View Full Version : Archtop Jazz style Tenor

03-04-2015, 08:23 AM
Hello everyone, I would like to post some progress pictures of the tenor Uke I'm working on. Its based on archtop guitar construction methods and will see some changes as it comes together. For now the specs are:
17'' scale
11.5 long body
9'' wide lower bout
6.75 '' wide upper bout
19 frets
machine tuners
Maple 3 ply neck
Doug Fir top
Walnut fingerboard, sides and back
Binding all around

I do my initial sketches in CorelDraw then export to the CNC for cutting.

Thanks for looking, Vince

03-04-2015, 09:45 AM
Here's a pic of the 3 ply neck blank, the center strip is walnut. The neck block is a 2 piece stacked glue-up. Some fine tuning was needed with a file and scraper on the cheeks of the neck to get a snug fit. I will likely change to a sharp florentine style cutaway with the 2 side pieces joining at the pointy end. Because the tight bend of the one piece side I'm currently making, that side (lower) kept cracking while bending. -Vince

03-04-2015, 10:27 AM
Looks great. I cant wait to see and hear the final product. I love archtops. :)

03-04-2015, 03:58 PM
Thanks Booli, I can't wait to hear it too. Glad to get the bending mold covered in sheet steel, I happened to have a piece of 22ga in the garage. Next is to make a stand to raise it off the bench when bending sides. In the pic attached here is a full size mockup I made to get an idea of the final dimensions. Also on the short list of jigs to make is a male or female mold for assembling the body and lining up the neck. My thoughts is to make this on a single long board. I did cut a female mold board in MDF and what a time it gave the router, the board was scrap after that. I may cut the work board in walnut which routes nice little chips and not a lot of dust. Thanks for looking -Vince

03-07-2015, 05:07 PM
After getting the bending form together I tried a couple of sides with the heat blanket. I had thinned the maple side down to about .075'' with a plane before placing it in the mold. I didn't have my thermometer on hand to check how hot the blanket was getting. I heat cycled it up to full hot 2 twice and left it clamped up overnight. When I removed it the next day there was a lot of springback, I touched it up on the hot pipe to get it closer to its final shape but I still wasn't happy with results. Also of note , this side was done dry with no pre-wetting. Next I tried a 3 layer laminate of Makore veneers I have here, each with an approx thickness is 1/42 of an inch. I stacked the three layers dry in the mold and bent them at the waist with the heat blanket, I followed the same routine of touching them up one by one on the hot pipe (very easy with 1/42 stock) I got the 3 layers uniform and applied titebond in between and placed them back in the mold., After being fully clamped over night the side popped out in great shape, no spring back and very firm for its thickness. My mold shape is made with some springback figured in, in the case of the glued up veneer side it kept the mold shape exactly, sort of over bent. I will try 4 layers on the next test with the outer most being a Maple Birdseye veneer. In the attached pic, the solid maple side is in the back and the 3 ply Makore is in the front. Any comments and tips are appreciated, Thanks Vince.

04-30-2015, 11:31 AM
I've made slow progress since the last post. I went with the laminated sides and have them glued up to the neck and tail block. The rounded cutaway was too difficult to get right so I opted for the pointy style Florentine cutaway. I laid out the finger board along with the block inlays for the CNC. I left the extra waste material surrounding the board so it would be square when I ran it thought the fret slotting saw. The board tapers from 1.5'' to 1.375 at the nut. Its walnut and the final thickness should come in at .20'' inches. Also it will have .060'' white binding, this was figured into the dimensions when cutting the board. Thanks for looking, Vince

Kevin Waldron
04-30-2015, 01:55 PM
As for bending..... if you are bending with a form...... .055-.065 is probably a better bend for archtop ukulele sides. If you were going to do this again you can make the bending molds somewhat different.... attaching photo of guitar.... for ukulele I'd add one more center section..... but otherwise the same...... you will need two different bending molds if you plan on doing a cut-a-way..... one for the straight side the other for the cut-a-way..... and you will need some kind of ram to force the material into the curve of the cut-a-way..... would suggest veneer softner overnight before attempting this for a ukulele cut-a-way bend. (Although this might better be performed with a hand heat bender....but it can be done with a machine if one has a desire to do so.)


Think you will be better pleased with the feel of the neck/fret board if you go from say...... 1.98 to 1.375' - binding/wrap thickness.....

