Bending problems

[benjoo]

Hey guys,
i am having trouble with the bending procedure. I've built a Fox style bender out of plywood and use a 600W lamp as a heat source. I place my woods between two sheets of 0.5mm thick Aluminium strips (i intend to order the stainless steel 0.3mm version which stays flat after bending and also a heating blanket).

I tried beding several sides and purflings and everytime after getting the sides out of the bender it doesnt stay in position. I mean it bends back and I would always have to "afterbend" it using a hotpipe. I never saw that on videos where people bend sides with a Fox bender. Where is the root of this problem? I think the the temperature is high enough since the sides bend quite easily and quick. I also tried letting the side stay in the form for a week and i even turned on the heat after some days for about 10 mins, but still the same result so I really want to know what it is and hope some of the experienced folks here could help me.

Benjoo

[tippie53]

I started with them , went to the heat blanket and will never go back. It is all about heat control and light bulbs just don't do it.

First can you post some pics of your rig and what is the thickness of what your bending and do you know what the heat is? You need to control the heat and get the wood to about 274 to 325 and let it for a few minutes

we can help we just need more information.

[benjoo]

Thanks for your fast reply!
I've bent Maple, Indian Rosewood and Mahagony with a thickness of about 2.0-2.5mm (0.08-0.1"). Problems were always the same.
I think i went above your mentioned temperature since i had some burning marks sometimes ( I guess i let the temperature turned on for too long). So my question is wheather it is a problem for the bending process when the temperature goes above 325 (not to mind the burning, just the wood physiology itself). I usually let temperature turned on for 5 mins after they are clamped in their final position; I also finish the bending process in more or less than 4 minutes like you explain in your videos.
I've uploaded some of my recent tries with the bindings, maple and Rosewood, i think the Rosewood one shows it quite obvious.

Benjoo

[tippie53]

your binding appear too thick I use 1/16 in feel free to call me

[benjoo]

I had those problems with thinner materials, too.

Benjoo

[tippie53]

2 things that are a problem
1 light bulbs
2 how long are you letting them in the bender and what is the actuall heat attained?
if you are not using a thermometer the best your doing is guessing.

my experience is telling me your not hot enough and not enough time in the bender.

[benjoo]

Yeah i find it quite annoying to use the light bulbs, it doesn't provide an uniform temperature all along the bender and the only reason why I don't have heat blakets yet is that i need the controller also which is very expensive.
I haven't measured the temperature but isn't it enough when the sides start to sizzle when coming in contact with the steel sheet well obviously it isnt...I think i will just spend the money for the blanket in the near future and see if that is the solution.
Thank you so far!

Benjoo

One of our members has a heating blanket and controller in the Trading Post section.
Here's a link: viewtopic.php?f=23&t=7135
Perhaps it is still available. PM David if interested.

[benjoo]

Problem is that I am not from the states, would buy it immidiately for that price otherwise...

Benjoo

[tippie53]

3 bulbs in the bender would be close to ideal.
I used 200w at the upper and lower bout and 150w at the waist