View Poll Results: 1st Build Floater Suggestions
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KA Handwound 12-pole PAF humbucker
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Biltoft Dual Blade Humbucker
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Originally Posted by rlrhettOriginally Posted by Matt Cushman
Thanks, Rhett. I’ve found Tomy Hovington’s stuff in my internet research, and have seen that video. As Matt mentioned, he had a flat area for attachment on the top plate and it didn’t appear to involve a neck extension, and I sort of abandoned that method as I didn’t have a solid resource for instruction.
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10-15-2019 09:53 PM
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Obviously, there are lots of variables and ways to skin the cat.. tapered, straight, etc.
I decided to make a neck dovetail tenon jig a la Cushman. I started with a piece of 3/4” plywood, and traced the outline of the dovetail template and drilled 2 pilot holes:
I then jigsaw’d out the central portion:
Next, I used the plunge router with a 1/2” straight bit set to the depth of the template (1/4”) and removed the inlay for the template itself:
I used a longer piece of 3/4” plywood and routed a 3/4” channel using on the table router with a straight bit to meet the top piece at 90°:
End of Pt1
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I then took a square board and cut 2 right-angle pieces on the compound miter saw. I nailed them with a pneumatic nailer and placed 2 screws from the top:
Again, disregard the fact I’ve placed the in template upside down.
I realized my heel was very oversized, so I measured out the distance from the top plate to ~1/4” from the inside of the back plates. I decided to leave an extra 1/2” beyond and decided to leave an extra 1/8” or so (second line) to be safe, which I can shape later. I then cut off the heel excess on the table saw:
I then held my neck blank up to the jig and realized it was was too far back to get the bottom of the dovetail to be at my mark:
So, I realIzed I’d have to extend back my template cavity with the router and jigsaw:
PS - to make the cavity, I knife marked out the template and routed up to near the line. I then mallet/chiseled the edges clean to get a snug fit.
This is where it stands currently- noticed I had the template orientation right this time!
I still need to make a pretty fat 4degree wedge to get the jig to appropriately get the dovetail where I need it.
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I see you are well on your way with the router jig. But the hand cut dovetail mortise and tenon is done exactly the same whether you are adding a 1/2” fingerboard extension or leaving a raised area on the top itself. Those are really independent considerations.
Also, Robbie O’Brien (O’Brien Guitars) sells plans for a jig that holds the body of the guitar and neck for using routing templates. It is a good jig, works with the LMI templates, and worth buying his plans. No reason to try to reinvent the wheel.
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Just to clarify. I was trying to point out the difference between the use of a V shaped mortise in mandolin neck attachment as compared to straight walled mortice in archtop guitar neck attachment. Not how they are cut. The v shaped mortise works well for the mandolin as the fingerboard extension is added after the neck is glued in place. Whereas with the guitar neck the fingerboard extension is in place when you glue the neck to the body. This does make setting the neck height a bit different. I also have a router jig for my mandolins that cuts a V shaped mortise.
Not to beat a dead horse, but Chapter 14 of Benedetto's book "fitting the neck to the body" shows the method used for a straight sided mortise and tenon dovetail joint. A V shaped mortise will have an added element of difficulty when it comes time to fit the neck.Last edited by Matt Cushman; 10-16-2019 at 09:12 AM.
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Originally Posted by rlrhettOriginally Posted by Matt Cushman
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With the straight sided mortise and tenon I think the fitting of the neck will be much as is shown in Bob's book. The size of the mortise and tenon is what will be affected by the size of the template and bit size and guide ring relationship. Not having worked with the LMII templates, it is difficult for me to speculate on what size bit and guide ring will be required to cut the proper size mortise and tenon. When I say proper size, I am referring to the dimensions that Bob shows in his plan.
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Did that horse show signs of life? Here, let me give it a whack! ;-)
I actually use a “V” dovetail, which used to be common on Martin/Gibson flat top guitars as well. The argument was that it cinched up on itself. You could clamp down on the neck to the body to pull it tight. A straight sliding dovetail had to be perfect everywhere to pull tight.
But just to be contrarian, I have also used a butt joint and inserts. I used a long threaded rod with a coupler and Allen key at the end to fasten the bolt. I used the endpin hole for access.
Also, I fit the joint without the fingerboard extension or fingerboard. Once properly fit to the body I use the body to tell me where to cut the rabbet.
