Building a bentside spinet

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Charlie Schultz
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Re: Building a bentside spinet

Post by Charlie Schultz »

Thanks Randy & Beate.

I don't know of any forums, but there is a harpsichord mailer list that covers both building and playing.

The soundboard will be a glue-up- I got the spruce (~5 foot long pieces) from Brent at Alaska Specialty Woods.

I'll have another go at the bend tomorrow. Laminating something up is still an option.

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Charlie Schultz
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Re: Building a bentside spinet

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Finally some progress. I tweaked the bending jig a little and soaked the tightest radius of the bend in some "SuperSoft" for a day or so. The soaking seemed to do the most good. My heat pipe isn't quite big enough to do much. Short of laminating, I may try a steam box next time.

The bent side:
bentside.jpg
I traced the actual bend onto the base board and then cut. In retrospect, it probably would have been better to do this before the rest of the assembly...
base.jpg
Fitting the side to the baseboard. Still have a few miters to cut.
fitting.jpg

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Charlie Schultz
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Re: Building a bentside spinet

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I finished out the case sides. Per the book's recommendation, I started in the front and worked around the sides.
IMG_20170225_190504051.jpg
Ok, for authenticity, I would have used cut nails here, but I went with screws. In either case, there will be moldings applied along the lower edge to cover up the fasteners.
IMG_20170225_190543151.jpg
Here's the back being glued on. I digressed from the original assembly by not gluing on the back rail first. The side rails are glued on after this step, so I figured I'll do the back rail later too.
IMG_20170226_192014723.jpg
Next I should make some glue blocks for all the corners to reinforce those joints.

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Bryan Bear
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Re: Building a bentside spinet

Post by Bryan Bear »

This is fascinating!
PMoMC

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

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Charlie Schultz
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Re: Building a bentside spinet

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I added three corner reinforcements. The first couple were easy. The third one (the dark hole) was tough. Note to self- next time, fit this before gluing on the side.
IMG_20170303_190805624_HDR.jpg
IMG_20170303_190819732.jpg
Next was adding the liners. These serve to support the sound board (much like on a guitar), but they also hold the hitch pins (to which the strings will attach). The liner for the bent side is kerfed.
IMG_20170304_084123779.jpg
IMG_20170304_084146969.jpg
IMG_20170304_084202548.jpg

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Charlie Schultz
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Re: Building a bentside spinet

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Next were the liner braces- these are three cross pieces that are fitted below the liners.

The first picture shows the braces cut, mitered and rabbeted and just resting on the liners.
IMG_20170304_193200690_HDR.jpg
They were glued in place and then triangular brackets are added for reinforcement.
IMG_20170304_205818930.jpg

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Charlie Schultz
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Re: Building a bentside spinet

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One other thing were the two spruce spacer strips that keyboard will ride against (one on the bass side, one on the treble side). These also reinforce the butt joint on the sides of the keyboard (these still need to be trimmed back):
IMG_20170305_162527421_HDR.jpg
Then I started on the keyboard. First up is the basic frame which is just two sides, the back member and balance rail (the keys will pivot on the balance rail). The keyboard assembly can be slid in and out of the instrument.

Here it is by itself:
IMG_20170305_195940374.jpg
And in place in the instrument:
IMG_20170305_200002207_HDR.jpg

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Charlie Schultz
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Re: Building a bentside spinet

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Glued up some wood for the keyboard last night. While that's drying, I added the wood bits to lock down the keyboard.

This triangular wedge keeps the back down (this one is on the treble end and there is another on the bass end). The rear of the keyboard slips in underneath the wedge.
IMG_20170306_190611747.jpg
These turnbuttons (one on each side of the keyboard) keep the front of the keyboard assembly in position.
IMG_20170306_204240263_HDR.jpg

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Charlie Schultz
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Re: Building a bentside spinet

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Building the keyboard is a 7 step process. Here's the prep and step 1.

First is getting the blank to shape. It's about 800 mm wide, 12 mm thick. The treble side is about 260 mm deep and the bass side about 300 mm deep. I'm using poplar.
IMG_20170307_193732800.jpg
Next is the keyboard ruler that marks the edges of the natural and sharp keys. Barnes drew this on the plan, and I copied that to a stick.
IMG_20170307_193655271.jpg
Here we extend the lines for the natural key edges from the ruler onto the keyboard blank using a square.
IMG_20170307_220052343.jpg
Completed. The tic marks at the top of the line indicate where the sharps will be.
IMG_20170307_220114630.jpg
Next is to glue on the tops of the natural keys. The original Keene & Brackley used ebony for the naturals and ivory for the sharps. I've probably got enough ebony (in fretboard blanks) to do ebony naturals and then maybe use maple for the sharps. But I'm also thinking of maybe cherry naturals and maple sharps. Could also go with maple naturals and cherry sharps too...

