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Myka Inspired Neck Carve Jig


jay5
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Here is a neck jig I have been planning on building for a while. David Myka's jig really got my attention when he posted it some time back. I decided to take his design and modify it a bit. Whereas David let the bearing run down the back of the neck, I decided to place the neck fingerboard down and have the bearing follow the sides. I was afraid that after one side was cut that there wouldnt be enough room for the bearing to run when cutting the other half. When I began drawing thins out I found that I couldn't get either a 7/8" radius or a 1" radius to work quite right simply letting the bearing follow the neck. I ended up setting the whole thing up with a bearing below the cutter that would follow the sled instead of the neck. This allowed me to make the sled slightly oversized at the nut end keeping the cutter from "overcutting" and changing the thickness of the neck. Anyway, it works pretty well and was fun to build. It takes me about 4-5 minutes to get a really good, consistant rough carve.

neckcarve3.png

This picture shows the bearing below the cutter.

This picture shows that headstock support that is adjustable for slight variations in headstock angle.

This picture shows a neck off the jig. Right now I am just free handing where I start and stop on the shaft. I will probably add some removable pieces to each end that will allow me to blend the cut instead of just stopping.

Finally, this picture shows the neck after the transitions have been roughed it with a rasp (about 5-10 min).

All and all I'm pretty happy with how this thing worked out. Thanks for the inspiration David!

P.S. Sorry about the crap pics, I'll try to get some better ones.

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Yeah Rick, thats somthing I forgot to mention. A multispeed router is a must with such a big bit I think. I run the thing at about half speed. Tell me, has your power swith started to crap out yet? Mine is getting there, supposidly its a known issue with the Bosch 1617.

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Yeah Rick, thats somthing I forgot to mention. A multispeed router is a must with such a big bit I think. I run the thing at about half speed. Tell me, has your power swith started to crap out yet? Mine is getting there, supposidly its a known issue with the Bosch 1617.

Nope, mine's been rock solid all the way around. I've had it for maybe two years. Only started using it heavily the last six months or so.

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Very nice. I haven’t really seen the need for one myself but when I see yours I start thinking it would speed up the process quite a bit. Also very smart and simple (I always like simple solutions) adjustment for head angle.

I can see it in use on a mahogany neck. Have you tried it on something a tad harder (maple)? I don’t see any problems with that but it is interesting to know if the router has the power. BTW how many watts/hp does your router have? Do you have a picture with the neck in the jig and the ball bearing against the jig (or without the neck as well)? Might help if I decide to try it myself. And one last: What radius does the router bit have?

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Peter, my router is a 2.25 HP Bosch, not sure about the amps though. I havent tried it on anything other than mahogany but I imagine the router could handle it. Right now I am taking 4 passes to carve to final depth. I would probably take lighter passes in maple. The bit is a 1" radius Grizzly bit. It is working well so far but I plan to replace it with a whiteside bit when it starts wearing out, I went cheap to make sure everything was gonna work. There are a few more pics on my photobucket site, just search jaysguitarpics. The pics kinda suck, I'll try to get a few more.

Erik, I was hoping to just have a bit follow the profile of the neck like you do but I couldnt get any of the different radii to work quite how I wanted. The 7/8" was almost perfect at the nut but left a flat at the 12th. The 1" bit would have been perfect at the 12th but would have overcut at the nut end. I figured that if I was going to go to the trouble of building the thing that I would get it to cut as close to perfect as possible, hence the flared template and bearing. I remember seeing your duplicarver and being really impressed. I may try to start planning one out soon!

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Jay5 that is absolutely an amazing jig and the best I have seen so far. The issues you have with the router bits are "EXACTLY" what I am experiencing and I cannot seem to solve mine without alot of final hand shaping and carving. How do you allow for the thickness in the neck ie thinner at the nut and thicker at the twelve fret ?? does the jig have a built in slope ?? I have experimented with mine and have found the 7/8ths bit is ok but the 1" would be better like yours. Would it be possible to do a building log on how you made yours for us all to share?? Also when you mention the oversized sledge to avoid overcutting what exactly is this ?? Sorry for all the questions but that jig is a must build on my list, many thanks for your help :D

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Thenaks for the kind words Kammo! The jig does in fact have a built in taper so the back of the neck lays parallel to the table, very critical. I have a tapering jig ala Benedetto that I used to make the tapered part of the jig so the angles are exact opposites. As far as the "overcutting", if the 1" bit simply ran against the neck, the bit would have cut about 1/8" past the center of the neck. From my drawings, this would have cut into the neck about 1/16" or so at the nut end. By flaring the jig out towards the nut and using the bearing in the table I made it so that the bit wont cut across the centerline thus maintining the thickness taper. As far as a build log goes, the jig is very simple when you have all your specs and dimensions together. These will all depend on your neck specs. What I will do when I have a bit of time is draw up a little diagram to try to better illustrate how the bearing and flared jig work. Give me a couple days.

