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Top Fabrication continued

Thickness sanding the tops to near 5/8"




Cutting the tops out. I cut just outside the outline.


Here they are with their rims.


I'm using Graham's contour map. I poked holes on the contour lines so I can make pencil marks directly on the tops.


Here they are with their contour lines ready for shaping.

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Chris Oliver
Infinity Luthiers
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Love what im seening Chris , real nice work . This thread is a great tutorial on building a mando Chris !

_________________
The Shallower the depth of the stream , The Louder the Babble !
The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
http://wiksnwudwerks.blogspot.com/
http://www.facebook.com/groups/GatewayA ... rAssembly/

I keep forgetting to check in on this forum. When I do, I'm glad I did. Keep the pics coming.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I know this does seem to be an outpost of sorts at the olf.

Nice work Chris.

_________________
Regards from RangeView, Bill

Thanks guys. I hope in the end this will motivate some folks to give the carved tops a shot.

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Chris Oliver
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Carving the Top 1

Here is the method I use to carve the top of the tops. I have seen other methods but have settled, for now, on this one. It is dangerous to you and your tops/backs, but, when given the proper attention and patience is a very fast way of getting the soundboard hogged out.

I use a three fluted down spiral bit for this job. It grabs the top less than other bits and helps keep it flush against the bottom of the jig while cutting.

Here is my step block. I use it to set my bit height for the different contours of the top. If you are able to see the measurements on the step block you will notice that the heights do not correspond directly to the contour map of the top plate. I created the step block with additional height to allow for sanding and finger plane shaping later.




Here I am working the bit across the grain of the top. Be sure to know which way your cutter is cutting and how quickly it will chip out if you go the wrong direction. Another possibility is that it will grab your top and throw it across the room (ask me how I know).


Here I have completed the first and second contours. Notice there is no recurve. I will complete the recurve with a finger plane after the top is nearly complete. Also, the edge height of the top will be taken down to a consistent 3/16" at a later time.


Here the graduations are all complete except around the neck/body joint area and the sound hole.


Here I have used a small hand plane and finger plane to begin smoothing the ridges.


Once I have knocked all the ridge down and smoothed it pretty good I use a ROS with 60 grit to smooth out the top. I look for humps and grooves as I go.
Here is the top with a straight edge to help show the contour.


Now that I have my contour complete, I take a measurement of the thickest part to use in calculations for the recurve, break angle and neck angle.

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Chris Oliver
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Calculating Neck Height, Neck Angle and Break Angle

In a factory, the top, neck angle, break angle, etc. are all identical. Machines carve the top, inside and out, it cuts the neck mortise, tenon and neck angle. The factory instrument cares not about the differing stiffness and weight from top to top.

It is time to separate the factory instrument from the luthier built. You have already had the opportunity to choose specific woods for the project. Either you wanted specific grain or beautiful figure or both. Here is your first opportunity to fine tune the down pressure of the bridge to the top of the instrument.

Graham suggests in his book and through correspondence concerning Celtic style mandolins, a break angle of 17 - 19 degrees. Some correspondence to Roger Siminoff revealed that 16 degrees is a maximum to shoot for in F5's.

I found that I had been measuring the break angle incorrectly recently but here is a diagram showing the break angle.


You can see that the break angle is a function of the neck angle, neck height, thickness of the top and the height of the bridge. Since we have now carved the top and can measure the height, we only have the neck angle, neck height and bridge height left to calculate. Bridge style will greatly change your angles here. If you go with a carved bridge you can make it shorter than if using an adjustable bridge. In this case I will be carving my own bridges but will also make the adjustable bridge available as an option.

The Loar style adjustable bridge is 3/4". So now we have data points to calculate our break angle. The only variables left to decide on are the neck angle and neck height from the top. I am following Graham's suggestions in most cases and modifying as needed or to show alternate ways of completing the task. In this case, the 3/16" top edge height will be used in the calculation.

The only variable left is the neck angle. The suggested neck angle is 6 degrees to allow room for the adjustable bridge. Try not to increase your neck angle too much or you may have trouble finding a case to fit (thanks Graham).

