Posts Tagged ‘one-piece cello back’

2014 Musical Instrument Makers’ Show at Marylhurst University

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Marylhurst University Musical Instrument Show

For those who missed it:

The following photos were all taken before the public was allowed in, so the tables are not fully set up, but you can see the size of the room, and some of the instrument displays. I believe there were 80 tables, and each table had one or more makers exhibiting, so probably in the neighborhood of 100 makers. Possibly ten were violin-family makers. One was a maker of wooden flutes and drums. Usually there is an orchestral harp maker there, but he was not there this year. There were several mandolin and ukulele makers, some makers of middle-eastern or South American instruments, one or two banjo makers, and all the rest were either guitar-makers or vendors selling materials to makers.

Once the doors were open, I am told we had about 300 visitors the first day, and 500 the second day. I don’t know how accurate those numbers are, but it definitely seemed more crowded the second day.

 

No sales at our table this year, but lots of interest, and several good players. A good weekend all the way around. The one-piece-back cello, of Oregon Big-leaf Maple was very popular, as was the five-string fiddle and the Lion-head Viola.  I did not have a double bass there this year, but several people asked, so I intend to do so next year.

We had a very pleasant visit from violin-maker Kenneth Pollard and his lovely wife (who took the photo below), both of Nampa, Idaho. He and I have corrresponded in the past, but this was a first “face-to-face” meeting. Hope to see them again sometime…maybe at the next show, if not before.

Ken Pollard and Chet Bishop at the 2014 Marylhurst Musical Instrument Makers’ Show

 

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2013 Marylhurst University Musical Instrument Makers’ Show

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2013 Marylhurst Musical Instrument Makers’ Show

Here are some photos from the 2013 Marylhurst University Musical Instrument Makers’ Show: (Most were taken before the show was open to the public– these people are all the makers and vendors.)

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It wasn’t all guitars and fiddles, as you can see. This couple makes Persian instruments called “Tars” (the larger ones) and  Setars, (not “Sitars”, which have 30 strings…traditionally, a Setar has three strings, but apparently about a century ago, a tradition of four-string setars began.) That little thing to the right of center is a setar.

There were also two banjo makers, several ukulele makers, mandolin makers, an orchestral harp maker, and, yes, even a few fiddle makers. And every kind of guitar imaginable.

The table in the next photo was mine…I was sharing it with my son, who makes guitars. That worked out well. We had someone at our table nearly constantly.

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In the picture above, Brian, my youngest son, had not yet arrived. In the one below, his girlfriend was helping set up his display.

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There were approximately 500 visitors each day…it was a pretty encouraging weekend.

The five string fiddle (left-most in the rack) sold, so that was nice, but unfortunately there were not very many cellists in the mix…only two stopped and played the cellos, but they really liked both of them. The five-string was the real star. 🙂

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How I varnish a cello (part one)

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Beginning the cello finishing process.

Preparation for varnishing

Once I am sure that all the construction, carving, assembling and scraping is done, I go over the entire instrument looking for “bumps”; tiny discontinuities that will definitely catch the eye after varnishing, but are difficult to see in the white. (Violin-family instruments in the unvarnished state are referred to as being “in the white”, as the color of the wood is very light cream colored, as a rule.)

I use low-angle, relatively dim light to make shadows, hoping that even tiny irregularities in the wood will make enough shadow that I can detect them and gently remove them with a very sharp scraper. In may case, my wife has a better eye for these sort of flaws, so I enlist her help, to find ones that I miss (and invariably, she does). Once the edges, corners and all other surfaces are as close to perfect as I can get them, I brush a weak water-based stain all over it…well…actually, coffee, as strong as I can make it, but it makes only a small change in the color of the wood. the spruce becomes a very light tan, after two coats have been applied and allowed to dry. Between coats, as the water swells the grain of the wood, I sand all over, very lightly, to remover little splinters and rough spots that the water raised up.  I happen to like the spruce grain slightly raised, so I am not trying to remove the “corduroy” effect. I just want it to be smooth to the touch, in spite of the ripples.

Seal coat(s)

I have been using rosin for a sealer…the last cello, I used rosin mixed with turpentine, which worked nicely, but took a few days to dry. This time I am running out of time, and do not have a few days…so I mixed the rosin with alcohol, and a tiny bit of yellow dye. I sealed the whole instrument except the handle area of the neck, using the rosin, allowed it to dry, and put on a coat of spirit varnish to complete the seal. The next step will be a color coat that I hope will define what the cello will look like. If that succeeds, then the remaining coats will be pretty much clear spirit varnish.

So here is what the cello looks like with just the seal coats, as described:

Cello front with one coat of varnish.

Here is the front, with the one coat of varnish over the rosin sealer.

