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Jul 29, 2010, 09:40 PM
Registered User
Quote:
Originally Posted by flyinguy
I finally started cutting my mold! Just a few quick shots to share.
Cool. Do you flycut the milled/rolled surface face to true it up, or does that come later?

What kind of cnc & cam package are you using?
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Jul 29, 2010, 11:15 PM
Registered User
flyinguy's Avatar

Progress


I didnt get much done tonight. Just made a .006 step along the trailing edge due to the fact that my model's trailing edge came pretty much to nothing, .0005". I did manage to outline the mold itself with a 1/2" end mill to excise it from the large piece of material after the locating holes are reamed.

I am not going to flycut the the top actually. I have it clamped to the bed of the mill and I measured it at .002" from one side to another on my sweep which was about 24" so I decided that will be good enough. Im using a Fanuc Supermax from the mid 80's. I drew the model in Solidworks then imported it into surfcam to post the code.

Just one pic for tonight.
Jul 30, 2010, 11:06 AM
Twisted and Confused
flyonline's Avatar
Hi guys

I'm trying to get a quote to get a set of wing molds (or positives rather) made for me.

To do this, I need to give them a step over/cutting rate.

As I have a reasonable amount of spare time and not a huge amount of cash, I'm happy to do a bit of finishing off.

Can anyone suggest a reasonable but cost effective rate of cutting etc. It will be done on MDF with a max height of 6mm.

Cheers

Steve
Aug 01, 2010, 03:09 PM
who has rabbit ears down
Captain Canardly's Avatar
Steve!
the (gone) previous mold shop I was at used .003 steps for a .030 cutter,I believe you can increase that by quite a bit by verifying the smallest radius of the leading edge, finding that as the largest(standard) cutter size for the project.If there is a (4th) axis or tilt-
(bridgeport type) available, you can modify a circle- (1") cutter- fly cutter to both increase the smoothness and step factor by locating the path to needs.
Johnny
Latest blog entry: My new factory
Aug 13, 2010, 12:16 PM
Registered User
flyinguy's Avatar

First part


Well the other half finished running and after many hours of sanding and polishing I layed up a quick part. Just 2 layers of 3oz cloth. Results are very positive!
Oct 13, 2010, 08:08 PM
Dieselized User
gkamysz's Avatar
I'm ready to give up on SW2008 and elliptical wings. Nothing I try works, not lofts, not sweeps. I can get sweep and loft to do what I want with a simple arc shaped profile, but an airfoil won't. Anyone have an elliptical wing they want to donate to see if it works on my PC?

Greg
Oct 13, 2010, 09:04 PM
Registered User
Ward Hagaman's Avatar
Quote:
Originally Posted by gkamysz
I'm ready to give up on SW2008 and elliptical wings. Nothing I try works, not lofts, not sweeps. I can get sweep and loft to do what I want with a simple arc shaped profile, but an airfoil won't. Anyone have an elliptical wing they want to donate to see if it works on my PC?

Greg
You might want to just check out Profili Pro....I still can't believe how simple it is to create an elliptical wing, complete with dihedral, even elliptical dihedral! You do need a CAM package that can cut a .STL file, though.

(I have no affiliation with Profili, just a satisfied customer.)

Ward
Oct 13, 2010, 10:46 PM
Registered User
Quote:
Originally Posted by gkamysz
I'm ready to give up on SW2008 and elliptical wings. Nothing I try works, not lofts, not sweeps. I can get sweep and loft to do what I want with a simple arc shaped profile, but an airfoil won't. Greg
I'm not an expert on SW, but there are few subleties on Rhino that might help.

- generaly I loft the upper airfoil surface as a seperate entity to the lower surface. I actually cant remember exactly why, but a habit Ive drifted into. Sometimes lofting closed shapes (like a full rib) can cause surfacing issues depending on a few factors like how the TE is defined (point vs truncated) particularly as it scale reduces & attempts to wrap around the tip.

- I found it best to split the eliptical planform into a LE & TE segment out at the tip. That split point could be for ex the outermost (~mid chord) extremity tangent if its a normal elipse. Reason: I typically use a 2-rail sweep surfacing command so it needs... well... TWO rails! If the SW surfacing is failing it might be because it doesnt know how to handle the continous 'loop' profile shape. If you mean 'eliptical type planform' but it has say a straight TE & eliptical curve shape LE, then this split point becomes quite important or you can get weird results. In this ex the split would likely work best at the tip end of the TE line, not in the mid chord position of the tip.