Below I have diagrammed the instrument with .583 thickness, 3/16" top edge, 3/4" bridge. I have given 1/4" from the neck to allow for a 3/16" fretboard, fret wire height and strings. I hope the diagram allows you to visualize the system.


You can see that I have a greater break angle(21.2) than recommended. There are two additional factors that can change the break angle. The first is the tailpiece height. I typically use James tailpieces. Here is one on an A model mandolin. You can see that the hinge pin is just over 3/16" from the top of the top edge. The hinge pin is in line with the base plate of the tailpiece, so, the strings are just above the hinge pin.

NOTE: Something to consider when raising your tailpiece to reduce the break angle is the added torque placed on the tail block. Raising the tailpiece acts as a great lever that tries to pull the top of the tail block forward and down. If too much pressure is place on the top this could implode. Roger Siminoff has done some research on break angle and top pressure here.

With this information I can now change my diagram to incorporate the change. Now I have a break angle of 19 degrees.


One issue I still have is that the neck angle is at 6.8 degrees. The only way I can lower the neck angle while keeping the 19 degree break angle is to raise the neck.

Here I have raised where the neck meets the body from 3/16" to just over 1/4". This will cause more work when binding the top. But, my binding is 1/4" tall so it will not be a great problem. Also notice that this lowered the break angle to 18.1 degrees. This is right in the middle of the recommend range.


Another method to consider when needing to reduce the break angle; you can sand the feet of your adjustable bridge.

Based on this information I now know what angle to plane my neck ramp, how high on the body and neck meet and have a good feeling about getting the most out of the mandolin top. Of course there are other factors that will play a part in the overall performance but not many are as important as the bridge height, neck and break angle.

_________________
Chris Oliver
Infinity Luthiers
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Fretboard Ramp Sled

In woodworking you should find yourself building a lot of jigs and sleds. These increase your repeatability and generally make life easier and safer.

If I were only building one mandolin of this style I would have used a hand plane. Since I am building 2 concurrently and will build several more in the future I decided to build a sled to help with the process.

It is constructed using some 3/4" mdf. I built it to slide along the fence on the table saw and hold the top perpendicular to the table surface. I have a perpendicular pencil line on the sled to line up the top. Total time to build the sled was about 20 minutes.

Here I am using one of the best new products of the last decade. I use this digital angle finder to zero out the top of the table saw and set the blade angle. In this case it is 6.1 degrees.


Now... since my big Oliver saw tilts in toward the fence, I put a temporary fence on the other side of the blade to guide the sled.

Here I am lining up the height of the cut (as compared to the top of the mandolin top).


Saw through the top nice and easy.


Here it is, perfect 6.1 degrees.




The second mandolin top is measured at .591. That is less than 100th taller than the top above so it will get the same ramp angle at 6.1 degrees.

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Chris Oliver
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Carving the Top 2

Now that the fretboard ramps are profiled, we can finish up a lot of the top carving, inside and out.

Here I use a hand gouge to shape my fretboard ramp edges and area in front of the sound hole.


On the left I have marked a top with three marks. The outside is the outside of the top. The middle line is about 3/8" inside that mark signifying how far in to bring the edge height (3/16"). The inside line is the area of the recurve.

On the left is the back of the other top. I have marked an area inside the recurve. I do not want to thin the area outside the line from the back.


I have used my router profiling jig again to bring the 3/16" edge height in over the recurve (see the plate in the top left). On the plate on the right, I have used a finger plane to smooth out the transition.


I use the drill press to get me close to my maximum thickness... around .2".


Here are both plates after drilling and then using the palm gouge to rough out the really high areas.


I use a rough grit semi-flexible sanding disk on the drill press to clean up the inside of the top. I keep the drill press speed low to avoid throwing too much saw dust.


After the inside is pretty smooth, I draw the contour lines for final thickness.


With the sanding disk, I take down the thickness from middle to out side. I use my thickness gauge often.

Once done I measure the thickest part of the top. This top was measured at .198". I can now bring the recurve down to within 60% of that, or, .120". I accomplish this using the finger plane and measuring often with the thickness gauge.

