CNC cutting blades

[Seekscore]

I recently got a new CNC router. I've been trying to learn the machine and the associated software that goes with it. I hired a kid that is going to an engineering school to create some CAD drawings. It is based on the Dans design. It took a while to get it figured out how to make both sides of the blades. I think I have crossed that hurdle and can index it so that the back side is cut correctly as well. I made 3 24" blades and using scrap material, made a 4 foot wind mill that only spins in the wind. Those blades came out really good. The surface was really smooth as it came off the router so I didn't even sand them. With those blades under my belt, I decided to make some full size blades out of laminated cedar. They are going to be 6' long. Here are some pictures of the front side of the blade as they are being rough cut. I've made them so they will spin CCW.

The machine I am going to put them on is one that I helped build up at Dans. Its a 12 foot axial flux machine. I'm going to be data logging the power output. I'll get some good data using the Clark Y blade profile and hopefully be able to generate a power curve. Once I have sufficient data, I plan on making another set of blades with the NREL S822/S832 profile. Swap the blades out and see if they will increase the performance. It will be interesting if nothing else.

Mike


This is a rough cut with .1 inches overlap


This is the front side being cut with a finish cut


Here is the front side tip view with the finish cut on the right side and the rough cut on the left.


Another view of it just getting started.

[taylorp035]

What is your travel on that machine? 

I have made two sets of blades on a CNC router before, one an 8ft set and the other a 30" set.  The 30" set was designed to be very flat and high rpm.  They hit 3,000 rpm one day, which was good for about 30 watts on a small dc motor.  The 30" set was made out of pine, and I used a 3/4" router bit at 200 ipm.  My machine only had a 11" x 19" travel   Good luck.  Maybe you can design your own blades on your software.

[bradyaero]

Really nice job!  I hope to cut a set on my cnc sometime in the near future, so what you are doing is an inspiration to me!

Keep up the good work!

[Seekscore]

I'm not doing too bad learning the software. I can get a blade cut out pretty good and after just a little sanding, it looks really good. The machine I am using is an 4'x8' with 9" in "Z" axis. It took about 10 hours total to cut out, but I think I can work with the tool paths to speed that up. Something I need to learn in the software and creating the tool paths. I roughed it out with a 1/2" End Mill bit and then did the finish path with a 1/4 inch ball nose bit. This is the Clark Y airfoil but I didn't do the blade twist correctly in my design. I have that figured out now so the next ones should be correct.

Mike

Here is my router


Here are the finished blades...

[jeraklidis]

Can it take dxf files or used G code?

[Seekscore]

The machine uses G code. I use software called Aspire. I import the files into Aspire and then use it to create the tool path for my particular machine. It outputs custom G code for my router. It can import dxf or others, but I have been using .stl files. I import them and then lay it out on the wood and then create the rough tool path with several options from cutting depth to cut overlap and speed of cut. I then create the finish tool path. Once I have it carved out, I create a cut out tool path. I've been cutting from 200 to 400 inches a minutes. The biggest problem I have now is that the cedar I'm using doesn't chip like I would like and leaves string like cuttings that plug the vacuum foot. I am pretty sure I can get the cut time down by playing with how the tool paths are done.

Mike

[DanG]

All the 'ceder' - western red ceder - that I've known is shipped soaking wet to keep this higher value wood from checking & warping in transit & storage, and mainly to keep fasteners from splitting it on installation, plus allow the stick built decks, fences, etc. to dry in place and shrink over their fasteners to inject higher rigidity into the structure...

My stash of ceder in outdoor covered storage has freeze-dried in the Minnesota winters and makes dust similar to what redwood cuts produces. Maybe rack the wood up for a couple of months to allow it to fully dry before routing?

[bradyaero]

Hi Mike,

I would do the complete operation with a 1/2" ball nose end mill.  That will help alot with the grain tearing.  With my software I can specify the angle of the cut, so if following the grain causes tearing, you can change the ange to 45/90 degrees, whatever you want.

Interesting that you are using Aspire, I use rhino / rhinocam but would like to get Aspire/Cut3D for its slicing ability, that looks like alot of fun.

Nice machine btw.  Vacuum holddown?

