Building a hurdy-gurdy

[Charlie Schultz]

We're relaxing the "only posting completed instruments" policy and I've finally started building a hurdy-gurdy (ok, I had an ulterior motive <g>).

I'm using the GAL plan #49 (from issue #77). This is HG #1 for me, so there will be some (a lot of?) trial and error here.

Here's the wood for the back and sides and. I'm using sycamore (not sure what I'll do for the top yet). The back is 3 mm thick and the sides are 2 mm. The "kerfing", which goes on the outside, is also sycamore, about 5 mm x 5 mm.

Back & sides

Here are the side ribs (I still need to slot them to accept the sides):

Side ribs

Here are the braces, I still need to notch the ends and of course drill the holes for the wheel axle:

Braces

And here is the wheel, cut to rough size:

Wheel

I plan to figure out how I'm going to do the axle, then mount the wheel and true it up on the lathe. The smaller wheel will be doweled and glued to the big wheel and allow a pin or screw through it and the axle to connect them.

So I think my next task is to figure out what to do for the axle and bearings/bushings. I've got a steel rod that's about 7/16" in diameter as plan A, but I'm going to check out the hardware store this weekend. I also need to take better photos...

[Peter Wilcox]

Looks very interesting - I've always thought of building one, but it just looks too complicated mechanically. I'll be following closely - good luck!

BTW, your photos aren't bad - just need some added contrast in your imaging program.

[Charlie Schultz]

Thanks for the tip Peter!

Again, this is the first one I've built, so all suggestions welcome!

One thing on the plan- the printed width dimensions for braces "A" and "B" are significantly off (13 mm short), the 255 mm dimension should be 268 mm and the 225 dimension should be 238 mm. The wheel, which is superimposed on the "B" brace has a printed dimension of 135 mm and that matches the actual measured diameter on the plan. Brace "C" dimensions also match.

A friend had some steel rod (about 7/16" diameter), so that's my plan for the axle. Here it is, not cut to length (I think I need to lose the threads on the one end):

Steel rod for axle

I've drilled and tapped the end of the axle for a 1/4-20 bolt:

For the crank

Now that I have my axle, I've drilled the wheels. The two holes on the side are for short dowel pieces):

Drilled wheels

He also had some plate aluminum (about 0.2" thick) that I plan to use for the crank. Here I've cut out the pattern and done some filing and sanding on it. I think I'll wind up painting it:

Crank

Here's the Acetel plastic I plan to use for the bushings:

Bushing

And sort of how it fits together (I'll use a bolt instead of the knob shown):

Subassembly

This is a side view towards the front from the plan. Not sure what the rectangle with the half circles on the end is. I don't recognize anything in the pictures. Maybe a decoration? Any ideas?

[Michael Lewis]

Charlie, so what is the body shape? I too am puzzled regarding the design you asked about. Looking for pics on the internet shows nothing like that so far.

Perhaps it is a pattern to be put on a cover over the strings.

[Charlie Schultz]

Here's a link to a thumbnail of the plans on the GAL site: http://www.luth.org/images/plans/pl49.jpg. You can see the instrument shape there, and the section in question is at the bottom of the top page. Maybe it's just an inlay?

[Nicholas Blanton]

I don't know whether you'd call that section a neck, or an upper bout. Anyway, it has the look of a marquetry panel, so you'd assemble out of veneers and then glue onto the upper bout. I would imagine the rectangle-with-round-ends would be curly maple or something like, bordered by some kind of black or black-white-black purfling, and then the outside section beyond that would be something like mahogany.

Of course a hurdy gurdy ranges in sophistication from totally rustic to pretty. I would not be surprised if that design wasn't also drawn on plain maple with a hot iron.

[Bob Francis]

I Google searched and was amazed at how many shapes there are.
There was one about 8 rows down that had the same or similar shape.
I'm betting inlay!
Bob

[David Ackley]

Charlie, that shape is obviously where the pickup goes .
Seriously, since I got the plans for a hurdy-gurdy, and have a friend who is an active player, I'm excited to follow this post and hopefully also follow in your footsteps.

[Michael Lewis]

Maybe contact the GAL or whoever drew the plan, for clarification. That's not a plan, it's a suggestion. (Oh, did I say that?)

[Charlie Schultz]

Ha, or maybe it's the battery cover <g>.

