Radius Dish CNC info needed

Timbuck

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I have the CNC m/c available and I'm looking for info ..So I can make Radius dishes..Up to now all machining weve done is in 2D..and I require 3D for a Radius dish ( I think)..can any one help :)
 
Ken, actually, most CNC machines work in 2.5 D...that is they go to a certain spot in the X, Y, and Z axes and then just work 2 D, move over, and work 2 D again line after line after line. It's like a scan in 2 D.
 
Rick I know what you're saying but.. I'm hoping someone out there will just send a ready made file:eek:...My Son Mike is slogging away learning "Alibre" and "Solidworks" 3D CAD at the moment and it will be a few days before he starts to get somewhere with it
 
I could ask my programmer to write the program for you but I know he'd want reimbursed. If you're interested then PM me. I think I paid around $45 for the drawing, machining and material to make a 15' dish with a 18" diameter, so I can't imagine the program would be all that much.
 
Progress report..Mike (Timbuck Jr) says he's got the CAD sorted, and the dish is now drawn in 3D ..and now he's working on the CAM..We could be there within the next 24 hours.:)
 
Solid Works is good, very good. It integrates perfectly with "Visual Mill" for developing the CAM part...tool paths, tooling, and all that for outputting G code. We use Rhino with RhinoCAM which is an adaptation of Visual Mill. Rhino has fewer features, but all we need, and it's about 20% the cost of Solid Works.
 
Timbuck Jr spent several hours on a CAM program he downloaded free on the web, called Meshcam ..and he got a lot of problems with it and gave up (He do's all this stuff without any manuals or anything "completly self taught".. My brain can't do that :eek:) ..I will recomend " Visual Mill" as per Rick and see how he gets on with that....He's not learning this stuff for my benefit..it's for his own business, he needs to make some new molds for forming plastics on his latest creation in "Electronic Drums"..and the Radius dish is a nice easy shape to start with.
 
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Success at last..Number one Son..has got it sorted....I asked for a boat curve 10ft Rad across by 5ft-2" Rad lengthwise so I can radius sand the backs of my sopranos with confidence...We dug out an old scrap piece of kitchen worktop to practice on..now we know it can be done i'll buy some decent MDF and make a decent one...The CAD used is "Solidworks" and the CAM is "ArtSoft Mach3"...It would be very difficult to make this without CNC
Here is the 3D drawing
PICT0001-12.jpg

Here is the CNC in action
PICT0081.jpg

Here is the roughed out sample.
PICT0087.jpg
 
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So how is it going to work Ken? A boat curve is a 'changing' shape isn't it? Does it mean the taper on the sides is straight or to the curve?
I'ts hard to explain..but the sides taper upwards into the curve the're not flat..I'll try and record the method when I put the next one together...
But the end result is like this one I did earlier "the hard way".. (I put a pencil on the back to show the detail of the arch)
PICT0009-5.jpg
 
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Are you saying that you have a recurve around the perimeter of the top similar to how an arch top is carved?
 
While waiting for number one Son to make my new dish.. I took the 1st roughed out dish unit..slapped some sandpaper on it and gave a try out..and it worked perfectly..as promised I recorded the method on camera and made a bit of a slideshow.
Click on the image to view it
 
Experiment a success

All glued up and ready for next operation..I've discovered that a "radius dish" dosn't have to be circular (unless it's meant to rotate like Chuck's on his potters wheel).. a rectangle is an ideal shape if you sand back and forth and easier to fit the sandpaper..and also it can be a double radius like this one at 5ft rad lengthways and 10ft rad across...(You can't do that with a rotating one)
I found it very quick to sand down with 80 grit and I'll be using this method from now on.
ON the downside "Just to prove that i'm normal"..I accidently glued the back on with the bracing clamps left inside the uke???? (Oh Bollocks! I said, or words to the same effect) and then I had a devil of a job getting them out thro' the soundhole.

Here are the pic's of the finished job
Across the upper bout.
PICT0006-6.jpg

Across the waist
PICT0008-6.jpg

Across lower bout
PICT0004-10.jpg

And lengthways.
PICT0011-4.jpg
 
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I found this old thread when searching for CNC-related info but those 3D softwares are difficult and expensive.
wolframalpha.com (with wikipedia) is great free browser based site to refresh your geometry studies.
An ellipsoid like Timbuck is actually making above (AFAIK) can be represented with equation
x^2/(2a)^2+y^2/a^2+z^2/a^2=1.
WolframAlpha solves z from it easily, see
http://m.wolframalpha.com/input/?i=x^2/(2a)^2+y^2/a^2+z^2/a^2=1&x=0&y=0
and with replacing a with real value (in millimeters) and moving origo 50 mm south you get plot
http://m.wolframalpha.com/input/?i=...0000),+x=-200+to+200,+y+=+-100+to+100&x=0&y=0
But if you are still interested and have access to CNC-router, you will need some CAD etc sw.
 
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