- as mentioned on another wing/rhino wing post (do a search here) I like to place lots of 2D scaled 'control' ribs along the span of the panel... as opposed to one 'root' rib & lofting out to the tip from only that. If you find the post Im referring to it will be obvious as to why. The ribs give surfacing control otherwise vs shape distortion. If you are blending airfoils, you would have to do this in any event.

I cant imagine SW can't do this operation & a whole lot more. But these are a few stumbling blocks similarly encountered in Rhino. Seems like they all have their quirks.

/pt
Oct 14, 2010, 07:48 AM
Dieselized User
gkamysz's Avatar
I'm able to use multiple profiles to loft, but this doesn't help me make a wing tip. I have TE gaps filled with a single vertical line or two segments to the chord line. I'm fairly certain the the sweeps everyone else is doing in later versions doesn't work in SW2008. I just tried sweeping an ellipse. If I select one guide curve, it effects both the TE and LE as if it were mirrored selecting the second guide curve does nothing. Single segment arcs top and bottom are no problem, even with sharp edges. Arcs with vertical gaps filled work, except the LE or TE thickness doesn't scale with chord properly.

I'd love to be able to do what Eraz did with the tail section in this thread. If anyone has actually done this in 2008 I'd love to see how.

Greg
Oct 14, 2010, 02:57 PM
Dieselized User
gkamysz's Avatar
I might have this licked. Even though the airfoil coordinates had a 0,0 point the spline apparently didn't actually go through that point. This wasn't obvious even though I looked for it. SW even gave me a pierce relationship when I drew the LE guide curve. You can't actually see it by zooming in because things don't display correctly zoomed in that close. It didn't become obvious until I drew a vertical line tangent to the LE. The sweep now works. The last thing to fix is the reduced TE thickness as chord is reduced, This can only be possible by using a loft with a tip profile having appropriate TE thickness. The loft should work now too, but I haven't tried it yet. I assumed the imported profile was correct. Last night in bed, I got to thinking about how some airfoils LE vertical tangent is not at 0,0 and that's what I looked at today.

Greg
Nov 18, 2010, 10:05 PM
Registered User
Quote:
Originally Posted by erazz
OK, Back to the mold....
erazz, going back to your post #15 showing the original wing surface with 'open' tip. Im guessing this was by intent & an intermediate step to making the female mold with that slightly lopped off feature? Or was it because SW was having issues lofting to a terminal 'point'?

Anyway, got me wondering about SW vs my experience in Rhino on another aspect - filleting...

If your wing was fully closed as a 'solid', would this give you some advantage in terms of SW auto-filleting commands, specifically wing root > fuse where the wing mates? Ive always found this to be kind of a headache. But what Ive seen of SW filleting so far, it is very powerful. But my experience is limited to messing around with typical blocky mechanical type objects as they arise in training excercises vs swervy airfoils. I was wondering if you crossed this bridge in SW with your particular model & if you have any pics showing fillets?
Dec 12, 2010, 03:46 PM
Horten Freaky
I have tried to make the wing with sweep method, but it was impossible, only with loft. But as you can see, the ribs are deformed. how can I do?

Thanks
Dec 13, 2010, 06:50 PM
who has rabbit ears down
Captain Canardly's Avatar
Hi Guys!
It looks to me like some data needs re arranging: Here's what i had to do 'back in my youth"
Johnny
http://www.youtube.com/user/drawmeol...10/kRNLMLH9nMI
Latest blog entry: My new factory
Dec 13, 2010, 11:39 PM
Registered Snoozer
FairlyFaded's Avatar
Howdy,

Great thread!

I am having the same problem as Edu ns with deformed ribs (mine are straight not curvy, but at an angle). I'm not actually sure if it's messing up the loft, but it sure looks like it is.

Any help would be great! Thanks,

Michael
Dec 13, 2010, 11:58 PM
Psionic001's Avatar
Are they really ribs being deformed, or is that part of the loft visual?
I bet that if you took a LE to TE section, you'd have clean ribs.

The way I lofted mine was to create all the ribs first along the span, then loft across them. I had 5 ribs I think.




Quote:
Originally Posted by Edu_ns
I have tried to make the wing with sweep method, but it was impossible, only with loft. But as you can see, the ribs are deformed. how can I do?

Thanks


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