MIMF

I've built a router jig for cutting the binding channels on my archtop body. Something like this one:


All I'm missing is the "donut". That little ring underneath that rides on top of the edge of the guitar body. But after fussing all day trying to make one out of wood, it just isn't working out for me. Anyone have a suggestion on how they did their donut?

Here is a donut in case you're not following me:

I got a piece of thick, slippery plastic from Woodcraft (something like umhw hdpe). I cut a block and mounted on my router. Then I lowered a spinning bit into it to mark the center. With the center marked, I mounted it on the lathe and turned the bottom, leaving the doughnut in the center. Restoring it to the router, I lowered a large bit through it to cut out the hole in the doughnut. I used it for years with no discernible wear.

All I did was cut a 2" round piece of 3/4" plywood with a hole saw, drill a hole in the center and mount it on my router table. The arch of my guitars is 3/4", so I rest the guitar on the center of it's arch and the edge on the plywood, and spin the guitar past the bearing-guided bit. So far it works perfectly, but now I have binding channel router jig inadequacy depression.

Brian Evans wrote:All I did was cut a 2" round piece of 3/4" plywood with a hole saw, drill a hole in the center and mount it on my router table. The arch of my guitars is 3/4", so I rest the guitar on the center of it's arch and the edge on the plywood, and spin the guitar past the bearing-guided bit. So far it works perfectly, but now I have binding channel router jig inadequacy depression.

That sound good, but I have to figure a way around the lack of a lathe. Now that I've had more time to ponder it, I wonder if I could use just a ring of plastic like you suggest (maybe one of those slick cutting boards) and not worry about the roundover. It would have to be narrow, maybe 3/8" larger than the router bit I'll be using. Might have to give it a try and see.

Brian Evans wrote:All I did was cut a 2" round piece of 3/4" plywood with a hole saw, drill a hole in the center and mount it on my router table. The arch of my guitars is 3/4", so I rest the guitar on the center of it's arch and the edge on the plywood, and spin the guitar past the bearing-guided bit. So far it works perfectly, but now I have binding channel router jig inadequacy depression.

Brian, I saw something similar (Bob's archtop blog) while I was researching my build. I thought about going that way myself but it seemed like everyone else had a dedicated router jig. So, yes, I have also suffered from BCRJID.

A drill press with a dowel mandrel that press fits into your piece or even a hand drill held in a vise will get you there. I like to use 60 grit sandpaper glued to a stick or a very sharp toothed rasp to do the rough shaping.

The outside edge of the doughnut needs to be significantly eased to keep it from marking the top. It doesn't take much to make an impression in spruce. For those of you with jig envy, I testify that I have been cutting my binding ledges freehand (with a bearing guided router bit) for well over 100 guitars. When I started, I didn't know about jigs. I just keep the router axis lined up with the side.

The donut needs to be rounded but it doesn't have to be symmetrical. The only critical dimensions of the donut is the very inner edge adjacent to the router bit which is where the depth of cut it controlled. All other parts just need to get out of the way of your guitar plates. So when rounding the donut, make sure you leave at least 1/8" of that inner circle untouched.

Thanks for the advice guys. I'm working on it now, so I'll show you what I came up with soon-ish.

I made one out of a cheap plastic cutting mat. Cut out a circle with a circle cutter in a pillar drill. Put a bolt through and a couple of washers and a bolts and put it into the pillar drill. Used 80 grit on hardwood block and a scraper to shape it. Easy to shape but makes a mess! I drilled a couple of countersunk holes before shaping it so I could screw it to the bottom of my jig as that plastic is a sod to glue. Bob

I wonder if stewmac would sell you one as a replacement part for the unit they sell??

Try the drill press idea and a series of rasps and files

I am lucky enough to have access to pieces of teflon. I cut a piece about 2 inches square, and rounded it off at the band saw.
Then I drilled a hole in the center and used a drill bit stuck in the hole, on the drill press to shape with sandpaper.
I then superglued it to my plexiglass router mount, and ran a router bit through it to center the hole.

I made mine out of an old plastic cutting board. Cut it out with a hole saw, shaped & mounted it to my Dewalt laminate trimmer.
I believe John Hall at Blues Creek Guitars sells the donut separately.