generate triangle using span lengths

This forum is for general discussion about Aspire
Post Reply
Gerald Martin
Posts: 8
Joined: Thu Jul 20, 2017 6:47 pm
Model of CNC Machine: ShopBot PRS Alpha 96-60

generate triangle using span lengths

Post by Gerald Martin »

This seems too simple. I need to cut stair treads where I only know the dimensions of each span of the triangle. Each tread will have different dimensions for instance - 66.875" x 21.125" x 53"

Is there any function for this in the software? If not, a gadget or plug-in of some sort that does this? I could work around it by using an online triangle calculator or Microsoft Mathematics program to solve for angles...what a hassle.

Surely there is a better way?

Gerald Martin
Creative 3D WoodArt
Dongola, IL USA

User avatar
FixitMike
Vectric Wizard
Posts: 2173
Joined: Sun Apr 17, 2011 5:21 am
Model of CNC Machine: Shark Pro Plus (retired)
Location: Burien, WA USA

Re: generate triangle using span lengths

Post by FixitMike »

Are you asking about laying out the stringers? The stair tread is what you step on. With dimensions similar to: 1 1/4 " x 36" x 12" Try searching Google for "stair stringer calculator".
Good judgement comes from experience.
Experience comes from bad judgement.

ger21
Vectric Wizard
Posts: 1592
Joined: Sun Sep 16, 2007 2:59 pm
Model of CNC Machine: Custom DIY
Location: Lake St Clair, MI, USA
Contact:

Re: generate triangle using span lengths

Post by ger21 »

Surely there is a better way?
Geometry.

Draw one leg of the triangle. Then, draw two circles, with the center points at the ends of the line you drew. Each circles radius will be the length of one of the triangle legs. Then draw lines from the existing line, to the point where the circles intersect.
Gerry - http://www.thecncwoodworker.com

User avatar
Leo
Vectric Wizard
Posts: 4082
Joined: Sat Jul 14, 2007 3:02 am
Model of CNC Machine: 1300 x 1300 x 254 Chinese Made
Location: East Freetown, Ma.
Contact:

Re: generate triangle using span lengths

Post by Leo »

Stair Treads?

Stringers?

Perhaps you have something else in mind, but if you are talking about stair stringers there are building codes for rise and run. Building codes are there for a reason and really should not be violated. Not because we don't want someone telling us what to do, but because the code specs help us humans as we use the stairs. Having different rise or run in a set of stairs is a very definite no-no.

If you really want to use Vectric to calculate triangles, you can use the lines and vector editing. Draw a line horizontal starting at 0,0. Use node edit and properties to set the note that is not 0,0 to the exact number that you want. Do the same on a vertical line. Now you can draw a hypotenuse line and snap to endpoints. If you want you can dimension angles.

That's a lot of work though. Internet search "trig calculator" and get the same answers but WAY faster.
Imagine the Possibilities of a Creative mind, combined with the functionality of CNC

Dale Vanderlaan
Posts: 14
Joined: Sat Feb 25, 2017 6:57 pm
Model of CNC Machine: Axiom 8 Pro
Location: Ravenswood, WV

Re: generate triangle using span lengths

Post by Dale Vanderlaan »

How about using the fact that you know a triangle contains 180° of interior angles and you already know all the sides:

Sides
66.875"
21.125"
53"

Sum (perimeter):141"

Interior Triangle angles total: 180°

To calculate angle opposite 66.875" side (X):
As a ratio: 66.875" is to 141" as X° is to 180°
Written as an equation: 66.875/141=X/180
Solve for X: X = 180 * (66.875/141)
X = 85.372°
Repeat for the other 2 sides and you've got all three. A spreadsheet like excel could make multiple calculations for many steps a lot faster.
Good Luck!

PaulRowntree
Vectric Wizard
Posts: 1687
Joined: Sun Oct 24, 2010 7:28 pm
Model of CNC Machine: homebuilt 4'x2' (Mach3+G540)
Location: Guelph, Ontario
Contact:

Re: generate triangle using span lengths

Post by PaulRowntree »

Dale Vanderlaan wrote:How about using the fact that you know a triangle contains 180° of interior angles and you already know all the sides:

Sides
66.875"
21.125"
53"

Sum (perimeter):141"

Interior Triangle angles total: 180°

To calculate angle opposite 66.875" side (X):
As a ratio: 66.875" is to 141" as X° is to 180°
Written as an equation: 66.875/141=X/180
Solve for X: X = 180 * (66.875/141)
X = 85.372°
Repeat for the other 2 sides and you've got all three. A spreadsheet like excel could make multiple calculations for many steps a lot faster.
Good Luck!
Perhaps I misunderstand, but this doesn't look right. Imagine a right angle triangle, with the sides in the 3" - 4"-5" proportion. Sum is 12". Long edge is opposite 90 degree angle, but 5/12 is not 90/180.
Paul Rowntree
WarpDriver, StandingWave, Topo and gadgets available at PaulRowntree.weebly.com

Dale Vanderlaan
Posts: 14
Joined: Sat Feb 25, 2017 6:57 pm
Model of CNC Machine: Axiom 8 Pro
Location: Ravenswood, WV

Re: generate triangle using span lengths

Post by Dale Vanderlaan »

Oops! Sorry! You're right. I was thinking something else - the law of sines. Disregard that whole whacked out dissertation, please. I've been calculating the exterior and interior of the back plate of a cello for so long that I think some brain cells have been damaged. Over 363,000 elevation points per surface. Finally have them ready for a prototype run. I hope the brain was still working at that point!
I think what he wanted anyway was not the angles found but a macro-type program that would just draw the triangles with the given 3 side measurements.
Dale

Gerald Martin
Posts: 8
Joined: Thu Jul 20, 2017 6:47 pm
Model of CNC Machine: ShopBot PRS Alpha 96-60

Re: generate triangle using span lengths

Post by Gerald Martin »

Some great ideas here and I appreciate your input. Microsoft Mathematics - free download - is a pretty neat PC calculator and it does the calculations perfectly.

I still think that there should be a gadget or something that lets you input the three span lengths then generates the triangle. You could then scale/flip/rotate...

Better yet a function built right into the program.

Gerald Martin

Post Reply