Backbowed Neck will not cooperate!

[Mario Kessels]

Dear all,

I wish you all a happy and healthy new year. I am working on a musicman 7 string guitar with backbow in it. Obviously the trussros can only tighten so no use there.
I have been bending the neck in my jig with heat blanket up to 95C for like 30 mins or so. Looks good for a few days, but eventually there is some backbow again. What to do? Can I go higher with the temp you think??

best regards Mario

[Barry Daniels]

I would apply the heat a bit longer (like an hour) then clamp the neck into a proper relief and let it sit for a few days before unclamping. There will always be some springback so clamp with a little more relief than you need.

[Mario Kessels]

Thank you Barry. I will do that. I am actually clamping with some relief during the heating proces already. Only thing I wonder is if there is a even bow along the whole neck when doing this. I have placed the blanket on app 1cm thick multiplex and the neck on top. Under the multiplex I have plec a small woodstrip to cause the bow while clamping the neck down on both sides. I think other than making a full size curved jig/ support that supports the whole neck in a radius this is the best I can do I think.

[Mario Kessels]

I changed the setup, i think the solution with a small inclination in the middle of the neck causes a non uniform radius. Now I made a radius in the wood underneath with a plane. Lets see with longer baking