Carving the recurve area

[Kent Barnes]

I was just curious how other builders "create" the recurve area on the top and back? Carve, sand, other? I guess the guys who use a duplicator or CNC don't have this issue as much as the rest of us who do all of this with chisels and planes.
Thanks!!

[Chadmills]

More experience with fiddles than mandolins but I bring the recurve area down to a flat 5-6mm with the router or Safe-t-Plane when I cut the contours for the arching. #Once I've rounded the arched area and hollowed the back to about 7mm I drill "graduation" holes to a suitable thickness at the lowest point of the recurve from the "outside," then use gouges or mostly thumb planes with toothed blades to cut the recurve out to a pencilled edge line, and blend it with the arch. #I guess I'm then about at the point machine cutting would reach! Tiddly work with thumb planes and scrapers from then on.
Tom

[Stanley Cox]

Kent, I did mine with the finger planes,#10 and #12. But you know how much experience I have.
Stanley

[sunburst]

I, too, cut a "plateau" with the Safe-T-planer (more of a terrace, actually), then "scoop" out the recurve area with finger planes, followed by scrapers, followed by sandpaper.
I don't drill guide holes for the recurve, but instead check progress occasionally with a violin caliper.

[Kent Barnes]

Something like this? #
My current method is to leave the outside edge of the top and back at about .20 inches, then carve/sand the little "ditch" into the outside edge. #I was just wondering if there might be an easier way for those of us who still do all of this with handtools.
Here's a picture of a top plate under construction. One of my steps is to cut/sand the recurve in the flat area on the outside edge.

http://www.kentium.net/mandolin/mando4pics/top3.jpg

[sunburst]

I was just wondering if there might be an easier way for those of us who still do all of this with handtools.
What could be easier than a sharp finger plane?
That's almost exactly how I do it.

[Kent Barnes]

"Sharp" is a very subjective term! # http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif
Yeah, that's another skill I'm still working on - getting those "scary sharp" edges on my tools.......

[Chadmills]

That picture looks very familiar!
Tom

[Michael Lewis]

Keeping the tools sharp and clean is the first order for me. Those little finger planes are real work horses if you get them sharp and keep them clear of debris.

Just focus on getting the excess material off of the plate and pretty soon you will be done. The more of these you do the quicker they go and the better you get at controlling the surfaces. A glove or some sort of padding on your fingers that hold the plane will go a long way to prevent blisters forming. If you do it enough you will figure it out, just like the rest of us.

[ShaneJ]

Kent, here's what I did to solve the blister problem. Just drilled 4 or 5 holes into the end of the handle and dug out the slot to accept the back end of the blade. Had to countersink a little bit for the wheel, and then the handle fits fairly snugly. Sure did make that little finger plane a LOT more comfortable. Of course, getting that little bugger sharp helps a bunch too. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

[sunburst]

Keeping the tools sharp and clean is the first order for me. Those little finger planes are real work horses if you get them sharp and keep them clear of debris.
Michael, if you have planes that don't shed the chips and tend to clog up, try re-shaping the cap "iron".

I had one in particular that was hard to keep clean, so I took it apart and compared the pieces to one that does shed the chips well. That little bronze cap piece, it would be the cap "iron" if it was iron, was shaped very differently. The one that worked better was sharper at the edge, and rounded back at a better angle for clearing the chips. The one that tended to clog was more blunt with a steeper curve going back from the blade. I filed, sanded, and polished the part until in looked more like the one that worked better, and now that plane too sheds the chips well.

