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09-28-2006, 06:21 AM
|  | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | | bending purfling tips
 I'm bending my home made purfling glued with hide glue. I'm coming up against two problems.
1. bending the tight curves near the corners on the hot iron causes the inner strips to buckle.
2. bending the gentler curves sometimes causes the strip on the inside to come unglued, almost as if it's shrinking longwise.
Are these things normal purfling behaviour? I am using just a lick of moisture on the strip befor bending.
I've started to resort to white glue to glue the strips back together. Doesn't seem as problematic as hide glue cos more flexible. I was trying to be a purist but now I can't be buggered. Is there a better glue?
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Last edited by Matthew Tucker : 10-02-2006 at 07:40 AM.
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09-28-2006, 02:07 PM
|  | Registered User | | Join Date: Jun 2006 Location: Eugene, Oregon | | | It might be too late for this, but what about gluing the strips together and bending them to the correct shape before the glue dries? Then the strips will slip against each other and dry stress-free in the correct shape.
Good luck.
Michael
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"I've got no desire to carry a Stradivarius, but there's no limit of primitive tom-tom in my tum-tum. Mama I wanna make rhythm..." www.blueskiesbigband.com |
09-28-2006, 02:19 PM
| | Jeff Bollbach Luthier, Inc. | | Join Date: Dec 2001 Location: freeport, ny | | | Don't use moisture, dry heat only. You might want to consider another glue next time. |
09-28-2006, 04:44 PM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | | Ok I did a bit more this morning, I tried the no moisture method but the white inner strip started to crease instead of bend :-(
So I was brave and dunked the whole strip in water. Now, as long as I bend from the middle outwards, the strips slip a bit as the glue softens. Where the strip buckled I slit diagonally with a blade and will try to glue back down again and sand flat ... Its tricky, but still fun, and only a few burns this morning ... and slimy glue muck all over the bending iron! |
09-28-2006, 04:53 PM
|  | 'Woodworker - Witch Doctor - Luthier'
Owner/The Bass Spa, String Repairman/L & M Vancouver | | Join Date: May 2006 Location: Crescent Beach, BC | | | Not to mention the heady aroma of sizzling hide glue! |
09-28-2006, 10:29 PM
| | Registered User | | Join Date: Apr 2004 Location: Traverse City, Michigan | | | Matthew I think your problem may be more related to the center wood type and thickness rather than the glue.
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Ken McKay - Michigan - USA
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09-28-2006, 11:23 PM
| | Supporting Member/Luthier | | Join Date: Jan 2002 Location: Cincinnati, Ohio | | | Lower the heat on your iron... go slow... don't use water. |
09-28-2006, 11:46 PM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | | Thanks for your hints. I have the whole weekend to practice - and I'm bending these BEFORE I cut into my precious top! |
09-28-2006, 11:51 PM
| | Supporting Member/Luthier | | Join Date: Jan 2002 Location: Cincinnati, Ohio | | | What is your black? Wood or fiber? |
09-29-2006, 12:58 AM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | | |
09-29-2006, 06:13 AM
| | AES Fine Instruments | | Join Date: Feb 2002 Location: Brewster, NY, USA | | | When buckling occurs, it's ususally because heat is not distributing evenly. I had some horror-shows bending poplar ribs. My friend Robbie McIntosh suggested warming the outside of the piece while bending it. So we applied hot air from a heat gun to the outside while using a metal bending strap. The result was a clean bend with no buckling. In your case I think you are right that you need a more friendly glue. I think you'd be better off glueing up your purfling with a less-brittle glue that has a bit of "creep" and more water resistance. A simple white glue would work fine. Also. if your purfling is a bit flexible, you may not need to pre-bend it as much as you think. |
09-29-2006, 07:19 AM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | | I did some more this evening, sloooooowly and without moisture. Apart from singed fingers, it went quite well. Also I think that I'd be better off if my centre strip was cut along the grain rather than any old how because it tends to split when it gets hot and dry. And the black strips just seem to get brittle and snap too. But on the whole, nothing is irreparable, and I'm having fun with clothes pegs and white glue. The only regret I have is grabbing one of my long bits for the lower bout and using it for the upper bout by mistake! Wondered why it was too long and like a royal twit I snapped the surplus off :-(
I had cut just four matching strips for each bout; now I'll have to make another when I do the back.
I must say though, that of all the jobs so far, bending the purfling has been my least favourite ... |
09-29-2006, 10:45 AM
| | AES Fine Instruments | | Join Date: Feb 2002 Location: Brewster, NY, USA | | Quote: |
Originally Posted by Matthew Tucker I must say though, that of all the jobs so far, bending the purfling has been my least favourite ... | Wait until you cut the channel and install it...  |
09-30-2006, 03:36 PM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | 
Today is channel-cutting day  |
09-30-2006, 05:37 PM
| | Supporting Member/Luthier | | Join Date: Jan 2002 Location: Cincinnati, Ohio | | | Let's see if you still use that emoticon later...
may the force be with you, young jedi. |
09-30-2006, 08:48 PM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | |  You're watching this live. I'm at work, in my office - the best place to do this with no distraction. Ahmad Jamal on itunes and all my sabres sharpened. I hope the force is with me ...
Refresh my memory - does the bee-sting on the lower bout point up or down? |
09-30-2006, 09:08 PM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | | Stanley knife - too big
Box cutter - too flimsy
Scalpel - too pointy
Old double-sided knife I've been carrying around in my box of things for thirty years without a use for it - just right! |
09-30-2006, 09:28 PM
|  | Journeyman Clam Artist Moderator | | Join Date: Nov 2002 Location: Winnipeg, baby | | | That's a marking knife, or a "striking" knife, i'n't? Is one side flat? You use it instead of a pencil.
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There's a joker in every deck... |
09-30-2006, 09:49 PM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | | I'm not sure - I think its an old fashioned scalpel with a very worn-down blade. Its sharpened on both sides, both edges. Nice rosewood handle. Its good for cutting the purfling groove because you can run the centre of the blade against the wall of the groove when deepening the cut, avoiding jabbing into the side of the groove itself. And cut in bothe directions just by rocking the knife. 
"Rodgers, Cutlers to Her Majesty"
I'm guessing thats Queen Vic?
Last edited by Matthew Tucker : 10-01-2006 at 02:53 PM.
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09-30-2006, 09:55 PM
| | Supporting Member
Luthier: Bresque Basses, rep: Paulin EUB | | Join Date: Aug 2002 Location: Sydney, Australia | |  What's with the grain on the upper bout???? Its like a rollercoaster ...
Last edited by Matthew Tucker : 09-30-2006 at 10:03 PM.
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