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I cannot seem to find any articles on this online. Perhaps it's poor searching skills but does anyone know of an article on how archtop guitar wood is processed?

I've decided to take the plunge and build one and have 3 top wedges on order from Maderas.

I have maple that I cut from the tree some years ago but the backs are not wedges but rather blocks or boards about 1" thick. The boards are book matched. It seems that everything is sold as wedges I presume to take some work out of carving. So I was thinking about resawing the boards on an angle to create the wedges and it got me to thinking about how this is all processed in the first place.

The reason they cut them into wedges in the first pace is because it wastes less wood than cutting them into planks and you get a better bookmatch.

I guess you cut the wedges to take some of the meat off, although I have never done that. I use the lancelot carver and pin router to hog off the bulk of the wood, so it wouldn't make much difference to me.

Even though spruce can be split, wood processors only saw out top wedges. Splitting large chunks can stress the wood and cause issues like cracks. Maple can't be split with any degree if control.

Woah! I had to look that up. That thing looks like a beast.

One of the guys who got me into building to begin with back in the 70s built flat top guitars, banjos, Gibson style mandolins and arch top autoharps of all things! He did most of the rough carving on his arch top instruments using a 30 or 40 grit sanding disk made for a floor sander, mounted on a mandrel on a motor. Without any backing, the disk would flex to the curves he needed to carve, and he had an amazing amount of control over the whole process. Tossed a lot of dust up, but it was fast and did a good job. He could even sand a good start to the recurve using that sanding disk.

Before I started roughing plates out with CNC, I used templates and a router for the outside and a drill for the inside. Never was comfortable with that coarse grit disk...

Dave

I saw violin backs all the time with a hand saw. I split a board of Padauk on an angle to get two flipped halves for a violin the other day. And the back and ribs for a small Viennese guitar too. My archtop was from a one piece 1 inch thick maple slab, but it is very full. Not worth trying to cut it. It I just used a large concave hogging plane that I made. Didn't take long. Makes.a.nice.swish sound.

I did my archtop from.the inside first. Same way I do violins.

I will cut a wedge on a violin back if it's thick enough, to get ribs, but you won't get guitar ribs off a back. I used cello ribs. They are wide enough.for.baroque guitar backs, at least the one I made in G.

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Why be normal?

That’s pretty much what I have done too except I use a flap sander on a die grinder with 40G to rough contour after terracing it with the pin router.

Unbelievably messy and I have not devised any decent form of dust collection so I have done it outdoors and carving plates has become a fair weather activity. Have you devised any good dust collection system Brad?

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Violin and viola tops are typically split out, but anything larger tends to be sawn. Backs, as has been said, are not split out, since the curly grain causes the split to wander.

I use a drill press planer to remove most of the wood from the outside of the arch once the plate halves are joined and the inside surface leveled. I've made up contour maps, with 2mm steps, and use those to mark the levels one at a time, working from the top of the arch down. It's relatively quick, doesn't produce the find dust a sander does, and gets quite close to the contour. One drawback; with the cutter that far above the table it's possible to get your hand under it, which is not advised. I have not been bitten in that operation yet, but I've had students who have gotten nipped. It seems easy to get focused on the where the cutter is, and forget to keep track of your fingers.

I know some bass makers who use chain saws to rough out contours, using short bars and the special chains that have been developed for carving. With all such tools the key is to keep the cutter moving; if you stand still it digs in.

Another flap sander in angle grinder guy here. I use the 60 grit. Obviously I finish with a finger plane and scrapper, but rough carving is a 15min affair per side.


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I *think I understand what you mean... If the top is laying down flat on a table lets call the length of the top the y-axis and the width of the top the x-axis, is your 2mm "step" measurement sort of like looking at a topo map in the Z-Axis?

And are you talking about one of those Saftey Planers?

Outside would be a must for me.

I've followed the Benedetto procedure using a 3 1/2 inch curved bottom homemade hand plane to create the arch on the flat maple backs.
No dust or safety issues with spinning tools but a lot of flying chips.

Wedges make sense if you think about cutting quartersawn wood from a round tree. You get more pieces with the wedge shape.

No, it is a dusty mess,but I can fully rough carve a plate in under 2 hours.

After the lancelot carver I use a 4" 36 grit disc .

I have 2 seperate shops, so I do it in the power tool room

So I guess what they do is lets say the wedge target thickness at the thick side is 1in. They cut a 2.1 inch wedge then line that up and resaw it down the middle to have two 1in book matched wedges? The bark side of the tree would be the thick side right? And the side that gets joined?

2 hours, wow! That seems fast. You don't happen to have a video of you using that thing do you?

Many Cello makers like gouges for roughing. It may be fast, but I've never been a fan of gouges. If all wood carved like clear basswood? They would probably be great. I like the steady, easy cut of the plane.