[Michael Lewis]

Cool John. I thought it was part of my technique. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif

[reb0964]

On my first mandolin,,,i just had some basic tools i used but was wondering around in woodcraft one day before i started carving my mandolin top and back and found what is called a spoon cravers tool,,,it worked well,,,nice curve to it and a lil bulkier then the average silverware teaspoon,,,it eased in recurves nice enough to light sand the finish edges. I really liked it,,it has a nice handle on it to pull with and pretty easy to control and cost about 15.00 dollars.. Maybe some of the other builders use this too...or like to check it out ,,,it works nice...

whttp://www.woodcraft.com/family.aspx?familyid=4867ould

[Gavin Baird]

For some time I have been using this method of creating the recurve portion of the top and back of my Mandolins. The reason I produced this method, was because I felt it was significantly important that the transition line [ thin section of the recurve ] be at as close to being equal distant all round the perimeter of the instrument. It seems logical to me that if it is not, the ability of the top or back to vibrate freely will be inhibited.
What I have done is make a simple jig that allows me to machine a groove around that portion of the top or back that represents the centre line of the thin section of the recurve. This operation is done with the top or back already machined or carved to its rough contour.
The final shaping of this area is done, first with finger planes, then with specially shaped scrapers and finally with shaped sanding blocks.
Once all the shaping and final sanding of the outside shape and contours are complete, the jig is then used to transfer visible lines onto the surface by which you can take accurate measurments while graduating the plate.
As with any situation like this, you must have a bench mark from which you work from. For me it is the overall height of the plate as well as the accurate outside shape. This requires an accurate template of the top or back. Once the plate is rough carved, I then use my thickness sander or router to bring the outside edge to the required height.
The jig is a piece of 3/4" plywood that has a centre line marked on its centre. There is a 1/8" dia. groove machined along its centre line as shown in the photograph. On the same centre line are drilled a series of 1/4" dia holes at 1" centres. These holes will allow you to first machine the groove at 7/8" from the edge and to the perscribed depth as well as to mark your refrence lines for graduating.
The machining of the groove is done using a 1/4" dia. ball nosed end mill....Note that everything is done using an accurate template of the outside shape of the plate
`As shown in the photographs, I have made templates of my arching as well as templates for shaping the various scrapers. The arching templates have a common point of intersection which is the apex of the curve along the centre line of the plate.
This point is the location where the 1/8" dia. dowel is inserted in the template. The jig is attached to the drill press table and with the cutter in the chuck, and the quill extended and locked, the jig is then aligned with the first of the series of the ¼" dia. holes. By placing a short dowel in the 2nd. hole the template will travel around maintaining the cutter at a distance of 7/8" from the edge. The cutter depth is set using feeler guages to locate the cutter the required depth above the face of the template.
Once the blank is firmly attached to the template and the points of start and finish are marked, I begin on the left side looking down on the plate towards the neck end of the plate and mill the pocket to depth. The drill press is stopped and the mill brought to depth and locked. The slot is then milled around to the tail end of the plate and stopped. The right side is done in the same way except you are starting at the tail end.
You must be certain that the plate is flat on its bottom for this to work properly. Feed slowly and maintain pressure on the edge of the plate adjacent to the cutter. I run the cutter at 1500 RPM.
I hope I haven’t bored you with this long description but thought of all those without CNC equipment who might benifit..Gavin

[Gavin Baird]

two of five

[Gavin Baird]

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[Gavin Baird]

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[Gavin Baird]

five of five

[sunburst]

Gavin, it is interesting how different builders develop different methods.

I used to do a very similar rout of a reference grove around the perimeter for the bottom of the recurve area, and quit doing it for several reasons. 1.I've concluded that my recurve does not have to be equidistant from the rim, and I prefer that it is not, in fact. 2.Routing the grove didn't save me any time. 3.I can get just as much accuracy in the thickness without routing.

[billhay4]

Gavin,
Don't know if you're so inclined, but an article on this method would be very valuable for American Lutherie.
Looks like you've done most of the work (i.e. pictures and thought) already.
Bill

[ErikAitch]

For the Safe-T-Planer adept: how do you do your setups for this job? Templates like Gavin's? Tilted table to cut a cove while you're at it?

[sunburst]

I just cut a flat "terrace" with the Safe-T-Planer, and I just eyeball the distance in from the edge. (Granted, I measured it out and marked it on early attempts, but after that I know what it looked like.) I use that cut to establish the edge thickness, and as a visual reference for cutting the recurve area, along with occasional caliper measurements.
To add a little to this discussion, I found that ball end router bit (two different ones that I tried) left damaged, compressed wood in it's wake, so I had to carve below the router cut anyway, and use measurements to complete the recurve. Not much extra work to just start with the finger plane, especially considering set up time for routing.