One-piece cello back with one coat of varnish

And the one-piece back, with the grain beginning to show. Varnish does wonders, doesn’t it?

Front quarter view of cello with one coat of varnish

Here’s a front-quarter view with one coat of varnish over the rosin sealer.

Back quarter view of cello with one-piece back, and one coat of varnish.

Back quarter view, same light.

Showing the flame of a one-piece cello back, with one coat of varnish.

Showing the flame of that one-piece back.

Neck joint of cello with one coat of varnish.

Interestingly, the sides were actually cut from the same billet as the back, but that portion evidently had a good deal less flame. The neck is a different billet entirely. Nice flame, there.

Cello scroll with one coat of varnish.

And there’s the scroll. Funny, from this angle, I am seeing things I want to correct. It may be too late. I will have a close look at it tomorrow evening, and make a decision.

Anyway– there you have it. The varnishing process is begun. I use spirit varnish which dries very rapidly, so I may be able to make pretty rapid progress. I hope so– the show is in less than two weeks. 🙁

And after varnishing: final assembly and set-up!

 

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Final assembly of a Davidov model cello

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How to complete the assembly of the cello

Remove the mold and clean up the interior of the corpus.

In my case, since the mold is collapsible and comes apart in several pieces, it is pretty convenient to get the mold out. I use a small electric screwdriver to remove eight drywall screws, and back off twelve more, and the thing just comes right out…no fuss. The twelve that were just backed out are the ones securing the corner blocks and neck and end blocks in the mold. So, here is the corpus, fresh off the mold, with all the blocks still square and rough, and the linings only roughly trimmed, not scraped.

Rough cello interior

Cello interior immediately after removing the mold. All the blocks are still rough and square. Linings still need final scraping.

Rough cello end block

This is the end block. You can see the rounded part that I shaped before installing the front plate, so that I would not risk damaging the front plate while shaping it. The rest of the block was out of reach in the mold. Now it is time to shape all the blocks.

Rough cello corner block and linings.

Here’s what the corner blocks and linings looked like. The linings had been trimmed with a knife, but not scraped.

So– the next hour or so was spent chiseling, planing and scraping all those blocks to their final shape, and scraping the linings as smooth as I could get them. Here is what it looked like afterward:

Cleaned cello interior, just before closing.

I tend to make my neck and end blocks a little oversize. I have seen blocks split and break, because they were too small…it seems an easy way to insure against that sort of thing. All the blocks are now the size and shape I want them, and scraped smooth.

Install the Back Plate

So, the next step is to get the back plate in place. I aligned it carefully, checking all the margins to see that the overhang was fairly even all around, then clamped it in place, dry, using spool clamps. After I was satisfied that the overhangs were correct AND the elevation of the fingerboard was correct (an easy thing to mess up, as the corpus is quite floppy at this point), then I clamped everything solidly, and began removing a few clamps at a time, and inserting hot hide glue, using a palette knife. I washed off the excess glue with hot water, and re-tightened all the clamps.

Here the cello is in all its spool clamps, with one bar clamp to secure the button to the heel of the neck.

Callo back installed with hot hide glue and spool clamps.

The cello back is fully installed, with hot hide glue and spool clamps. The bar clamp secures the back button to the neck heel.

Cello glue drying by woodstove.

The house was pretty cold this morning, so I decided that the cello would dry faster in a warm room. Close to the woodstove (but not too close) is the best place I could find.

Final edge-work, scraping, preparation for varnish

After the glue was thoroughly dry, I removed all the clamps and began trimming edges, and perfecting the scroll and heel. The heel was almost a half inch high (which I expected…we leave extra, so that the heel and button are trimmed and shaped together, and match perfectly when we are done.) The scroll was still quite rough. I spent the rest of the day and late into the evening, scraping and planing, and trying to get the cello ready for finishing. Finally ran out of steam about nine PM, but it is nearly complete. Here is what it looks like tonight:

Cello in the white from front side.

Cello in the white, from the front. A little more edge-work to do, tomorrow morning, and I can begin the finish work.

Cello back in the white.

And there is that one-piece back…it has come a long way since that big slab we started with, hasn’t it? I still have some final smoothing of edges, etc. to do, then it is time for varnish.

Actually, I typically use a very weak water-base stain first, which will make the spruce a tan color, instead of cream-colored. Then I will sand it lightly with fine micromesh, seal it, and start applying varnish. (On the home-stretch, now!)

For those wondering about the pegs, saddle, nut, etc.; I wait until the varnish is complete before adding those fittings.

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Back Graduation Complete

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The Inside carving (Graduation)on the one-piece Cello back is complete.

Planes and scrapers ruled the day

Here is what it looks like now:

Inside one-piece cello back with shadow to show curves.

