Parabolic curves for solar collectors/hot dog cookers

[olivier]

I have seen the tool path for the parabole on the Vector site,
I do not understand how you rough the shape before finishing it.
Is the cutter suposed to cut the shape in one go ?

Olivier .

[jorgy.tucson@worldnet.att.net]

I think Gerald is on the right track, a couple of frames with a parabolic curve and shinny stuff. A round parabolic dish would be perfect for super heating the end of the hot dog. It seems a less than perfect long curve would end up heating the whole thing. Probably find just what you need in something like "Mother Earth News".

[imserv@imsrv.com]

Olivier - Vector has a built in function for making roughing passes for 3D contours. It is called Contour Tooling (I call it copy contour). The function works very much like the pocketing function, in that you specify depth of cut per pass and total depth to be cut. It automatically makes multiple copies of the contour and connects them together. You may need to combine it with the Cut above Z function to remove air cuts. I had actually conceived of making the dish in slices from MDF or particle board. Something like the way that Millit processes a 3D model.

In Version 9 of Vector, there is also a new pocket function that will directly develop roughing passes in 3D from the finish passes created with the X-Z profile, swept toolpaths. This one does not copy the profile to rough out the pocket, but rather makes Z depth planar passes, within the constraints of the pocket. It properly handles submerged islands, so that you could design a standoff in the center to place the food on.


J.Jorgensen - The contour developed with the PLC spreadsheet on our web page could as easily be rotated flat & become 1/2 of a parabolic frame cut from sheet stock. By selecting just the curve of the spline, and Special - Verify, you could also develop the length of the material that you would attach to the frame. I would think that cardboard with aluminum foil would make an excellent reflector for cooking purposes. Not as durable as steel or plastic, but good enough for a prototype. ;-)

[birdsofplay]

I have created a small tutorial in html to
explain my ideas for parabolic creation and
cutting from a single block of "Whatever". ie foam

http://www.birdsofplay.com/sbpix/parabola.htm

Be patient, I used lots of screen captures !

I probably wont ever actually DO this parabola THANG, but it was a FUN exercise.

Fred will have to assist with discovering Vector
functions that match ( or best ) the functions
that I used in my MicroStation 3D-CAD.

[swims@mindspring.com]

Hi Fred,

I'm running Netscape 4.76 and get nothing when I follow the spreadsheet link.

[roney]

Fred...where do we find your posted pics?
My vector site at centriforce.net doesn't even mention Vector 9? Could you please give those of us who are interested a link?

[imserv@imsrv.com]

http://www.vectorcam.com or http://www.imsrv.com

Steve, you will need to have MS excel to use the spreadsheet file. Right click the link and save it to disk.

[fuzzygrub@sinclair.net]

Actually I can't stand hotdogs personally but the parabolic idea I gleaned from MotherEarth News years ago. Think that copy is still in the spare room. 5 yrs ago I made the cooker from their layout the old fashioned way "sabersaw" It looked kinda like half a 55 gallon drum with 3/4 ply ribs, cardbord skin lined with alum foil and got hot enough to burn your hand when passed thru the focal plane. If instead of a skewer, a water line was run at the focal plane, and a few or more hooked up in series etc. etc. hot tub heaters, hot water preheaters, steam generators?? Anybody out there know anything about stirling engines? Solar powered shopbots? Thanks for the input folks ko

[fuzzygrub@sinclair.net]

Forgot to ask. Question still applies. Does anyone out there have a DXF or ? of a parabolic curve? tnx ko

[Gerald D]

Thought your question was fully answered above?? If you want dxf, this means to me that you want to import it into a CAD program for scaling. If you have CAD then you simply draw your own parabola, there is no rocket science involved. Maybe we got carried away (and how!), but drawing the parabola is really the simplest part of the whole exercise. (For my sketch, I actually had it on CAD, but didn't really think to keep and e-mail the file - sorry)