Just my .02$
I personally do this by running some scrap wood thru the tablesaw.
Make small cuts, as you can then increase the cut angle as needed.
Holy crap! Has the entire world forgotten trigonometry (http://en.wikipedia.org/wiki/Trigonometry)?
I think you need to use the inverse trig functions (http://en.wikipedia.org/wiki/Arc_cosine) (e.g. arccosine) to figure out the angle given the lengths of two sides...
Holy crap! Has the entire world forgotten trigonometry (http://en.wikipedia.org/wiki/Trigonometry)?
I think you need to use the inverse trig functions (http://en.wikipedia.org/wiki/Arc_cosine) (e.g. arccosine) to figure out the angle given the lengths of two sides...
Scott, with the info given, we don't have the lengths of the sides.
ScottS,
What you've drawn is the process to use if we had been supplied with the dimensions A, B, & C. Those are the dimensions I believe Akuma is really interested in and what he's drawn is probably mis-communicating what he's looking for. My point about the difficulty of calculating it was almost completely in an academic discussion, to calculate exactly the information that the original drawings requested would have been much more complex, almost definitely excessive, and a waste of time compared to getting the information in a different way.
Provided somebody knows the desired finished exterior dimensions or interior dimensions of their project the information posted by ScottS is correct. Thank you Scott for posting it for us all to see. Given the same known dimensions I could also do a drawing with no math involved and have the computer spit out the angles, the original problem was that we didn't have the finished dimensions of the part.
Oh, and yes I was making it more complex than it needs to be to build the project, but no more complex than the problem originally was.
Scotthh,
I'll have to give that workbook a look, it sounds interesting. Thank you.
Again, Unless you have some super accurate table saw, your math
wont mean too much.
How will you know your table saws angle is exactly 132 degrees for
example?
And, are you accounting for the blade width removal in your calculation?
Which side will it remove from... and or will it be centered removal?
What if your saws guide is slightly off?
There are many issues. mostly to do with material removal of the
blade thickness, and the less that adequate angle measurement on
most tablesaws.
This is why its much easier and accurate to do test cuts on scrap.
Again, Unless you have some super accurate table saw, your math
wont mean too much.
Again, Unless you have some super accurate table saw, your math
wont mean too much.
:banghead:
As a long-time woodworker and budding machinist, I would have to completely disagree with you! Accuracy of your table saw is almost completely irrelevant to this discussion. More important is the accuracy of your measuring tools. Anyone with $10-15 in their pocket can buy a Starrett angle meter that's accurate to a degree. If you've got another $5 or $10 you can probably score a machinist protractor that's twice as accurate. Either one is good enough to be able to setup a table saw or circular saw well enough to make cuts that are more than accurate enough.
Once you know the angles on your saw are correct, you just need to calculate how long your pieces need to be. There's no magic here. If you can measure the width of the top and bottom, you can use the formula I gave to calculate the length of the sides. Dealing with the saw kerf for these angles cuts is just like dealing with the saw kerf for any other cut! The kerf really only comes into play when you're laying out your cuts; if you want to get multiple pieces out of a single board, then the kerf becomes more important.
You're more than welcome to spend an afternoon in the garage hacking around on scrap wood and hoping that everything will work out when you scale things up to a full-size cabinet but for myself I'd rather do the math, make a single series of cuts, and have everything go together without needing a gallon of Bondo to mask the screw-ups. But that's just me...