Many ways to skin the cat.
I’ve made several jigs over the years, and Robbie’s is the one I use most. I think you’ll like it. He has a video on using it that is very helpful. Dovetail bits are relatively cheap, so you might as well use the one LMI calls out. One less place to make a mistake.
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Originally Posted by rlrhett
As a side note, I like to join the extender to the neck with a dovetail joint for a bit of added strength and to simplify the clamping of the extender to the neck while gluing it to the neck. I borrowed this idea from D'AquistoLast edited by Matt Cushman; 10-16-2019 at 01:58 PM.
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Originally Posted by Matt Cushman
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Made some headway on the O’Brien jig using his plans. I ordered a few star knobs from Rockler that are slated to arrive tomorrow and the straight mortise/tenon LMI template and bits get here on Wednesday. I didn’t photograph the whole process since you can check his plans and YouTube videos, but here’s a synopsis till my current status. This was definitely more about function than beauty, and I think will work well.
Hopefully can get most finished tomorrow night and be ready to test some bits this weekend.Last edited by sbeishline; 10-22-2019 at 01:40 PM.
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Got the O’Brien neck jig completed today. This is a feat in itself!
Feels great to have that finished. Will plan to practice on some wood this week with the various dovetail bits, etc.
As if this guitar isn’t enough, I’ve started to make a small 14.5” x 14.5” x 11.25” speaker cabinet to use with 12” Cannabis Rex speaker - and probably - a Quilter 101R amp head.
Will probably start a new thread for that side project to use with this future guitar. Have the pine cut and currently marking the dovetails...
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Make a little noise if you're stoked for the continuation of the archtop!
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Originally Posted by sbeishline
More archtop!
John
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More, more, more please!!!
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I had been stuck at the neck dovetail joint for a bit and bit the bullet to make the O'Brien neck joint jig, which came out well. I was also held up because I had planned to forego on the toggle clamps and use removable clamps to hold the neck in place, but none fit. So, the toggle clamps just arrived yesterday and I'll screw those on the jig tonight.
In the meantime, I milled a small piece of cherry scrap to 7/32" wide to use as a guide pin for the neck on the jig that holds the neck at exactly 90 degrees:
Next up will be to install the toggle clamps and practice on my erroneous first neck blank..
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Feels good to have the wheels spinning again after the pause. Drilled some pilot holes onto some blocks and screwed the neck-holding toggle clamps into place:
Tested out the clamps and it holds pretty well. That guide pin used in the truss rod channel is awesome!
I then used some scraps and made a faux neck blank templates to practice using the dovetail jig. I cut the blank to 4° setback angle to match jig and ran them on the table router to make a truss rod channel:
I used the LMI dovetail templates, 1/2” shank straight and dovetail bits, and their 5/8” outer diameter (17/32” inner diameter) with centering bit to use in the router.
I used the centering bit and locked down the guide bushing. Then placed the straight bit for a test cut for the dovetail mortise.
Took the plunge (ha!) to 3/16” and made the cut:
The router cut real smooth without much issue.
Moved over to the dovetail tenon side and gave it a go:
One thing I learned is that because of the guide bushing, the bit cuts the tenon ~1/8” longer than I had marked (see previous 2 photos) and the mortise gets cut a tad shorter than marking.
Ran out of time to switch to the dovetail bit on Day 1.
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Building a guitar is a bit like building a house: the foundations and rough framing go in relatively quickly and it LOOKS like a house; but the finish carpentry is where the real time is taken.
Keep at it. You are doing great! When I used to help teach a guitar building class 25 people would start and we would be lucky if 5 fully completed a guitar. Such a shame! The worst sounding and playing guitar is the one in parts sitting in a box in your garage.
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Back to shop for more practice!
Having closed an archtop body, I can tell you the dovetail joint has been the most mentally challenging concept to get a handle on, by far. It’s not only a dovetail, but 2 dovetails in 2 different directions. There has been lots of speculation and discussion of whether it’s best to cut the dovetail or mortise or dovetail first, and how best to refine these to create a super tight fit at the right level.
I should preface that I did most of this practice session with an incorrect end goal- I attempted to make the top of the tenon flush with the body. I think I thought this because the video I watched was an acoustic guitar. That being said, I cut about 3 mortises and tenons, of which all mortises were too wide. The following pictures were the 4th one that got near a locked fit.
