Can't get my lam stack calculator to work until I pay microsoft some money....:0
Can anybody give me some numbers for the new stack please.
Original stack - 0.286" - 42#
Looking for 49# off the form on this one.
Thanks in advance.
42/49 = 1.16 cu. = 1.05 x .286 = .300
I also have used the stack calc. Most times they a right on or a couple thousands difference.
Many thanks for that .300" it is.
Just off to grind that last parallel lam to get the stack dead on.
Will post some pics when I get her done :)
Quote from: Crooked Stic on January 19, 2022, 08:20:38 AM
42/49 = 1.16 cu. = 1.05 x .286 = .300
I also have used the stack calc. Most times they a right on or a couple thousands difference.
X2
😲🤔 stack calculator. Didn't know there was such a thing. JF
(https://i.imgur.com/pEdFIoq.jpg)
Quote from: Jeff Freeman on January 19, 2022, 09:12:24 AM
😲🤔 stack calculator. Didn't know there was such a thing. JF
Yup that's what ole KennyM uses. Ya didn't thunk he wuz dat smart did ya?
LOL
Ughh...Ugh... I missed something...
The additional data in the bottom of that chart says that increasing riser length will increase bow weight....
That is backwards...
Not really...you are shortening the working limb.
She is in the hotbox now :)
Quote from: Appalachian Hillbilly on January 19, 2022, 01:08:08 PM
Ughh...Ugh... I missed something...
The additional data in the bottom of that chart says that increasing riser length will increase bow weight....
That is backwards...
????
I think it's correct. It's the equivalent of shortening the limb.
Ok, as long as bow over all length stays the same? I know for a fact on take down bows that longer risers of bows with same limb length makes weight less and vice versa.
My medium limbs on my 25" riser pull 30 lbs.
On my 17" riser, they are 38 lbs.
I guess "all other things being equal, refers to over all length". I took it the other way, all other things being equal such as limb length being equal...
So does this stack calculator work for longbows also. I like to keep my fade outs about no less than 1.090
My original stack .430 original pounds of 42 desired weight 45 lb what would it be? Math was never my favorite subject. JF
Quote from: Jeff Freeman on January 19, 2022, 02:09:17 PM
So does this stack calculator work for longbows also. I like to keep my fade outs about no less than 1.090
My original stack .430 original pounds of 42 desired weight 45 lb what would it be? Math was never my favorite subject. JF
.440
This is for glass bows only I think, R/D and long bows, seems to work on recurves too.
If you have Microsoft excel
I think all I have to do is copy it and send it to a email, and you open in Excel
If anybody want's it?
BJansen is a member here and he sends it out to us :thumbsup:
.440 is what I used and it will end up 45# I'm almost there now.
Mine was just a guess going off my records from previous longbows built. JF
Here is more Info he gave me
1/4" narrower limbs = 14% loss in weight--55lb x 14%=7.7lb
I went from 1-3/4" wide to 1-1/2" wide on a recurve and got 8.5#--55# to 46.5# :thumbsup:
Ole kennym don't even know how to excel at Microsoft... :laughing:
Quote from: kennym on January 19, 2022, 04:36:13 PM
Ole kennym don't even know how to excel at Microsoft... :laughing: me neither
Quote from: kennym on January 19, 2022, 04:36:13 PM
Ole kennym don't even know how to excel at Microsoft... :laughing:
Me nitter:)
I would like to have it.
Quote from: Buemaker on January 19, 2022, 04:59:02 PM
I would like to have it.
I sent it to you
Let me know if it works Bue
I'm not a big computer nerd so I don't know if it will work :pray:
This may work too
http://www.mediafire.com/file/ckul4wdru1oq97o/Stack_Calculator.xls/file
Thank you Max. Will see tomorrow if I can load it up to Exel.
Quote from: Buemaker on January 19, 2022, 05:34:04 PM
Thank you Max. Will see tomorrow if I can load it up to Exel.
:thumbsup:
I think all I have to do is copy it and send it to a email, and you open in Excel ?
If possible, could you please send that to me? I'd like to see how it compares, if my iPad will open it.. its supposed to I think.
Thanks!
Noah
My phone opened it but I only got the lower half on an Excel graph sheet. I can't read anything on the top to slightly left of what I got. JF
Quote from: Jeff Freeman on January 19, 2022, 02:35:31 PM
.440 is what I used and it will end up 45# I'm almost there now.
Mine was just a guess going off my records from previous longbows built. JF
Changing limb width is linear. IOW, a limb 2" wide and 50# would be reduced to 25# if the limb were reduced to 1".
As regards limb thickness, the changes in thickness effect draw weight with a factor of eight.
I have two stack calculators and they both function based on that math. They aren't perfect but they are very very close.
For the type of bows that you mostly build, as do I, the Bingham chart is very close but you have to remember that it's based on the width of the Bingham design. But, it's very easy to use the linear aspect of the width formula to calculate weight.
Quote from: Noah70 on January 19, 2022, 06:03:03 PM
I think all I have to do is copy it and send it to a email, and you open in Excel ?
