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Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 12:10 am
by Kbore
Routing the channels is presenting a challenge with the radiused plates. I'm tapped out on tools so I'm doing it by hand held router. Not working too well on practice piece due to the radius. I'm thinking of wedging common cedar shims between the router base and top ( and bottom) to level out the base to 90^ to the sides with double stick tape. I haven't been able to cut accurate wedges on the band saw. Any tips would be appreciated (without the use of a routing fixture please- Budget is tapped out on tooling). Using a colt with proper bit and bearing....

Re: Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 12:55 am
by johnnparchem
When I made my first, I had the same issue. Instead of a wedge I unscrewed the base of the router, placed a correct sized shim on one size between the base and its mount and screwed it back down. Far warning it is really easy to mess up the channel routing by hand by accidently tilting the router. I was able to do it one my first though. Hold the router near the base and there is less chance that you will accidently tilt it forward.

Here is a picture with a colt! It is currently set for the top. The pencil is pointing to the shim I used for the back.
router.JPG
If you have a plane you can make a wedge. Make a shim twice the thickness you want for your wedge. double tape a bit of wood you are using for the wedge to your bench so the edge you want thin is at the end of you bench. Double tape the shim you made one wedge length behind the wedge blank. With the back of the plane on the shim plane away until the thin edge of the wedge is fully planed.

Re: Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 6:27 am
by MaineGeezer
After a couple of near-disasters with a router, I've started using a gramil to cut binding and purfling channels. It's not as onerous a job as I thought it might be, though it does take time and patience. The gramil in the picture is one I made based on the design of the gramil available from LMII.

You can certainly do it a lot faster with a router though.

Re: Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 6:32 am
by tippie53
I use the binding machines. You need something to compensate for the angles . The top is usually pretty easy but the back is what presents the biggest issues.
The angle and radius can present a problem so think of staying parallel with the sides

Re: Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 3:17 pm
by MaineGeezer
Notice, if you haven't already, that the slope of the back (or top) changes according to where you are on the perimeter. This makes any wedge only an approximation.

Re: Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 7:46 pm
by Kbore
MaineGeezer wrote:Notice, if you haven't already, that the slope of the back (or top) changes according to where you are on the perimeter. This makes any wedge only an approximation.
Excellent point. It is so slight to the eye- one small slope for man, on giant leap for the router bit. I have arrived at a combination solution (money, slope, sides). Bosch makes a $15 all metal, screw adjust, locking edge guide that indexes off the side. It is indexed to the router base. I have a page from some Bosch manual showing it, a pic of the attachment is below. I believe if I modify it to provide a holding handle, to hold the device against the side (leaving my hands off the top of the motor) and maybe a larger longer contact area, it will be the solution I'm dreaming of. Thank you everybody for your guidance and advise!!

Check this out; almost made for routing channels:

Re: Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 8:57 pm
by MaineGeezer
That would keep the depth of the sideways cut constant, at least in theory, but how about the vertical distance? Say you're installing binding 1/16" thick that you want to finish off at 1/4" high. That attachment will (in theory) assure a constant 1/16" depth of cut so the binding will be flush with the side, but what gives you a constant 1/4" width/height?

Re: Routing The Channels on Radius Plates

Posted: Wed Aug 23, 2017 11:30 pm
by Kbore
MaineGeezer wrote:...but what gives you a constant 1/4" width/height?
If I understand the question, The depth of cut adjustment of the bit through the router base determines the depth of cut, or height of the binding/ purfling (a.k.a. The channel depth (of course I will be using a bearing piloted bit for the vertical cut- width of the purfling, not the straight bit pictured). The base will still have to contact the top near the edge of the guitar, to some degree, to control the depth, but the ANGLE OF THE ROUTER BASE, with a shim for insurance, will be indexed by the side. Great question, I'll have to ponder that deeply. Should have read this in the morning, I won't sleep all night for " pondering" that one. Thanks for the question.

Re: Routing The Channels on Radius Plates

Posted: Thu Aug 24, 2017 6:58 am
by tippie53
that is where it fails.
The back wedge and radius will lift the router and tilt it. You can make this work but you will have to do a number of stepped cuts then file everything so the rout is parallel to the sides. Also note you want to get the rout so the sides get sanded to the binding not scrape the binding to the sides.
Do a number of set up cuts and take your time. Trust me , I tried about every imaginable method of routing. Once I discovered the binding machines I never went back.
There is one more thing. The guide is only as accurate as you use it. Here is another variable you must consider. The guitar is only accurate when your base is square to the object so be away of that as you work the curves. Make multiple cuts. Once you start using it you should see this .
I like the picture with the wedged base john parchem shows. It isn't perfect but it is better than the flat base. As you come around the bout at the neck , especially on the back , it will lift the router. That tilt help to move the location of the base on the work more to the edge. You will still have some blending in but it will help.

Re: Routing The Channels on Radius Plates

Posted: Thu Aug 24, 2017 9:03 am
by Kbore
Yep, it fails with out adding a "sub base" that both raises the colt's base clear of the top and also present a limited area to ride upon the edge of the top of the guitar. I found and reposted another members solution in his original thread. Here is what he did:
IMG_0301.JPG
Thanks all for walking me through this.