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Ken_N

Inside First

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Well I've been back about 3 weeks since the VSA.  I want to finish a couple of violas, and make two violins this year.  I've been wanting to make the Plowden for a while, so I started one up.  First I checked my form, the only thing that I already made.  I've been drawing things up on my own, but the Plowden gives you the form with the ribcage scan.  Mine had the block notches done like a Strad, so I got the Ole Bull one that I made, and it was only a little too big in spots.   

I tried bending the ribs with only a light brush of water; and by hand because I can never find the bending strap.  Surprisingly it worked better than ever!  Let the steam and heat do the work, and your fingers, can feel when it is ready to bend.  I used to not give the ribcage a thought, but now I see that it has to be done right.

This one I arrainged the ribs so it looks like it was made out of one long piece of stock.  I'm happy with that.  I decided to post here because I might get more feedback.  I don't know much, and any advice might help.

Here are the ribs:

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The form is made on some thick MDF.  I had some 1/2" or 12mm stuff, but this is thicker.  It is a little tight for linings.

Ken Nagy

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I start my plates on the inside.  Always have.  It seemed to me that the arch was on the inside, and the outside was just a result.  I saw a website by WIlliam Johnston that talked about roughing an inside arch the way is should be, and roughing the outside thickness down, and then gluing it together, stringing it up, and carving the outside until it sounded good.  He called it a Brescian Arch, and Ive been searching for it since.  I first made a template and tried that.   Then I even carved the inside in  halves, roughed the outside, and then glued the halves together.  Then I read the Inside Information article in the Strad by Torbjorn Zethelius, and it made perfect sense.  

I still don't do mine exactly as he does.  I still want to try different styles, and I can't see how a Guaganini inside could be the same as a del Gesu, or a Strad. So I figure out each one as I go.

This Plowden is the first go of a low arch.  It also has a lot of warp, which doesn't help things any.  For the back I always make the outside a circle.  I used to make it whatever, but Michael Darnton makes his long arches a circle, I think for both, and it makes sense.  It is very easy to make an arc section, and use it as a templet on the outside.   Del Gesu used a lot of recurve.  It doesn't dig down like an Amati, but it is a lot of recurve.  Guads seem to be almost all arch.  Strads are the closest to the "perfect" curdate cycloid that Mr. Darnton favors.  

The amount of recuve will determine how far over the inside cross arch goes.  Guads could go right to the linings maybe.  Strads not that far.  This one doesn't go over very far at all.

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The Lie Neilson plane is ideal for cutting the inside.  I use it on the outside too.  My curved scraper is the same way.  It is my go to tool.  A cheap 23" Walmart chain, a pencil to mark spots that are still high, and a flat edge for the ends of long arches that don't go end to end is all you need.  This one is about ready to get roughed out on the other side.

Ken

 

 

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I used to cut the outside just like normal people.  Then I was reading a post about drilling the holes to rough out an ID and thought: Why not do that on the outside?  Yes; it works great.  But there are a few things we must do.  We can drill the edges 5mm thick.  Then we can drill the center parts before the recurve starts to about a mm thicker than finish.  Then (the thing I forgot on this one!) we have to add some in the middle of the back, maybe 1.5-2 mm because the two curves used to make up the long arch of the back will possibly make a 7 mm thick back if they aren't thinned out when the outside arch is finished, and the center proves to be too thick.

Even with the holes you still have to be carefull around the edges.  I never have been any good with a gouge on the outside, or the inside for that matter, and I hog at it with my trusty plane.  It gets HOT.  I blend the center down to the edge, and just work on evening it up, and getting rid of the holes.  This is just roughing the shape in for now.

Ken

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I work getting the long arch right on the outside, and then make the arch on the inside deepe if it needs to be.  On the back, since the long arch is in halves I may move the centers of them as well.  When the thicknesses are about right, or a little thick, I even out the outside to the same thicknesses; but only for a little more than a third of the way out.  The rest can't be done until the outline is finalized, and the edgework is done.

Ken

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I just wrote a bunch of stuff and deleted it by mistake!  OK, let's do it different.  News flash!  I'm making a cello.  NO poster.  NO instrument to copy except pictures.   I just bought some CHEAP shelving (49 cents after rebate from Menards) and some 1 X 2's, and a peice of 1/8 hardoard for a pattern.  It will be a Gagliano.  I've been liking Gagliano since i saw a cool photo of a cello and a violin in the 2008 Chritsophe Landon Calendar.  I drew up a viola to bridge the gap between the two last Christmas, and that one is not too far from getting put together.  

