print area do you need, have you tested slicing your file or do you at least know what you're designing for so there's a fair chance it will actually print, how much material will be needed) at least initially; people were apparently expected to do this for free (or at least there were no mentions made of compensation even for material) which might be slightly understandable for a student but doesn't mean people are going to offer to help at their cost; and perhaps most significant of all, the time frame was very short. I know students are legendary for their tendency to leave things to the last minute, but asking for free help on the 25 November for something which may take quite a while to print, when you want the parts at the beginning of December always has a strong risk of not going well...

Edited 1 time(s). Last edit at 12/12/2013 09:43AM by Nil Einne.

Your local hackspace has 3D printers: [shackspace.de]