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tom kovalcik
07-12-2011, 11:46 AM
Hi,
I am building the stew-mac violin kit and I wanted to get some thoughts on how to bend the purfling. The manual says to wipe the purfling with a wet cloth, but not to soak it as it may come de-laminated. It also says you may need to use a torch and a copper pipe as a bending jig, but does not give any details on how to do this.

Has anyone else done purfling for a violin? How did you bend it to fit without cracking?

Thanks

John Coloccia
07-12-2011, 11:58 AM
re: the torch and pipe.

Here's a picture of what they mean

http://www.luthiercom.org/phpBB3/viewtopic.php?f=89&t=1935&st=0&sk=t&sd=a

Scroll down about 1/4 of the way and there's a picture of what they intend. It's a cheap alternative to a bending iron.

Mike Langford
07-12-2011, 9:34 PM
I've assembled two stew-mac fiddle kit so far....first one was a kit an old friend of mine (Richard...he's 78 now) bought back in 1985.(I assembled it for him in 2006)
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This was the first time I tried to assemble one, and when it came time to do the purfling (not knowing any better) I simply mitered the ends, ran glue (Duco cement) in the channel and slowly worked the purfling around the curves and everything worked out fine! I remember thinking to myself "This is easy" ;)
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Now, this purfling (that came in the kit) was real flexible and it never gave a problem with cracking or breaking when going around the curves.

I finished the fiddle "in the white" for Richard and he was well pleased....He was going to stain and finish it himself, but I asked him a couple months ago if he ever did, and he said "Nope" :D
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HINT: - Do the purfling on the BACK first so you'll have all your learning mistakes worked out before you do the TOP (show side!)

Continued in next post....

Mike Langford
07-12-2011, 9:59 PM
The second Stew-Mac fiddle kit was one I picked up at a flea market for $20 bucks (I gloat about it in this tread.... http://www.sawmillcreek.org/showthread.php?54764-Had-a-great-day-at-the-market (http://www.sawmillcreek.org/showthread.php?54764-Had-a-great-day-at-the-market).... )
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Well, This time thinking, I'm an "experienced" builder/assembler, I started in on this one to give to a pro fiddlin' friend of mine for a gift....

Now, I don't know how old this fiddle is, but when I assembled Richard's fiddle in '06 it was 21 years old at the time and the purfling was still flexible. The purfling in this kit was dried out and so brittle that you couldn't even make a slight curve without it snapping!
I tried wetting it like the (on-line) instructions say and yes it did de-laminate and still broke at the slightest bend.
It got so bad that I'd use up almost ALL the purfling just trying to get the back done!

So, I ordered enough purfling to do an entire fiddle (3 strips) from Stew-Mac just to have enough to finish the top.
The purfling I ordered wasn't much better....It didn't snap as easy as the other but it was still a chore to get it to form a curve without cracking.(in fact I use up 2 1/2 strips just on the top)

Since the instructions mentioned using a bending iron I thought I'd try heat!

I've used a pipe and torch before to bend wood for a mandolin's sides, but I figgered a large pipe was a bit of overkill for the purfling....
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So, I got the bright idea and downsize the pipe to a soldering iron!
My wife does stained glass work and she just happened to have an extra 100W iron AND a temperature control, to dial in the heat range....
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It worked O.K. but I noticed that when bending, sometimes the heat would "flatten" or "compress" the purfling in spots, making it thinner in sections of the strips (not extremely noticeable, but if you look real close you can make it out)

But once the purfing was glued in (moisture from the glue?) and everything was trimmed, scraped, and sanded it looked real nice!

I was lucky enough to have access to a temperature control for my soldering iron, but I think if you have a lower wattage iron, you can make it work!

Sorry for such a long post....but I like to talk with pictures! :D;)

tom kovalcik
07-13-2011, 8:27 AM
Thank you both for the replies. I think I will try the soldering iron. I do electronics so I have a nice temp control one. I am going to try to combine it with the idea of putting a wet cloth on the iron to get a little steam and see what happens.

Thanks again.

John Coloccia
07-13-2011, 9:56 AM
Soldering irons operate in the 600F-800F range. We typically bend wood anywhere from boiling (212F) to maybe 300F or so. The temperature control seems like a really good idea. :)

Mike Langford
07-13-2011, 2:08 PM
The wet cloth to create a little steam sounds like a real good ideal Tom (I didn't do that :o ....maybe that's why it flattened! :rolleyes: :D)

If you have a micro chisel, you may want to go around the purfling channel and just clean up and make sure the channel is nice and uniform. In hindsight, I remembered Richard's fiddle having nice, clean, straight sided channels, but the second one being kinda tight or restricted around the "C" bouts....

What violin tools do you have? (I know the post setting tool comes in the kit...)

tom kovalcik
07-13-2011, 3:45 PM
I have a well stocked shop, but not a luthiers shop. I made a chisel by grinding down a small screw driver to clean out the purfling channel. The only other specialty tools that I have are a neck angle guide, the sound post tool from the kit, and some digital calipers. I plan to make a bunch of bobbin clamps to clamp the body together. I also bought a spoon plane to thin down the front and back to match a standard profile I found in a book.

Can you suggest anything to add?

Mike Langford
07-13-2011, 6:29 PM
Sounds like you've got it pretty well covered....I was going to ask you earlier if you had a neck angle guage.

Most of the tools are std. woodworking tools. Of course Stew-Mac or other luthier supply places can provide the specialty stuff that you can't make yourself.

Looking at their suggested tool list below, I don't see much you don't already have covered.
Unless you want or need the nut slotting files and the tapered peghead reamer....


stewmac.com
Recommended tools and supplies
Tools

Steel rule with millimeters (#4894), or at least 1/64" scale
Chisels: variety of micro chisels (#1628)
brace chisel (#1629)
X-acto knife, several blades
Clamps: variety of C-clamps (#3721) or
small spool clamps (#0683) or
violin clamps (#3713)
Drill with 1/16" and 1/8" (or 1.5mm) drill bit
Feeler gauge (#1811)
Scraper blade with curved end (#0628)
Violin Neck Angle Gauge (#0349)
Files: miscellaneous sizes; round, flat, and curved shapes
nut slotting files .010", .020", .032" (#0821, 0828, 0831)
Razor saw (#3598)
Tapered violin reamer, #0344
Soundpost gauge (#0389)

Supplies
Pencil
Binding tape (#0677)
Titebond wood glue (#0620) or
hide glue (#0669) and glue pot (#0668)
3M Gold Fre-CutŪ Sandpaper 150, 220, 320, 400, 800-grit
Micro Finishing Paper 1500-grit
(#5562 Sandpaper/Finishing Sampler Package)
Quality paint brush
Lint-free cloth and cotton
Behlen Violin Varnish (#0747)
Behkol solvent (#0774)
ColorTone Concentrated Liquid Stains (optional)
medium brown (#5033), vintage amber (#5030)
Tung oil (#0624)



Post us some pics of your progress (we like pics.;))