I recut a new mortise:
And another tenon. And changed from the straight cut bit to the 7° dovetail bit:
Once cut with the dovetail, it was proud, but did have a decent lock:
I assumed the tenon bottomed our and trimmed the tip of the tenon. This helped it drop a bit further in:
I then used a file and tried to narrow the sides and tip, keeping the file at the 7° dovetail angle:
After refining this a bit:
And eventually ended up here:
I must not have done accurate filing because the dovetail became much weaker and slipped out towards the tip of the tenon.
At the end of day 2, I was glad to get closer to a locked joint. Being that the 5/8” rabbet needed to be cut, I felt the tenon would end up being pretty short. I still felt a bit lost as to the best method to get this mysterious joint where its supposed to be in the end.
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This brings us to real time (12/1).
I decided to go back and watch the O’Brien jig use video- and this helped. At this point, I also realized I didn’t want the dovetail flush with the body, because we needed to add the neck extension.
After some more banter, I decided to try a real dry run. I would first cut the mortise to my desired length 2-1/4” using the original, abandoned full neck blank and planned to cut the tenon to 3/4” and the mortise to a depth of just greater than 3/4” - I would do all fit adjustments to the tenon.
Started by cutting the mortise into a piece (acting as the guitar body) just a hair wider than 2-1/4”, which ended up being a blessing in disguise! Explanation forthcoming.
First, I measured and set the template for the LENGTH to 1/8” beyond 2-1/4”- this is because it cuts 1/8” short due to the guide bushing. Then set the router DEPTH stop to hit just beyond 3/4” on the “body” piece, and took multiple 1/8” passes with the 3/8” straight bit until down to bottom. I then set the template at the max on the neck blank (remember stopping 1/8” short this time, because the guide bushing cuts long on the tenon template). Using the same bit, set depth stop to exactly 3/4” and cut in multiple 1/8” passes until it was finished.
Then switched to the dovetail bit and plunged down and set the depth to hold at level of the previous cuts. The cuts with the dovetail bit have to be cut in only 1 pass. End result:
First look at fit was really promising! Tight lock fit, shoulders pretty tight, but was quite prominent. This is fine because I was going to adjust the tenon:
To adjust the tenon (make it a bit more narrow to sit lower), you move the template up (toward the top, or wider part of the tenon). Taking it ~1/8” at a time, it sort of correlates to the tenon moving ~1/8” down:
You can see each pic of tenon gets successfully shorter as I move the template up and re-route with the dovetail bit in 1 pass.
I mentioned above about the blessing in disguise- see below:
I happened to use a practice scrap just bigger than my goal length of dovetail. This created 2 teaching points:
1. If you don’t leave yourself enough room before the end of the neck block when planning your dovetail, you’ll risk ending up blowing out a hole in your back plate. This is because of the nature of the dovetail bit being angled, in my case 7°. Straight bits cut straight, so no problem. The dovetail cuts wider than the 3/8” straight bit!
The other teaching point was almost nonexistent. It presented itself by a hair- the fact the dovetail bit does cut wider allowed only a sliver of a blowout. But the blowout allowed a window into the internal anatomy of the joint, typically unseen. It shows that this particular joint is close, but not bottomed out in the mortise. Pretty cool, by chance!
Took me about 4 refinements, which got me to my goal (chose arbitrarily) of 5/8” prominent of the ‘body.’ Photos in following post.
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I’m very happy with how my practice progressed and the knowledge it’s given me. The practice experience is invaluable.
I feel that I can now go into the real neck and body, and hopefully get the right fit at the location I need it. I’ll assume I’ll screw up somewhere, but plan not to. Haha
Hit photo max in last post, but here’s how I tracked my tenon refinement depth as I moved the template:
Here’s the final fit:
Less nervously looking forward to cutting the real deal.Last edited by sbeishline; 12-02-2019 at 08:17 AM.
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Originally Posted by rlrhett
Thanks, Rhett. Words of wisdom- much appreciated.
Is there an ideal amount of protrusion of the dovetail I should aim for if the neck extension will be 5/8”?
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What happened with the template that was marked LMI M&T for cutting a straight sided mortise and tenon?
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Originally Posted by sbeishline
Your heel is long enough to reach the bottom of you rims, right?
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Originally Posted by Matt Cushman
Originally Posted by rlrhett
All of Me - A7 on measure #28 (9th?)
Today, 10:24 AM in Theory