Help with spacing dadoes evenly - Page 2 - Woodworking Talk - Woodworkers Forum
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post #21 of 32 Old 02-10-2013, 09:42 PM
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Quote:
Originally Posted by TheShaver View Post
I am looking to cut 7 half-inch dadoes, in a board that is 5 & 1/8 inch wide. I am having a hard time spacing these slots evenly and have tried the mathematical formula of 5 & 1/8 (width of the board) - 3 & 1/2 (the total amount of dado) to get 1.625, which I then divided by 8 to get 0.203125 which on the conversion chart of fractions is between 3/16ths and 4/16ths of an inch. At this point I am lost. I just want to space these dadoes evenly so that they look even after they are cut. I would just like to know how much space to have before/after the first/last dado and how much to have in between each. Can someone help me figure this out? haha
When working with so many dimensions, the fractions really make things complicated. Use a metric tape as it is a lot easier.

5 1/8" = 130.2mm
1/2" = 12.7mm

You will have 7 dados, 6 spaces between the dados and another 2 spaces, one each edge of the board.

7 x 12.7 = 88.9mm

130.2 - 88.9 = 41.3mm

41.3mm / 8 spaces = 5.2mm

Now just keep measuring from the same side and add the numbers up as you go.

First dado starts at 5.2mm
Second dado = 5.2 +12.7 + 5.2 = 23mm
Third dado = 40.9mm
Fourth dado = 59mm
Fith dado = 76.6mm
Sixth dado = 94mm
Seventh dado = 112.3mm
And as a check add another 12.7 and 5.2 and you are at the other edge of the board right at 130.2mm

Pure mathematics is, in it's way, the poetry of logical ideas. - Albert Einstein.
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post #22 of 32 Old 02-10-2013, 09:59 PM Thread Starter
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Straight razors. Sweet. Im heavy into straights. Its the only way i shave. Will this box be for customs or just your collection?
It's for customs. I will be making them to sell. I just want the slots that the razors are going to rest in, to be evenly spaced.
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post #23 of 32 Old 02-10-2013, 10:33 PM
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It's for customs. I will be making them to sell. I just want the slots that the razors are going to rest in, to be evenly spaced.
Have you made them before?
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post #24 of 32 Old 02-10-2013, 10:49 PM Thread Starter
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Have you made them before?
I made one and ended up selling it so I could buy the Dovo storage box. But I couldn't ever get the slots spaced out evenly, I just eyeballed it. So this time I decided to go with measurements and preciseness so that it would look more professional.
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post #25 of 32 Old 02-10-2013, 10:51 PM Thread Starter
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So I found a solution. By removing the 8th notch and leaving the last slot a rabbet(?) I got all seven 1/2 inch slots spread out evenly. The rabbet slot will be towards the front end of the box so it won't stand out, problem solved. Isn't this fun! Thank you guys for helping me out, I really appreciate it!
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post #26 of 32 Old 02-11-2013, 12:27 AM Thread Starter
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Quote:
Originally Posted by WillemJM View Post
When working with so many dimensions, the fractions really make things complicated. Use a metric tape as it is a lot easier.

5 1/8" = 130.2mm
1/2" = 12.7mm

You will have 7 dados, 6 spaces between the dados and another 2 spaces, one each edge of the board.

7 x 12.7 = 88.9mm

130.2 - 88.9 = 41.3mm

41.3mm / 8 spaces = 5.2mm

Now just keep measuring from the same side and add the numbers up as you go.

First dado starts at 5.2mm
Second dado = 5.2 +12.7 + 5.2 = 23mm
Third dado = 40.9mm
Fourth dado = 59mm
Fith dado = 76.6mm
Sixth dado = 94mm
Seventh dado = 112.3mm
And as a check add another 12.7 and 5.2 and you are at the other edge of the board right at 130.2mm

What if I were to adjust those numbers to 4 and 58/64 wide and 7/16 wide dadoes (7/16 x 7)? I'm trying to plug in the numbers but I got stuck with 9/40 th of an inch?
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post #27 of 32 Old 02-11-2013, 08:05 AM
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Do u have a pic of the razor you made?
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post #28 of 32 Old 02-11-2013, 08:34 AM
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the suggestion was ...Go Metric.

Quote:
Originally Posted by TheShaver View Post
What if I were to adjust those numbers to 4 and 58/64 wide and 7/16 wide dadoes (7/16 x 7)? I'm trying to plug in the numbers but I got stuck with 9/40 th of an inch?


The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #29 of 32 Old 02-11-2013, 02:50 PM
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For Android users there is s pretty handy App for free called Woodworking Utilities. It's got a lot of useful little programs that I have found helpful, one of which was a Spacing Calculator. And it's free.
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post #30 of 32 Old 02-11-2013, 04:30 PM
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If it were me, I'd install my dado blade in my table saw with 3/8" width. Put my fence at 2-3/8", run a test board through on one side, flip it then run it through on the other side. That will give you a dado that is smaller than 1/2" but then you can gradually move your fence in, run the board through on both sides until you get a 1/2" dado. This method will give you 1/2" dados and you will be certain they will be exactly in the middle of the board.

Do this on a test piece since my math may be off slightly. However, the process will work every time.
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post #31 of 32 Old 02-11-2013, 06:02 PM
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he needs more than one centered dado

More like about 7, evenly spaced. The issue is the spacing, not the width of the dado. Obviously the width of the the dado must be known exactly to proceed with the spacing math. Shims and practice passes are the only way I know to get it right on the money. Start with more shims than you will need and remove them one at a time based on the remaining gap with a known 1/2" wide test piece.

Another way to look at this is.... 7 dados, and 2 end gap spaces.
OR, 9 X .50" just in dados and end spaces or 4.50"

Width of the material (W inches) minus 4.50", divided by 9 = width of one space:
W - 4.50" / 9 = one space

Best I got for Ya.....

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 02-12-2013 at 07:06 AM.
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post #32 of 32 Old 02-11-2013, 08:00 PM
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I plugged it into the aforementioned App. Try first piece at .203", with .203" gaps.
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