I built my own cnc machine, 9x6 bed with 16" of Z axis.  I do 2d and 3d cutting, I originally built my cnc to do blades but I haven't gotten to that project yet.  Here's a pic:

Brady

[Seekscore]

Wow! that is a nice machine you built. I didn't get the vacuum hold down because it was another $8000 for the full setup. Spoil boards are cheap and so are screws. I may build the vacuum hold down in the future.

I haven't thought about using the same bit to rough out and then finish. I'll give that a look and see. I can change the angle of how it cuts. That is one part of the software that I need to get more experience on. There are a lot of options that I can use for the tool paths. That will also eliminate a lot of the time it takes to carve it if I can get it tuned right.

Mike

[taylorp035]

Maybe using a different type of wood might help.  Maybe ash or maple would work better. 

Also, 10 hours is a long time for one blade.   I bet you could cut that down to less than 2 hr's.  Mine took about 15 minutes for one side, but of course they were only 15" long...

Keep us updated because many of us are very interested into this stuff.

[DragonFly III]

I almost fried my laptop with the druel that was comming from my mouth when I saw that CNC machine.  Bravo

DFIII

[Tritium]

The "Floor" under that CNC machine looks good enough to play pool on.  ;>P

Thurmond

[DragonFly III]

Those blades look to be comming out pretty good from my house.

[Seekscore]

The blades aren't coming out too bad at all. I still have a hurdle that I hope to overcome soon. I've ordered some longer bits so I can get all the way thru the material without the router spindle nut hitting the material. I should be able to make repeatable blades soon. I've got some practicing that I need to do on laminating. It's not as good as I would like. I'd post some more pictures but blades are so hard to get a good picture that actually shows them. I've got a CAD drawing for the NACA4412 profile and also a modified S822/S823. I've cut out each and like the looks of them. I should be getting some data logging hardware soon so I can compare energy outputs with the different blades.

Here are a couple of screen shots from my CAM software which shows them probably better than I can take with a camera. I have the trailing edge flat at an 1/8' as you can see.

Profile...


Arial...


Mike

[Seekscore]

I've almost got a blade petting zoo. Now its time to make three identical ones since I think I have the process almost down.

My modified S823/S822 blade. 1st attempt and a good looking blade. I scaled it to a 2x6 I had. It came out 44" long and about 1.375 inches thick. With a 2x8 it should be 1.5" thick and 60 inches long.


Blades i've cut out. The second one up is the Modified 823/22 airfoil.


Another view

[taylorp035]

Very nice! ( and jealous )

[bradyaero]

Fantastic Seekscore, you're really getting the hang of it!  

Are you using end blocks and cutting them off after flipping everything over or did you make a blade holder to machine the reverse side?

Greg

[bradyaero]

and btw your shop looks way too clean for the amout of chips that you are making 

[Seekscore]

I put a guide board on the table long wise. I drew a line on that board with a square to mark my Y axis "Zero". The edge of the guide board is the "Zero" for the X axis. I've been using boards that are 6" longer than the blade so I have 3" on either end which is where I screw the board to the table. I put a line on my blade board on top and bottom so that when I flip it over, I just line up the lines to my guide board. Then butt it up against the guide board. Once I screw it back down, I set the router to cut the back side. I leave all extra wood that I can so that it doesn't flex. I learned this the hard way Once I get the profile cut, I then use a .25" end mill to cut out the entire profile to remove the blade from the wood.

I'm rough cutting with a 1/2" ball nose and then the finish cut is with a .25 ball nose. I found a vacuum system made by Shop Fox that was about half what others sell for and it works great.  I've been pretty good so far to clean up all my dust when I finish a blade. Just easier that way

Mike

[Ungrounded Lightning Rod]

I've been pretty good so far to clean up all my dust when I finish a blade. Just easier that way

Now if we can just find a good, cheap, smaller-than-an-industrial-plant, pellet-maker for turning the sawdust into feed for the wood stove in the winter... B-)

[Boss]

Nice nice
there are two different CNC machines pictured here which is which?
Water cooled cutting head, awesome
It does seem to be an artistic endeavor matching the router bits to the style of cuts
Brian