 

These are the sizes I came up with, accounting for around 4 mm or less overhand, and 1.75 mm or less rib thickness:

 

OAL  732

UB   332

CB  222

LB  420

Ribs?  maybe 230 tapereing to 215?

 

Am I in the ball park?

 

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Ken

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I see that a 380 stop would give me a 646 string length.  If I blow it up about 2% to a 746 body I'd have a 388 stop, and a 660 string length, which is really more like 670+ with the string angle.  Lower the notch a little, and it is closing in on normal. 124-116 mm is probably more like it for the ribs?  I don't want to be too crazy.

 

I could just do Rogeri.  Or, stretching the neck ratio a little like the Rogeri I'd be up to 676 string length.  F's aren't that much different, there just isn't so much on the outside of them.  Arch for volume, or ribs.  This is like a math problem in school.   Cool.

 

Here is the final drawing.  

 

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What would you do?

Ken

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I have my cello mould almost done.  It has a central layer with 1 X 2's glued and screwed on it.  These are spacers for the top and bottom layer that are both just screwed on so the ribs come off easier.  I tapered the top blocks to make the ribs taper 6 mm  or so, and still have room for liners.  I may have to chamfer the top and bottom eges because I only have 20 mm for liners.  I'm making the Gagliano just as I drew it up, but making the top 2% bigger than the bottom. The three layers will come in handy for bending the ribs.  These photos will show what I mean.

 

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Now I have to smooth up the other side.

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I had my first run in with a 3-part mould in Oberlin a couple years ago-- I put the ribs on the group Kreisler, and had to copy the warp and wear. What are your reasons for doing so on your new cello here?

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I like the look of  the Gagliano. Especially this one that is a little slimmer all around.  I like all of his stuff, but the cello is like the Guadagnini cello, and is a little shorter than 'standard.'  I didn't want to do my first one and have people ask, "Are you going to make a full size one now?"  So I  made the top 2% bigger all around.  Guadagnini made his tops bigger, but it seems that he especially expanded  the middle bout, so the shapes are different from front to back.  This way the shapes are the same, and I end up with a 'full size' cello, with more leg room under it.  It should make it more comfortable, and might look kind of cool too.  At least it won't look clunky.  I thought of doing the flour de lis in the back corners,  don't know if they are on the front because I don't have a photo of the front,  or maybe the lilly medalian that was on the violin.  The maple I have is quite plain, so a little extra stuff might  liven it up.

Ken

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It's funny cutting the rib ends at an angle; don't forget to leave your ribs three or four mm higher than your blocks to adjust for it! It's a good point you make about Guads-- I've noticed the same on violas. The two Guadagnini violas I made this year, I carved the blocks agressively from the top to the back, slanting them down, shrinking the back compared to the top. Your way is cleaner!

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I have the blocks done.  The corners are long because I left stock behind the inside curves at the point so that they are easier to blend in when I cut the extra length off.  The bottom is pretty flat so it stands up.

 

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Should be some interesting angles on the corners from the side.

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For Christmas I got a saw tooth set.  I can finally sharpen up my garage sale find, and slice this maple cello back in halve.  My first attempt had negative rake, and it just kind of floated on the wood.  After filing them back to square they cut better.  It still doesn't have the nice feel as a Japanese saw, and it is only one handed, but I got the back split in two.  It is quite an ordeal.  After about 3 hours I had it cut 3/4 through, and around to the end so I could work on it from the other side.

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After ten minutes, the blade is only down this far:

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And 45 minutes to get this:

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I'm not liking the feel of the saw.  I'm spoiled by the Japanese saws.  My sharpening job must be bad.  I was thinking of buying a big ryoba, but I have a blade for a frame saw that they sell at Highland Woodworker.  I made a frame for it, but it snapped, and I threw it away.  I could buy the entire saw, that comes with a tall blade for straight cuts, and use it for my scroll saw, since nothing I have will cut out a cello.  My narrow blade would work good.  It would only have a 3" stroke on a cello back, but it might work.

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For Christmas I got a saw tooth set.  I can finally sharpen up my garage sale find, and slice this maple cello back in halve.  My first attempt had negative rake, and it just kind of floated on the wood.  After filing them back to square they cut better.  It still doesn't have the nice feel as a Japanese saw, and it is only one handed, but I got the back split in two.  It is quite an ordeal.  After about 3 hours I had it cut 3/4 through, and around to the end so I could work on it from the other side.

