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Side Busting Situation... :(
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=43592		 Page 1 of 2
Author:  meddlingfool [ Thu Jun 05, 2014 12:07 am ]
Post subject:  Side Busting Situation... :(
Does this ever happen to anyone else? We've hit a patch of Padauk that seems to not want to bend. We've bent Padauk lots of times before with no difficulty at all. Between these bends, we've bent lots of other woods including highly flamed walnut without issue, so I don't think it's technique or setup, as we're just following SOP. Yet three padauk's in a row have gone popsy.

These are all from the same suppliers. When something like this happens, I'd be inclined to say 'toughpoop' if I was a supplier. But this is a staple wood and I'm getting gun shy about ordering more from them. It is cutting into my grocery money which gives me sad face.ImageImageImage
Author:  DennisK [ Thu Jun 05, 2014 12:21 am ]
Post subject:  Re: Side Busting Situation... :(
I haven't bent padauk, but I have heard that it can be difficult.

What's your current bending procedure? They look thin enough from what I can see, so it must be the combination of heat and moisture that's off. If you're using a heating blanket setup, it might be good to switch to a hot pipe so you can feel how it responds and figure out what it likes (my guess is more heat). There's also Supersoft 2. And if all else fails, you can thin further and laminate after bending.
Author:  timoM [ Thu Jun 05, 2014 12:42 am ]
Post subject:  Re: Side Busting Situation... :(
With all due respect that doesn't look like padauk. Perhaps one of the Asian "pinkwoods". The wood wholesale vendors are pushing them. Looking at your results I would say too much water and/or too little heat.

Tim
Author:  Herr Dalbergia [ Thu Jun 05, 2014 1:21 am ]
Post subject:  Re: Side Busting Situation... :(
This is padouk, bent with too much water and too less heat, I would also switch to a hot pipe, than stuff like this would never happen because you would feel it ;)

cheers, alex
Author:  meddlingfool [ Thu Jun 05, 2014 2:15 am ]
Post subject:  Re: Side Busting Situation... :(
It's padauk for sure. Same supplier, I trust them.

Too much water can yield to rippling but I've never encountered where too much water leads to a full on rupture like that.

Heat is around 320-350f.

The thing is, these were bent the same way as hundreds of other sides in the same benders, which makes me wonder, what happened? I suspect grain runout.
Author:  Colin North [ Thu Jun 05, 2014 2:23 am ]
Post subject:  Re: Side Busting Situation... :(
:-( Looks like classic runout to me.
Author:  Tom West [ Thu Jun 05, 2014 3:46 am ]
Post subject:  Re: Side Busting Situation... :(
No expert on wood ID here but I must say that does not look like any Padauk I have seen. Agree with Herr Rosewood that more heat may be in order.
Tom
Author:  Haans [ Thu Jun 05, 2014 5:12 am ]
Post subject:  Re: Side Busting Situation... :(
Did you use copious amounts of Super Soft II? Did you let it soak in for a few hours?
I have run into flamed maple that was hard to bend for F5's, but it's usually a lack of heating or sugar maple. Bending by hand over a hot pipe is more forgiving as you can feel the point at which it's going to break. Can't do that well with a bender.
Author:  bluescreek [ Thu Jun 05, 2014 5:33 am ]
Post subject:  Re: Side Busting Situation... :(
Padauk is a bear. Lots of heat. I bend it at about 350+ Use wet paper with the wood stack. Definitely not run out . Sand thin to about .080 use wet craft paper and super soft 2. slat wet paper wood wet paper blanket slat.
Author:  klooker [ Thu Jun 05, 2014 5:49 am ]
Post subject:  Re: Side Busting Situation... :(
It looks like most of your breaks are on the bouts as opposed to the waist?

This makes me think not enough heat is getting into the wood because you usually get good heat transfer at the waist because the caul holds the heating blanket tight against the wood where on the bouts you (or I for that matter) have spring clamps holding the sandwich together and it's less than ideal.

I had a similar problem with some Sapele. I got around it by slowing down when I bend the bouts. I move the bout cauls slowly so that I know the blanket is making good contact and try to feel the wood as it starts to give.

On the other hand, if you've bent hundreds of sides, this particular batch may just not want to bend.

Kevin Looker
Author:  mkellyvrod [ Thu Jun 05, 2014 7:25 am ]
Post subject:  Re: Side Busting Situation... :(
Looks like padauk to me (appears darker in photo than it really is). I wonder if you may have bent too fast. It's hard for me to comment because I've only bent one set of padauk sides and one set of bindings thus far, but I encountered no problems. I followed the Todd Stock utube video. Wet kraft paper against the sides and started bending around 250, ending at 320. Didn't use supersoft. Only problem I've encountered like this was on a set of zebrawood (guitar #1). I was using a pipe at the time, and don't think I had the heat right. I chalked it up to my newbie impatience. I typically bend all my sides at about 0.08 inches. Have you bent any sides since just to make sure your heating blanket is working properly?
Author:  meddlingfool [ Thu Jun 05, 2014 10:45 am ]
Post subject:  Re: Side Busting Situation... :(
Yes, we've bent several sets in between the Padauk breaks just to test the blanket, including some orphan mahogany just in case, and several other sets including flamed walnut.

