Author Topic: Radiant heater  (Read 3263 times)

0 Members and 1 Guest are viewing this topic.

Offline DC

  • Member
  • Posts: 10,396
Radiant heater
« on: February 16, 2017, 01:12:03 pm »
A while back Beadman asked to see my radiant heater(a long while, sorry Ed), I finally got it out again to treat this yew bow. I just tore the element and insulating posts out of a 1500 watt heater. At about 2" away from the bow it took about 15 minutes to turn the bow brown. That distance might be a bit close. My laser thermometer said the bow was about 525 degrees F. I'll move it out to 3" for the other limb. The browning seems nice and even but maybe a bit hotter in the middle. It's not any good for limbs with any character so it won't replace the heat gun but I think it will be faster and make a nicer job once I sort it out.

Offline Pat B

  • Administrator
  • Member
  • Posts: 37,637
Re: Radiant heater
« Reply #1 on: February 16, 2017, 01:14:51 pm »
Just be sure the heat doesn't wrap around to the back.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline DC

  • Member
  • Posts: 10,396
Re: Radiant heater
« Reply #2 on: February 16, 2017, 01:17:47 pm »
The whole reason for making this was my idea that radiant heat wouldn't wrap around the back. There is no hot airflow involved. As soon as it comes off the caul I will check for that. Another 10-15 minutes :D

Offline bjrogg

  • Member
  • Posts: 11,018
  • Cedar Pond
Re: Radiant heater
« Reply #3 on: February 16, 2017, 01:37:42 pm »
Very interesting DC
Bjrogg
A hot cup of coffee and a beautiful sunrise

Offline DC

  • Member
  • Posts: 10,396
Re: Radiant heater
« Reply #4 on: February 16, 2017, 01:54:47 pm »
No sign of scorching on the back at all. It seems to be hotter in the middle. I don't know if that's a characteristic of a heating coil but I'm going to have to bend it a little ore to move the middle farther away. Second limb was 3" and took substantially longer, about 20 min. I'll go for a walk and see how the reflex hols when I get back. 

Offline Stick Bender

  • Member
  • Posts: 2,003
Re: Radiant heater
« Reply #5 on: February 16, 2017, 02:31:17 pm »
Good idea hope it works out !
If you fear failure you will never Try !

Offline aaron

  • Member
  • Posts: 1,037
Re: Radiant heater
« Reply #6 on: February 16, 2017, 02:55:00 pm »
is that a hollow limb bow? never did understand those...
Ilwaco, Washington, USA
"Good wood makes great bows, but bad wood makes great bowyers"

Offline DC

  • Member
  • Posts: 10,396
Re: Radiant heater
« Reply #7 on: February 16, 2017, 03:19:27 pm »
No it isn't, it's the browned part looks like a shadow. I never noticed it until you mentioned it.

Offline Aaron H

  • Member
  • Posts: 3,437
Re: Radiant heater
« Reply #8 on: February 16, 2017, 04:45:20 pm »
Very interesting

Offline BowEd

  • Member
  • Posts: 9,390
  • BowEd
Re: Radiant heater
« Reply #9 on: February 16, 2017, 06:29:20 pm »
Interesting yes.That will work for bows that are worked down enough that you can clamp down right away to the profile you want.20 minutes is'nt long.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline DC

  • Member
  • Posts: 10,396
Re: Radiant heater
« Reply #10 on: February 16, 2017, 06:44:14 pm »
It seems that electric heater coils get hotter in the middle. So it charred the center of the limb but not the end or the fade and I couldn't bend it enough to even the temp. I had to stagger the coils, there are two, which meant tearing it all apart. I'm testing it now to see if it chars a board evenly.

Offline Springbuck

  • Member
  • Posts: 1,545
Re: Radiant heater
« Reply #11 on: February 16, 2017, 07:14:45 pm »
You can still get some wrap around on the heat, if the form is too wide, but less for sure.  I use an electric griddle that had a removable griddle part over the elements, but it only does half a limb at a time!  I'm Jelly.

Offline bjrogg

  • Member
  • Posts: 11,018
  • Cedar Pond
Re: Radiant heater
« Reply #12 on: February 17, 2017, 08:01:55 am »
I like how many creative people we have on this site. Might not solve all the worlds problems but sure solve ours.
Bjrogg
A hot cup of coffee and a beautiful sunrise

Offline DC

  • Member
  • Posts: 10,396
Re: Radiant heater
« Reply #13 on: February 17, 2017, 11:43:10 am »
You can still get some wrap around on the heat, if the form is too wide, but less for sure.  I use an electric griddle that had a removable griddle part over the elements, but it only does half a limb at a time!  I'm Jelly.

Do you put the limb over the heat or the heat over the limb? The way mine is the air flow from convection would be going up, away from the bow so the back will always be in cool air. That's my theory anyway :D :D

Thank you Bjrogg.

Offline k-hat

  • Member
  • Posts: 1,058
Re: Radiant heater
« Reply #14 on: February 17, 2017, 06:03:22 pm »
I been planning to scavenge heating coils and do something like this myself.  Best bow toaster i've had was actually a gas spaceheater in the last house I rented.  It had the ceramic diffusers that made this beautiful wall of evenly distributed heat, and it was wide enough I could set my bow on the form sideways in front and toast the whole limb in under 20 min.  Sure beats sitting with the heat gun for hours.  It also created a very uniform charring, no hotspots at all.  Of course the belly is curved on the form, but that I think was good because the hardest working parts got toasted more, then it tapered off toward the tips.  I sure miss that thing. :'(