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After ten minutes, the blade is only down this far:

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And 45 minutes to get this:

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I'm not liking the feel of the saw.  I'm spoiled by the Japanese saws.  My sharpening job must be bad.  I was thinking of buying a big ryoba, but I have a blade for a frame saw that they sell at Highland Woodworker.  I made a frame for it, but it snapped, and I threw it away.  I could buy the entire saw, that comes with a tall blade for straight cuts, and use it for my scroll saw, since nothing I have will cut out a cello.  My narrow blade would work good.  It would only have a 3" stroke on a cello back, but it might work.

That saw should be able to cut through a cello back in minutes not hours.  It might be a good idea to send it to a saw doc to get it sharpened and tuned up correctly.  Then it you can easy to maintain it for the rest of your life.  I sent a saw to Bad Axe Tool works once and was happy with the results.  http://badaxetoolworks.com/bad-axe-restoration-services.php

 

Cheers,

Jim

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Jim,  I was just reading about that yesterday!  Never heard of it.  I  looked at the blade and noticed that three of the teeth broke off.  I heard two cracks, but three?  I might check around for another this spring.   I had it set at a midrange setting, but that gave about a .01" set.  I do have an 8 tooth Disston rip saw (this one is a 6 tooth Disston) with really worn  teeth.  It must have been the go-to saw for the amount of wear it has.  No one has time to sharpen?  Seems like it would be easier to touch up, than to use a dull saw, over and over.  You make a good point.  I had no idea a good saw would cut that fast.

Ken

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Hi Ken,  I was headed down the excact same trail you're on.  I picked up a yards sale saw for $10.  I knew to check to see if it was straight and to bend it a bit (not much with the owner watching) and it should return to true.  Then I dated it as a civil war era Disston (no sons), and decided to have it fully restored, i.e. sent to Mark Harrel at Bad Axe Tool Works (see Mark's article on "Is my saw worth tuning up).  A word of caution he gave me was that if the teeth start breaking when they are set, the steel has gotten too brittle to be used as anything but a wall hanger.  Good luck saw hunting.  I hope you post again if you find a keeper.

 

Cheers,

Jim

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I drew up a full scale side view to see how the neck would fit on, see how the string angle would come out (drawing side views, and trigging them out, it NEVER seems possible to get the flat string angles that are published as the norm) and seeing where the scroll ends up, and how the long arch resolves on the ends.  

 

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The drawing has opened up more questions than answers.  I'll start with this one:

 

The way the long arch resolves on the ends.  Everything about a cello is done double size, so you have to do things right, because it will show up, and it can't be something that is fudged in.  On violins, it seems like the arch rises right up from the purfling, and you end up with a thick spot just inside the blocks.    You can see it on CT scans:

 

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Yet the cross arches have nothing like that,  or do they.  On the older violins they have a deep recurve, and the edge is the thinnest area.  Others have no recurve to speak of, so the edges are no longer the thinnest area.  I see the cross arch with thin egdes as a free moving edge, and the others as a stiff edge.  The long arch looks like a mounting for the ends of a bridge.  That part is stiff, and the rest of the bridge is frre to compress under load. 

 

There are some cool cross arches here: http://waddleviolins.com/index.php?contentID=120  You can see that they made the thinnest areas near the edge for the arch to be sprung there.  The later arch by Bergonzi shows that he moved the recurve out so that it starts closer to the edge, instead of being  in from the linings.  

 

But what about the long arch?  I remember Roger saying that the arch doesn't start concave on the inside, yet all the scans I see, (most just show cross arches) shows them as concave.  But we have options don't we?  Look at this:

 

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With the first one we could even make the recurve larger, and blend it up from the inside,  making it just like a cross arch.  The problem is this; the top, and especially the bottom is quite flat, so as we move over from the centerline, the arch on the outside will drop even lower,  and get even thinner.  So now we need to check those  lines out to find a solution.  Like I said, the drawing raised more questions.

Ken

 

 

 

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It was quite an ordeal to get the bottom of the back halves flat enough so that they don't rock.  I cut away the area on the outside of the form, and inside the linings; leaving at least 10 mm. I figured that way, if a corner was high, or a cental area was high, it wouldn't throw me off.  Then I just put them on a flat board, and found the high spots, and planed them down.  It wasn't enough.  I had to add some stock to fill in the low areas that just wanted to rock. Then I started thinking about the "potato chip syndrome" I had on the last couple of backs, both from the same piece of wood; but I have had a milder case of it before; so I roughed the inside, and the outside out some, so it shouldn't surprise me later.  It didn't seem to move at all, but I don't want that again.  Today I'm gluing them together.  The bench works good for that.  

