My Brain Hurts

A simple bit of trig but I just cannot seem to get my head around it. Trying to work out metalwork size for a mixer side piece. There is 320 mm from the point of the sloping panel to the rear of the mixer. The sloping part is 400mm and the top of the sloping part is 220mm deep. I need to work out the angle of the slope (theta in the attached diagram)

Cheers

Ian

76.0 degrees exactly. Actually it's 74.3.

Sketchup will make your brain hurt less. It looks complicated but just watch the tutorial videos for an hour and you'll be on your way. IMO this stuff isn't practical without Sketchup.

Hi Ian,

If I remember my trig.

place the 320 side flat on a level surface
use a plumbob to drop a line down to the 320 edge from the upper right angle
measure the length of the drop
Opposite over hypotunuse = Sine of Theta (OHMS??)

Mike

I was usually looking out the window (at a girls gym class the same period) but if you know the height of the back you could break that into two right triangles and use the simpler trig identities.

JR 

PS: or cheat and use CAD

squarewave said:

76.0 degrees exactly.

Sketchup will make your brain hurt less. It looks complicated but just watch the tutorial videos for an hour and you'll be on your way. IMO this stuff isn't practical without Sketchup.

Click to expand...

Thanks for that. Never been able to get my head around Sketchup either. I was going to use the normal 2D CAD program I use bu I could not work out how to do it.

Cheers

Ian

from pythagora triples:
B*B=220*220+400*400
B=456.5
A*A=B*B-320*320
A=325.6
and from trigonometric functions:
sin(alfa)=220/B
alfa=28.8 deg
sin(beta)=A/B
beta=45.5 deg
theta=alfa+beta=74.3 deg

Hello Ian

tan a' = 220/400 --> you solve the a' angle

cos a'=400/x --> you solve x

cos a'' =320/x --> you solve a''

theta =a' + a ''

hope i'm right  :-X

Best
Zam

HAAAA Moamps faster  8)

congratz

(edit: I confirm moamps result, 74,3)

Whoops. Sorry. I got one of the dimensions wrong. Sketchup confirms 74.278 degrees.

squarewave said:

76.0 degrees exactly. Actually it's 74.3.

Sketchup will make your brain hurt less. It looks complicated but just watch the tutorial videos for an hour and you'll be on your way. IMO this stuff isn't practical without Sketchup.

Click to expand...

I second this. My workflow is Sketchup and then I go into Rhino 5.

JohnRoberts said:

PS: or cheat and use CAD

Click to expand...

Yes; the fact that not all answers were unanymous shows that there are mistakes to be made, using math.
I'm not that keen on Sketchup, but I was trained on Autocad; I don't have a licence anymore but Dassault Systems have a fully compatible program, Draftsight, that is free for DIY'ers. That's what I currently use for a number of things, of course front panels, but also furniture (my latest being an electrically height-adjustable coffee table), luthiery, interior design...
I guess it would take 2 minutes to work out your little problem.

abbey road d enfer said:

... but I was trained on Autocad; I don't have a licence anymore but Dassault Systems have a fully compatible program, Draftsight, that is free for DIY'ers.

Click to expand...

This is interesting. Abbey, since you also come from AutoCad, what kind of re-learning curve would I expect, considering that I come from AutoCad R12 for DOS?

It would be nice to not have to fire up the ol' Pentium 60 with win 95 on it, just to draw something.

Thanks,
Gene

what is this, Quiz Kids or something?    just use a protractor. or a laser from a surveyor.

yeah, just construct a hipot and you have side- angle- side  then the rest is cake.

more than one way to do it,  brute force works best on tests.

74.3 degrees as mentioned above>

I was off a half-degree or so on some of my 'eyed' panel cuts.  I just hit that section a little longer with the buffing wheel.
I'll tell people I was just trying to keep the console fully analog. =P

Thank you everyone for the many and varied solutions to my little problem.

Do you think 74 degrees or so is too steep for a mixer front slope?

Cheers

Ian

CAD server is offline, so I can do some local fiddling and Creo says 74.31 degrees (see attached drawing).

I have the file now, Ian, and since it is parametric CAD I can easily adjust dimensions ad the drawing will update. Let me know if you want different dimensions and I'll fill them in and get you the updated drawing.

The 1608 has 75 degrees for the meters so the 74 would seem a good choice

http://barryrudolph.com/recall/manuals/api1608dimensions.pdf

I think it is interesting that several methods were proposed for the same problem - all viable

Raw brain power/Calulation
Measurement with a plumbob and a bit of trigonometry
Draw it out to scale

My wife also went for the - just get a protractor and measure it - that'l do.

I suppose the CAD answer is the most appropriate given the title of this forum section.

Show that our brains are all wired differenty .  - Fascinating Captain 

Mike

Gene Pink said:

This is interesting. Abbey, since you also come from AutoCad, what kind of re-learning curve would I expect, considering that I come from AutoCad R12 for DOS?

Click to expand...

Minutes; beware there are two GUI's, one is very similar to Autocad 12/14. Once you selected it, you should be going quick.
In my particular case, when I lost my license, I was looking for a crack substitute; after having tried a couple of alternatives, I stumbled on Draftsight. It was so similar to Autocad that I was wondering if Dassault Systems had rebadged it.

madswitcher said:

I think it is interesting that several methods were proposed for the same problem - all viable

Raw brain power/Calulation
Measurement with a plumbob and a bit of trigonometry
Draw it out to scale

My wife also went for the - just get a protractor and measure it - that'l do.

I suppose the CAD answer is the most appropriate given the title of this forum section.

Show that our brains are all wired differenty .  - Fascinating Captain 

Mike

Click to expand...

Must say that one does get a bit lazy, but the advantage of the program I use at work (Pro/Engineer/ Creo Parametric) is that you can easily finetune dimensions or dimensioning schemes and have the drawing update automatically (similar to other 3d software like Solidworks). I was pretty fanatic about AutoCad, but I even do not have it on my work laptop anymore. If I need to do anything 2d I use Adobe Illustrator (also very handy when you want that technical drawing from a datasheet in PDF format).

Will have a look at Draftsight, wasn't aware of it, but it looks interesting, especially if you can edit a lot of other fileformats (I am hoping Microstation).