[Paraprop]

Hi Guys,

After duplicating props manually in the time elapsed. I now finally build a 3-4 axis milling machine where I want to proove the entire prop digitizing and cutting concept on 1 single blade before I then do a tailor made router for the entire prop as discussed in the start of the thread.

I went with the DeskCNC software, controller and TP100 probe.
Gecko servo drives and a lot of second hand ahrdware I gathered over the 2 years.

In the pics. below is the result:

I have started digitizing my first propeller blade on both sides. At a raster of 1mm x 1mm, I come to about 66,000 points in the stl file, the system works well but I bump into a major issue.

If you look at the probe tip shown in one of the pics. As long as the probe is no top of the propeller averything goes fine, However when it touches the edge, it will try to go down till it reaches Z=0 setting. Doing this, the 2 mm tip will pass the edge and then a short segment smaller than 2 mm comes into contact with the blade edge, going further done, comes the taper and then a thiker 3.15mm stemm. Given that the software does not know about this, it always compensates only for the 2 mm diameter tip.

As a result, everything on the blade surface is fine however the edge shows a mess of 3 dimentionall stairsteps which can't be cleaned up in the Cad program.

I don't now the solution yet for this issue. My first idea is to fix a cardboard below the propeller surface and fill the gap between prop edge with some silicone or similar so as to have a vertical contact from the prop edge down to the cardboard surface. this should force the probe tip to always be in contact and avoid the wrong diameter compensation issue. Does someone have experience to share on this subject ?

Right now I am using Vector Cad Cam to edit the stl. files. Any experience to share for this program ?
Would Rhino have advantages ?

Thanks

Paraprop

[Bent]

If you dont have any fine detaile then you could go for a bigger ball on the probe so the stem is smaller.

Bent

[Paraprop]

I have lost more than a year trying to find a software method to clean up the steps left by the digitizing probe on the .stl file. To no avail !

A few months ago I got in touch with a company who owns a Faro laser scanner.

They scanned one of my blades as a sample. Cleanned the .stl file up and rotated a copy of the blade 180 degrees around it's center axis to make a 2 blade prop out of it.

No I got a complete propeller data file ready to cut my wooden prop.
Looks great ! but the cost of such a setup is not within my reach. For the timbeing I'll have to outsource the scanning until I find a more affordable solution for my needs.

On the hardware side, next to my mill I have built a tailor made wood router for the propeller cutting. X 53.5" x Y 6" x Z 4"

After some progressive stiffening/strenghtening work on the entire system and bench, I can achieve an acceptable surface quality at a reasonnable speed. see pics.

[Paraprop]

For the moment I do use DeskCNC as well as Cut3D as the CAM tool to make the G code.
Both lack of some flexibility to make proper tabs in the right postion and right directions. Also they do ct a lot of air with the complex shape of this 2 blade propeller.
Hope to find a better software which is smarter but not too dounting to learn how to use. (I have to admit that the 2 above ones are very easy to master).

I saw in another thread a 5 axis router making propellers. Amazing.
One good idea is that once the top of the prop. is cut, they remove it from the jig and put it top down into a mold like jig to cut the bottom side.
I think I'll try to go that way too in order to avoid to have to create tabs on the blade so that the blade does not bend or start to vibrate when the router cuts the second side of the blades.

http://www.cnczone.com/forums/showth...t=22659&page=2

[ame="http://www.youtube.com/watch?v=Cm_9LmXz4Mk"]YouTube - Routech Chronos working wood 1[/ame]

Step by step I'll try to improve the propeller cuting an the fixing method so as to be able to make batches of the same prop without a lot of setup time.

For scanning I just had another look at the Nextengine laser scanner solution. it is now close to 3000$ but I get the feeling it would be able to do my job given that a single blade is no longer than 26" and it's width max. 5 1/2"

I guess I could get the blade to stand on the rotary table provided with nextengine and move the scanner gradualy up till it covered the entire height.
Does anyone have experience with a similar task ?

[Paraprop]

Can someone advise the best RPM and feed speed for carbide ball nose router bits of 1/4", 3/8", 1/2", 3/4" and 1" on beech wood plans ?

[Xnaron]

I have lost more than a year trying to find a software method to clean up the steps left by the digitizing probe on the .stl file. To no avail !

A few months ago I got in touch with a company who owns a Faro laser scanner.

They scanned one of my blades as a sample. Cleanned the .stl file up and rotated a copy of the blade 180 degrees around it's center axis to make a 2 blade prop out of it.

I am wanting to do the same. I have an existing prop I can take and get scanned (for my hovercraft www.hovercrafters.com ). I'd prefer to be able to have the prop modelled in 3d and then be able to make subtle changes to it to improve performance. I have just finsihed building Joe's Hybrid 4x4 CNC router and plan to use it to cut the props. I just need the 3D model. Is there any chance you would be willing to share your 3d model?

thanks,
Brendin