Bending misery

Timbuck · Feb 21, 2015

Yes ! The wrinkles are back..I tried the washing up liquid trick..also Chucks CA glue method ... I tried bending hotter, more slowly, and even praying to St Luthier all to no avail.....But I give in..When I've finished this cuppa tea I'm going back in the workshop and I'm going to destroy this batch of side wood before it makes me mentally ill :wallbash:....its a weird type of South Amercan mahogany with a very soft and wooly texture more like Balsa...its ok for tops and backs but sides NO !:wtf:

Pete Howlett · Feb 21, 2015

I have a parcel of 2 surplus to requirement heat blankets plus controllers 110V which I will ship to you on Monday ken. You will be able to heat above and below and even use Chuck's envelope method.

I've got some of that - really hard to work. I have also some of the real stuff - Swietenia Mahagoni - cuban mahogany: brick red and ready for resawing into bookmatched sets

RPA_Ukuleles · Feb 21, 2015

Wood gonna do what wood gonna do.
Resistance is futile.

Dan Uke · Feb 22, 2015

sell it to all those luthiers who said it's just cosmetic!

Timbuck · Feb 22, 2015

nongdam said:
sell it to all those luthiers who said it's just cosmetic!

Too late !! I've fixed the problem....I feel a lot better now

BlackBearUkes · Feb 22, 2015

Excellent solution!

Dan Uke · Feb 22, 2015

Here's a link of the wrinkles you spoke of last time

http://forum.ukuleleunderground.com/showthread.php?97075-Wrinkles-in-the-waist

sequoia · Feb 22, 2015

Wow! The nuclear option... Great picture.

connor013 · Feb 22, 2015

"And he took the image he had fashioned, and set it in a great furnace, and gave it to the fire."

Kevin Waldron · Feb 23, 2015

Ken,

We've had this happen occasionally and think that it is caused by Case Harding of the material when it is dried ( usually this occurs when the material is allowed to dry to quickly with to much heat )...... Your wrinkles are actually micro-fractures we think.... One solution to help remove Case Harding is to re-heat material in some kind of chamber with moisture at around 90 degrees F for several days with the moisture not being allowed to escape and allowed to slowly be re-absorb into the material. When done with this you can then attempt to re-dry slowly with a maximum drying temperature of 175 degrees F and do not go below 6% moisture value. ( We have two kilns and normally we introduce a buck of water close the outside fan exhaust and allow the material to adjust for several days at 90 degrees........ then re-heat and slowly dry)

Blessings,

Kevin

BlackBearUkes · Feb 23, 2015

When the wood fractures, nothing is going to restore it to an unfractured state. Broken wood fiber remains broken.

Kevin Waldron said:
Ken,

We've had this happen occasionally and think that it is caused by Case Harding of the material when it is dried ( usually this occurs when the material is allowed to dry to quickly with to much heat )...... Your wrinkles are actually micro-fractures we think.... One solution to help remove Case Harding is to re-heat material in some kind of chamber with moisture at around 90 degrees F for several days with the moisture not being allowed to escape and allowed to slowly be re-absorb into the material. When done with this you can then attempt to re-dry slowly with a maximum drying temperature of 175 degrees F and do not go below 6% moisture value. ( We have two kilns and normally we introduce a buck of water close the outside fan exhaust and allow the material to adjust for several days at 90 degrees........ then re-heat and slowly dry)

Blessings,

Kevin

Timbuck · Feb 23, 2015

Kevin Waldron said:
Ken,

We've had this happen occasionally and think that it is caused by Case Harding of the material when it is dried ( usually this occurs when the material is allowed to dry to quickly with to much heat )...... Your wrinkles are actually micro-fractures we think.... One solution to help remove Case Harding is to re-heat material in some kind of chamber with moisture at around 90 degrees F for several days with the moisture not being allowed to escape and allowed to slowly be re-absorb into the material. When done with this you can then attempt to re-dry slowly with a maximum drying temperature of 175 degrees F and do not go below 6% moisture value. ( We have two kilns and normally we introduce a buck of water close the outside fan exhaust and allow the material to adjust for several days at 90 degrees........ then re-heat and slowly dry)

Blessings,

Kevin

With respect to your case hardening theory Kevin, I don't think it applies in this case as I had only a few hours before bending, thickness sanded the sides down from .365" to .075" so any hardened outer skin will have been removed before bending...I know it's not wood related but when I was in engineering and involved with bending metals...the outer bend stretches and the inside of the bend compresses .. So on a pipe bend you got a thick inner wall and a thin outer .....So I figure that this wood can't handle compression of the fibres on my bender....if I had a bender that gripped and supported the wood firmly before bending (like the one I've seen at Taylor Guitars HERE https://www.youtube.com/watch?v=UxFINvii-KQ ) then my problems would be over.

So now back to the laboratory c/w new idea in head

Michael N. · Feb 23, 2015

I sometimes get those compression marks when bending the softer woods eg. Spruce or Cedrela. I can't ever recall seeing them on harder woods like Cherry, Maple, Walnut or any of the Rosewoods. Having said that I've never had them with Cypress, which is a pretty soft wood - certainly no more dense than Cedrela. Perhaps it's a combination of the wood density and the grain structure.

Kevin Waldron · Feb 23, 2015

I wasn't referring to after the fact bending and removing the case harding........ we typically bend 1 set at a time...... after the first observance of fracture..... I'd consider doing something else with the raw wood...... Still think this is a case of Case Harding........ we have kiln dried several hundred thousand board feet of lumber......and do have a fairly good understanding of what happens..... do what you wish.

Blessings,

Kevin

Timbuck · Feb 23, 2015

I've just made up a new set of mahogany side ribs..Looks very much like the duff stuff, only this time it's not soft wooly wood, it's bony type wood and bends beautifuly .. no cracks or wrinkles, and now i'm happy again.:cheers:

tinguitar · Feb 24, 2015

nongdam said:
sell it to all those luthiers who said it's just cosmetic!

troll.

nongdam said:
Here's a link of the wrinkles you spoke of last time

http://forum.ukuleleunderground.com/showthread.php?97075-Wrinkles-in-the-waist

Failed troll tries again.

Inksplosive AL · Feb 24, 2015

Rob-C said:
troll.

Failed troll tries again.

Useless reply is useless. When in doubt call a PRO!

Dan Uke · Feb 24, 2015

Rob-C said:
troll.

Failed troll tries again.

So are you going to buy it next time?

Pete Howlett · Feb 24, 2015

Blankets on the way Ken so you can try Chuck's method which is the poor man's way of solving the support problem... might require a little help from Mrs Timbuck

Timbuck · Feb 25, 2015

Pete Howlett said:
Blankets on the way Ken so you can try Chuck's method which is the poor man's way of solving the support problem... might require a little help from Mrs Timbuck

Thanks Pete...The blankets and controllers arrived today..Pity they are not 240 volt units

...But I do have a voltage dropping transformer
somewhere in the shed..that should be ok to run them

....I'll let you know if i can get them working or not..Then I'll see if I can fit them to my bender...Once again thanks

Bending misery

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