Heat treat and form musings.

[dwardo]

I have recently been monitoring my heat treating, shaping and forming.
Few things I have noticed. Please agree or disagree and would like to hear your thoughts experiences and opinions.

Heat treating for me seems to work best at around 20 inches of draw. By heat treating I am talking light brown for about 15-20 minutes per limb. My laser temp reads around 180DegC which seems to be a happy medium of heat verses penetration. Hotter and the wood just scorches, any cooler and I dont get the colour I want over a time period that isnt glacial.  One thing I have been monitoring is the weight loss over the period of the heat treating, its next to nawt. The last three bows have only lost 0.1 of an ounce. It recovers this weight in a couple of hours so how much moisture are we really losing and this time to hydrate, is it really needed?

In regards to heating reflex and curves in general I have found I only need about 120-130Deg C and no colour change.
I also remove the bow from the form/clamps as soon as the bow is cool. This only takes about an hour rather than the next day or several hours later. Once the wood is roughly at room temperature or slightly above then surely its done moving? If not we would be seeing movement on a warm day and wood would be pretty useless.
The added bonus of this is that you can do all the heat corrections you need to in an afternoon rather than dragging it out for days. These smaller movements seem to make no difference to the weight of the bow and I have taken to just stringing it up a few hours later and getting on with it.

Lets hear your experiences.


 

[JW_Halverson]

I think some serious quantitative work is needed to either prove or disprove a lot of the mythology of heat treating.  And the tool to do that is your laser temp gun!  Marc St. Louis has done a lot with trial and error, but I think the time has come to start putting some science to this process. 

I know I have spent hours getting the "color" right on heat treated limbs and that burns a lot of electricity.  I less time yielded better efforts, I am all for that improvement. 

[dwardo]

I think some serious quantitative work is needed to either prove or disprove a lot of the mythology of heat treating.  And the tool to do that is your laser temp gun!  Marc St. Louis has done a lot with trial and error, but I think the time has come to start putting some science to this process. 

I know I have spent hours getting the "color" right on heat treated limbs and that burns a lot of electricity.  I less time yielded better efforts, I am all for that improvement.

What would be even better is a 3D scanner with an accuracy of a fraction of a MM that can measure the mass properly after heat treating. Not much chance of that. Wonder how accurate Archimedes method is, probably not very.

I hear you on the electricity burning too. I can hear my meter whining over the noise of the heat gun.

[Del the cat]

I did some work with a temperature controlled heat gun (before I melted it by forgetting to leave it nose up to cool off   )
That at least told me the max temp I was reaching, but of course it didn't tell me how far into the limbs it had penetrated.
I've found that a couple of slats clamped to the edges of the bow stop the heat getting to the back and also direct it along the belly giving a more even distribution. It speeds the process a little too.
I still think there's a point where experience, feel and patience trumps instrumentation and youthful impatience.
There is a big difference between heat bending and heat treating... off the top of my head the heat treating was up around 200-220 C whereas heat bending obviously only needs 100C (e.g Boiling water temperature)
Don't get me wrong JW I'm not calling you youthful 
Del
(BTW... I'd originally got my fingers burned (see what I did there?) by rushing at heat treating, merely charring the surface and generally being an ass. The guys on here soon set me straight, and gave me some humble pie to chow down on... V tasty it was too )

[dwardo]

I did some work with a temperature controlled heat gun (before I melted it by forgetting to leave it nose up to cool off   )
That at least told me the max temp I was reaching, but of course it didn't tell mehow far into the limbs it had penetrated.
I've found that a couple of slats clamped to the edges of the bow stop the heat getting to the back and also direct it along the belly giving a more even distribution.
I still think there's a point where experience, feel and patience trumps instrumentation and youthful impatience.
Don't get me wrong JW I'm not calling you youthful 
Del

I just use a normal heat gun Dell and adjust the surface temp of the wood by the height of the gun, then use the laser thermometer reading the surface temp. I have had to bend the handle on all of my recent bows to bring the alignment in and its made a whole lot easier knowing I just set it at 130 max and not have to watch it like a hawk in-case it burns but it gives me enough hea to bend easily. 
Not much help unless you have a Buck Rodgers laser gun though.

