Just Fun

[Mad Max]

I've been CAD drawing for 30+ years and I love figuring out how I want these bows to look.
A lot of math is involved and limbs and riser are accurate for a actual build.
Inspired by this Damon Howatt El-Dorado 1974ish
I have a lot of drawings for different bows.
I will show how I do the math for the limbs latter.



7-1/2" brace  62" EDIT 64" NTN, string length and brace profile are a good guess with the math. 

[dbeaver]

An incredible feat, I'm sure you hours have gone into this practice.   A beautiful shape for sure amd interesting too.

[mmattockx]

I will show how I do the math for the limbs latter.

I look forward to this.


Mark

[Kirkll]

That riser shape with the cup shaped limb pads remind me of the "Cascade golden Hawk" built years ago. I played with that design a bit back around 2012 and found it to be a pain in the arse to fit the limbs to the riser flush.... But those shorty bows were pretty impressive to shoot...I believe this one is a 48".

  Have fun with that one...

[onetone]

I also look forward to more info Mark. 

[Mad Max]

This is NOT AMO
I am NOT a math guy, but I do know how to use Pi (3.1416) and Degrees of angle for a Diameter.
Pi is the measurement around a circle and has a lot more decimal points that I will not use for this because I am not building a Rocket ship

We have 4 radius for this limb, 2 is all you need for a recurve but sometimes I use 3.
 


See how the Centerline of the blue Radius end's on the center of the Yellow Radius.



These are the degree's of each PART of each circle


EDIT/ADD----Measuring on the back of the riser doesn't work for this one, but I do for most 1 piece bows.
Starting at the Nock
Radius/ Diameter -----Degree
4.75"/9.5"                   61.139*
14"/28"                        8.699*
48"/96"                       12.026*
12"/24"                       23.943*

9.5 X 3.1416 divided by 360 degrees x the degree 61.139 = 5.0686"
28                                                                      8.669      2.1255"
96                                                                     12.026    10.0749"
24                                                                     23.943     5.0146"
                                                                                      + ----------
                                                                                       22.2836" is the length of the limb from the nock to the end of the riser. Riser is 18", so add 9" to the limb= 31.2836, I want it to be 32" for a 64" NTN so it is .7164 short, we can draw a radius of .7164  and make the limb longer at any of these points.



If you want more or less reflex from  the nock you need to change your radius.

[Mad Max]

https://www.google.com/search?sca_esv=c60dab5b25f63d56&rlz=1C1GCEA_enUS770US770&q=Golden+Fibonacci+Ratio+Spirals+Gold+Section+Stock+Vector+(Royalty+Free)+767996152+%7C+Shutterstock&tbm=isch&source=lnms&sa=X&ved=2ahUKEwi4jfPogPeDAxXkmmoFHQYVCYAQ0pQJegQIDBAB&biw=1366&bih=607&dpr=1

[derekdiruz]

I start on my cad software for every bow design. Then my Cnc cuts the form and all necessary jigs. I absolutely love deciphering a thought in my head to a shootable rig.

That design you posted in the first post looks awesome. I love love how it’s back mounted limbs, yet almost matches a widow in appearance.

[Mad Max]

I started using a CAD for Old School Tool and Die work.
It helped a lot with progressive dies.
The CNC's are to costly for me but would love to have one.

I like drawing Risers, with a insert on the form I can make all these on the same 1 piece form.




Back and belly shaping, I print and double side tape to the riser for shaping.

[Kirkll]

That would be fun calculating all those arc's and intersection points, drafting it in auto cad, and plugging it into a CNC program. That would be a whole new ball game setting up a CNC and learning what bits cut the best shapes, and how to secure the block. Then you deal with different types of issues like grain tear out...

I have a real love Hate thing about cutters and hardwood after spending time with an experienced Mill worker on various high speed shapers and learning to mill radius Crown mouldings... Scary stuff.

For me i use Carpenter Cad....  A Hand full of nails and some fiberglass strips flexible enough to bend to my radius or elliptical shapes for limbs.... For risers i just shape my patterns by hand using 1/4" MDF or Melamine.  All the other shaping is done by hand on the edge sander, and spindle sanders, and polished up with a random orbital sander. the shelf cut outs i do on the band saw by hand rough, then use a right angle die grinder to shape the radius shelf.  Are they all exactly the same? Nope....But i can easily customize grip angles and shapes for customers..... You develop  a feel for it after doing several hundred of them over the years.

Here are some of my carpenter cad programs... I have a couple drawers full too that i have saved for other bow projects.

 

[mmattockx]

Mark,

I understand what you are doing with the Fibonacci sequence for the limb shape, but does that get you to the limb bend you want at brace and full draw or is it just a way to get a reasonable recurve limb shape that looks good?


Mark
 

[Mad Max]

The Fibonacci sequence is just getting the 2 arcs/circle split on the tangent to one another for those who do/do not know how.

Long lean butt wedges like kirk does or multi tapered lam (super lams) can help Performance.

Also the Damon Howatt El-Dorado was a Competition Target bow. I think some were up to 70" long 

[Kirkll]

Mark,

I understand what you are doing with the Fibonacci sequence for the limb shape, but does that get you to the limb bend you want at brace and full draw or is it just a way to get a reasonable recurve limb shape that looks good?


