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| Quick dish radiusing jig http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=18587 |
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| Author: | Brad T [ Fri Aug 29, 2008 7:27 pm ] |
| Post subject: | Quick dish radiusing jig |
I made a quick and dirty dish radiusing jig today and thought I would post it if anyone is interested. To begin with, I already have a brace radiusing jig that I use on my router table, so I used it as the template for the router guide rails on the dish jig. Attachment: radius jig 005.jpg I took the brace radiusing jig, and used the radius as a pattern and traced it onto a piece of MDF, and then cut it on the bandsaw. I cleaned up most of the bandsaw marks with a rasp, carefully. Then I stuck some 120 grit sandpaper to the brace jig, and used it as a sanding block in order to get the arc correct and smooth it. After getting one rail arc right, I screwed another piece of MDF to it, and used the pattern bit on the router table once again to make a carbon copy of the first. Then I glued and bradded a piece of 1/4" ply to the outer side of each rail in order to capture the router base, and assembled the rails the proper width apart to capture the router base. Next, I made a base for the rails with 2 uprights to hold the rail assy and elevated it the thickness of the MDF plus the thickness of a framing square (really technical stuff I know!). I drilled a 3/16" hole in the center of the base and used the pin that comes with the Stewie mac circle cutter for a pivot. Attachment: radius jig 001.jpg The brace radiusing jig sits very nicely in the rail with no gaps showing. When making one like this, you have to be sure you have a router bit long enough to reach the final dimensions of the dish, which I do. I had to make about 5 passes with the router, taking off small amounts at a time. Initially, the bit would contact the dish at about 3/4 of the way to its center, and a little further out each time I lowered the router in its base. Also, this thing will get the dish spinning on its own. If it gets spinning too fast, the bit will take a rougher and rougher cut and will eventually end in a screwed up dish (Damhikt) so I took my time so I wouldn't need to use wood filler! I did not notice any deflection in the rails, and I did not need to bear down on the router, as its own weight was sufficient. The whole thing from turning on the shop lights to screwing the dish to a backer board took me only a few hours to do. Now that I have the jig, I should be able to punch one out in half an hour or so. This is just a down and dirty jig, no math involved and simple to do so I thought I would share it. Thanks |
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| Author: | Chris Paulick [ Fri Aug 29, 2008 8:03 pm ] |
| Post subject: | Re: Quick dish radiusing jig |
What would your final radius be? |
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| Author: | Brad T [ Fri Aug 29, 2008 8:44 pm ] |
| Post subject: | Re: Quick dish radiusing jig |
Chris Paulick wrote: What would your final radius be? Well, if the rails are radiused to 28', and the distance from the top of the rail/router base is 2.5" (thats a guess because I'm not in the shop) I guess it would be 28' 2.5"...........hey now wait a minute......  See, now you went and involved math!!! ![[headinwall]](./images/smilies/headbangwalluf8.gif "Mad") ![[xx(]](./images/smilies/smiley11.gif "Dead") 
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| Author: | Ricardo [ Sat Aug 30, 2008 12:50 am ] |
| Post subject: | Re: Quick dish radiusing jig |
Yup, thats how I built my dishes. In fact, I use a similar jig as your first pic to shape my braces. |
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| Author: | Chris Paulick [ Sat Aug 30, 2008 7:46 am ] |
| Post subject: | Re: Quick dish radiusing jig |
I'll do the math. 28' radius=3.36" or 3 11/32" 
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