[Badger]

  I heat treat everything but I never use the color or browning. I heat the entire limb by going back and forth from handle to tip with my heat gun on high, I go by the smell in most cases but I see a slight color change take place ( not browning) I think I spend about 10 min per limb ( depends a lot on the gun you are using) I let cool for no more than about 30 min then remove. I never use the browning technique and see no need for it. When heating the entire limb in long strokes each end tends to get a bit hotter at the turn around point so a little extra speed is used at the ends. I started doing it this way about 6 years ago.

[Marc St Louis]

You can heat-treat over a fire but there is much to be said for the control you have with a heat-gun.  Up here the cost of electricity varies according to time of day and weekends have a lower cost.  I try to heat-treat when costs are lower.  The method I use has changed a bit since my first experiments with a hot-plate.  I still temper to the same degree though.  If you have doubts about your methods then watch my vids in the Library, I know the sound sucks  .

[blackhawk]

Dwardo....your observations n findings match mine to a T....a few others and I have been trying to tell people for the last 3 years that you can take it off the form once close to room temp and start working it whenever....I did a lot of weighing the staves before and after heat treating and never had one stave lose more than a tenth of an ounce like you....and a tenth of an ounce is a fraction of a a percentage point in moisture content...if you know your staves general mc within a percent point one way or another(which we should anyways) then you know your stave is ready to work right off the form the same day...I might rattle some folks opinions here,but the whole waiting days after tempering is nothing but a hogwash myth...if ya wanna wait then fine by me...that's your prerogative to do so....but I and more than several others have more than disproved the whole you need to wait theory....and have built oodles of bows this way...now lately I do wait,but that's cause of I'm not as much in a rush anymore these days,and its not because to wait for it to "rehydrate" as they say...I also do all my corrections and tempering in one heating session....and I temper after floor tiller when I'm ready to brace it and I can feel I have ~ ten pounds left in weight..and I think I temper a lil heavier and darker than what your describing as well possibly

@badger....do you think your method is actually tempering the wood,or just shaping it? I lean to more just shaping it than actually tempering it IMHO....

These thread s always open a can of worms....let's see his much worms this one spills..lol

[dwardo]

  I heat treat everything but I never use the color or browning. I heat the entire limb by going back and forth from handle to tip with my heat gun on high, I go by the smell in most cases but I see a slight color change take place ( not browning) I think I spend about 10 min per limb ( depends a lot on the gun you are using) I let cool for no more than about 30 min then remove. I never use the browning technique and see no need for it. When heating the entire limb in long strokes each end tends to get a bit hotter at the turn around point so a little extra speed is used at the ends. I started doing it this way about 6 years ago.

How long do you leave it for before going at it again? When I say brown thats probably a poor description, more golden than anything. A slight colour change.

You can heat-treat over a fire but there is much to be said for the control you have with a heat-gun.  Up here the cost of electricity varies according to time of day and weekends have a lower cost.  I try to heat-treat when costs are lower.  The method I use has changed a bit since my first experiments with a hot-plate.  I still temper to the same degree though.  If you have doubts about your methods then watch my vids in the Library, I know the sound sucks  .

I have watched and read everything you brilliantly put into the idea and its made a vast difference to every bow I have made thankyou.
What I am trying to do is quantify things so its easier for us beginners to replicate and implement. I will go back and re-read your chapter on HT in the Bowyers bible.

[Buckeye Guy]

Now you young wipper snappers listen up ! 
I agree as much as I can tell with you about your findings its just that my meter( fingers ) says that is getting kinda hot to be touching for more than a few seconds when the temp is right for bending and it reads man I am not sure I should have touched that when its heat treating!
That's about as scientific as I like to get but you folks go ahead just make sure your having fun while your doing it !!
Wish I had more time to respond , gota go

[dwardo]