I got all the internal braces cut out and shaped, here's one of them:

Brace section before glue-up

Here they all are, glued together:

The glued up braces

I slotted the ribs for the sides using the bandsaw. The kerf wasn't wide enough, so I stuck some sandpaper to the side of a scraper and opened them up so the sides just fit in:

Slotted ribs

And finally, sitting on the back in their approximate positions:

Braces sitting on the back

The next step is to probably drill the holes in the braces for the axle. After that, I'm not sure. Maybe glue the back to the braces, then bend and fit the sides?

[Charlie Schultz]

Preparing to drill the holes for the axle. I lined up the pieces and used double-sided tape to keep them aligned during drilling.

Lined up and taped together for drilling

Holes drilled.

Drilled braces

With bushings installed.

Braces with bushings

Bent sides and "linings" (the linings go on the outside- top and bottom to glue the top and back to the sides (in place of insided kerfed strips)). One set goes in the middle of the sides. Everything here needs trimming yet.

Bent sides (not trimmed yet)

Truing the wheel on the lathe. The author of the GAL article says that no matter how well it is trued on the lathe, additional truing will be needed once installed.

Truing the wheel on the lathe

[Steve Senseney]

Does the wheel need to be that robust? It looks kind of heavy.

Would it be better to build it as a build up of laminations. Or with some areas cut away to reduce weight?

If it was laminated, it would have less tendency to change shape with humidity changes.

(Of course, I have not built a Hurdy Gurdy, so I really know nothing about this!)

[Charlie Schultz]

Hi Steve,
Well, the wheel is sized per the drawing, perhaps it will look more the right size when it is installed in the instrument. As for laminating the wheel, yes, from what I've read it seems common for the wheels to be made of plywood with a maple veneer on the rim (to reduce the chance of warping). So maybe I'm taking a chance here... As for reducing weight, I could turn away some of the inside part of the wheel- food for thought, thanks.

(Of course, I have not built a Hurdy Gurdy, so I really know nothing about this!)

Well, me too!

[Darrel Friesen]

Nice work Charlie. I'll be very interested to see how this turns out.

[Michael Lewis]

Charlie, it's starting to take shape quickly now! You are going to be swamped with hurdy-gurdy requests!

[Yuri Terenyi]

A quick note on the wheel.
All old (read historic) h-g-ies had wheels just like per photo. The drawback is that wood has a different shrinkage ratio slabsawn v. quartersawn. With the inevitable result of the wheel slowly getting oval in shape, necessiating a periodic trueing-up. In the long run that means the wheel keeps on getting smaller and smaller, eventually necessiating a replacement. That's why ply wheels with a solid wooden rim have been pressed into service lately in spite of the un-historic connotations.They simply stay in shape.

[Clay Schaeffer]

Is there some reason to not use plywood wheels without a solid wood rim?

[Yuri Terenyi]

With just plywood the grain will become a bit of a problem when it comes to applying the rosin. The reality is that all plywoods are made from relatively soft and porous woods, and their endgrain is far from perfect. It's not impossible, but not really a great choice. (unless you can source some plywood made from something like pear, which is highly unlikely)

[Charlie Schultz]

Re: an earlier post (bottom of http://www.mimf.com/phpbb/posting.php?m ... 29#pr17107) where I was wondering about the pattern on the upper bout. I was able to contact the author of the GAL plan and article, Wilfried Ulrich, and he was kind enough to answer:

At the original in the museum there is a carving out with a depth of 1 mm. This depends on how thick the wall is. I made one instrument with an overlay from the inside to keep it stable. On the other hand it’s just right to create a shadow line. Of course you are free to make an inlay from contrasting wood or leave it pure.

If you look here: http://www.ulrich-instrumente.de/9.html, you'll see a couple beautiful HGs he made based on his plan.

[Jon Whitney]

With just plywood the grain will become a bit of a problem when it comes to applying the rosin. The reality is that all plywoods are made from relatively soft and porous woods, and their endgrain is far from perfect. It's not impossible, but not really a great choice. (unless you can source some plywood made from something like pear, which is highly unlikely)

There's no reason a luthier could not mill pear into thin plys and glue up or build his or her own plywood. That said, it's a lot harder than using some baltic birch or other good quality plywood and facing it with a wood veneer as Charlie mentioned. Although, trueing up the edge of plywood disks on a lathe isn't exactly a picnic either.