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Basic Centipede cabinet build help
hurtz:
Been lurking here for some time, and recently decided I wanted to build a Centipede replica. I've been working from Jakobud's plans, and so far have everything cut out.
Last night, I did some dry fitting to see how it would look before I started assembling, and I'm wondering if I may have not cut everything out right. Anyone familiar with these plans could you answer some questions for me:
1) What exactly is 5.4, and 5.7 inches? .4 is less than a 1/2 inch, and .7 is greater than 1/2, but less than 3/4, 11/16 is about .6875, or am I being way too technical with my measurements?
2) Take for example the side view of the cab. From the bottom right to under the CP, the measurement is 33.5 inches. So does the front piece (where the coin door is) get cut at 33.5 inches, or do you have to take into account the .5" inset? Then, do you miter cut an angle from the top of the coin door piece and the bottom of the CP?
Hope that makes sense.
Attached a screenshot. The red circle is the area I'm referring to in my 2nd question.
shardian:
Question 1)
5.4 inches is 5-13/32"
5.7 inches is 5-11/16"
If you do alot of measuring/ building, do yourself a favor and get a construction master calculator. They Rule!!
Antother thing you could use is an engineers Rule. It divides inches up into 10ths.
As to question 2, the plans I have for centipede only include the side profile. I looked at the galaga plans, which are mostly complete, and determined that the front piece and the CP angle piece are both mitered at a 21 degree angle to fit together. The dimensions are measured on the front of the piece. When you miter cut on this line so that the rear will be longer, the pieces will fit together at that angle. Hope I didn't confuse you. Good Luck!
hurtz:
Ok, so I understand fractional inches now. Thanks!
As for the angles I'm still not sure I get it. Found a couple of little tidbits of information:
(rise/run) x 100 = angle
So in the case of a Centipede cab: (I attached the front view)
(2.75 / 5) x 100 = 55
So now what do I do with 55? Cut both at 55 / 2 = 27.5 degrees?
Possible to do with a circular saw, or am I going to need to invest in a table saw?
shardian:
Yes, you can cut this angle with a circular saw. You may want to actually draw the angle on the piece of wood since the circular saw adjustable table isn't accurate to a degree.
To get an accurate measurement on the board, you can do 1 of 2 things:
Get a protractor and mark the angle out on the edge of the board.
Or you can to the trigonometry to determine the change in length of the rear face of the wood.
To do this, you know the 1st measurement is 3/4" since that is the thickness of the wood. To determine the next dimension, you will use the 3/4" and the 27.5 degree angle.
tan (angle) = opposite/adjacent --> tan (27.5) = opp/.75"
After doing the algebra, the change in length due to the 27.5 degree cut would be 0.390425287914", or 3/8" with my trusty calculator. Make you cut line mark on the side of the wood, and then make another mark 3/8" farther out on the wood near the bottom edge. Connect the marks to make the cutting line. Set the saw on the wood, and adjust the table of the saw to align the blade with this line.
Voila! A (somewhat close) 27.5 degree edge.
u_rebelscum:
--- Quote from: hurtz on May 17, 2006, 02:30:15 pm ---(rise/run) x 100 = degrees angle
--- End quote ---
Not quite:
rise / run * 100 = percent slope
For small degrees or slopes, you can go by slope (not percent) ~= angle in radians: 25 percent slope = 0.25 slope = ~0.25 radians. (26 percent slope rounds to 0.25 radians.) But you have to convert to degrees if you want to use it.
Now
tan (angle) = rise / run
angle degrees = angle radians * 180 / pi
so, arctan (rise/run) = angle
What you should use is:
tan (x) = 2.75 / 5, or
arctan (2.75/5) = x degrees
You get x = ~28.8 degrees
But what you really want to cut each board is 1/2 of 90 - 28.8, or ~30.6 degrees. (Subtract from 90 since we computed the angle from horizontal, while the reference board is in the vertical position.) Did I confuse this enough for 3 degrees? ;D
FWIW from the numbers, IMO the angle was supposed to be 30 degrees, and we're getting the just off numbers from rounding and (not enough) precision of the length measurements.
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