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Radius Dish Jig
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=13232		 Page 1 of 1
Author:  jonhfry [ Wed Aug 15, 2007 6:29 am ]
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For those of you making your own dishes, what kind of bit do you use in your router?
Author:  Michael Dale Payne [ Wed Aug 15, 2007 6:32 am ]
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3/4" round nose 1/2" shank
Author:  jonhfry [ Wed Aug 15, 2007 6:39 am ]
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cool, wrote it down, that must be why my last dish came out looking a staircase.
Author:  Michael Dale Payne [ Wed Aug 15, 2007 6:45 am ]
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Yep, but a little time with a ROS will fix that. don't you just love transforming into Granola Man
Author:  Shane Neifer [ Wed Aug 15, 2007 7:06 am ]
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John,

I use a .5" upcut spiral solid carbide. Basically it is just a staright morticing bit. They are about 3" long and fairly pricey in the $75 to $80 CDN range. But I use them when I timberframe as well. I built a motorized rim sander so the dish spins as I route down the sleds. I do it in about 3 passes, then a a minute or so with 80 and 120 grit paper (leftovers from the drum sander) and they finish up quite nice.

Shane
Author:  Bob Garrish [ Wed Aug 15, 2007 9:10 am ]
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You'll get the nicest finish out of a big round-nose bit (also called core box by some suppliers). You can get 'em in huge sizes.
Author:  Brad Way [ Wed Aug 15, 2007 10:06 am ]
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I used a 1 1/2 core box bit but found better results from a standard straight bit. I am sure a spiral bit like Shane mentioned would work well.
Author:  jsimpson [ Thu Aug 16, 2007 6:12 am ]
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I use just a cheapie 3/4 inch rabbeting bit, which works well with the jig I made.  The dish blank is centered underneath on a dowel pin, with the "radiused rails" for the router to slide on straddling the dish on top.   Starting at the outer edge of the rails, once the bit touches the MDF, it wants to start spinning...in a big hurry, so be careful....but by the time I get to the center and take one slow pass back to the edge, it does a pretty good job. 


Author:  gozierdt [ Thu Aug 16, 2007 1:13 pm ]
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I also use a 1/2" sprial upcut bit, which normally cuts a flat bottomed cut. But I use a "long compass" jig, and like jsimpson spin the dish blank on a center pin. A little work with an ROS after the router takes care of any small imperfections.
Author:  gozierdt [ Thu Aug 16, 2007 1:14 pm ]
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Oh, and it's a carbide bit, as Shane mentions. Lasts a lot longer on MDF that HSS.
Author:  psl53 [ Sat Aug 18, 2007 10:55 am ]
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I used a 1/2" bit and once most of the cuts were made I spun the jig to clean up the ridges.
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