If possible, could you please send that to me? I'd like to see how it compares, if my iPad will open it.. its supposed to I think.
Thanks!
Noah
Reply #22 has a link
For these things to work you have to have a bow already built and know its stack. Everything the same except the stack. I have found that if the desired weight is is a bunch more say 20 lbs. you might be off some.
Quote from: Crooked Stic on January 19, 2022, 07:10:21 PM
For these things to work you have to have a bow already built and know its stack. Everything the same except the stack. I have found that if the desired weight is is a bunch more say 20 lbs. you might be off some.
I found the same. Using 1# for every 003 seems to be pretty much the same.
Quote from: Noah70 on January 19, 2022, 06:03:03 PM
I think all I have to do is copy it and send it to a email, and you open in Excel ?
If possible, could you please send that to me? I'd like to see how it compares, if my iPad will open it.. its supposed to I think.
Thanks!
Noah
Lets see if the copy for Bue works
Quote from: Mad Max on January 19, 2022, 09:16:26 AM
(https://i.imgur.com/pEdFIoq.jpg)
That's a good calculator but..... that other good data info on the bottom is bogus.
Lengthening a riser with the same limbs will decrease the draw weight, not increase it.
Ok so how does the calculator work. Need to show your work, to come up with the boom. JF
Quote from: Jeff Freeman on January 21, 2022, 11:18:04 AM
Ok so how does the calculator work. Need to show your work, to come up with the boom. JF
Bending stiffness of a rectangular section beam of a homogeneous material is proportional to the thickness cubed. The calculator uses that to calculate the new stack height. It isn't strictly accurate because the fibreglass lams carry much more of the load than the core material, but it is close enough to accurately predict small changes in weight.
Mark
Quote from: Jeff Freeman on January 21, 2022, 11:18:04 AM
Ok so how does the calculator work. Need to show your work, to come up with the boom. JF
Weight increase % =(C9-C8)/C8
Target Stack increase =-(1-(POWER(1+C10,1/3)))
Target Stack Thickness =C7*(1+C11) Boom
Quote from: Mad Max on January 21, 2022, 03:33:08 PM
Quote from: Jeff Freeman on January 21, 2022, 11:18:04 AM
Ok so how does the calculator work. Need to show your work, to come up with the boom. JF
Weight increase % =(C9-C8)/C8
Target Stack increase =-(1-(POWER(1+C10,1/3)))
Target Stack Thickness =C7*(1+C11) Boom
Phew. Finally someone simplified it. :biglaugh:
Oh yeah now I get it 🤣🤓 much easier to understand
Bow came out right on inteneded weight. One veneer moved so had to narrow it a mm or two more than I would've wanted but hey....I've still hit weight and she has pretty limb edges now haha...
Osage and Honduras Rosewood - not too shabby.
I was able to move it to Exel and could plot in the numbers I wanted, but I can't make it calculate. I have to find someone who knows this stuff.
Yeah clear as mud.
Quote from: Longcruise on January 21, 2022, 10:11:11 PM
Phew. Finally someone simplified it. :biglaugh:
You need to calculate the % increase (or decrease) in weight you want, then take the cube root of that to get the percentage change in the stack height.
For example:
Existing stack is 0.500", weight is 50# @ 28". Say we want the new bow to be 55# @ 28".
% change in weight = 55/50 = 1.10
Take the cube root of that = (1.10)^1/3 = 1.032
New stack height = 0.500 x 1.032 = 0.516"
Works the same way for reductions. Say we want the new bow to be 45# @ 28" instead of 55# as above.
% change = 45/50 = 0.90
Cube root = (0.90)^1/3 = 0.9655
New stack = 0.500 x 0.9655 = 0.483"
Quote from: Buemaker on January 24, 2022, 06:07:49 AM
I was able to move it to Exel and could plot in the numbers I wanted, but I can't make it calculate. I have to find someone who knows this stuff.
That is bizarre, it should automatically recalculate when opened in Excel. Do you want to try the copy I have? I could email it direct to you if you want.
Mark
Yes Mark, that would be great. I sent a PM
Quote from: Buemaker on January 24, 2022, 02:51:26 PM
Yes Mark, that would be great. I sent a PM
Email has been sent. Hopefully this one is more successful for you.
Alternatively, you could use the method I showed above with a scientific calculator to crunch the numbers if this file won't work either.
Mark
It works, thank you. :)
The cube root method is what I us .
You can Google cube root calculator that will ease your brain. :bigsmyl:
Like I mentioned. I'm not good at math. I'll use my bowyerscore math. Time X's trial and error - a few errors + keep records ÷ 1 decade ## = I'll stick with how I've been doing it.✓ works for me 😂🤣🤓
Sorry Bue
I must have missed something :knothead:
Did anyone try the link I posted on Reply 22
Quote from: Mad Max on January 29, 2022, 08:55:41 AM
Sorry Bue
I must have missed something :knothead:
Did anyone try the link I posted on Reply 22
I just downloaded it and it works for me. Ad Aware did give me a security warning for that page, though.
Mark