It appears that you have Aspire ....... it's possible to cut your top& back with this software if you have a desire to do so...... you will need to research and find out how to make the file for cutting/shaping ... but it can be done.... should take about 45-minutes to an hour for both top&top inside with the CNC. ( We use other software )

7903179032 Sorry! no final pictures..... we gave this to one of our grandchildren.

Hope you enjoy and get more time to work on this.



05-01-2015, 01:01 PM
Hi Kevin, thank you for taking the time to post. You've been down this road and I appreciate your advice. I'm not using Aspire but another Vectric product called Cut3D. I'm working on a model of the carved top now, its a slow learning curve for me but I'm confident I'll get there. I went with the pointy Cutaway on this one and will re-visit the rounded cutaway down the road for sure. Best regards, Vince

05-04-2015, 04:59 PM
Tonight I'm testing a neck jig I made over the weekend. It has a 15 degree ramp to work with the headstock angle. I used it to surface the top and back of the headstock down to .45 inch thickness. I milled the tuners holes by using the laser as a guide. I will cut the outline of the head shape on the bandsaw and use a sanding drum chucked in the drill press to get to the final shape. I hope to eventually cut the head shape on the CNC including the binding channel. The third picture is checking how the fingerboard lines up with the neck. The inlays are white swirly acrylic cut from a 1'' x 5'' block sold by pen-turning suppliers.That stuff sure stinks awful when you cut it. There will be no radius on the fingerboard and there will be a bone nut. The extra wood I left around the fingerboard will serve as extra surface when I flat sand it, so to prevent me from rolling off one side and ruining the board. Thanks for looking, Vince

Not shown in the third pic is the 3 boards that went to the scrap pile. It took that long to figure why my inlay pockets were off center. When changing from a 1/4" to a 1/8" mill I ever so slightly moved the router on its sliding gantry. So when beginning the finish pass it was slightly off. The solution was to leave the power turned on that feeds the stepper drive motors, this keeps them locked so the router won't move.

Vespa Bob
05-04-2015, 06:06 PM
Amazing work, but too high tech for me!


Kevin Waldron
05-05-2015, 02:18 AM

You will find all kinds of ways to do necks..... probably best to do peghead reverse of what you show and make it 90 degrees to bit. If you do it this way you can shape and cut it out and drill peg holes with cnc. Attaching some photo's of fixtures we have used..... the most elaborate one is by Chris Klumper of LuthierTools..... a close friend. The first fixture is to be used with a shaper or router.

Hope this gives you some more idea's, part of the fun for me is figuring out how to conquer the problems......




05-08-2015, 12:57 PM
Thanks Bob, I'm still learning while I use this machine. But I gotta admit its a lot of fun!.

Kevin, your suggestion is right on target, I intend to flip the neck for machining with a spoil board underneath. The jig you posted looks very well thought out. I also enjoy the challenge of figuring out ways to machine and hold down parts on the table. It's good exercise for this old noodle of mine.
Below are 2 pics of adding kerf lining to the sides. Thanks for looking .Vince

05-08-2015, 04:00 PM
Thanks for sharing, Vince!

05-08-2015, 07:48 PM
My Pleasure BigMamaJ40. Here' tonight's work on the top. I cut a test piece on the CNC to see where I'm at with my contours. My previous method would be to use a Wagner Safety Planer which scared the heck out of me at times. The top blank is .625'' (5/8'') thick overall. The first pic is my drawing of the contour layers which is imported into the CAM (computer Aided Machining) Program, 2nd pic is the CAM software rendering before anything is actually cut, pics 3 and 4 are the test piece which took 23 minutes to route. Thanks, Vince

05-08-2015, 09:01 PM
I am very intrigued by cnc machining. I'm thinking of making some parts for resos in one if I can get it to work. For an arch top I would probably hack away with chisels and planes but that looks like great fun too.

05-08-2015, 09:37 PM
My Pleasure BigMamaJ40. Here' tonight's work on the top. I cut a test piece on the CNC to see where I'm at with my contours. My previous method would be to use a Wagner Safety Planer which scared the heck out of me at times. The top blank is .625'' (5/8'') thick overall. The first pic is my drawing of the contour layers which is imported into the CAM (computer Aided Machining) Program, 2nd pic is the CAM software rendering before anything is actually cut, pics 3 and 4 are the test piece which took 23 minutes to route. Thanks, Vince

Thanks for sharing. Those pics look interesting. Can you tell the CAM software to render a 'negative' cut (180 degree flip, and then mirrored image), and reverse the wood (flip it over), insert it into the CNC and recess the wood down with the same gradations?

