Posted: 1/6/2013 3:18:01 PM EDT
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Building a simple wall mounted rifle rack, top piece is 20" long, U-shaped slots for 5 rifles. How do I figure out problems like this using algebro? Want each slot to be equal with an equal space in between including each end. Like this: |_n_n_n_n_n_|
Is it 5X + 6Y = 20? How do I solve it? 5 = # of slots, 6 = # of gaps? |
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Pick a width for the slots - say 2 inches Amount of wood left for the gaps = (20 - 5(2) ) = 10 Since you want 6 gaps, width of gaps = 10/6 Looks like I need at least 2 1/2" to fit an AR handguard. Only have 20" to work with. In that case gaps would be only (20 - 5(2.5))/6 = 7.5/6 |
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Quoted: Building a simple wall mounted rifle rack, top piece is 20" long, U-shaped slots for 5 rifles. How do I figure out problems like this using algebro? Want each slot to be equal with an equal space in between including each end. Like this: |_n_n_n_n_n_| Is it 5X + 6Y = 20? How do I solve it? 5 = # of slots, 6 = # of gaps? I'm sure he can help, but you're going to have to ask him yourself.  |
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centers at:
3 3/8", 6 3/4", 10", 13 3/8", 16 3/4" will divide it up will 5 slots close enough for your purpose. Algebro wont help.... but...by the time you lay out the bottom piece....these long guns are going to be cramped in a pretty small space....go for 30" min and put all the centers 5" apart. |
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Pick a width for the slots - say 2 inches Amount of wood left for the gaps = (20 - 5(2) ) = 10 Since you want 6 gaps, width of gaps = 10/6 Looks like I need at least 2 1/2" to fit an AR handguard. Only have 20" to work with. In that case gaps would be only (20 - 5(2.5))/6 = 7.5/6 Ahha! Got it! 2 1/2" gaps, 1 1/8" spaces. You win!! 
Thanks, I absolutley vapor lock with math sometimes. Numbers have no meaning, Lexdsycia is a bitch! 
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Quoted: Building a simple wall mounted rifle rack, top piece is 20" long, U-shaped slots for 5 rifles. How do I figure out problems like this using algebro? Want each slot to be equal with an equal space in between including each end. Like this: |_n_n_n_n_n_| Is it 5X + 6Y = 20? How do I solve it? 5 = # of slots, 6 = # of gaps? You wont be able to solve a system of 2 variables without at least 2 equations (ie you need the one you came up with, plus another equation). Does "Want each slot to be equal with an equal space in between including each end" mean you want the size of the slots the same as the space in between the slots? if so that provides your additional equation, namely x=y your system of two equations to solve then is 5x+6y=20 x=y which we can easily solve via substitution 5x+6(x)=20 11x=20 x=20/11 x=1.818 so the width of the slots and the space in between them (and the space from each end slot to the end of your piece of board) is about one and thirteen sixteenths inches. |
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Pick a width for the slots - say 2 inches Amount of wood left for the gaps = (20 - 5(2) ) = 10 Since you want 6 gaps, width of gaps = 10/6 Looks like I need at least 2 1/2" to fit an AR handguard. Only have 20" to work with. In that case gaps would be only (20 - 5(2.5))/6 = 7.5/6 Ahha! Got it! 2 1/2" gaps, 1 1/8" spaces. You win!!
Thanks, I absolutley vapor lock with math sometimes. Numbers have no meaning, Lexdsycia is a bitch!
4F, were ya? 