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I remember seeing your duplicarver and being really impressed.

Don't be too impressed yet...I haven't copied anything, it has mostly served as an overhead router. But I'll me making a LP carve top template none too soon.

Yeah, the 7/8" does leave a flat near the heel (especially on a 5-string bass...), but it is just a rough carve after all. CMT also has these big ol' bits called "table edge" bits with a compound radius that I may try once the 7/8" craps out.

Edited by erikbojerik
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Fantastic! It reminds be of pics of the jig used at Wahl for their basses. (see Melvin Hiscock's book) They use a very large roundover bit. I'm sure it's custom made. You may want to check some shaper bits if the shafts will fit in your router. I have the Porter Cable 690 series with variable speed. Do you think I can use that in the jig (by using lighter passes, too)? Would you be willing to post plans for the jig? Thanks in advance.

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  • 1 month later...

Ok, Ive got a few minutes to answer some questions about this thing and hopefully clear up some stuff. I don't have time to draw up a scale diagram quite yet but lets see where we can get without it for the time being. In addition, I will inevitably answer a few questions I already addressed before, but bear with me.

So Kammo, the "oversized sled" is actually very simple. My router is set up like a very small pin rouer in this jig. The bit sits directly above a 1/2" pin in the table. I decided that if I was going to take the time to make this jig I wanted it to do as good a job as I could engineer. I did several drawings and found that if I let the bearing of a 7'8" R cutter run against the neck itself, I would have a nice shape at the nut end of the shaft but would leave about a 1/4" of "flat" at the 12th where the cutter would finish. My drawings also showed me that doing the same thing with a 1"R cutter would give me a perfect cut at the 12th but the nut end would suffer. What would happen is that since my nut width is under 2", the cutter would cut past the centerline and make the neck thinner than my desired specs, see the stellar diagram below. The "overcutting" looks minor in the drawing but again, I wanted the thing to work as well as I could make it. OK, so what I did was simply build the sled (the template) 2" wide the whole way down. What this does is allow the cutter (at is full depth, the final pass) to cut right to the centerline of the neck, the whole way down. This way the two radii meet at the center of the neck and give an even carve the whole way while not affecting the already thicknessed neck. You can see how the template keeps the bit off the neck in the 2nd drawing (the red is the template). This diagram is NOT to scale. As a result, it appears that a large flat is left on the side of the neck at the nut end but this isnt accurate, it actually follows the fingerboard seam quite well.

neckthing.jpg

So, as I said in my original post, this is probably a bit overkill for the hobbiest. In addition, I certainly imagine that others have come up with far simpler (and far more complicated) ways of doing this. Part of the enjoyment I get from building guitars is finding different ways to do things, hence this jig. As a result, designing and building it was just as enjoyable as seeing it work. So, I hope that I answered some questions and didnt confuse anyone else more.

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Jay5, many thanks for all the valuable info you have provided, now I can see how this works out. I will try and come up with a jig like yours and see how mine works out, also where is the best place to get a 1" radius roundover bit at a decent price and quality ?? Here in the UK they are horrendously expensive maybe we can buy some in bulk from the US and pass on the savings ?? many thanks for all your advice it is greatly appreciated.

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You don't want to skimp on big bits, and if you don't have a powerful enough router, don't even bother. Routerbits.com has good prices on great bits (Whiteside), but a roundover that size is still might expensive. Other than the fact I quite like hand-carving necks, that's my main reason not to even bother considering a jig like this. I just don't make enough guitars per year to make it a sensible investment.

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The bit I bought was a cheap ($30) Grizzly bit, mainly to make sure that everything actually worked out. I will definately buy a Whiteside bit after this one has a few more necks on it. The whiteside is about $70 but so worth it, all my other bits are whiteside cutters and are all phenominal. I was really hesitant to go with the Grizzly but it cut the mahogany well. Being that carving is at the tail end of the build you would hate to trash a neck with several hours already into it. So, good bits are a must. Now, about the router. I have a bosch 1617EVS which is listed at 2.25HP and is variable speed. It adjusts from 1 to 6 and I run this bit at about 4. The idea of that big thing whirling at 22K rps scares me. The 690 is a fine router. The only thing I would have reservations about would be the single speed. I imagine that a real good bit and several light passes would work fine.

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I have the 690 with the variable speed. It came with all three bases (original, plunge and D handle) and different collets. It seems fine as I don't spend enough time with a router right now to warrant a bigger size. It was a great deal when I got it and the newer 1.25hp ones had just come out and a bit more in cost. They look beautiful, but in the scheme of things the 690 was sufficient. By the way, I got the router table from Sears, on sale. It's the professional model that looks similar to a Bench Dog model. It's been great. By the way. can the jig be modified to do bolt ons? It seems from the pics that it shouldn't be a problem.

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