Biesseworks and Trigonometry

[cbkrahn]

Hello,

I'm an employee at a small woodworking shop, and we just recently bought a used Rover 4.35. I've been given the wonderful task of learning how to use this machine. So over the past couple weeks I've spent a good deal of time with said machine, and we've gotten along pretty well, right up until the point where I tried getting Biesseworks to do some trigonomety for me. Now, my trigonometry sucks, even more so when you throw in Radians, so I'm hoping someone here can help me with a program.

I'm designing a program to cut stair stringers, which works wonderfully, right up until try to get the program calculate the length of the stringer for me. I need to find three variables, then add them to give me the length of the board I need. These variables are XA, XB, and XC. XB I have already calculated, works great. I cannot however, figure out how to get XA or XB to work (XA and XB being the height of the triangles formed by the stringer greometry at the top and bottom of the board).

Instead of me very poorly explaining myself I'll attach the Biesseworks file and hopefully somebody can see what I'm doing wrong and help me out. Thanks.

[Kiwi]

Not sure what the XA XB XC relate to. Would need a sketch. This may help.

Each step stringer length = square (treadlength^2 + riseheight^2)

Angle = Atan(RiseHeight/TreadLength)
Each step triangle height = Sine(Angle) * Treadlength

[cbkrahn]

I'll try to explain better, now with pictures!

I already have the stringer geometry figured out, which makes me happy, cause it took forever to figure out how to do it! Here's some code:

'Solve Stringer Length
Dim XA
XA=??

Dim XB
XB=Sqr((RU^2)+(RI^2))

Dim XC
XC=??

Dim SL
SL=XA+(XB*(Nrise-2))+XC

LPY=SW
LPX=SL
UpdatePanel

So the program uses the variables XA, XB, and XC to figure the length of the stringer board. XB, the middle section, is already figured out, and you can see the stringer length is calculated to exclude the first and last rise at the moment.

LOC=MC|25.4|Converts Inches to Metric|0|
LOC=RI|RISE*MC|Rise in MM|0|
LOC=RU|RUN*MC|Run in MM|0|
LOC=TRI|RI*NRISE|Total Rise|0|
LOC=TRU|RU*NRISE|Total Run |0|
LOC=FR|RI-(TREAD*MC)|First Run|0|
LOC=SA|ATN(TRI/TRU)*(180/PI)|Stair Angle in Degrees|0|
LOC=SW|WIDTH*MC|Stringer Width|0|

These are the vairables I used. Boss measures everything in inches, instead of trying to get him to change, I just convert in machine.

SA is the stair angle, which is roughly 35.8 degrees. FR is the first rise, which is the normal rise minus the tread thickness. This is where my math fails me.

Type Sin(35.8)*139.7 into a calculator and you get 81.72, which (I think), is exactly what I want. It's the height of the small triangle at the beginning of the board, which I want to use to add length to my stringer. But the computer calculates in radians, and if you use that same formula in radians you land up with a negative number. That's where I get stumped. I was able to get the Stair Angle (SA) to convert into degrees from radians, but I can't figure out this one.

I hope that's clearer and someone knows more than I do :P

[Kiwi]

IMHO...XA = Sine(Angle) * (Riser - TreadThickness)
XC = (Cos(Angle) * TreadLength)