CNC files

[JohnF]

A discussion of CNC routing sprung up in the building tips/techniques forum. In the thread it was mentioned that files exist in the Yahoo Group files directory that could be used to cut wing parts. I have access to a production CNC facility and thought I would cut a master wing form to compare to the mylar to see how they compare before I made the decision to cut all wing parts so I went looking for the files and got "document not found."

I was hoping we could bring that information to this site for archive so I'm wondering if anyone has files they could download here?

[X'N]

They worked fine for me. http://groups.yahoo.com/neo/groups/Bearhawk/files

[JohnF]

Well...

Okay, it worked and then it didn't and then it did again... I stuck it out and eventually downloaded all of the autocad files that looked like they belonged to the Bearhawk 4 place. There were a few of the ribs so I checked them out with Sketchup and it appears to me to be updates of the same file so I am only uploading the most recent.

WING RIBS.zip contains rib files uploaded to the Yahoo group by drandall99031 on 2003-01-12
Wing Spars.Zip contains a spar file uploaded to the Yahoo group by lathropdad on 2004-12-08
NACA4412BearhawkChord.zip says it is the NACA 4412 scaled to the Bearhawk uploaded by nzbearhawk on 2009-09-26

I do not have any idea how accurate these are.
The user IDs above are the Yahoo group Ids - We cannot assume that same ID in this community is the same person as the ID in the other community.
A lot disappears when you open these in Sketchup and I do not have Autocad so someone that does might be able to better make a statement as to usefulness.

One thing that struck me is the detail for the rib joggles - they seem to cut off the material for the flange. There may be a note mentioning this as Sketchup ignores Autocad text and such.

Oh yeah, I didn't find files of just the forms.

[Jflyer]

I've opened these in AutoCAD and DraftSight (free CAD software) and the flanges are on the drawings. I've also cut out some test pieces in thin ply and aluminum flashing. All looks good. I'll test some more and size up to the drawings once mine arrive from "The Bob"

Also. for a great free 2-D CAD software, take a look at DraftSight by Dassault Systems. The free version is a fully functional 2-D CAD that is incredibly similar to AutoCAD. Many of the same functions, clicks, key-strokes, and symbols are identical to those found in AutoCAD. I actually use the Draftsight more than AutoCAD mainly because it opens faster and in many ways, is easier to navigate.

http://www.3ds.com/products-services/draftsight/overview/

[JohnF]

Excellent! Thanks for the ap link. From '85 to '91 I wrote CAD software - haven't been involved since.

Hmm. Check the detail at the front spar center rib. If you were to cut the outside green you would be missing the bit of rib flange that goes underneath the spar flange. Wouldn't you?

It's really obvious on the aileron and flap ribs.

[X'N]

just do an offset line from the main shape for your flange

[JohnF]

Understood. Just didn't want to see someone CNC cutting from the files without consideration for what I perceive is an error.

[Tom W]

No problem opening the wing spar files. I couldn't get the NACA file to open.

I did a similar air box for hold down. Yes, top board was surfaced (2" planning bit) on both side. Vacuum sucks down through the mdf, just pourous enough to hold a larger sheet in place.

When I went to cut a smaller inspection ring, as you can imagine it did slip.

[Tom W]

NOSE BOWL..... does anyone have a 3D Nose bowl? Need something to make up a buck from, ideal would be a drawing of the nose supplied by Avipro.

[Jflyer]

Excellent! Thanks for the ap link. From '85 to '91 I wrote CAD software - haven't been involved since. Hmm. Check the detail at the front spar center rib. If you were to cut the outside green you would be missing the bit of rib flange that goes underneath the spar flange. Wouldn't you? It's really obvious on the aileron and flap ribs.

John, Is this what you are referring too? See the "RED" additions at the flange.

[JohnF]

Yes. Also on the back/aileron/flap ribs.

[Jflyer]

John F. (confusing as I'm a John F also)

Got it, and thank you.

My plans arrived today and I am now officially #1316. Whew-Hew! Release the Doves!

There looks to be a joggle at the Center rib flange to Spar Flange area, which I believe is why the CAD drawing has this part of the flange missing. My guess is the CAD drawer/drawee may have thought the flange ended at that point. However, as I'm sure you know, there is a note on the drawing stating the rivet to use for this connection of the Rib to Spar Flanges.

Thanks again for pointing this out.

[JohnF]

John F.,

Yes, that's probably what happened. Another thing I see is that you will need to add a few more jig pin holes.

[Jflyer]

I agree. I plan to use the Rubber Press scenario for flanging the lighting holes as well bending the outer rib flanges at one press, so yes, more jig holes.

[DRLPatrol]

I agree. I plan to use the Rubber Press scenario for flanging the lighting holes as well bending the outer rib flanges at one press, so yes, more jig holes.

I hope when you do ,you document it well on here as I am very interested in that method. I am a few months out from starting my Patrol. I don't think you can get 90* on the rib flanges but at leased get them started, then finish with the hammer.

Doug

[Jflyer]

http://www.eaavideo.org/video.aspx?v=1277219627001

This EAA video is impressive for what he's been able to accomplish. In the video he mentions using this process on larger pieces with 2024 T3 up to .060 thickness.

Funny story is that I first saw this video a couple of years ago, about 2 days before going to Sun-N-Fun. On Saturday morning at the hotel in Lakeland, my wife and I got on the elevator and there was Brian from this video. He's as nice in person as on the video. I asked him about using the process for larger/longer pieces. I was thinking specifically of the center rib section for the Bearhawk. He said the only limiting factors so far were the tonnage of the press, length of the support beam on the press, and strength of the mold/plug that we'd be forming around.

I have some ideas to turn the support plate sideways on the press. Perpendicular to the normal support beam that you would press against. We'd have to add extra supports as well to handle the length. We'll see, and I will definitely post the results. Good or bad. :-)