rim bending help needed

Discussion in 'Luthier's Corner' started by Flyin Z, Sep 25, 2017.

  1. Flyin Z

    Flyin Z Member

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    tried to bend .050" maple for es 339-ish build. First attempt. All I ended up with is a cracked piece of blackened maple. Furthermore, I burned my stomach with my make-shift bending iron made from a piece of 1" conduit with propane torch stuck inside. Clearly, I don't know what temperature to bend the wood at which accounts for the blackening of the wood. Is 400 degrees to high?
     
  2. paulmarr

    paulmarr Senior Member

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    SOunds like the wood wasn't "wet enough" ... you did either spray the piece with water or soaked the piece in water prior to trying to bend?
     
  3. ARandall

    ARandall Senior Member

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  4. Dutch harbour

    Dutch harbour Junior Member

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    If i bend sides (with a heating blanket) the right temperature is around 140 degrees celsius (I'm in Europe), thats about 280 F. So 400 degrees is definitely too high. Furthermore I personally think 0.05" is a bit on the thin side, I usually thin the sides down to around 0.07"to 0.075" (depends on how stiff that particular side feels in your hands) spray on some water, pack up in Aluminium foil to prevent the water from evaporating and than most wood species will bend just fine on the above mentioned temperature.

    Succes with your project
     
  5. geoffstgermaine

    geoffstgermaine Senior Member

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    Other's have hit it on the head. I've found that figured maple can be tricky, but 280-300F with water usually works. For my archtops (which predominantly use Flamed Maple), I soak the sides for about 15 minutes in a PVC pipe filled with warm water (cap on one end of it). I'll then take it out and start bending, applying more water as needed. If you have things set up properly then the wood should start feeling a little like it's starting to melt as you apply it to the pipe and shouldn't require much pressure. If you're applying a lot of pressure then it's a good indication that you're going to break the piece trying to bend it. I normally use 0.080" thick sides with no issue, so 0.050" should bend with no issue if you follow the advice given in this thread.
     
  6. Brewdude

    Brewdude Senior Member

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    Have you looked at this video (and amazing build)? Seems like a pretty cool steam setup and jig system to get it done. Perhaps a lot of setup just to get one set of sides completed but looks like it would be a good way to avoid overheating the strips.
     
  7. Bill Hicklin

    Bill Hicklin Senior Member

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    .050 is really, really thin: .090 is more usual.
     
  8. moreles

    moreles Senior Member

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    All the suggestions are good. Maple is annoyingly "splittable" when bending. You can't rush the soaking, and keeping it wet is essential. It's when the water turns to steam that the wood fibers go from rigid to pliable. I have a homemade bending pipe, and I fill the interior with rods and bolts to arrive at a mass that doesn't lose it's proper heat when hit with water and wet wood. Good luck. Patience and correct setup are critical. I do fine bending sides, but I can't claim to like it!
     
  9. Bill Hicklin

    Bill Hicklin Senior Member

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    Better idea: get the plans for a Fox bending machine (it will cost maybe 20 bucks in materials, if you use the original light-bulb setup rather than a heat blanket). No fuss, no scorching.
     
  10. Flyin Z

    Flyin Z Member

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    I think I'm going to try a 4" piece of PVC steam box.
     
  11. Flyin Z

    Flyin Z Member

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    ok, so I tried the pvc steam box with hose connected to pressure cooker. Temp only gets to 211 deg. which stands to reason b/c boiling temp is 212 F. I Let it cook for about 45min. and my .050 maple still cracked when making horn bend.
    But. . . I tried sticking a piece right into the boiling water with a strip of metal to back it up, and doing this repeatedly was able to make a fairly sharp bend. It looks to me like the best way to bend wood is to boil it.
    I never hear ppl talk about boiling, but is there some reason that you can't just boil the crap out of it???
     
  12. the great waldo

    the great waldo Senior Member

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  13. geoffstgermaine

    geoffstgermaine Senior Member

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    I'd say it's likely because a well set up bending iron or Fox style bender can probably do as good as (or better) job without fussing with a pot of boiling water. Also, there are woods that will not bend at such a low temperature.
     

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