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| Input on how to do a couple small circles on a rosette http://luthiersforum.com/forum/viewtopic.php?f=10101&t=48585 |
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| Author: | Paul Burner [ Wed Nov 23, 2016 2:30 pm ] |
| Post subject: | Input on how to do a couple small circles on a rosette |
I am wanting to do a couple round circle inlays along the path of my rosette. The circles (with inlays) will be Larger circle: 1.25" including .05" purfling. Smaller circle: 0.625" including .05" purfling I need a way to cut the circles at 1.2 and 0.575 and then I need a way to route into my redwood top to allow me to put them into place - and those are the dimensions mentioned above. My StewMac dremel tool won't allow me to do this small of a circle. So - I'm here looking for ideas. Thanks!!! |
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| Author: | DennisK [ Wed Nov 23, 2016 2:37 pm ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
Get yourself a ruler and go hunting around the house. Coins, cups, cans, bottle caps. All sorts of round objects that you can scribe around. |
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| Author: | bcombs510 [ Wed Nov 23, 2016 2:52 pm ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
I'm not sure about the smaller circle, but if you are looking for a jig to do this, I have one of these Jasper circle jigs. It goes down pretty small, but only to 1". http://jaspertools.com/model-400-circle-guide/ Edit: I didn't realize the hole from the jig would cause an issue for your scenario. So this probably won't work for you after all. 
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| Author: | James Orr [ Wed Nov 23, 2016 3:38 pm ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
I think part of this is that none of the circles that will be inlaid can have a hole in the middle from an index pin, correct? If you find a very small diameter circle cutting jig, you can rout the negative cavity into the top because the positive will cover the indexing hole. If you use a soundhole reinforcement patch, it will support the area for you. I can picture roughing out the positive circles, then carefully shaping them on a disk sander or something similar. |
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| Author: | Bryan Bear [ Wed Nov 23, 2016 4:10 pm ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
A good and sharp set of forstner bits might do a good job of excavating the circles. What are you inlaying into them? Could those circles be turned and sliced off to thickness. Also, I think your disks need to be 1.15" and 0.525" if the purfling is 0.05" because you will be taking 0.05 of both sides. . . |
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| Author: | Paul Burner [ Wed Nov 23, 2016 4:19 pm ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
Bryan Bear wrote: Also, I think your disks need to be 1.15" and 0.525" if the purfling is 0.05" because you will be taking 0.05 of both sides. . . 
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| Author: | Jim Watts [ Wed Nov 23, 2016 4:26 pm ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
As was mentioned, Forstner bits are available in those size. You might want to use a sound hole reinforcement patch as on a classical guitar in case the drill point punches through. |
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| Author: | Ken Lewis [ Wed Nov 23, 2016 4:33 pm ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
A router guide bushing, a small bit and two appropriately sized holes in a piece of plywood for a jig. One for routing the pocket and the other for routing the inlay.?? Unless I'm missing what you are trying to do.  Ken |
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| Author: | Clay S. [ Thu Nov 24, 2016 8:11 am ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
You might be able to use a Hole saw with the drill bit removed in a drill press. An inch and a quarter and a three quarter ( or 5/8ths) inch might get you close. |
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| Author: | Mike_P [ Thu Nov 24, 2016 9:50 am ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
Ken Lewis wrote: A router guide bushing, a small bit and two appropriately sized holes in a piece of plywood for a jig. One for routing the pocket and the other for routing the inlay.?? Unless I'm missing what you are trying to do. Ken +1 or use a top bearing pattern bit...your problem is going to be having to sacrifice your ideal size with one that is possible using drill bits to make the pattern out of. a hole saw is only going to create a circle (which would be useful for making the inlay but not the route in the top) and too boot they are prone to not giving very clean cuts, a forstner bit will have the point left and possibly go through. I would suggest using a drill press to make your pattern so that you can be confident your hole is true. while I am many times forced to bore cabinet doors in the field for Blume hinges, I know that it is nearly impossible to make a true bore with a hand held drill that would be satisfactory for a pattern where tolerances are going to be very tight. in the end I think you will have to come up with a process of making your inlays and being limited to a certain possible size, and in combination with the bore on the top being faced with the only solution being adjusting your purfling size to make it work. you might be able to come real close to ideal using a combination of metric and imperial bits |
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| Author: | SteveSmith [ Thu Nov 24, 2016 10:08 am ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
If you use a forster bit just grind the point off and make sure the wings are sharp. It will work just fine in a drill press. Don't try it in a handheld. |
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| Author: | George L [ Thu Nov 24, 2016 11:14 am ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
I'd go with Ken's router bearing/custom circle jig idea myself. However, I've had success using forstner bits to make small circles in headstock veneers. On a top plate, I'd do as Steve suggested and grind off the point at the center. |
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| Author: | Clay S. [ Thu Nov 24, 2016 11:43 am ] |
| Post subject: | Re: Input on how to do a couple small circles on a rosette |
"a forstner bit will have the point left and possibly go through." "If you use a forster bit just grind the point off and make sure the wings are sharp. It will work just fine in a drill press. Don't try it in a handheld." I wouldn't think this would be a big deal. I wouldn't ruin a perfectly good bit to avoid a possible small punch through that could only be seen with a mirror. I've used my forstner bits in a hand drill several times and having the guide point makes all the difference. If you are good with calculations a router and template and inlay kit might be a good option.http://www.rockler.com/inlay-bushing-an ... j0KEQiAvNr I've used the collar and bushing and they do work well for simple inlays. |
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