Once complete, I hand sand a bit with 60 grit. Here is the top, ready for an oval hole to be cut.

_________________
Chris Oliver
Infinity Luthiers
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live every minute...

Creating the Rosette.

I built a little jig to help in the rosette shaping process. It is a plexiglass base with plywood oval for the rosette materials to form around. The black knobs tighten down to help keep the shape of the rosette while it dries.


Here I have a piece of herringbone inside a tube hooked up to the faucet. I let hot water trickle over the herringbone for around ten minutes.


After the soak, I split the herringbone. Notice the direction of cut and that the holly strip in the middle is kept on one side of the blade.


Here the herringbone strips are laid out with some additional BW's. One each on the outside and one on the inside to balance the holly strip attached to one half of the herringbone.


I keep the herringbone moist by spritzing once in a while. Be careful not to get the BW strips too moist if they are fiber and holly... the fiber tends to swell and split.

Here I have one end clamped and am pulling the rosette around the oval.


I try to keep the rosette flat against the glass and wrap it tightly.


Here the rosette is fully pulled and trimmed at the ends. At this time I introduce ca glue.


The rosette is now hardened and ready to be pulled from the oval. Notice the red wax on the oval...this is to keep the rosette from sticking when the ca glue is introduced.

_________________
Chris Oliver
Infinity Luthiers
...in the shop.

live every minute...

This thread has been very interesting Chris ... Great work . I like how you heated up that Herringbone strip , great ideas here .

_________________
The Shallower the depth of the stream , The Louder the Babble !
The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
http://wiksnwudwerks.blogspot.com/
http://www.facebook.com/groups/GatewayA ... rAssembly/

Ditto Jim's comment. I'm about to start my first oval s.h. mando.

_________________
Regards from RangeView, Bill

Another Rosette

One of these mandolins is going to a young performer who requested an outdoors theme. Well, a bit of bling(did I really just use that term) in the rosette is a good place to start.

I start by tracing out the minimum sized oval.


I picked up these shell off-cuts from the Duke of Pearl (Chuck Ericson) during the GAL conference last July. I'll be gluing up a bunch of these and cutting the ends to make a vine like oval.


Here I found some prefab vine and leaf inlay that I really like.


I've glued up some pieces and trimmed the ends. Here I'm starting to make up the oval. The ends will all have to be filed make the fit just right. Once glue together, the oval will be filed, or more likely ground with the Dremel tool, to make the pieces appear seamless.


There goes the pretty vine set. I sawed some of the leaves from the set while it is still attached to the backer board. These leaves will be incorporated into the oval as part of the rosette.



More on this later... this should be a lengthy and photo rich part of the thread.

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Chris Oliver
Infinity Luthiers
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Cutting the Oval Hole

Folks, this is a pretty simple task with the proper tools.

Trace out your hole.


Drill some holes so you can turn your blade.


Insert fret saw and saw close to the line... but not on or over it.


Sand out the hole to the pencil line using a OSS or drill press drum sander. Use the larges size that will still make it into the smallest radius of the hole.


Ready for inlay.

_________________
Chris Oliver
Infinity Luthiers
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live every minute...

Another Rosette part 2

Using the shell pieces from the rosette post above, I have created a rosette for the oval hole. If you find yourself using shell in anything make sure to wear a proper mask. The dust from shell is not something you want to be inhaling.

I take the fattest part of each of the glued up pieces and saw them down to fit close to the oval line. I attach these to the stiff poster board using hot hide glue.


Continue this method making sure to sand each edge to mate with the neighboring piece as you go. Overlapping the line by a little is preferred as I will grind this out later.


Once the oval is complete, I use ca glue to solidify the rosette


Here I have cut out the poster board from the center of the rosette. Using a dremel with sanding drum, I grind the inside of the rosette until smooth and uniform.


Now using hot hide glue, I attach the piece to another piece of poster board.


Here I have cut away the poster board from the outside of the rosette.


You guessed it. I used the dremel tool again to smooth the outside of the rosette.