The thing is, we just followed normal routine. Every other time Padauk has been bend friendly. I'm fairly confident it is Padauk, smells right...
Author:  Pmaj7 [ Thu Jun 05, 2014 11:35 am ]
Post subject:  Re: Side Busting Situation... :(
I had 3 sets of curly hondo from the same billet do that. Almost certain it was runout.

bluescreek wrote:
slat wet paper wood wet paper blanket slat.
John, are you using slat on top of blanket these days?
Author:  James Ringelspaugh [ Thu Jun 05, 2014 11:41 am ]
Post subject:  Re: Side Busting Situation... :(
Just a thought... Padauk, like a lot of other African woods such as zebrawood and khaya, is prone to small compression failures which when pressed crack just like your sides. They look like little lightening strikes across the grain and can be tough to spot without wetting the wood with naptha or similar. Here is an extreme example... take a very close look at the next slats in the flitch and see if you find something similar... if you do that wood is good for nothing but headplates and inlay:
Author:  Herr Dalbergia [ Thu Jun 05, 2014 12:48 pm ]
Post subject:  Re: Side Busting Situation... :(
This is never runout...come on...if it would be runout it would tear apart and not breake thru.
James post is also interesting, but I have bent quite a few sides of Padouk and other Pterocarpus species, and they all need to get really hot for bending. it is very clearly for me that these sides have been bent way to cool, because I can not see any burning marks, which would happen a bit if they would have been bent hot enough.

cheers, alex
Author:  bluescreek [ Thu Jun 05, 2014 3:35 pm ]
Post subject:  Re: Side Busting Situation... :(
yes I use the slat on top but only when using wet paper.

Padauk needs a lot of heat.
Author:  meddlingfool [ Thu Jun 05, 2014 4:46 pm ]
Post subject:  Re: Side Busting Situation... :(
Never had an issue bending at 350. Followed the same procedure as other sets...
Author:  bluescreek [ Thu Jun 05, 2014 6:48 pm ]
Post subject:  Re: Side Busting Situation... :(
sometimes you just get a piece that doesn't want to bend.
Author:  Arnt Rian [ Fri Jun 06, 2014 4:17 am ]
Post subject:  Re: Side Busting Situation... :(
Looks like lack of heat to me, too. I would consider sanding the wood thinner, perhaps a lot thinner and laminating something on the inside for strength if necessary, doing the super-soft thing, and using more heat.
Author:  Terence Kennedy [ Fri Jun 06, 2014 8:20 am ]
Post subject:  Re: Side Busting Situation... :(
Two blankets may help as well. One on top and one on the bottom. That plus the brown paper has been great for me.
Author:  Pmaj7 [ Fri Jun 06, 2014 9:38 am ]
Post subject:  Re: Side Busting Situation... :(
Yes, actually the cracks look too narrow to be run out.
Author:  Darryl Young [ Fri Jun 06, 2014 10:33 am ]
Post subject:  Re: Side Busting Situation... :(
meddlingfool wrote:
Never had an issue bending at 350. Followed the same procedure as other sets...


How did you measure that temp of 350F? And were you measuring that temp at the waist (where it appeared to bend fine) or at the bouts near where it split? Also, how long was the blanket at 350F AND in contact with the bouts before you bent them?

I'm thinking out loud but the wood relaxing is a function of temp and time. I've been guilty of not clamping the ends of the sides so it stays in contact with the heat while bending. I got away with it but I was using wood that bends easily. You may need to modify your "standard procedure" when you have wood that is difficult to bend. I'm doubting there is one method that will work on all woods with no changes to time/temp/moisture etc.
Author:  meddlingfool [ Fri Jun 06, 2014 11:45 am ]
Post subject:  Re: Side Busting Situation... :(
I may have a go at super soft...
Author:  Toonces [ Fri Jun 06, 2014 12:21 pm ]
Post subject:  Re: Side Busting Situation... :(
John is right -- sometimes wood doesn't want to bend. I strongly recommend using double sides for this very reason. It is extra work and slightly more expensive but it completely eliminates trouble with bending of difficult woods and ensure stability for woods that want to warp. Moving onto the issue at hand -- I would recommend more water and more heat. Some of these woods have very little oils in them and they are harder to bend because the heat doesn't retain in the wood as well. When hand bending, woods like Cocobolo get and stay super hot against the iron while woods like Mahogany dissipate the heat very quickly. I have found that soaking the woods beforehand has helped me get much better results that when I was just lightly spritzing these woods. Again, oily woods like the Rosewoods can be bent with very little water added but less oily woods really benefit from a good soaking beforehand. I also wrap my sides in aluminum foil to retain the moisture. Everyone has to find their own method but these small changes have made my life a lot easier.

Best of Luck!!!
Author:  RaymundH [ Fri Jun 06, 2014 12:27 pm ]
Post subject:  Re: Side Busting Situation... :(
I have bent two sets of Padauk using Super Soft 2 and John Hall's bender (and technique) and they bent like a dream.

We sprayed Super Soft 2 on both sides thicknessed at .080 then wrapped them in kraft paper overnight to let the softener do it's thing. Next day we just took the sides and re-wrapped them in fresh kraft paper set up the bender and bent them at 320 ish. After the initial cook I put a fan on to cool it off quick then hit it with heat one more time to set it.

I have used Super Soft 2 on Padauk, Cocobolo, EIR, and ZebraWood and for what ever reason the stuff is great!
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