Primitive Archer

Main Discussion Area => Bows => Topic started by: JonW on April 23, 2019, 01:35:59 pm

Title: Reflex caul
Post by: JonW on April 23, 2019, 01:35:59 pm
I made my old caul using a formula with vertical and horizontal lines and making the curve where they intersect. I got the formula somewhere online but can't find it now. Anyone know the formula I'm talking about?
Title: Re: Reflex caul
Post by: Bayou Ben on April 23, 2019, 02:59:42 pm
I don't have a specific formula.  But this has worked for me.

Figure out how much reflex you want, and where you want it.  For instance, you want 4" of reflex, starting 14" from the end. 
Now divide both of those measurements by lets say 7.  So starting 14" from the end, mark your form horizontal every 2".  Then mark your vertical every .57".  Connect the marks as per the picture. 
If you want your curve to be more precise, divide your measurements by a higher number. 
I draw them to scale on paper 1st to get the curve I'm after.
Title: Re: Reflex caul
Post by: willie on April 23, 2019, 05:12:52 pm
would there be merit in trying to approximate a curve that would be the same as the deflection the limb would undergo?

the shape of the curve being dependent on the width/thickness of the limb shape in question?
Title: Re: Reflex caul
Post by: bradsmith2010 on April 23, 2019, 06:01:54 pm
my friend had one, and I traced his,, :)
Title: Re: Reflex caul
Post by: IrishJay on April 23, 2019, 06:23:16 pm
I typically just use a batten (1/4" dowel works well). Measure the depth of the curve across the width of your board and place a finishing nail, measure the length of the curve along the length of the board. Place the batten against the nails and push on the center of it to bend it to a nice parabolic shape between your 2 end points, the trace along the batten.
Title: Re: Reflex caul
Post by: Bayou Ben on April 23, 2019, 07:19:26 pm
Sorry, after re-reading my post I realize I have a way of complicating things. 
2” horizontal for 1/4” vertical should give you a nice shape for general straightening and adding a little reflex.
I think it was one of Steve’s post where I got this original idea.
Title: Re: Reflex caul
Post by: JonW on April 23, 2019, 07:31:38 pm
Sorry, after re-reading my post I realize I have a way of complicating things. 
2” horizontal for 1/4” vertical should give you a nice shape for general straightening and adding a little reflex.
I think it was one of Steve’s post where I got this original idea.

I got my original formula by dividing my length in half. Vertical marks every six inches but I can't remember the measurement for my horizontal lines.
Title: Re: Reflex caul
Post by: osage outlaw on April 23, 2019, 07:51:17 pm
Gary Davis showed how to make a caul like that on his Rattlestick DVD.  He gave the measurements
Title: Re: Reflex caul
Post by: JonW on April 23, 2019, 08:20:56 pm
Gary Davis showed how to make a caul like that on his Rattlestick DVD.  He gave the measurements

Do you remember Gary's measurements Clint?
Title: Re: Reflex caul
Post by: osage outlaw on April 23, 2019, 09:10:03 pm
I can watch it in the morning and let you know.
Title: Re: Reflex caul
Post by: Bayou Ben on April 23, 2019, 09:11:54 pm
I found the thread that I got this idea from. 
Attached is Badger’s responses on paleoplanet. 
Apparently this is the method that Gary Davis describes. 
Title: Re: Reflex caul
Post by: Bayou Ben on April 23, 2019, 09:15:05 pm
Forgot this one
Title: Re: Reflex caul
Post by: Selfbowman on April 25, 2019, 06:03:26 am
I did not know there was a formula! I just been bending a piece of wood or glass to what I think looks good.
Title: Re: Reflex caul
Post by: Knoll on April 25, 2019, 07:37:36 am
Not sure there's a "definitive formula".
Some of us just can't have fun unless there's a bit of math/measuring involved.
 :BB     >:D     :BB
Title: Re: Reflex caul
Post by: JonW on April 25, 2019, 09:12:41 am
I did not know there was a formula! I just been bending a piece of wood or glass to what I think looks good.

Arvin old dogs can learn new tricks!
Title: Re: Reflex caul
Post by: Selfbowman on April 25, 2019, 03:15:17 pm
Not sure about that Jon. That algebra makes me look dumb. Maybe I am.
Arvin
Title: Re: Reflex caul
Post by: SLIMBOB on April 25, 2019, 03:27:20 pm
Me too.  Bend it till it looks right.  I didn't even know there was a formula.
Title: Re: Reflex caul
Post by: TRiggs on April 25, 2019, 06:55:10 pm
OK I'm kinda simple I wanna know why you just can't take a bow you have re curved and just lay it out on what your going to make a new caul from draw it cut it sand it call it good ???
Title: Re: Reflex caul
Post by: Bayou Ben on April 26, 2019, 07:14:46 am
OK I'm kinda simple I wanna know why you just can't take a bow you have re curved and just lay it out on what your going to make a new caul from draw it cut it sand it call it good ???
You can certainly do that.  More than one way to get it done.   
Title: Re: Reflex caul
Post by: DC on April 26, 2019, 08:04:56 am
OK I'm kinda simple I wanna know why you just can't take a bow you have re curved and just lay it out on what your going to make a new caul from draw it cut it sand it call it good ???
As long as you remember that there is going to be some spring back. If you copy an existing bow on a new caul the bows you get from that caul may not have as much recurve.