Post by: Mad Max on January 24, 2024, 09:05:13 AM
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.
(https://i.imgur.com/USqrYfb.jpg)
7-1/2" brace 62" EDIT 64" NTN, string length and brace profile are a good guess with the math.
(https://i.imgur.com/afODLw3.jpg)
Post by: dbeaver on January 24, 2024, 09:10:43 AM
Post by: mmattockx on January 24, 2024, 11:04:44 AM
I will show how I do the math for the limbs latter.
I look forward to this.
Mark
Post by: Kirkll on January 24, 2024, 11:45:59 AM
Have fun with that one... :thumbsup:
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Post by: onetone on January 24, 2024, 03:07:28 PM
Post by: Mad Max on January 24, 2024, 04:17:52 PM
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.
(https://i.imgur.com/o5BeA3H.jpg)
See how the Centerline of the blue Radius end's on the center of the Yellow Radius.
(https://i.imgur.com/bafQkGV.jpg)
These are the degree's of each PART of each circle
(https://i.imgur.com/OgZAR7v.jpg)
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.
(https://i.imgur.com/Pcw7emF.jpg)
If you want more or less reflex from the nock you need to change your radius. :thumbsup:
Post by: Mad Max on January 24, 2024, 04:52:29 PM
Post by: derekdiruz on January 24, 2024, 05:31:53 PM
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.
Post by: Mad Max on January 24, 2024, 05:58:31 PM
It helped a lot with progressive dies.
The CNC's are to costly for me but would love to have one. :jumper:
I like drawing Risers, with a insert on the form I can make all these on the same 1 piece form.
(https://i.imgur.com/AQeuFg1.jpg)
Back and belly shaping, I print and double side tape to the riser for shaping.
(https://i.imgur.com/V5AU92J.jpg)
Post by: Kirkll on January 24, 2024, 09:05:30 PM
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. :o :o
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.
Post by: mmattockx on January 25, 2024, 10:59:45 AM
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
Post by: Mad Max on January 25, 2024, 03:17:46 PM
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
Post by: Kirkll on January 26, 2024, 11:39:33 AM
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. :banghead: :banghead:
Post by: mmattockx on January 26, 2024, 03:19:19 PM
It’s an endless battle. :banghead: :banghead:
Yes it is. The number of variables involved mean there is essentially an infinite number of combinations available to try.
Mark
Post by: Kirkll on January 26, 2024, 08:50:14 PM
It’s an endless battle. :banghead: :banghead:
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. :laughing: :laughing: :laughing:
Post by: mmattockx on January 27, 2024, 10:52:24 AM
Yup..... But the funny thing is... It's probably already been done before... We keep reinventing the wheel. :laughing: :laughing: :laughing:
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
Post by: Mad Max on January 27, 2024, 11:49:25 AM
Was this glass special or just better than what they we using??
:dunno:
This is on the 1961 catalog so they started using the glass in 1958
(https://i.imgur.com/ex9Bm4a.png)
Post by: Kirkll on January 27, 2024, 02:08:04 PM
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.... :dunno: :dunno: This is the first i've even heard of it.
Interesting subject to research....
Post by: Mad Max on January 27, 2024, 02:52:37 PM
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.... :dunno: :dunno: 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
Post by: Kirkll on January 28, 2024, 07:24:39 PM
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.... :dunno: :dunno: 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
Post by: Mad Max on January 28, 2024, 09:22:49 PM
Mike Bush on Facebook was running the Martin/Damon Howitt bows for sale the last 4/5 years on a Facebook page I know of. Some of the old bow makers are still around on that page giving Info on the Dates/years made for almost all of the bows from the past. I has a big following. :thumbsup:
Post by: Crooked Stic on January 29, 2024, 12:12:20 PM
Post by: Longcruise on January 29, 2024, 01:46:38 PM
Post by: Mad Max on January 29, 2024, 04:23:59 PM
Max, any information on the new DH owners?
Facebook page is Damon Howatt Traditional Bows
Look and ask around :thumbsup:
Post by: Mad Max on February 08, 2024, 09:26:10 AM
I use this method a lot too. 1" circles, copy from arch center to intersection and 2" circles for the flatter radius, delete every other one and count the inches.
(https://i.imgur.com/oOh2JxY.jpg)
Post by: mmattockx on February 08, 2024, 10:53:29 AM
I use this method a lot too. 1" circles, copy from arch center to intersection and 2" circles for the flatter radius, delete every other one and count the inches.
That's pretty accurate with small circles, the segments don't lose much over the true arc length. I don't know what cad package you are using, but in Autocad I can get arc lengths for each arc in the limb and add them up or make the line into a polyline and get the total length of that joined line by checking the properties of the line(s). There is no need to measure graphically as you are doing. I would think your cad can do the same.
Mark
Post by: Mad Max on February 08, 2024, 01:27:55 PM
I have a free program CadStd pro v3.7.7
Post by: mmattockx on February 09, 2024, 11:17:51 AM
Yes it is accurate.
I have a free program CadStd pro v3.7.7
Can you right click on a line and get the properties of that line? That should give you the actual length, no matter if it is straight, an arc or a random polyline.
Mark
Post by: Longcruise on February 09, 2024, 01:27:06 PM
Post by: Mad Max on February 09, 2024, 02:07:04 PM
Post by: mmattockx on February 09, 2024, 10:27:39 PM
No right clicks
:dunno:
Mark
Post by: Mad Max on February 10, 2024, 07:21:57 AM
No right clicks
:dunno:
Mark
Right click is stop what you are doing and do something else.
Post by: Kirkll on February 11, 2024, 03:01:54 PM
Post by: Richard Korte on February 12, 2024, 10:50:52 AM
Post by: Mad Max on February 12, 2024, 02:32:32 PM
I draw all my bow patterns with a pencil and a French curve on a sheet of tagboard. Old school, I guess. RKKorte
Nothing wrong with that :thumbsup: