Bending... What am I doing wrong?

[Jim_H]

I don't know much about bending and nothing about Paduak.

That break does look fairly clean, like the wood snapped off cleanly as opposed to a splintered break, which is what I would expect.

I wonder if the Case Hardening John mentioned is the culprit. It almost seems like the wood got very brittle at some point and just kinda snapped...

[hummingbird]

It actually cracked and splintered along that line. When I took it out of the form it broke off very easily.

[tippie53]

You have to be careful as if you wait too long to bend you go past bendability and it gets case hardened at that point it is like untying a pretzel
Think of water being an anti scorch agent . Call me if you need to

[Ken Hundley]

Sorry I am just getting to this...I have bent 4 sets of sides now, and only cracked one trying to do a cutaway. I have bent them form .075 to .083"....the .083" cracked around the cutaway. I used my lightbul-based bender (I know, I know).

1. Pre-heated bender until metal slats sizzled. I use one under and one over...
2. While preheating, I wrap the sides in tinfoil to eliminate scorching and oil transfers to metal. both sides of each peice are lightly spritzed with water.
3. When hot enough, I remove slats from heater, then lay the side into the slats, and put the sandwhich in the heater, lights still on.
4. I slowly begin cranking my waist clamp down. (I need to improve mine, just a section of stairway hand rail...works fine on OM, but seems to just barely start to feather-crack the waist on the jumbos)
5. Once the waist is clamped, I fairly quickly bend and clamp the lower bout....takes about a minute.
6. Now I go for the upper bout, and spend a little more time slowly bending it...but not much more time. You will know immediately if it will bend quickly or not, it either starts to curve right away, or stays fairly stiff. If stiff, I will bend as much as I can, hold for 30 seconds to allow for more heat penetration, then bend some more. Eventually, it gets clamped.
7. Once it is fully clamped, I reset my timer for 15 minutes. If I start seeing steam anywhere, I move my dimmer switch to about 50-60%, again to prevent scorching.
8. When the timer shuts it off, I pull the mold off of the heater and let it cool to ambient temperature, 20-40 minutes depending on the weather. Once the side has cooled in the form to ambient, I pull it out and get minimum springback.

It is a crude bender, but it has bent a dozen sides for me so far. I broke one two zebrawood sides, and one padauk, all in the cutaway area.

I will be re-working it this winter to make it more user-friendly, and will post pictures of it when I do. I will probably keep it as a bulb bender (until I get a funded build, I suppose, and can afford blankets), but it will be easily converted to a non-bulb bender.

I cant recall, did you support both sides during your bend?

I wonder if foil wrapping helps force the steam deeper into the wood, since it can't escape.

I would try the next time taking the side below .080", and see if that works. it is such a beautiful wood, don't give up on it yet. Good luck, and let us know how it works out.

[hummingbird]

Thanks everyone. Ill try...

More water
A little more heat
Start bending sooner
Foil wrap
Bend slowly till it stops then wait 30 second till continuing bend

Ill let yall know how it goes.