Here I have soaked the rosette in some warm water to release the shell from the poster board backer. Because of the ca glue used earlier, only the latest piece of poster board is removed. The original piece of poster board is softened by the h20 and in the next post you'll see where this helps.

_________________
Chris Oliver
Infinity Luthiers
...in the shop.

live every minute...

Another Rosette part 3

Here are the steps in inlaying the shell rosette. I am not using a router with jig here. I am using only an exacto knife and dog leg micro chisel (that I micro'd even more on the disk sander).

First I check that the rosette is large enough.


Now I use the exacto blade and cut a line right on my pencil mark all the way around the oval hole. I peel the inlay pieces of the wet poster board backer one at a time, hold them in place on the pencil mark and trace around them with the exacto blade. Then I use the chisel to make the inlay channel. I go back and forth between the exacto and chisel until I get the piece to fit just right and deep enough to just barely stand proud of the top.


As I go, sometimes I have to sand the edge just a bit to make them mate up perfectly.


Once the oval is complete, I carefully remove all of the inlay pieces and place them in order on a nearby sheet of paper. Then I clean the channel of any debris and/or wood pieces and coat the entire channel and area with shellac.


This shellac will act as a barrier and help stop the ca glue from wicking into the spruce top.


The shellac has dried and I put all the inlay pieces back in the channel. Next add ca glue all in between each piece of inlay an along the edges.


The ca glue should wick into and around the inlay.


Here it is rough sanded and a coat shellac wiped over the entire top.

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Chris Oliver
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Adding Shell Inlay to the Top

Here I am cutting a pocket for each shell inlay. I trace around the piece with a pencil, then score just inside the line with the exacto knife. I follow with a die grinder with very small bit. As I get the close to fully cleaned out I test the inlay piece and make additional cuts to the top as needed.

The pockets are coated with shellac before using ca glue to hold them in permanently.

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Chris Oliver
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3 Piece Necks

I am building 3 piece laminate necks using black walnut and maple.

First I locate some lumber to build the necks. I have resawn the maple down to around an 1/8 inch and trued the faces parallel with the drum sander. I have done the same to the walnut although leaving it around 3/4 inch thick.

Here I have traced out the rough outline of the neck pieces (this is for two necks).


I have cut out the rough pieces and put them together with all the supplies and tools needed to complete a good glue-up.


Here's a neck all clamped up. We'll be trimming the necks to size after the glue dries.


I have trimmed the necks to shape and created a plane for the fretboard on the jointer. Here is a jig to rough cut the approximate headstock angle.


Here is the dovetail end of the neck. Notice the grain direction. This, along with the center strip, will make the neck very stiff.


Here I'm cutting a channel to fit a carbon fiber rod. I cut the slot just a little deeper than the rods. By little, I mean a few thousandths. This will give the adhesive some space and I won't be flush sanding/scraping down the carbon fiber later.


The rods fit nicely so it is time to glue them in the slot.


I use epoxy to glue these.


The necks will have dovetails cut and fitted to the body before the headstock ears are attached and veneers applied. If the necks turn out not to be right or I totally ruin them, I wouldn't have wasted my time on the headstock.

_________________
Chris Oliver
Infinity Luthiers
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live every minute...

Bracing the Tops

The tops get an X brace. One here is getting an extra brace that lies directly in front of the bridge location.

I first lay out the location of the bracing.


Trace them out using a flexible straight edge.... like a piece of scrap.


Cut the bracing out of some straight grain spruce. I used the same Sitka as the tops here.


I rough cut the braces and then use a small washer to follow the contour of the top and make a nice line on the brace.




After making the line, I use the bandsaw and then belt sander to get the brace to fit perfectly to the top. I glue my first brace in using hot hide glue. Then notch the cross brace and carefully fit it perfectly. It is then glued in using hot hide glue. Sometimes the notch is too wide... glue in a wedge while gluing the brace.


Here is one of the tops with the extra lateral brace.


Here the braces have been glued and profiled.