Thus you would get a rough arched top with symmetrical gradations on both sides....

How will you smooth out the gradations to a nice fluid slope? By sanding it?

I need a 3D PRINTER, a 3D-Scanner, Laser or Plasma Cutter, and a CNC machine !!! But I have no space for them now, nor funds for such a setup.

Alas, oh but to DREAM! :)

05-09-2015, 11:17 AM
I am very intrigued by cnc machining. I'm thinking of making some parts for resos in one if I can get it to work. For an arch top I would probably hack away with chisels and planes but that looks like great fun too.

I encourage you to consider building your own CNC machine, I did. The shapes you're making in your blog for the reso's would be ideal to machine. -Vince

05-09-2015, 11:30 AM
Hey Booli, What you describe is basically true for carving the underside of a archtop. All the design elements like 'mirror, flip and rendering a negative from a male shape' are included in most CAD programs like the free SketchUp program, the trick is figuring out the sequence of those steps to get what you want in the end result. For me its trial and error but I enjoy the challenge. I was doing basic generic shapes only a year ago and can now create more complex surfaces. Google SketchUp, the free 3D Software is easy to learn and has great features for anyone looking to learn to model in 3D. The next step for this top will be to knock down the stair graduations with a sharp chisel and a finger plane, then sand and scrape. Then back onto the CNC to cut the 'f' holes. Thanks , Vince

05-09-2015, 06:22 PM
Here's the result of tonight's work in the shop. It took about an hour total because I took breaks to let my fingers get back their feeling ;). I knocked down the stair edges with a chisel first, then used a finger plane to slowly work the shape using the bench light to better show the curves. Running my hand over the top also reveals any high spots that needed attention. Thanks for looking. -Vince

Kevin Waldron
05-10-2015, 03:55 AM
Early before worship and had a little time to play....

I'd suggest that you try using curves rather than graduations..... you will get a better top/back.......most of the 3D modeling packages that I'm aware of allow you to draw surfaces along curve lines and blend/merge/loft curves. When we are doing a new model we always first do a wire frame ( we almost always draw a 2D drawing one top view, and one side view ) and basically use cross sections through what we are doing to form our initial tops.... the more wire frames the more molded your top can be.

You will need to add re-curve to the outer edge of your existing top.

Attaching some photo's showing what I'm talking about. By the way brought a model into Aspire with no problem...... (We personally don't use Aspire for this kind of work ... we do have it.... it will work. It maybe that the software that you have want do 3D following but only level cutting... Sorry, don't remember... if this be the case you could use a third party programs to slice the model much like the 3D printer works and you would still get a more accurate top/back with much less hand work.... just some thoughts.....)




05-10-2015, 05:04 AM
Hey Vince! it looks as if you'll have to make a case that will fit that uke as well. ;)

05-10-2015, 12:01 PM
you'll have to make a case that will fit that uke
Yes. Archtops don't fit well in uke cases unless specifically designed to do so. The added height of the bridge is an issue. I solved that problem by buying a second hand viola case and performing a little surgery to adjust the width. Cost me $12.

05-10-2015, 05:23 PM
Hi Kevin, I'm working on a rough 3D drawing with curved elevations of the top for the next build. I have software on hand to go from model to carving on the CNC but didn't want to get side tracked with this Uke while working on that model. The stepped carve was a quick 2D file I generated and was'nt sure how it would come out in the end. I appreciate the pictures and advice you've been posting as they serve as motivation for me. Keep it coming ! Thanks

Timbuck and Miguel, Yes I'll need at least a case with the foam/upholstery re-worked to fit the Archtop. I originally thought the neck angle would be a problem with a case, and now realize the bridge would sit higher than usual also.

