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]

(rise/run) x 100 = degrees angle

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?

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. 

[Fozzy The Bear]

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.).......SNIP......

Geezzz Guys!!! What are you trying to do here, turn it into rocket science. You don't need all that calculation. You just take the measurements off the drawing and draw em out on the timber. It ain't that complex to do. This is timber cutting not precision engineering.  You're still going to need the wood filler handy when you get done cutting.

Any Noob reading this thread would think you have to be genius just to knock a cabinet together. Stop over complicating the stuff.

Best Regards,
Julian (Fozzy The Bear)

[DaveMMR]

I took my measurements from Carlos's Centipede Cab (who modified it from Jakobud's measurements of an actual Centipede).  They were all in half, quarter and three-quarter inches.
He may have rounded some of those, but it all fits together fine.

I still modified it slightly (an extra inch - give or take -  in all directions) but mostly, I drew out the side panels to the desired width and height and drew out all the major pieces (front panels, slants, etc.) more or less relative to the original.

Yeah, that cut is 30 degrees.  As bad as my cutting skills are, I was able to make that and the other angles with a circular saw with little problem. 

So do a quick graph paper mock up, get a good ruler and protractor, and you should be fine.

[shardian]

29 degrees according to my CAD drawing, but get it between 27 and 31 and you are good to go. That is what sander's are for.

Sorry about the math. I do have an engineering degree, so I am a weirdo who actually likes math. One time I actually used Calculus to estimate the amount of beans in a jug for a contest.

[DaveMMR]

29 degrees according to my CAD drawing, but get it between 27 and 31 and you are good to go. That is what sander's are for.

Sorry about the math. I do have an engineering degree, so I am a weirdo who actually likes math. One time I actually used Calculus to estimate the amount of beans in a jug for a contest.

Did you win?

[shardian]

29 degrees according to my CAD drawing, but get it between 27 and 31 and you are good to go. That is what sander's are for.

Sorry about the math. I do have an engineering degree, so I am a weirdo who actually likes math. One time I actually used Calculus to estimate the amount of beans in a jug for a contest.

Did you win?

Actually, the lady told me I was quite close, but I never heard anything back. Sometimes I wonder if those contests ever actually have a winner. The crappy thing about taking alot of higher math is that you forget how to do simple stuff...you know, like simple division and subtraction.