[Gavin Baird]

John,
The cutter I use is a high speed ball nose end mill ground with a high positive rake angle [Aluminum ]. If using the router for the edge height, I use a small pin router with the router mounted over head. A 1/2" dia bit and a 1/4" dia. pilot. Leaves a very nice 1/8" ledge to finish to...Gavin......No tear out/clean cut...g

[Gavin Baird]

John,
Since I don't make my living building instruments, time is not an issue, if it was I would go CNC for as much as the industry does if I could afford it.
I assume that when you say that you prefer to have the recurve off set, that you are referring to the change in frequency response from side to side. If this is not correct, I would like to hear from you what your reasons are.
As I said before set up time is not a concern for me although I really don't see that that could be significant.
As with most of the posts I make on this site, I really want those who are looking for ideas or suggestion to take advantage of the ideas expressed by all the knowledgable builders out there. I think that is what the "Builders/Repair" is for...Best regards...Gavin

[Cragger]

I began carving my recurve yesterday and found that my 10mm finger plane would bind up after maybe one pass. Every time it would happen I would have to unscrew the thing, remove the cap iron and blade and clear out the chips. I thought the blade might not be sharp enough so I worked it until it was razor sharp, well sharp enough to shave the back of my hand. I put it back in the plane and began to work again. The same thing happened. I tried adjusting the blade deeper, shallower and nothing seemed to stop it from binding. I remembered this thread so I compared the two finger planes that I have. The 18mm plane has a completely different shape to its cap iron so I modified the smaller one like Sunburst said. It did help clear the chips a little better but I think what is happening is the the chips get caught on the side of the blade between the point and the side of the mouth. Does this make sense? Also, it leaves two big gouges where the points of the sides of the blades pass, no matter how shallow I have the blade set. After butchering part of my top, I put it up and worked on something else. Any help would be appreciated.

[sunburst]

I assume that when you say that you prefer to have the recurve off set, that you are referring to the change in frequency response from side to side. If this is not correct, I would like to hear from you what your reasons are.
Gavin, my recurve is symmetrical side to side, but wider at the tail end of the mandolin and narrower toward the neck. It's one of the things I like about the old Gibson A mandolins in particular, but see in the Loar models too. It's just a cosmetic thing, and I found that when I routed the depth guide around the edge I had trouble getting the look I wanted because of the equal distance around the perimeter.

[sunburst]

This picture shows the "tapering" recurve about the best of any that I can find.

[ndy9691]

Hi Cragger, I use a small Ibex thumb plane that did the same thing (the edges cut in to deeply) so I took my dremel tool and rounded the points of the edges, then re sharpened, It made a world of difference, Its my favorite tool for carving, On my recurve I use that plane then a oval shape violin scraper. The scraper is the gives a consistant recurve all the way around.

Dale

[sunburst]

Cragger, there are a few things you can do to help your finger plane situation.
The first thing to try is a tighter curve on the iron (blade) of the plane. That brings the corners up where they don't dig in. You can also re-shape the sole of the plane itself a little flatter, but I wouldn't try that unless I had to, or knew some specific shape I wanted.

One of mine is made similarly, with the iron too narrow for the opening so that chips can get lodged in beside the iron. It's a manufacturing flaw, actually, and the real fix would be a wider iron. Some day, I might make a wider iron by grinding down an iron meant for the next larger size plane, but somehow, that hasn't established itself as a priority around here.

[Cragger]

O.k. I thought I might try and grind the corners down to fix that issue and I agree that I think the iron needs to be wider to keep the chips from binding in the sides. It is aggravating to spend good money on a specialty tool and have a problem using it. I'll see what I can do to fix it and keep on going.

[buddyellis]

I had the same problem initially with an Ibex I just bought, too. I worked more curve into the iron itself during honing, and it went away. I agree though, when you spend $50 on a tool, the darn thing oughta work.