Timbuck, I read you were an Engineer, our son goes off to Study mechanical engineering at the university in the fall. My wife and I are very proud of him.
Best regards,

01-27-2016, 05:59 PM
The binding on the fingerboard is installed. The top plate is getting closer to its final shape. The inside still has to be carved and f- holes cut in. Thanks for looking, Vin

02-11-2016, 10:28 AM
Glued the fingerboard on and installed the frets, well almost all the frets. I came up one short. A result of cutting frets late at night no doubt. I did some shaping on the neck, it still has a ways to go. I have to decide whether to go with a surface mounted pick up like originally planned or one under the saddle (Piezo) both are on hand but honestly I'm leaning towards the traditional pickup. I have to either make a mounting ring for it or have several 3D printed in plastic if the cost is reasonable. The Piezo came as a kit with 9v battery holder and an end-pin jack that uses a cool mini thumb wheel pot. If there's a way I could use that mini volume pot with the 4 pole pick up that would be great. -Vinny

02-13-2016, 05:04 AM
Yesterday I worked on a ring to surface mount a pick up. The pick up is the same as used on a Fender Precision Bass at the neck location, I'm separating them and using one for now. The material is 1/4'' - 6mm PVC sheet. Lots of fuzzies on the cut out as my cutting mill was too aggressive and the feed speed could have been raised. overall it went good for a test piece. The last 2 pics are after I sanded off the fuzzies with 320 grit paper. The initial drawing was done in Google SketchUp. The final version will be cut from black material. Thanks for looking, -Vince

02-13-2016, 02:10 PM
Vince, Nice work. I'm a Johnny come lately to this thread but I quickly read through it and couldn't see where you stated if this instrument is using classic strings or steel strings or what string spacing you are using. Those bass pickups only work for steel/metal string at bass string spacing.

Classic strings won't work at all and ukulele string spacing will mean that the signals are week and uneven.

What strings, and bridge for that matter do you intend to use?


02-13-2016, 04:07 PM
Thanks Anthony, On these Fender pickups there are 2 of these staggered like in the pic I attached below. When one of the pair is used for the Uke's string spacing it falls into place as in the 2nd pic. I will need to ground the steel strings at the tailpiece to prevent humm. Separating the 8 ohm set of pickups left me with a scorching hot 3.75 ohms each LOL ! I'm still curious as to what sound I'll get. Glad you brought up strings as I'm open to suggestions on what to try. -Vince

02-13-2016, 08:29 PM
OK, thats interesting. Those pickups may be designed for bass frequencies only though. I'm not sure what they will sound like with treble strings so you will have to see. I always use the top four stings from a 10-46 gauge guitar sting set on steel string ukuleles. Some insist on using the middle 4. The top four will have less tension than the middle four. What are you using for a bridge?

Remember that steel strings need more saddle compensation than classic strings do due the stiffness of steel strings. Adjustability is desirable too because if you change string gauge you will need to change the compensation and if you start out not being sure of what compensation you need in the first place then you really do need to design in some adjustability.


02-14-2016, 05:47 AM
Thanks Anthony for your insights on steel strings, I wouldn't have thought of those options and they'll surely help getting this Uke sounding good. Yes its true I may end up with a very deep tone from this pick up. I also have the Piezo under saddle kit here, maybe the solution is to install both, Ha! . I will be making the bridge in the style of an Archtop guitar, either from maple or walnut with adjustable thumb wheels and a bone saddle. I attached a SketchUp drawing I made of the general idea. Thanks again, Vince

02-14-2016, 12:03 PM
If you work it so that the bridge assembly floats then it will be OK but if the bridge needs to be fixed you will have problems. If your going for linear tuning then tilting the bridge assembly should work but if you want reentrant tuning there won't be enough adjustability in that design to deal with the reentrant string.

A couple of years ago we did a group order here for arch top steel sting ukuleles from a builder in China. They used a somewhat similar bridge design and the number one problem with the design was that the bridge was fixed on in the wrong position.


02-15-2016, 05:17 AM
Wow ! Super useful information Anthony, I greatly appreciate you sharing your experience with archtops. Sorry to hear about getting those ukes with glued bridges, what a disappointment. I didnt plan on gluing this bridge as that's the beauty of a floating bridge, you loosen the strings and can adjust them. The plan is to go with low 'G' tuning for this and tilt the bridge back as you mentioned. As I get on with making the bridge I can use advice on adding a little compensation to the bone saddle when I shape it. Also there's no radius on the fingerboard. Does the low G string buzz more or less when using steel and nylon? Thanks again, -Vince