If you ever decide to make a plane, the one I made works great. I used a Lie Nielson scrub plane blade. Light hardwood for the body; I used cherry; and a wood you would use for fingerboards; I don't know what mine is; but it is hard. I based mine on the inside of a cello, and made sure that it would work on the inside of the guitar. You have to look at the long and cross arches.

I can probably rough it, inside and out in a few days. But I'm mot making them for a living, so I don't have a lot of experience; and I don't put in 8 hour days! I imagine that in some of the shops in the 17-1800's an apprentice could rough out a larger cello back for the master in a very short time, with planes or gouges. At least when they needed to. It's hared to believe that they ALWAYS worked like dogs. The shops where it was only one guy? He could do it pretty fast too; he worked with his tools every day. Just like a guy with a modern shop with jigs, and setups for different operations; just a different tool set.

I worked as a machinist for 40 years, So I'm over all of that!

The body is about 9 inches long, a foot overall, and 2 1/4 inches wide.

I found a nice way to make the sole: split it in half at the blade. It makes the notch easy.



To get the blade to be held square, and for more chip clearance: you will need it; make the inside wider than the blade, and shim the sides where the blade sits.



Comfortable handles to work two handed.

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Why be normal?

jfmkenna asked:
"...is your 2mm "step" measurement sort of like looking at a topo map in the Z-Axis?

Yes. I'm trying to think of how to describe the layout, but maybe I can just post a picture instead.

That is my assumption. However, I am not a wood processor so I could be all wet.

Love it. I always wanted to make for mandolins. Before I get started on one I'm going to build this.

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Hutch

Get the heck off the couch and go build a guitar!!!!

I hopeI'm not hijacking the thread too much

Here's a shot of the layout for the top arch of my most recent one, along with the pattern I have been using. The new pattern is closer in shape to the old Gibson: the customer wanted a 'tonal copy' of a Loar L-5, and the arch shape matters. You can see how the card stock has been cut in the upper pattern to allow for tracing the contour lines on the outside of the top. The layout of the lengthwise arch bottom out at the top of the outside ledge, 5 mm above the table surface. That's used to lay out the cross arches using 'curtate cycloid' curves, and the contours are derived from those.



Here I'm starting to mill off the contours. The center line and the cross line for the bridge locate the pattern for each subsequent step. The first one is at the full height, and they drop down in 2 mm intervals. LEAVE THE LINE. There will be a 5 mm ledge all around the outer edge. You can see that this was a split top. It's European spruce that came from my teacher's old stash, and may have been a top that she bought in the early sixties from the widow of a former maker, so who knows how old it is. It had a knot in it that precluded making a 'cello, but left it just big enough for this 17" arch top.


Here's a shot of the rough contours. The plate has been cut to exactly fit the rim in the mold, and the line parallel to the edge marks the inner limit of the liners.This is the low point of the arch, and I'll actually mill in a groove there to nearly the final depth. This leaves a flat ledge around the outside to guide the router for cutting the binding ledge.


And here's the finished top on the guitar. The sound ended up pretty much where we wanted it.

Beautiful "F" holes.

One thing I don't understand about the method of using topographical contour maps is that all the other lines are erased when you cut the first contour. How do you bring back the subsequent contour lines after each cut?

Thanks for putting that together Alan that's what I was seeing in my minds eye. I like that technique but I wonder if my Delta bench top drill press is good enough for that.

For many years, my only drill press was a Rockwell (before it became Delta again) radial drill press. Probably lighter duty than the Delta benchtop press you have. I ran a safety planer for operations like that and it worked fine. I imagine you'd be fine.

The caveat to using any drill press for operations involving a lateral load (like a safety planer), is that if you push it too hard, the jacobs taper can come loose and the cutter, chuck and everything go flying. I've had this happen several times on different drill presses and it's not pretty. The key is not to push too hard. The drill press wants a vertical load period. They make chucks with locking collars that keep this from happening, but they don't seem to be available for just any drill press without some modifications to the press.

Nowadays, I chuck the Safety Planer up in a 1/2 collet in my milling machine and don't worry about it.

Dave

After using the planer to take the top down to the level of the high point at the bridge you draw on the center line and find the bridge location. Lay the contour pattern down and trace out the outline for the top step. Lower the cutter by 2 mm and remove everything outside of that line, Then find the center line again, and trace out the next step.

I don't generally do the final trim of the edge to match the outline of the rim until I'm down to the next to last or last contour. I also note that what I took to be a pencil line just inside the edge on the second shot was, in fact, the rout for the low point. I used the Dremel setup that was made for cutting violin purfling grooves, with a larger bit, and don't go quite down to the final level, since the bits do seem to compress the wood a bit as the bottom.

I've never had a chuck come loose from the side load. Knock wood. As you say, echoing the foreman back when I had a summer job in a machine shop: "Let the tool do the work". You get a better cut and fewer problems if you don't push.