 

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I clamped them each to a piece of wood.  The purpose was two-fold.  First, my plane could then cut them square to the bench.  If they were right on the bench, there would be 1/8"  or so that wouldn't cut. But also I wanted to be sure it was still flat after gluing.  I don't have a lot of leeway.  You can see my scribbling to show me wher to, and where not to plane.  My method was to clamp them up, and use a piece of paper to find gaps.  It was pretty good, but it still took a few tries to get it so the paper wouldn't fit in anywhere.  I don''t know where my shims went to, otherwise I would have used them.  Thin paper will have to work.  

 

You can see the flat area on each side where it has less stock.  There is a lot of stock everywhere else.  I'll find out tomorrow how it did.

Ken

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I have the belly roughed out to 8+ mm inside and out, and the outside cut out way wide.  It is about twice the weight it will be at 880g, and rings at 360/180.  The wood is fairly soft Sitka, and seems quite flexible crossgrain.  It only took 5 hours to do it.  I should be able to hack out a violin in two hours or so, eh?

 

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I will flatten the bottom, re-cut the inside arches, trim the egdes to 6 mm, smooth the outside long arch to a nice radius, and bring the thickness of the central areas down to  6 mm or so, and blend it in to the edges.  After that I need the ribs done, so I have the real outline to go by.

 

Ken

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It's been cold in the basement.  I did cut up some stock for purfling.  Worked pretty easily.  I made 3.5-4 mm wide strips; three at a time with each swipe of the plane.  I think I"ll bend them in place with glue between them; maybe that casein paste that I made up before.  It was really nice.  Then I can fit them and glue them in place just like pre-bent purfling.  It may be more work in a way, but the strips were really easy and fun to plane up.  

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I cleaned up the inside of the cello plates.  I marked where the f holes would be on the inside of the belly.  This way I can see how it fits on the arch.  I think that making a cello is a very good way to see, with a 2X magnifier what you are doing while making a violin.  The things that can be seen in a cello, might be lost on a violin; but it doesn't mean that they don't have to be taken into consideration.

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 I drew up some cross arches at work the other day.  Today I marked the points were the catenary curve goes to, and the depth that I am at now.  Then I drew in how the recurve will be, inside and out.  As you can see, I don't get that close to the ends, and the recurve extends quite a ways in.  The drawing isn't a blueprint as such, it is mainly a sketch to reassure that something isn't amiss.

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I've been playing with oil to make some varnish.  Mostly just cooking it down some after washing it in water, and other stuff, to try to bend the color some.  My oil is just boiled linseed in a can, from Home Depot.  It looks really nasty when you pour it out into a jar; nothing like the nice oil most people show.

 

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But, back lit it shows some promise.

 

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For some odd reason the water doesn't separate out like it is supposed to, and turns opaque and even nastier.

 

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 So, I have to cook it in a pan at about 240 degreees F until the water is boiled out.    It splatters a lot.  Then it looks like this:

 

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Without the lighting it looks the same, just like dark cruddy oil.

 

Ken

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Hi Ken

I've used linseed in a can from the hardware store.   When I wash it then let it sit for a few days it separates from the water and comes out clear not cloudy.    You might try adding epsome salts to the water.  I've heard that helps it separate faster. 

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Hi Ken

I've used linseed in a can from the hardware store.   When I wash it then let it sit for a few days it separates from the water and comes out clear not cloudy.    You might try adding epsome salts to the water.  I've heard that helps it separate faster. 

Will what he has there turn darker if washed a 2nd time?

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When I have washed oil it seems to get lighter rather than darker although not a huge difference.   I don't know if this type of oil is just raw oil with driers added or if it has been cleaned in some way before they add the driers.   I'm not sure if it needs washing.  I don't notice a lot of difference really.  

If you put it in a pot and heat it on a hotplate it will get a lot darker but then it will get lighter again over time.  

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I like to start projects; not as good at finishing them.  Here is the latest as I go.  Only photos, no explanation.  I will say the stock is 3/4" thick.  The design is based on a very early instrument, but is altered some, and is not even the same instrument now.  In other words, it is basically original.

 

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