Primitive Archer

Main Discussion Area => Bows => Topic started by: wvarcher on August 20, 2011, 01:40:49 pm

Title: Heat gun to lower MC
Post by: wvarcher on August 20, 2011, 01:40:49 pm
     Anybody ever cheat and use a heat gun to lower the Moisture content in a floor tillered bow?  I want to finish tillering a pyramid board bow and would like to get the MC down around 9%.  The bow has been in a hot box for about a week and the humidity meter inside the box is reading 65%.  I'm guessing it's stayed around 70 degrees inside the hot box with one 40W bulb on.
Title: Re: Heat gun to lower MC
Post by: sonny on August 20, 2011, 01:54:03 pm
the heat gun will certainly drive moisture out of your bow but it'll return shortly.
Title: Re: Heat gun to lower MC
Post by: Pat B on August 20, 2011, 02:19:55 pm
Keeping your stave in the A/C in your house will reduce the M/C and maintain low M/C.
 
Title: Re: Heat gun to lower MC
Post by: wvarcher on August 20, 2011, 02:24:13 pm
I guess its a question of how long to heat the limbs and can it be done to heat the entire limb enough to remove moisture evenly.  Less wood to heat as you move toward the tips.
Title: Re: Heat gun to lower MC
Post by: wvarcher on August 20, 2011, 02:28:37 pm
Keeping your stave in the A/C in your house will reduce the M/C and maintain low M/C.
 

I want to get the MC down quick so i can finish the bow today Pat.   
Title: Re: Heat gun to lower MC
Post by: Pat B on August 20, 2011, 02:29:48 pm
You don't want to over dry the wood or you will have to wait for it to rehydrate.
Title: Re: Heat gun to lower MC
Post by: wvarcher on August 20, 2011, 02:33:32 pm
Pat, yep i am worried i might get it too dry. :(
Title: Re: Heat gun to lower MC
Post by: Primitive1 on August 20, 2011, 02:51:33 pm
I've played this dangerous game in the past and more often than not, lose.  One of my favorite parts of the Bowyer's Bible mention's (in regards to rushing and hogging a lot of wood off with power tools; '...immediately stop and go stick your head in a bucket of water...'.  I remind myself of that everytime I start getting excited or rushed and make the deliberate, hard decision to step away from my work.  I find that when I don't listen to that message, I lose a lot of valuable time and work...  My suggestion in this case would be to keep your bow in the hot box until you get to the moisture content you're looking for and don't rush it.  Using a heat gun to hasten the process could weaken the wood unnecessarily and you're just asking for trouble (thicker sections will have a higher moisture content as compared to the thinner sections).  Cheers, P1.
Title: Re: Heat gun to lower MC
Post by: wvarcher on August 20, 2011, 03:05:17 pm
I chickened out.  I'm probably gonna just stick it in my tuck until later 2day.  Its going to get up to 87 degrees here and that should remove some moisture.  Thanks guys!   
Title: Re: Heat gun to lower MC
Post by: Holten101 on August 20, 2011, 03:08:03 pm
I do it....or sort of.

I have a hard time to get MC low enough because of relative high humidity were I live (Denmark). So instead of letting my bows re-humidify for for days after heat treating I aim to let it rest for anly one day and night, then I seal it, and let it rest a few days to a week to let the wood re-distribute the moist that has survived the heat treating.

I have great succes with wych Elm with that method...and catastrophic failures with yew. So I ONLY do it with Elm and white woods like hazle and maple.

Cheers
Title: Re: Heat gun to lower MC
Post by: Pat B on August 20, 2011, 03:53:19 pm
Under normal conditions wood dries at 1" per year.
  What is the M/C of your bow now?  It will loose and gain moisture even after a finish is added as the R/H goes up and down.
Title: Re: Heat gun to lower MC
Post by: wvarcher on August 20, 2011, 04:20:52 pm
Pat, i think my bows MC would be about 12%.   For the last week, it was kept in my hot box.  average temperature and humidity was 70 degrees and 65% humidity. 
Title: Re: Heat gun to lower MC
Post by: Pat B on August 20, 2011, 04:29:48 pm
Go ahead and seal it the way it is. When you're not using the bow, after the finish has cured, keep it in the hot box or in your A/C house and you will be fine!