God help me, I was an EE major in college (okay, that was 30 years ago)… and fantasize about going back for physics someday. But… it’s been a long few weeks, I’m tired and I spent all day yesterday breaking down 13 sheets of MDF into cabinet parts which I’m now trying to assemble (on the last one).
So… where’s the dunce cap? I can’t figger this out:
I want to divide a rectangular box ( 67.25″ inside dimension) with two equally spaced 3/4″ MDF dividers. Simple, 67.25 divided by 3 gave me 22 7/16. I centered my dividers and voila… wrong!
OK, I must’ve needed to account for the thickness of the MDF (1.5″ total)? redo the math…wrong…
I must need to divide the remainder (after positioning the first divider) by 2 so to account for one half the MDF? wrong…
Helpppppppppppppppppppppppppppppppppppppppppppppppppppppppp
An embarassed PaulB
Replies
This graphic will help you I bet! Just replace the balusters with your 3/4" MDF dividers.
Just tried it Joe... still way off.
But thanks very much all the same.
Maybe there's some time space warping involved with MDF?
I must be over tired.
Edited 6/6/2006 4:43 pm ET by PaulBinCT
Here's my layout:
0 (3/4) (3/4) (67.25)
| ? | | ? | | ? |
The problem that you are having is that the two end section only have one 1/2 of the 3/4 divider.The center section has two halves of the divider.
21.92
Did this math prior to reading all post. Seems I was / am close.
Edited 6/6/2006 7:55 pm ET by txlandlord
Paul
Just a trick that I use when doing this type of cabinet.
If I want/need the spacing to be dead on I build the box first and then cut spacers to set the dividers.
I cut them maybe 1/32" longer then the math tells me the space should be, then I put the dividers in place(not secure) with the spacers. I'll cut(trim) all the spacers at the same time so that I'm keeping them all the same, and retry them until they all fit snug, that way I know that all spaces are equal.
On a frameless cabinet being off a tiny bit isn't all that big a deal but when I build full inset doors I want the space dead on, I want all the doors to fit the same space, or at least fit with minor trimming.
Doug
Edited 6/6/2006 10:51 pm ET by DougU
How bout this??
Paul, starting with the layout you posted I get the same as Joe Wood's drawing shows.
[67.25 – (2 × .75)] ÷ 3 = 21.91667, about 21-15/16"Joe Bartok
PAUL,
I WILL BE ATTACHING A SKETCH SHOWING THIS, BUT FOR NOW, MEASURE FROM EACH SIDE 22 5/16" AND MAKE A MARK. THOSE ARE THE CENTERS OF YOUR 3/4" DIVIDER MATERIAL. THE DIMENSION BETWEEN YOUR MARKS WILL BE 22 11/16" WHEN YOU BUT IN THE THICKNESS OF YOUR MATERIAL FROM YOUR CENTER MARKS, YOU WILL HAVE THREE EQUAL SPACES. SORRY ABOUT THE CAPITALS (CAPS LOCK ACCIDENTALLY ON)
Edited 6/6/2006 4:52 pm ET by xosder11
OK, so I'm naming my first ummmmmmmmmmm... new pet? xosder.
But splains to me the process when you get a chance, willya? I feel like a moron being stumped by this.
PaulB
Ah Algebra!
See box attached.
c - 2b = 3a
a = (c - 2b)/3
Hope his helps.
Paul,
You're figuring splitting the 3/4" MDF dividers in to two but not splitting the ends in to two. In other words, you need to measure from the center of the outside piece to the center of the outside piece.
The numerical answer is you need three spaces of 21.917" or 21-15/16".
Will post a graphic to explain in a minute.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Oops, I forgot to refresh. When I wrote my message only 5 messages were posted.
This is what I would have drawn (but it wouldn't have been so fancy)
View Image
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Sighhhhhhhhhhhh... I knew I was somehow not accounting for the thickness of some of the MDF. And to think I got a recommendation from a professor of applied physics at Yale to become a part time student. I better rethink that too ;)
(Gonna be cracking open "Algebra for Dummies" tonight)
I come up with 21 59/64 in. between the dividers. But I worked at Fine Woodworking for a year.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
I'd like to cancel my recent order for those 3 sundials I have placed with you, the first one is running kinda slow. :)
Spheramid Enterprises Architectural Woodworks
There is no cure for stupid. R. White.
Everybody's a comedian here...
;)
I'd like to cancel my recent order for those 3 sundials I have placed with you, the first one is running kinda slow. :)
Don't blame him--it's Bush's fault--the global warming has slowed the spin of the earth! Al Gore will fix in in '08. (But that'll really be '09, because, as I said, the earth isn't spinning as fast.)
Don't worry about the physics appointment, there you can always appeal to the uncertainty principal...BTW, are the 3/4" boards really 3/4"?
Yeah they are ... but where can I hide this dead cat?
Nope... not that way, because the first and last opening only have half of a partition(3/8") and the center opening has 2 halves of a partition(2 x 3/8"= 3/4").
Try:
67.25"- (2 x .75")= 65.75"/3 = 21.91666" openings
BUT.... do you want equal openings, or do you wants equal doors sizes???
The one above will not give you equal door sizes, not the way I would do it.
Oh god... now I DO have a migraine. You're absolutely right of course.
Someone just do this, I don't even care anymore...
I'll send you a kidney...
what's a good spec? 3/8 overlay doors? 1/4 between em?
I'm only kidding, btw I'm about to go se a new client (hope they don't want any cabinets), and I'll pour a drink and redo all this later... maybe...if I don't run screaming naked down the street...
actually, go metric when building these types of cabinets(like that will happen). Not really worth the "migraine" for just one or two
as for the gaps, shoot for 1/8" or less. Any more and the gaps get to pronounced.
squareness is everything when it comes to frameless cabinets.
Paul,
I actually rounded to the nearest 1/16" but I don't know your tolerances, so if you build cabinets to teh nearest 1/64" then here you go. My only saving grace is my CAD system. You carpenters should start putting laptops in your toolboxes next to your construction master calcs. (see attach)
From the outside start first partition at 22 and 11/16 and second at 44 and 5/16. 68 and 3/4 inch total length minus 3/4 for first side gives 68 inches. Divide by three gives you 22 and 11/16. Double that to get second partitition start point. Keep adding 22 11/16 until last partition.
Edited 6/6/2006 5:46 pm by ccal
I'd cheat and do what I did when I had to draw stair treads on a house plan--put down a scale (ruler) on a diagonal so that the third points fall on a convenient measurement that fits in the allotted space. It's easier to do than to explain. Lets say you can put your tape across so the end reads 75". Then mark where it reads 25" and 50". Those are the centers of the MDF boards, so measure over 3/8" from that tick and that's where you put the edge of the MDF panel. Should be about 22 -1/16", but I wasn't going from outside edges, which probably makes a difference.
If you want the spaces to all be the same, subtract the total thickness of the dividers (1.5") from the overall dimension (67.25" => 65.75"), then divide by three. This should yield the space BETWEEN facing surfaces of the dividers (=> 21.916666").
Now, for extra credit, do the balusters on a stairway.
Don't measure inside to inside.
Go same face to same face or center to center.
CL to CL = 68".
68/3=22 2/3 or
22 and 85.3/128" (85.3 = .6666 x 128)
22 43/64". . .21 (and a scant) /32". . .a light 11/16". . .a heavy 5/8".
Layout the same; face to face or Cl to CL.