Author Topic: CNC router blade carving (Read 3525 times)

Boss · « **on:** July 21, 2009, 03:49:23 AM »

Friday we worked with the new CNC router!

Let me show you some of the pictures I took, and briefly describe what you are looking at.

Above is one of many screens on the CNC router controller computer. This particular screen is displaying progress of the current operation as the router works through thousands of lines of code.

Above is the router bit in action, cutting across the laminated wood of the blade blanks we made from Maple, Douglas Fir, and Lodgepole pine woods. The Maple is on the left, and is rescued wood (stair steps) from the Ilfeld-Plaza hotel building. The Douglas Fir was salvaged from Old Wood flooring where they were using it for stickers (spacers between boards while the lumber dries).

Above, two blade fronts. Louie and I are still getting used to the spatial nuances of the CNC router. As you may be able to see in the above image there is a choppy edge at the top of each blade. We think this occurred because the bcause the actual blanks are .75 inch narrower than what we told the CNC router software the blanks were. We thought about making an adjustment but we already had one cut too far to one side, and the blades really need to be identical so we left it like that and cut the other two blades the same way. One of the things we need Kevin to fix is the original design so that the CNC router doesn't cut quite so much material away leaving the finishing and final shaping to be done by hand. One of the things we have learned and there have been many learning experiences with this machine, is that it can tear up the feathered edge of the blades, so we want to do the final shaping with a belt sander.

Finally you see the two blades on the CNC router table with one side cut, and the third is in the machine getting cut. Perhaps you can see the blade twist as they lie flat on the table. On the right the blade comes to a knife edge, whereas on the left it is square edged where once the back of the blade is cut it will have twist. The twist helps keep all parts of the blade as it spins in the wind with equal lift. If you think about it the center of the wind turbine like a wheel on a car is spinning slower than the outside edge, with twist, the blade tips have a slightly different lift than the root of the blades.

taylorp035 · « **Reply #1 on:** July 21, 2009, 03:06:39 PM »

This is the first other CNC blade project that I have seen yet other than mine.

I quickly realized that flipping the blades over to cut the other side was not going to be accurate, so I only cut the airfoil side. Once it cut out, I then took a large band saw and cut the twisted flat side.

For the tearing issues, I used a 1/2" flat router bit at a very high rpm and light passes at 200 inches per minute travel speed. I also used pine, which was very soft and easy to machine.

It looks like you you have a big machine, which comes in handy for large blades like yours. My machine only had a max long feed of 19".

Question: Did you use a 3D cad software to design your blades?

If so, did you calculate the center of gravity so the blades would be perfectly balanced?

And how big were your blades? It looks like at least 5 feet.

fabricator · « **Reply #2 on:** July 21, 2009, 06:49:28 PM »

I think when you get this down you could probably make a fair bit of money making and selling blades, I'd order a set of 8'6" blades today.

Tritium · « **Reply #3 on:** July 21, 2009, 07:11:05 PM »

fabricator,

check here

http://www.royalfabrication.com/

Thurmond

Boss · « **Reply #4 on:** July 21, 2009, 08:58:59 PM »

Thanks for the input, indeed we have had problems flipping the blades over and trying to line up the front with the back. At this point we are attempting to eliminate variables. Unfortunately when we are this green everything is a variable, even the details that shouldn't be. With our programmer out of town on a motorcycle adventure, east coast to west, we are left to trial and error everything.

What we learned, I think, right off the bat, is that zeroing the bit doesn't have the affect we at first thought it would. The next set of blades we'll make absolutely certain the planer makes every blank the exact same thickness. Somehow the software VCarve pro will compensate if the X axis (up and down)zero point is different for each blank. We sort of knew this intuitively but did not act on it, and re-zeroed for each blank, with the result being the bit did not penetrate to the bottom of the wood because it was told the top was higher or lower.

Yeah, so lesson #1 came pretty quick. Same was true when we used a blank that wasn't identical in width to what we entered in on VCarve Pro, the tool path was moved over by the same distance as the discrepancy between what we told the machine and what was actually there for it to cut, duh.

The original 3D CAD model was built using SolidWorks, and can be found in my files section:

http://www.otherpower.com/images/scimages/9419/blade_back.v3d

http://www.otherpower.com/images/scimages/9419/blade_front.v3d

http://www.otherpower.com/images/scimages/9419/blade2.STL

http://www.otherpower.com/images/scimages/9419/blade2.SLDPRT

VCarvepro http://www.vectric.com/WebSite/Vectric/vcp/vcp_index.htm

My buddy Kevin Murphy who did all the computer stuff said he can fix most of the little irritations we are having, like the fact that the blades are three inches on the tips and 7.5 inches at the root, and Vcarvepro wants a square blank which isn't too bad since the triangle gets removed by the router while cutting the front, but then we flip it over and the carving software wastes time cutting the same triangle out again, except of course it is already removed.

Our blades are 5 foot, but I found that one thing VCarve does well is let us change the size of the blanks, then stretch the blade model to fit, I want to try a set of 5.5 foot blades on my mill to see if this solves the stalling issues

Yep, a bunch of little things constantly.

