# Radius Dishes Again... need to explain for CNC



## Antz_Marchin (Mar 31, 2006)

Ok, I called a CNC machine shop and they are having a rough time over the phone understanding a 28' radius dish......haha. I told them it's only a 2x2' piece of MDF with a slight concave in it which would (if the arc of the concave were pieced together over and over it) eventually create a circle with a 28' radius. 

Now, I'm not sure if I'm way off but that's all I could some up with. I'm meeting with him tomorrow to give him a sketch of a general idea but how do I make him understand / make sure he accurately cuts the concave shape that I need milled in the 3/4" MDF???


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## WarrenG (Feb 3, 2006)

Is that actually going to be cheaper and less of a headache than: "Go-Bar" and Sanding Dishes


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## Antz_Marchin (Mar 31, 2006)

Ah cool, thanks Warren. I hadn't found them available from a Canadian retailer yet as cross-border shipping is brutally expensive for something of this size. 

Do you think seemingly simple CNC job like this would actually be that expensive?? ($140+tax/shipping)

And last regardless of the route I choose, what radii would you recommend? I know 28' for the top, but for a Martin dred shape and a Mini Jumbo do you think that 25' is the way to go for the back or 20'??? Thanks as always, I really appreciate all your help. (I'm going to be needing more....haha)

Just saw you had a Youtube link......watched Afraid to Dance (my fav D.R. tune along with First Ride). Holy Crap, very impressive.


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## ne1roc (Mar 4, 2006)

I have a tool & die shop. The minimum we charge is $65.00, even for a 10 minute job. You can probly get it done for $65.00 cash.

I would not recommend MDF though. It does not machine well and would result in a rough and unaccurate finish. What is the bought one made from?


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## ajcoholic (Feb 5, 2006)

ne1roc said:


> I have a tool & die shop. The minimum we charge is $65.00, even for a 10 minute job. You can probly get it done for $65.00 cash.
> 
> I would not recommend MDF though. It does not machine well and would result in a rough and unaccurate finish. What is the bought one made from?



Although I really dont like MDF to work with (mainly the dust) it does indeed machine very well and thats what the commercially made ones are made from. Its stable (as long as you dont get it wet) and wont warp. It does finish well - hence the use in stuff like moldings, raised panel doors, etc.

I think you explained it well... I mean, who wouldnt understand a concave, dished surface witha particular radius?


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## Antz_Marchin (Mar 31, 2006)

ne1roc said:


> I have a tool & die shop. The minimum we charge is $65.00, even for a 10 minute job. You can probly get it done for $65.00 cash.
> 
> I would not recommend MDF though. It does not machine well and would result in a rough and unaccurate finish. What is the bought one made from?


The purchased ones are made of dual layered MDF with waterproof coats. For these radius dish applications, they are the only mayerial I've head of being used (other than a laminate birch material from one place that have been discontinued due to low demand)

Hmmmmm $65.00 each looks like the base rate eh + materials (although I know they are cheap). Maybe I should just buy them waterproofed and professionally finished for $70 each.

Edit..^^Oh just noticed $65.00 cash, not each.....that may be a deal, maybe I'll check the place out.


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## WarrenG (Feb 3, 2006)

Antz_Marchin said:


> And last regardless of the route I choose, what radii would you recommend? I know 28' for the top, but for a Martin dred shape and a Mini Jumbo do you think that 25' is the way to go for the back or 20'??? Thanks as always, I really appreciate all your help. (I'm going to be needing more....haha)
> 
> Just saw you had a Youtube link......watched Afraid to Dance (my fav D.R. tune along with First Ride). Holy Crap, very impressive.


20' or 15' is fine. If you plan on making smaller bodied guitars in the future (e.g. classical, 00, 000, OM) then 15' is the way to go.

Thanks for the kudos on the playing - I'm thinking of posting some more shortly, maybe:

The Rootwitch, Jitterboogie, Ritual Dance, and/or Silent Anticipations - Michael Hedges
It's (Twice as) Fun Being Lucky (redux), and the First Ride - Don Ross
Angelina - Tommy Emmanuel
Low C - Erick Turnbull
Solsbury Hill - Peter Gabriel
and
Disco Dan Meets the Beat - : an original acoustic tech song


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## Antz_Marchin (Mar 31, 2006)

I think I'll go with the 20' then, I plan on making a Dred, then a mini jumbo, then a Taylor x14 shape. Smaller bodies than a GA just don't really do it for me. 

You should definitely add First Ride and Angelina. I'm working on The Hunt and Man with the Green Thumb by T.E. and some Trace Bundy stuff but I think with your tutorial, I may pick up on Afraid to Dance......fun stuff : )


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