Mark

Having a limb shape or form that is appealing to the eye only goes so far. And…You will find an elliptical shape distributes the load much differently than a true radius does, and manipulating how much and where that limb bends is your key to success.

It’s amazing how many different characteristics you can come up with just altering the location you place the limb in the form by moving the stop, and playing with different taper rates and shifting wedges. You can force the limb to store more energy into a shorter working section, or spread it out along the limb further changing the whole limb dynamics.   

Then when you finally get the perfect combo going, you’ll find out how different draw weights , draw lengths, and bow lengths effect your design, and how to manipulate  them further…. It’s an endless battle.   

[mmattockx]

It’s an endless battle.   

Yes it is. The number of variables involved mean there is essentially an infinite number of combinations available to try.


Mark

[Kirkll]

It’s an endless battle.   

Yes it is. The number of variables involved mean there is essentially an infinite number of combinations available to try.


Mark

Yup..... But the funny thing is... It's probably already been done before... We keep reinventing the wheel.

[mmattockx]

Yup..... But the funny thing is... It's probably already been done before... We keep reinventing the wheel.

That is probably correct. The biggest problem with a cottage industry/craft like bow making is the information is all stored in people's heads and maybe some rough notes in a drawer somewhere and keeps getting lost every time a generation dies off, only to be rediscovered by the next generation. If we could compile that info and make it available to the world then the next generation could stand on the shoulders of the one before and possibly reach higher levels of performance in the end and provide real progress, the same way the physical sciences have.


Mark

[Mad Max]

Damon Howatt had 1 bow out of 6 or 7 different bows they sold called Hi-Speed, 54" & 58", What made it faster? What kind of glass did they use back then??
Was this glass special or just better than what they we using??
 
This is on the 1961 catalog so they started using the glass in 1958

[Kirkll]

I'm not so sure those Damon Howatt "High Speed" bows were all that fast at all by todays standards. I knew a guys that was replicating them years ago and came up to my shop and spent a whole afternoon shooting about 8 different models he had built side by side with my own designs. we even ran them through the chrono
and he was having a tough time getting more than 187 FPS @ 28" and a bit higher with 30" draw. The shorter bows were faster at longer draw lengths, but i had bows 10 FPS faster just using glass than those designs.

As far as glass goes.... Gordon Glass started in 1953  and completely took over the market. Minnesota mining company transformed into the fortune 500 "3M company",  and they do not produce fiberglass laminates today. If this THERMO-GLASS was superior to Gordons you would think it would have taken off....   This is the first i've even heard of it. 

Interesting subject to research....

[Mad Max]

I'm not so sure those Damon Howatt "High Speed" bows were all that fast at all by todays standards. I knew a guys that was replicating them years ago and came up to my shop and spent a whole afternoon shooting about 8 different models he had built side by side with my own designs. we even ran them through the chrono
and he was having a tough time getting more than 187 FPS @ 28" and a bit higher with 30" draw. The shorter bows were faster at longer draw lengths, but i had bows 10 FPS faster just using glass than those designs.

As far as glass goes.... Gordon Glass started in 1953  and completely took over the market. Minnesota mining company transformed into the fortune 500 "3M company",  and they do not produce fiberglass laminates today. If this THERMO-GLASS was superior to Gordons you would think it would have taken off....   This is the first i've even heard of it. 

Interesting subject to research....

The shorter length is what made it faster I think, I had 2 and measure and log the thickness every 1" and came up with a multiple tapered lam .005/.002.

Just to be clear that Thermo-glass picture information was in there 1961 Catalog

https://nebula.wsimg.com/e1fe6ae48476194d659543b5400cf2f7?AccessKeyId=A203C91555201A4407B4&disposition=0&alloworigin=1

[Kirkll]

I'm not so sure those Damon Howatt "High Speed" bows were all that fast at all by todays standards. I knew a guys that was replicating them years ago and came up to my shop and spent a whole afternoon shooting about 8 different models he had built side by side with my own designs. we even ran them through the chrono
and he was having a tough time getting more than 187 FPS @ 28" and a bit higher with 30" draw. The shorter bows were faster at longer draw lengths, but i had bows 10 FPS faster just using glass than those designs.

As far as glass goes.... Gordon Glass started in 1953  and completely took over the market. Minnesota mining company transformed into the fortune 500 "3M company",  and they do not produce fiberglass laminates today. If this THERMO-GLASS was superior to Gordons you would think it would have taken off....   This is the first i've even heard of it. 

Interesting subject to research....

The shorter length is what made it faster I think, I had 2 and measure and log the thickness every 1" and came up with a multiple tapered lam .005/.002.

Just to be clear that Thermo-glass picture information was in there 1961 Catalog

https://nebula.wsimg.com/e1fe6ae48476194d659543b5400cf2f7?AccessKeyId=A203C91555201A4407B4&disposition=0&alloworigin=1

Ya I’ll bet they were bummed out when their glass supplier quit making it, and moved on to other things as they became known as 3M.

Do you know when Damon Howitt went out of business? I’d bet they were using Gordon Glass before they shut down….

If I had to put money on a glass backed speed bow design of days gone by, I’d put my money on  The old sovern balistic.  When I was playing with limb design a lot years ago I studied that limb geometry and went the same direction. Those old bows were fast.

Kirk