The scrap of lining material is only there to cast a shadow so you can see the curves.

Inside curve (longitudinal) of cello back

Same thing again, but with a bigger stick. 🙂

Again, you can’t see it very well, but I also rounded the edges, beginning the edge-work that is so important to the finished product. I do the inner edge first, as it is hard to access once the plate is installed. I began with a tiny plane, and cut a narrow bevel all the way around the edge, at a 45 degree angle. Then I used a file and a scraper to round it into what is essentially a quarter-circle curve.

This plate is ready for installation.

I will try to close the corpus this week, and then scramble to complete the neck and scroll.

 

 

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Bass Bar installed and trimmed–F-holes refined. Edge-work begun.

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The Bass Bar is in place and trimmed. The F-holes have been refined, somewhat, and the edge-work is begun.

Bass-bar was #1 on the list!

I installed the bass-bar first thing this morning (chalk-fit to the inside of the plate in the exact location it was to be glued, then glued with hot hide glue).

Then, while the glue was drying, I went and did other things. Swept up the shop, changed the tires on my car (snow tires have to be off this weekend), and designed some display stands for the upcoming show at Marylhurst University. I had intended to begin the graduations on the one-piece cello back plate today, but after I did the tires, I was pretty worn-out, and hurting, so I decided it was time for a break, and, since the glue was dry, time to trim the bar.

Bass Bar in the rough

Here’s what the bass-bar looked like in the rough, when I took the clamps off:

Cello Bass-bar in the rough, viewed from the top.

Bass-bar in the rough, viewed from the top

Cello Bass-bar in the rough, viewed from the side.

Cello Bass-bar in the rough, viewed from the side.

Bass Bar Trimmed and finished:

And here is what it looked like after planing it to the shape I wanted it to be:

Finished cello bass-bar from front

Finished cello bass-bar from front

Finished Cello Bass-bar from side

Finished Cello Bass-bar from side

Edge-work and final prep for finishing

Although you probably really can’t tell in the photos, I have also scraped the entire plate, inside and out, under low-angle light, to get every dip and hump as smooth as can be.

Also, I began the edge-work; I first planed a small (3mm) bevel all the way around the inside edge, then rounded it with a file, to establish the inside curve of the edge. The outside will be treated the same way, after the plate is installed on the garland. It is much easier to manipulate the plate by itself, instead of the whole cello, so I want to do as much as I can before it is assembled.

I also spent time refining the f-holes; smoothing the inner edges, matching bass to treble shape, etc. That, too, is much easier before the plate is assembled with the garland.

Tomorrow I will try to graduate the back plate.

Gotta do taxes, too, though.  (Hooray for Turbotax!)

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Front and back plates fully arched, f-holes incised

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Final arching is complete

Low-angle light and Scrapers

Today I used low-angle light to reveal all the humps and hollows, and used scrapers to bring all of them to a smooth continuum of curving wood.

“Flat F-holes”

Once I had the front plate fairly smooth, I laid out the f-holes, and incised them deeply. My reason for doing this is that every single instrument I have made, the arching proved to need correction, as revealed when I laid out the f-holes. Invariably the arching was too “puffy” around the lower ends of the f-holes, so I had to re-carve that area. Finally it occurred to me that if I cut the lines in, they would remain visible as I carved, and I would not have to lay them out over again. That turned out to work pretty well, so now I routinely assume I will have to correct the arching, and I incise the f-holes, then view the plate from the side: what I am aiming for is that the general shape of the f-hole will seem to lie in a plane parallel to that of the ribs when the instrument is assembled, rather than describing a lazy “S” from the side.

Here is an example from an unfinished viola, from several years ago:

Flat F-hole

Flat f-hole

It is not something “exact”, but more of a general impression. One way or another, it allows me to see when my arching is not right, and correct it.

So, here is the top plate with the f-holes incised. I will finish cutting them out after the inside carving (graduation) is nearly complete.

Cello Front Plate with f-holes incised

Cello Front plate with f-holes incised

Here’s an end-view…doesn’t show much:

End View of Cello Front Plate

End view of Cello Front Plate

And a sort-of  “3/4” side-view…trying to show the curves:

3/4 view of cello front plate

3/4 view of Cello Front plate

Here’s a close-up of the c-bout with the f-hole incision (I used a special f-hole cutting tool to incise the circular parts):

Cello C-bout with incised f-hole

C-bout with incised f-hole

Annnd the back plate: (still may be a bit puffy in spots…I will work on it more later. Right now my hands are hurting from all the scraping) That’s all for today! I’m worn out.

Side view one-piece Cello back plate

Side view one-piece Cello Back plate

End-view of one-piece cello back-plate

End view of one-piece cello back plate

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Cello Back freshly purfled

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One-piece Cello back purfling complete.