Kind of reminds me of getting older; forgetfulness makes everyday a new experience

dexxy · « **Reply #5 on:** July 22, 2009, 07:19:04 AM »

Try zeroing to your table, not to the top of your job. That way your cnc machine won't care what the thickness of your blank is.

Nice job so far!

JW Peters · « **Reply #6 on:** July 22, 2009, 07:41:08 AM »

Hello Boss; This is how I made my blades in 2007. JP http://www.fieldlines.com/story/2007/2/2/03059/10452

taylorp035 · « **Reply #7 on:** July 22, 2009, 11:25:33 AM »

I would be careful to zero the table because you could possibly take some super heavy passes and break your bit.

I always like to program in rough cuts first, and then come in with a finish pass that takes off the last .1" or so.

taylorp035 · « **Reply #8 on:** July 22, 2009, 11:33:23 AM »

I live only 45 min from that place. Nice web site, even though they don't tell you how they make the blades (CNC obviously). Also they have an advanced blade design, not one made by hand like mine.

taylorp035 · « **Reply #9 on:** July 22, 2009, 11:39:39 AM »

I opened up your drawing files in Inventor 2010, and I like what I see. The only thing that I did differently was I add a twist to the blade so the tip was about 5 degrees and 20 degrees at the root.

taylorp035 · « **Reply #10 on:** July 22, 2009, 11:52:37 AM »

And Yes, you should definitely make the wood the right size to start with so you don't have all of these problems.

taylorp035 · « **Reply #11 on:** July 22, 2009, 11:59:12 AM »

Boss,

After some more analysis, your center of gravity is exactly at the corner at the end of the blade (nice job there). You could also include the hole ( at least 1/3 of it anyways) for a perfect fit.

Yyrkoon · « **Reply #12 on:** July 22, 2009, 12:51:50 PM »

They do look nice, and I do like the look of the machine they have pictured on their main webpage. However, @ $135 per 6' blade for yellow pine, or ash . . . The cost is most likely prohibitive for the average DIYer. Also having worked in a machine shop myself for a couple of years, I do understand that software, and CNC mills can be very expensive too; But, an inventive person, or a person who can follow instructions, and make on-the-fly adjustments of their own can make a fairly inexpencive CNC "mill".

One thing I personally would like to do is make a fixture to flip the workpiece, and continue that backside as well. Takes a lot of knowledge, trial and error, and patience . . .

Right now, I think I would have to stick with my $50 worth of wood hand carved blades ( which are not completely finished yet ). However, I actually enjoy working with wood/Metals by hand, even if the finished work is not "perfect".

dexxy · « **Reply #13 on:** July 22, 2009, 02:34:57 PM »

If you zero to the table, you will know if your gonna kill your machine because you will drop into the negative when you start eating your spoilboard right?

I profile a job in 2d to drop the excess material so that I can proceed directly to a finishing pass. Lots less shavings to clean up after a job.

taylorp035 · « **Reply #14 on:** July 23, 2009, 09:20:09 AM »

This works too. It takes some practice to get good at using a cnc machine and its software.

Ungrounded Lightning Rod · « **Reply #15 on:** July 24, 2009, 05:26:44 PM »

Remember that you can make a jig from the original database for the first face. Just flip it over and make it negative (make the wood into air and vice-versa). B-)

mungewell · « **Reply #16 on:** August 18, 2009, 12:07:55 PM »

Regarding 'zeroing'...

I may be complete ingorant on this, but if you leave sufficent 'stock' at the top and base of the blade (or mill a 'stand' area of a specific height in the front face) then you will have a known dimension from the table surface to mill the back side of the blade.

Feel free to tell me I'm mistaken,

Mungewell.

Boss · « **Reply #17 on:** September 05, 2009, 05:23:50 AM »

Sounds right to me. I believe one trouble we've had is the blanks (boards) are all slightly different, and not getting cut in the same run, and the machine is being re-zeroed each time.

On a positive note Kevin our resident Solidworks CAD and CNC machine expert is back from his Summer of biking around the country, some 7,000 miles he put on his Honda.

Boss · « **Reply #18 on:** September 20, 2009, 10:24:34 AM »

Kevin created several new Solidworks 3D CAD blade designs,

You can download them from my photo area.

We are going to try 6 inch longer blades on out 10 footer, this and the increase in blade efficiency (on paper) we hope will make our turbine make more power. Right now in a 25-30 MPH (guesstimated) wind it puts out 10 amps > 27 volts. Every now and then the amperage goes to 12, but while watching the blades I see them stalling in higher winds.

The other issue Kevin is working on is the blank shape: for the last half dozen blades runs we did with the CNC router the machine wasted a lot of time cutting out the triangular area at the tips, we want to cut the blanks on a table saw and run them through a planner to get them identical. Kevin is using Mastercam to work on the blanks dimensions.

Next, we need to build a laminating table and start collecting wood for several test blades.

News:

Author Topic: CNC router blade carving (Read 3525 times)