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Chris Oliver
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Gluing the Tops

Here I am lining up the top and adding some marks to make it easy to re-align during glue-up.
Edit: This is what happens when you wait too long between taking the photos and posting!... So.. although you cannot see it in this photo. I drill a hole in the neck block where the dovetail will be and add a small screw.


I heat up the rim and top (edge) with a heat gun and brush on some hot hide glue.
You can also see the hole that the alignment screw goes in as well as the screw setting on the form.


Here you can see the rim and top with glue applied. I let them set a bit and gel up. Next I heat them again with the heat gun, add some more glue to the rim and align the top.


Here are the tops with the alignment screw and go bars in place. The go bars apply plenty of pressure for this operation.




Once dry, I remove the alignment screw and use the bandsaw to clean up any large overhang, a chisel for tighter overhang.

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Chris Oliver
Infinity Luthiers
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Body Dovetail Mortise

The dovetail in the body is a pretty quick procedure. I'm just posting pics here so ask questions if you have them.

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Chris Oliver
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Neck Dovetail Tenon

The neck dovetail is pretty simple as well. I have to admit, I use a template here made of some thin Lexan. I make a straight line on the Lexan and then line it up on the body and trace the dovetail mortise. I then use this tracing to outline the dovetail on the neck.

Here it is lined out and ready for trimming. Keep in mind that the distance from the start of the dovetail (the place where the neck meets the body) should be determined by your scale length and distance to nut/bridge area. This is not a 'willie/nillie' placement.


I use the table saw to cut the proper angle, in this case 6.1 degrees.


Here I am using a couple straight edged scraps to extend the angle as a base for cutting. The blue painters tape is added to the side I am cutting to give the dovetail another angle dimension, creating a dovetail wedge.


I cut the side with the tape, then remove the tape, apply it to the other side and cut the otherside of the dovetail.


I use the table saw again here to remove the cheeks and at a perfect 90 degrees. This will mate with the body nicely.

_________________
Chris Oliver
Infinity Luthiers
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Fitting the Dovetail

Fitting the dovetail can be a challenging experience. Just remember to set everything up before hand and the dovetail fitting will have a better outcome.

Here I'm testing the fit. Excellent. It fits nicely and is lined up straight down the mandolin. All I need to do is drop it until the top of the neck is flush with the fretboard ramp on the body.


I remove the neck and get out my dremel tool with a ball mill. In this photo you can see the areas where I removed some wood from the neck. This helps relieve some tension and helps immensely.


I use a little angled sanding block to sand both sides of the tenon until I can drop the neck flush.


Now I turn it upside down, clamp the neck down and cut the extra neck heel with a flush cut saw.


Here I used my sanding stick to make it nice. Now when its time to glue in the neck I'll have a perfectly flush heel.


It seems so easy, right?

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Chris Oliver
Infinity Luthiers
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Headstock Ears

This is a pretty easy concept. Though, there are a few tips to make your life easier.

Here I have already cut the ears from the same walnut lumber used for the neck. The headstock is clamped in place using backer board to help keep the ears in the correct position. The headstock is elevated due to some thick sandpaper I added to the backer board.


Here I'm clamping on the ears, making sure they are tight to the headstock and to the backer board.




You can see here that the ears stand a bit proud. Well... it is not that obvious because of the straight on photo. This is a result of adding the thick sandpaper under the main headstock.


The benefit is that you will only have to sand the ears down to the existing plane and the top is done.


Next the ears are trimmed on the bandsaw.




I used the belt sander to sand the backs flush and create a nice round lip under the nut.

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Chris Oliver
Infinity Luthiers
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live every minute...

Headstock Veneers

Both mandolins are getting 2-piece African Blackwood headplates and backs get a Macassar Ebony veneer.

Here I am cutting the AB on the bandsaw.


Glue them up.


Sand them in the drum sander.


I did the same steps for the ebony. Here I am gluing the back veneer on. I use a large dowel to coerce the ebony into the curve.




Here I am gluing on the top veneer.


These will get trimmed on the bandsaw and finished on the OSS.

_________________
Chris Oliver
Infinity Luthiers
...in the shop.

live every minute...