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Charlie Schultz
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Re: Building a bentside spinet

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I also started the lid and flap. Here I'm just getting some boards in place prior to glue up.
IMG_20170309_190606733_HDR.jpg
The lid is attached to the case (in the back) with three hinges. The flap (which covers the keyboard) is attached to the lid with three more hinges, and there is also a lock on the flap. The hinges are drawn full-size on the plan and they are really cool. I wasn't particularly looking for exact replacements, but I learned there is a guy over in the UK who actually makes replicas of these (and many others). As you can imagine, they are not cheap- I'm guessing US $350 (plus shipping) for the set. You can check them out here: http://www.traditional-brassware.co.uk/ ... 1/spinets/ (in my case, references 13 - 16).

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Re: Building a bentside spinet

Post by Bill Raymond »

Charlie, re: your kerfed bentside liner, how can you be sure that your hitch pins won't be driven into a kerf rather than the solid part of the liner, thus being subject to pulling out from the tension of the strings?

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Re: Building a bentside spinet

Post by Jim McConkey »

I think you should have a go at making your own hinges! Brass is easily cut with most normal inlay tools, and cutting these patterns is no different than cutting inlays. You can get brass sheets at almost any hobby or big box hardware store.
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Charlie Schultz
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Re: Building a bentside spinet

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Bill, I wondered that too. The kerfs were marked on the plan, so hopefully they are strategically located.

Jim, I had not considered that. Worth some research. Thanks for the suggestion.

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Charlie Schultz
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Re: Building a bentside spinet

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Got the top glued up and rough cut.
IMG_20170314_193417391_HDR.jpg

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Charlie Schultz
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Re: Building a bentside spinet

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Back to the keyboard- I'll use cherry for the naturals. I cut the pieces 4.5 mm thick and then cut the width so that the edges line up between keys.
IMG_20170309_190548394.jpg
Here they are glued on, with the lines redrawn. I used HHG here because some of the cherry will have to be removed and replaced with the sharps The sharps are also drawn on, and a couple horizontal lines that define the front of the sharps and the where the chamfers between the naturals end. The horizontal lines will be "boldly" cut as they are also decorative.
IMG_20170312_192446942.jpg
Another shot of all the lines- the two horizontal lines above the key tops mark where the balance pins will be drilled for. The sloping line is just to keep the keys in order after they're cut out. The top line is the end of the keys. As I type this, I remember that I need another line at the top to mark the depth of the slots that get cut in the end of the keys. I also should taper the key tops front to back (and redraw all those lines again...).
IMG_20170314_193443149.jpg
The recommended way of figuring out where to cut the keys apart is to locate where the jacks will go. So we make a dummy jack with two points on one end.
IMG_20170315_192436364.jpg
The keyboard is placed in position and the jack drops in the slot. You can see the jack resting on the end of the keyboard.
IMG_20170315_192503769.jpg
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Then we take a mallet and rap the top of the jack to make a pair of marks on the keyboard blank. Repeat 55 times.
IMG_20170316_184937.jpg
And here you can see the dents left in the keyboard.
IMG_20170316_185046.jpg

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Eric Knapp
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Re: Building a bentside spinet

Post by Eric Knapp »

This is getting more and more interesting! Thanks for sharing all the details.

-Eric

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Charlie Schultz
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Re: Building a bentside spinet

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Getting there- I extended lines from the key edges to the back of the panel. Each line was drawn so that it falls between the pairs of marks left by the dummy jacks.
IMG_20170318_140607.jpg

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Re: Building a bentside spinet

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Many apologies for slacking off here- it's been (and continues to be) a busy summer.

It took a while to get the right pins, but got some and drilled the holes for them, through the keyboard and into the balance rail. The pins will get tapped into the balance rail and then the keys will pivot on those. It'll become clearer later.
IMG_20170731_192206.jpg

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Charlie Schultz
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Re: Building a bentside spinet

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Next is the rack- this sits (vertically) behind the keys and acts as the guide for the keys, keeping them moving straight up and down. Here, I've transferred the center of each key to the rack, and extended the lines.
IMG_20170728_192208.jpg
IMG_20170728_192220.jpg
Now the idea is to cut slots (1.7mm wide) in the rack, centered on the previously drawn center lines, for each of the 56 keys. There's probably a number of ways to do this, but I followed the Barnes book here. Build a little jig with two fingers spaced about 1.9mm apart (you can guess I used an old hacksaw blade here).
IMG_20170728_192248.jpg
Center the line drawn on the rack between the two fingers and use a knife to score a pair of lines. Then use a chisel to chop out the slot.
IMG_20170728_192347.jpg
Well crud, perhaps I should have been a bit pickier about the wood I used for the rack. I can probably glue this crack, but I've got 55 more slots to do. Barnes recommends a chisel with a 12 degree edge.

Anyway, here you can see the scored lines and where I chiseled out one of the slots. To minimize friction between the key and the slot, we want just the front edge to be the guide, so we need to chisel at an angle (i.e., the slot will be wider at the back of the rack than the front.
IMG_20170731_191507.jpg
The slot in the back. Need to use a harder backing board too methinks.
IMG_20170731_191517.jpg

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Charlie Schultz
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Re: Building a bentside spinet

Post by Charlie Schultz »

Ok, take 2. Redone with poplar, much better.

Front:
IMG_20170806_170447.jpg
Back:
IMG_20170806_170454.jpg

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