Problem bending sides

[Charlie Sanders]

I just attempted to bend some Mahogany sides, with a cutaway, thickened to .87-.90 in a Fox style bender. When I took them out there was what I can only describe as "wrinkles" or "ripples" at the waist and cutaway on the outside. It also occurred on the inside at the adjacent part of the cutaway. I wrapped the sides in foil with a light spritzing of water, slat-wood-heating blanket-slat, started to bend around 250 degrees then cooked around 350 for 5 minutes then cooled and removed. I used the LMI temperature controller. Does anybody know what happened to cause this. I bent a second piece with same results. These are practice sides from LMI, I believe they are Mahogany.

[Glen H]

Mahogany can be a bit difficult to bend sometimes.  My guess, knowing nothing more than your description is you started bending a bit under temp, especially for Mahogany.  Also think your wood was a slight bit thick.  My max thickness is .85 and .75 on the cutaway area.  Good thing to practice.

[Charlie Sanders]

Thanks Glen I will try with thiner sides.  What do you recommend as far as a temperature to start bending?

[Charlie Sanders]

 Here a couple of pics of my bending issue.

[Glen H]

Charlie, unfortunately those are good old cracks. I start being at about 325 or 350 and stay there. Get hotter, thin more, and give it another go.

[Charlie Sanders]

 Thanx Glen, I will try again today.  I am also wrapping the wood in foil,  I have heard of people using parchment paper as well,  what is the difference?

 I did not expect cracks to look like that,  it looks more like the wood is compressing in those areas.  I can sand them out,  they don't go all the way through to the other side.  i have only bent by hand before, so I have never seen this.  Thanx again for your input, much appreciated.

  

[Glen H]

I’ve never used foil or paper. I think some guys use that to keep resins from staining their bending slats as well as keeping moisture in the wood. Koa creates a green mess sometimes. I have had cracks like those that I was able to sand out, similar to yours. I also saturated them with CA to prevent them from spreading.

[Charlie Sanders]

I always experienced cracks on the convex side when hand bending, I have never seen them on the concave side, so I find this very puzzling,  plus I have never bent Mahogany, only maple.  I also experienced the foil leaving small wrinkles in the wood, maybe because mahogany is so soft compared to other woods.  So you only have the bare wood in contact with the blanket and slat?