[Cragger]

I can understand if the iron needs honed but the thing ought to be the right size, shape, and have the correct angle grinded right out of the box. I was so irritated I put it in a drawer to keep it hidden. Then I got out my big jointer plane and made nice shavings and joined my sitka top which will hopefully be my number 2. That brought a smile to my face. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif

[sunburst]

The older Ibex planes seem to be better. I think they lost some quality control, at some point, from my own experience and from what I've heard from others.
They are pricey, and it seems reasonable to expect to get them more complete than in "semi-kit-form", but it's the way of the world, it seems.
OTOH, I don't think it's reasonable to expect them to work perfectly right out of the box without a little tweeking.
Once they are set up and working well, and once your finger tips are tough enough to use them, those little planes are a real pleasure to use.

[buddyellis]

Well when I say 'oughta work' I mean 'plane after a final honing without tearing gouges in your work because the iron is shaped wrongly and is too narrow. The one I just bought was a dog before I slightly reshaped the sole, reshaped the iron, and THEN honed it. Final honing is expected. Reworking a $50 tool to get it to work at all is not.

[sides7]

Due to a lack of tools,time,knowledge,and experience, I creadted my recurve by:
Drawing a pencil line 7/8 of an inch from the outside edge.
Using a dremel drum sander at a slant, sanded a trough along the pencil line.(Every effoet to keep in at an even depth)
Used an three headed "Norelco Style" floating heads sander to work from outside to center of trough & then work from inside to bottom of trough.
#I'm now in process of using a hard block sander with different grits to reach final recurve.
IT MAY BE CRUDE, BUT IT LOOKS PRETTY GOOD! Here's a pic:
http://i129.photobucket.com/albums/p236/sides7/P1210009.jpg

[markishandsome]

If you look at the other brands of finger planes on the market (internationalviolin.com has a few) you see the ibex ones are comparatively inexpensive. I hate to call them low-end, because they're nice tools, but they do seem to have a lot of obvious flaws that a "no expense spared" tool would not have. I always expect new tools to need a little tweaking. Even fine tools could use a little custumization to get them how i like them (new handles that fit better in my hand for example). A tool is a lifetime investment. An hours worth of modifications are nothing compared to the time spent using the plane on even one instrument.

[Cragger]

I just spent an hour on the phone with the company I bought my finger plane from and they said they would exchange it for me which I thought was pretty nice. They were really helpful and nice. What I really wanted was to call IBEX and talk with someone about it but the company I bought it from said they are unable to give me the number because it is against company policy. I can't find contact info for IBEX anywhere. I went home and ground the corners down on the iron which helped a little bit. It helped it from leaving gouges but did nothing for the chips binding between the side of the blade and the side of the mouth. Hopefully the next one I get will be better but I'm not all that confident it will be.

[nelson_luthier]

Any new tool will need to be set up properly, even the most expensive ones. #Often times a plane iron will come blunted from the maker. This is partly due to the fact that a blunted edge is safer for the maker to handle and partly because the maker has no idea what your sharpening preferences will be. I know that I set up my tools differently for spruce than for maple so how can I expect the tool maker to know my preferences?

A trick I learned years ago for even straight plane irons is to put a back bevel on the corners of the flat face of the iron. You can see this if you look closely at the iron on this Japanese style plane.
http://img.photobucket.com/albums/v57/nelson_luthier/planeirons.jpg
This minimizes the possibility of the corner of the iron catching and gouging your work. The Japanese style planes must be releaved significantly at the corners so that wood chips don't get bound up where the wood that is holding the iron in place is, but you can also see the back bevel used to "soften" the corner of the iron.

Some of the suggestions above border on this technique but would cause the iron to dig deeper in the center than at the edges. Rather than tapering the iron away I suggest shaping your iron to match the foot of your plane and then easing the corners as described above so that they don't catch.

Also, you need to evaluate where the chip will escape to after it is cut. If you allow the blade to cut in an area where the chip will bind up you will experience chatter and other unpleasantness, including frequent clearing of the planes throat.

Greg