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Building a simple wall mounted rifle rack, top piece is 20" long, U-shaped slots for 5 rifles. How do I figure out problems like this using algebro? Want each slot to be equal with an equal space in between including each end. Like this: |_n_n_n_n_n_| Is it 5X + 6Y = 20? How do I solve it? 5 = # of slots, 6 = # of gaps? You wont be able to solve a system of 2 variables without at least 2 equations (ie you need the one you came up with, plus another equation). Does "Want each slot to be equal with an equal space in between including each end" mean you want the size of the slots the same as the space in between the slots? if so that provides your additional equation, namely x=y your system of two equations to solve then is 5x+6y=20 x=y which we can easily solve via substitution 5x+6(x)=20 11x=20 x=20/11 x=1.818 so the width of the slots and the space in between them (and the space from each end slot to the end of your piece of board) is about one and thirteen sixteenths inches. Never could catch on to algebra/ physics, had to quit Engineering back in 1987 because of it. Have built things for years now from boats to machined parts and always revert to some sort of hybrid redneck math to figure out things. Thought there was a way to do problems like "you need a railing 35' long, has to have 18 posts spaced equally apart with 3" left at each end" that you could just plug into a formula and solve all the variables for. I usually mock things up using scale pieces to make it work and throw in some math when it fits. 
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Pick a width for the slots - say 2 inches Amount of wood left for the gaps = (20 - 5(2) ) = 10 Since you want 6 gaps, width of gaps = 10/6 Looks like I need at least 2 1/2" to fit an AR handguard. Only have 20" to work with. In that case gaps would be only (20 - 5(2.5))/6 = 7.5/6 Ahha! Got it! 2 1/2" gaps, 1 1/8" spaces. You win!!
Thanks, I absolutley vapor lock with math sometimes. Numbers have no meaning, Lexdsycia is a bitch!
4F, we're ya?
Hahah got that right! Can build/diagnose & repair anything mechanical but soon as I have to put it on paper...
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Pick a width for the slots - say 2 inches Amount of wood left for the gaps = (20 - 5(2) ) = 10 Since you want 6 gaps, width of gaps = 10/6 Looks like I need at least 2 1/2" to fit an AR handguard. Only have 20" to work with. In that case gaps would be only (20 - 5(2.5))/6 = 7.5/6 Ahha! Got it! 2 1/2" gaps, 1 1/8" spaces. You win!!
Thanks, I absolutley vapor lock with math sometimes. Numbers have no meaning, Lexdsycia is a bitch!
7.5/6 = 1 1/4" not 1 1/8" 
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Building a simple wall mounted rifle rack, top piece is 20" long, U-shaped slots for 5 rifles. How do I figure out problems like this using algebro? Want each slot to be equal with an equal space in between including each end. Like this: |_n_n_n_n_n_| Is it 5X + 6Y = 20? How do I solve it? 5 = # of slots, 6 = # of gaps? You wont be able to solve a system of 2 variables without at least 2 equations (ie you need the one you came up with, plus another equation). Does "Want each slot to be equal with an equal space in between including each end" mean you want the size of the slots the same as the space in between the slots? if so that provides your additional equation, namely x=y your system of two equations to solve then is 5x+6y=20 x=y which we can easily solve via substitution 5x+6(x)=20 11x=20 x=20/11 x=1.818 so the width of the slots and the space in between them (and the space from each end slot to the end of your piece of board) is about one and thirteen sixteenths inches. This is what I got as well because of the way op worded the question. 20/(X +Y) = 20/(6+5) = 20/11= 1.818 |
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Pick a width for the slots - say 2 inches Amount of wood left for the gaps = (20 - 5(2) ) = 10 Since you want 6 gaps, width of gaps = 10/6 Looks like I need at least 2 1/2" to fit an AR handguard. Only have 20" to work with. In that case gaps would be only (20 - 5(2.5))/6 = 7.5/6 Ahha! Got it! 2 1/2" gaps, 1 1/8" spaces. You win!!
Thanks, I absolutley vapor lock with math sometimes. Numbers have no meaning, Lexdsycia is a bitch!
7.5/6 = 1 1/4" not 1 1/8"
LOL see what I mean! I drew it out on the wood to cut at 1 1/4" without even thinking. When I had to write it down, it came out 1 1/8". 'Course I always get my lefts/rights/East/West mixed up too but dammnit I know which way it is!!!
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