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Arghhh!!! Side bending on pipe...
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=10944		 Page 1 of 1
Author:  Irwin R [ Thu Feb 15, 2007 9:05 am ]
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Hello all ..wondering if I can get some help...tried to bend my second side today after doing a Ok job on first..well...I thought it would be a little easier. The second side seemed a devil to bend..I touched up the first side today before I started the second, so I wasn't going in completely cold ,... well the kids were off school due to a storm, and they thought Dad was making fudge in the shop...only it wasn't "OH FUDGE!!..if you catch my drift


As I said the side was very hard to bend..and I developed a couple of cracks which I flooded with CA. ..I remembermaking my 1st, and I figure 1/2 of the side material ended up being CA.


Anyway here are a couple of photos.I don't know if they help any..The the direction of the cracks are from one side to the other, not spanning the entire width however( the are just above the black line




.as I said it cracked right at the waist..I thought I could move the bend down a little ( enough wood is avail) ..to the black line..and I'll give it another try tomorrow night..any idea what to expect when I go to bend?...how does wood react to bending with a little CA apllied..any input greatly appreciated..Thanks..


 
Author:  Rod True [ Thu Feb 15, 2007 9:22 am ]
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Irwin, One thing you will want to be sure of when bending your ca flooded sides is to wear a respirator, the fumes are killer. Maybe some safety goggles too.

A couple of questions for you. How thick are the sides? Did you go slow when bending? Do you know how hot your pipe is getting? How much moisture/water are you using.

All of these are factors of course to a successful bend.

Wood to thick, it will take a long time to heat up to correct temp, if at all and pushing the side to fast or hard can crack it instead of manipulate the bend.

Push to hard and/or fast can crack the side

Not enough heat......you get the picture I'm sure.

EIR is usually an easier wood to bend so I would suspect one of the aforementioned issues.

Take a look at some of these and make sure all is good and ready before bending again. The one hard thing with re-bending I find is that the piece will want to bend on the same spot as prior bending, you really have to get the whole area in question hot enough to bend. It's tough and I found with my first guitar, bend on a pipe (switched to bender and blanket since) that I had ridges or peeks and not totally smooth bends.

So, the side should be from 0.080-0.090 thick
heat should be from 280-300*F
water is a tricky one, some folks submerge and some use little to none
try moving the side over and back across the pipe to heat up a larger area than try the bend, if it's not seeming to bend with lite pressure, try heating it up some more.

Hope this helps in some way.
Author:  Irwin R [ Thu Feb 15, 2007 9:44 am ]
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Thanks so much Rod.The sides are between .08-.09, a little closer to .09..I'm spritzing with water, my pipe is form Stewmac, and is set on high ( whatever temp that is?..water bounces off...thanks for the warning about the bending fumes...I actually did try a little bending after aplication of the CA and now have a headache( may be causd by my bending inability, but the shop does stink, I'll air it out )


Thanks again for all the suggestions, I'll take my time and try again tomorrow...
Author:  Irwin R [ Thu Feb 15, 2007 10:22 am ]
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Sorry just to make clear , although I used the CA on # 1 , I didn't experience any cracking at the waist, and that's whats's scaring me... (..I am just a lttle aprehensive about bending it now..since it is an OM and the waist bend is fairly tight ( I suppose)..is irt a good idea to perhaps scape the thickness down a little at the waist?..I can get at it ok with a scraper..
Author:  CarltonM [ Thu Feb 15, 2007 1:13 pm ]
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[QUOTE=Irwin R] my pipe is form Stewmac, and is set on high ( whatever temp that is?)[/QUOTE]
Seems like I've read that it can go up to 500deg.F. Much too hot. Time to get a thermometer. Remember, water boils at only 212deg.F, which isn't enough. It's not the best indicator for proper heat in bending wood. Good luck!
Author:  Irwin R [ Thu Feb 15, 2007 1:34 pm ]
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Thanks Carlton, I'll back it off a little bit. I think I understand that water should just bounce off the pipe. It does seem that I have a fair bit of scorching as I look at the photos.


.
Author:  crich [ Thu Feb 15, 2007 2:12 pm ]
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There are some good suggestions here. A thermometer will help eliminate any questions on temperature, you know your side thickness, I seem to have better luck closer to 300 deg. Also what helped was not spritzing so much the top of the piece as you need to the bottom. The bottom will turn to steam which in turn goes through the piece to the top. Did that make sense? Are you heating a few inches on either side of the point of the bend? I think that .9 is a little thick, might want to go down to .8 inch. You should be able to feel the wood relax if you use steady pressure, but not too much pressure. I'm no expert but these are some of things that have helped me. Clinton
Author:  Serge Poirier [ Thu Feb 15, 2007 2:35 pm ]
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Irwin, i'm no expert using a pipe since i always bent on a form but the advice you've received here is consistent with what we're used to read here. if you ever consider building many more instruments, you might want to buy or build yourself a side bender and order a heat blanket that would help get your wood hot pretty quick and diminish the chances of cracking the wood.

Serge
Author:  EBarajas [ Thu Feb 15, 2007 2:49 pm ]
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I have a suggestion that works well for me, put a moist not soaking wet towel on the pipe and then also spritz the wood a bit and it should bend fairly easy. Keep wetting the towel so it doesn't dry out or catch on fire. This works very well with EIR and on maple but too much water can stain some woods. I bend venetian cutaways this way all the time at least before I got a heating blanket for my bender.
Author:  James Ringelspaugh [ Thu Feb 15, 2007 2:57 pm ]
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If you send me the Stanley No. 7 in the background, I'll send you a freshly bent replacement indian rosewood side.

But seriously... good luck to you, but I wouldn't hold much hope of getting the side with CA glue bent to your expectations. Fortunately (if you do fail), LMI will sell you just a side set for half the price of a back/side set.
Author:  Rod True [ Thu Feb 15, 2007 5:13 pm ]
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One other thing that may really help you Irwin is having something backing the side when you bend. A piece of metal flashing will support the back side of the bend and help eliminate cracking.

Take a look at this pic from Stew-Mac



This is what I'm talking about for supporting the bend.
Author:  Rod True [ Thu Feb 15, 2007 5:15 pm ]
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That picture makes it look like the side piece is really thick, but I think it's just the side is wider than the strap.

I do this with one of the long SS rulers you get from the office supply store for bending bindings sometimes.
Author:  Irwin R [ Thu Feb 15, 2007 11:58 pm ]
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..Thanks everyone, you have pretty well given me all the info I think that I'll need..I'll give it a go ..perhaps a quick shot of reassurance before I head down to the shop will helpI am not holding out too much hope..for what little time I did it, I really enjoy the process of pipe bending, so I think I'll get a thermometer and the metal flashing, If that fails then I'll try the side bender heat blanket route..Cheers
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