Narrow (violin-style) purfling, like the original

Today I completed the back plate purfling. Though this is a cello, I purfled it with violin-style purfling, as it was pointed out to me by Jacobus van Soelen that the original instrument (1712 Davidov Stradivarius) had narrow purfling, like a violin, not the wide purfling I used on my first cello (and which I actually like to use on violins and violas, as well.) I just like the eye-catching appeal of the larger purfling as a rule. In this particular case, I must concede that the wood is so beautiful that it really does not need additional “eye-candy”.

The job starts with layout and measuring

Last night I laid out the corners, and marked the whole purfling channel using a purfling marker (sometimes called a purfling cutter— but I only use it for marking– I use a knife to actually cut out the slot for the purfling).

Then cutting and fitting

This morning I incised the whole purfling slot, using a small, home-made knife, and then cleaned the waste wood out of it with a purfling pick.

While I fitted purfling into the slot, and carefully fitted the corner miters, the glue-pot was heating up.

Gluing the purfling

When all the purfling seemed to fit correctly, I tipped each center-bout purfling strip up out of its respective slot, so that it pivoted up and out on the two corner miters, but left the ends in the slots, unmoved. I slipped hot hide-glue (quite thin) into the slot, using a palette knife, brushed hot water to flow the glue, and pressed the purfling strip back into the slot, forcing it deep into the groove with a special tool. (Sometimes I use my purfling pick for that job. Today I remembered that I have a plastic wheel on a sturdy handle,  actually designed for forcing the rubber trim into screen window frames. It worked perfectly. :-)) Then I repeated the above process for the upper and lower bouts.

If I start toward the middle of a section of purfling, and work toward the ends, the glue is forced along under the purfling, and squirts out along the edges and, finally, out the ends, and the miters. The result is that all of the piece has adequate glue, even if some spots had been a little skimpy. Then I brushed more hot water to re-flow the glue, and wiped off the excess with a rag.

So– here is the completed back, ready for final arching, and for having the edge channel cut, etc. It will look pretty rough until the gouge slices along the channel, and trims that excess glue and damaged fibers off the top of the purfling strip. Then it will look very nice. (Purfling isn’t only for looks, by the way, on violins– it also helps stop a split from the edge from moving up into the plate…supposedly.) Anyway, this is how it looks for now:

Completed purfling on one-piece cello back, before carving the channel.

The channel still needs to be cut, but the purfling is complete.

Lower treble cello-back corner, freshly purfled

Lower treble corner, freshly purfled

The next step will be to mark an edge margin all the way around, locating the crest of the finished edges, after which I can use a gouge to carve the channel, and begin the final arching.

But, for today, I have a bow to re-hair, so this is as far as I am going with the cello.

 

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Rough arching completed on back plate

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One-piece back, rough-arched, ready for purfling.

Final arching is yet to come

This is all I got done tonight. The edges are all at about 6mm, now, and the rough contours of the arching are complete. Tomorrow, I hope, I will finalize the edge footprint, so that it is exactly the shape I want the cello to be. (I waited until the edges were thinned, because it is much easier to make small adjustments to a plate when it is 6mm thick than to do so when it is 35mm thick, as it was two days ago.)

Flattening and thinning the rough plate

Two days ago, I worked the thick plate from 35mm down to 29mm, and decided to start from there on the rough arching. I may bring it a little lower yet…I haven’t decided yet just how high I want the back arching on this cello. I am thinking a little higher than the last one. The original Davidov is pretty flat…I may still emulate that curve.

Rough Arching

Tonight I simply worked a flat area all the way around the plate, at about 6mm (which I had marked ahead of time with a marking gauge), and then used a variety of tools to bring the shape of the plate to a “cello-shape”, though still a little plump.

Cello edge-thickness marked with marking gauge

Edge-thickness marked with marking gauge.

This (above) is actually a photo from the previous cello…I forgot to take a photo of the edge mark on this current cello before I began carving. Once I have the edge shape exactly the way I want it, I will probably take it down to 5.5 or even 5mm. The 6mm mark was just a good starting point for rough work. I ran a ball-point pen around the groove, too,  after scribing it with the marker, so I could see it more easily, as it was sort of dark out in the shop. So, this is how it looks now.

Rough arching on one-piece back-plate for cello.

Rough-arching completed–almost ready for purfling.

Purfling is next

Once the edge is exactly the shape and thickness I want, I will mark the purfling groove location, and begin cutting the groove for the purfling. Once the purfling is completed, I can finalize the outside arching before beginning the inside carving. When this is completed, it will be a maximum of 8.5mm-9mm in the center area, fading out to 4mm or so around the flanks, and back up to 5mm at the edge itself. I have a long way to go. It is certainly pretty wood, though. That is always encouraging.

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