Dwardo....your observations n findings match mine to a T....a few others and I have been trying to tell people for the last 3 years that you can take it off the form once close to room temp and start working it whenever....I did a lot of weighing the staves before and after heat treating and never had one stave lose more than a tenth of an ounce like you....and a tenth of an ounce is a fraction of a a percentage point in moisture content...if you know your staves general mc within a percent point one way or another(which we should anyways) then you know your stave is ready to work right off the form the same day...I might rattle some folks opinions here,but the whole waiting days after tempering is nothing but a hogwash myth...if ya wanna wait then fine by me...that's your prerogative to do so....but I and more than several others have more than disproved the whole you need to wait theory....and have built oodles of bows this way...now lately I do wait,but that's cause of I'm not as much in a rush anymore these days,and its not because to wait for it to "rehydrate" as they say...I also do all my corrections and tempering in one heating session....and I temper after floor tiller when I'm ready to brace it and I can feel I have ~ ten pounds left in weight..and I think I temper a lil heavier and darker than what your describing as well possibly

@badger....do you think your method is actually tempering the wood,or just shaping it? I lean to more just shaping it than actually tempering it IMHO....

These thread s always open a can of worms....let's see his much worms this one spills..lol

Great info thanks Not having to leave the bow in the form to "set" means like you I can get all the alignments done far more quickly. Often I want the bow off the bench so I can get on with other work and not having to wait hours lets me do this.
Yesterday I heat treated the belly of a bow to golden brown, didnt add any reflex just removed half inch or so of follow and straightened up a natural kink. I didnt want to over-power an already quite stressed little bow. I then went to do some chores for a couple of hours and came back to the bow which had already regained its meagre  .1 ounce and braced it up. Shot a few dozen arrows with no signs of stress and a little more spring in its step. Had to scrape a little here and there to even it up again but all was well.

Now you young wipper snappers listen up ! 
I agree as much as I can tell with you about your findings its just that my meter( fingers ) says that is getting kinda hot to be touching for more than a few seconds when the temp is right for bending and it reads man I am not sure I should have touched that when its heat treating!
That's about as scientific as I like to get but you folks go ahead just make sure your having fun while your doing it !!
Wish I had more time to respond , gota go

If we could only import "experience" into an email or web-page and send it across the world. 

[Pappy]

I don't know that it matters how long you leave one, I usually leave it overnight if I have made some serious corrections or steamed it,I heat for corrections and reflex about like Guy,when I can touch it but know I don't want to hold it, I heat treat like Steve,no real rhyme or reason,just buy watching the wood color and smell.  I do usually wait a day or so after heat treating but don't think that matters,just am never in a big hurry so why rush it. Not sure on weight change,never weighted one in my life. You can tell I am a real scientific kind of guy. No worm here Chris,as I have said many many times,to each their own. you don't have to do it my way,just please don't tell me my way is wrong.
  Pappy

[dwardo]

I don't know that it matters how long you leave one, I usually leave it overnight if I have made some serious corrections or steamed it,I heat for corrections and reflex about like Guy,when I can touch it but know I don't want to hold it, I heat treat like Steve,no real rhyme or reason,just buy watching the wood color and smell.  I do usually wait a day or so after heat treating but don't think that matters,just am never in a big hurry so why rush it. Not sure on weight change,never weighted one in my life. You can tell I am a real scientific kind of guy. No worm here Chris,as I have said many many times,to each their own. you don't have to do it my way,just please don't tell me my way is wrong.
  Pappy

It isn't my intention to say anyone's way is wrong Pappy and hope it doesn't come across that way.
This lovely resource that we are all lucky to have (the interweb) and its brilliant for sharing ideas but what it does lack is the ability to share feelings, touch, gut-instinct, experience etc.
For instance we talk about draw weight in specific terms, draw-length and bow length. These are numbers that are easy to convey in text and can be measured and replicated at the other in end real life. It is much harder to convey temperature a smell or a feel.

Probably not explaining my self very well here.

[PEARL DRUMS]

Welcome aboard Dwardo!

[Pappy]

I understand and not a problem at all,didn't take it that way,I love seeing the intrest you guys are taking , I do most of my teaching on the personal level,so it is easier for me to relay what I am saying. Letting them see/smell and touch what I am talking about. It is much harder to put that into words. Some of us just do
things a certain way because we always have, it's how we learned and see no reason to change or make it more complacated that it is for us.What you are doing is a good thing,some folks need numbers or measurements and some don't, for those that do this is a great way and place for them to get that. Carry on,see still no worms.
   Pappy