mini-challenge

[jason_maranto]

I cleaned it up, streamlined the process a bit (removed a few unnecessary steps) and saved for version 6:

challenge_final.skp

I was looking at the very first image in the thread, is that not what we are shooting for here?

Best,
Jason.

[fredo6]

Jeff,

Not sure plugins are allowed in this challenge, and unless I am wrong, this could be done with the but normally Planar Shearing can be performed with FredoScale

Jeff Challenge.gif

Fredo

[Rich O Brien]

@Fredo

Is your frame changing thickness? It does for me

[Pilou]

A little light in my deseperation?

[pbacot]

Off-Topic:

The thing absolutly crazzy is that the Rotation tool
seems accept just the base alignement as only good alignement!
I am totally depited!

I love this word!

Yes if heights are not a given... Push pull the posts to the diagonal

[Dave R]

Jason, how do you determine the where the diagonals hit the sides of the posts?

Fredo's example does result in a narrower board. It could also be achieved with native tools by selecting one end of the board and moving that end up.

[jason_maranto]

The desired thickness is .5 meters -- so the first guides are each measured out to .5 meters from the main diagonal (the only one that is obvious and never changes).

So the next Diagonal can be found at intersections at .5 m guide up on the left post and .5 m guide down on the right post -- from there you delete the original guides and connect the diagonals with the line tool.

After that you pull off new guides to .5m from the bottom and top -- which again will give the corrected diagonal at the intersections on the left post and right post... the other diagonal has been known since the beginning(doesn't ever change).

All I used was the line tool, tape measure tool, and push pull.

Best,
Jason.

[Dave R]

If you measure .5m up and down the verticals, the board is not going to be .5m thick.

[jason_maranto]

It is as I show in the updated file.

challenge_final.jpg

Best,
Jason.

[fredo6]

@Fredo

Is your frame changing thickness? It does for me

Ooops. I should have read the thread in details.
Then, it just need a dedicated plugin, this won't be a conform transformation

Fredo

[Pilou]

No need to change anything!
With the fredo scale Planar Shearing shown previus!
Just make the rotation on the top of the block!

Perfect!

yes.jpg

yes2.jpg

[TIG]

A "plugin free" solution that is accurate to 0.009mm...

[thomthom]

No need to change anything!
With the fredo scale
Just make the rotation on the top of the block!

yes.jpg

yes2.jpg

That changes the width of the board, doesn't it?

[mac1]

rail rotation.jpg

[Pilou]

That changes the width of the board, doesn't it?

No nothing is changed
You have just to draw the block box to modify on the ground, with any measures (just fit the 2 pilars )
Nno need to push cut anything!

[thomthom]

When testing I recommend you put the posts further apart as with near square shape deviances might be so small that you think you have a correct solution.

[TIG]

Mac1

How do you get the rotated guide pt to snap exactly onto the horizontal top guideline ?

[Dave R]

Pilou, when I used Fredo's method my board went from 5" wide to 3-1/16" wide. The length of the miter remained at 5", though. I'd say that's a change. Mac1's idea looks interesting.

[Gaieus]

Is this "close enough"?

[jason_maranto]

Absolute accuracy seems to be something that would be pretty easy since we know all of the measurements, including the first diagonal -- I would just rotate a copy of the diagonal around the midpoint to make the second diagonal, thus giving all 4 ending points for the shape... but I would need to calculate the specific degrees for the rotation, and I'm not well versed in that level of math.

Definitely seems a plugin to make this is a need after all... if absolute accuracy is required.

Best,
Jason.

[thomthom]

Is this "close enough"?

Measurement.png

Very close - but surely it should be possible for full accuracy..?

[Gaieus]

I also noticed that if I crank up the decimals, I get an inaccurate measurement for that thickness (although a different one)

Now the very interesting thing is that I did not do any shearing but only worked with the rotate tool. So there could be inaccuracy but then it's Sketchup's tolerance when it merged two endpoints so close that I could see the electrons spinning. But then yes, I was indeed relying on this "tolerance" (just did not know how it will work).

[Jeff Hammond]

So how do you calculate it?

the way i calculate it in the DC :

mini4.jpg

you can find all the info of the hypotenuse (green) in a variety of ways .. (for instance, a^2 + b^2 = c^2 to get its length.. you'll know a & b in this case… then trig for the angles)

that hypotenuse is also the the hypotenuse of the un-trimmed board (red).. so you know the board width and the length of its hypotenuse which means you can get all other angles and lengths..

the rotation of the original hypotenuse minus the long angle of the board's hypotenuse give the correct rotation angle..

here's the DC i use (after i use 'component options' to enter the dimension of height, board width, and the space in between the two poles, i'll then trace the results and copy/paste it into my actual drawing.. not entirely ideal but it works..)

DC_Xbrace.skp

for whatever reason, i still think there might be a way to do it in sketchup itself.. maybe jean L can come up with something
so far, it's looking like true-tangents may be the key.. i haven't tried it yet in this circumstance but i imagine it will work.

[Dave R]

Excellent, Jeff.

[Jeff Hammond]

... thus - for best accuracy, draw it in ACAD and import into sketchup

Amen. Trimble, if you're reading this, we need actual arcs and curves in SketchUp.

i'm not quite sure they could give us true arcs in sketchup without entirely changing the way sketchup works.. (how would a cylinder be drawn if there were no segments in the arcs? a nurbs surface? )

what they can give us, i feel, is 'guide arcs' …which would also allow us to rotate this thing and snap it into place very easily.. basically, a smarter rotate tool.

.

[pbacot]

OK, what's wrong with Mac 1's version. Can the reference point from the tip to tip dimension be accurately placed on the horizontal guideline to give a marker for snap rotation of the board? I think it is the same problem, requiring math calculating length parallel to board tip to tip.

[pbacot]

... thus - for best accuracy, draw it in ACAD and import into sketchup

Amen. Trimble, if you're reading this, we need actual arcs and curves in SketchUp.

i'm not quite sure they could give us true arcs in sketchup without entirely changing the way sketchup works.. (how would a cylinder be drawn if there were no segments in the arcs? a nurbs surface? )

what they can give us, i feel, is 'guide arcs' …which would also allow us to rotate this thing and snap it into place very easily.


.

Someone at Trimble is saying "What? There aren't real circles? Oh crap! What have we done?"

[Jeff Hammond]

OK, what's wrong with Mac 1's version. Can the reference point from the tip to tip dimension be accurately placed on the horizontal guideline to give a marker for snap rotation of the board? I think it is the same problem, requiring math calculating length parallel to board tip to tip.

i'm still working through the thread.. checking mac's version next.. i'll report back

[jason_maranto]

The DC is not working for me for some reason -- I see it and formulas, but no interactivity.

This is a variation on few similar solutions here -- but they all have a minor (or not so minor) variance -- it just does not make sense to me why

challenge_alt.jpg

I mean the rotate tool should be accurate since it is not tied to polygons (like arc or circle), right?

Best,
Jason.

[bmike]

maths, gotta love it. nice problem to post jeff!
tricky little problem, hitting opposite corners on that board. especially when graphically, you can't quite get there with sketch up.

i've been working on a DC to sort of automate hip and valley creation in timber.
in order to get this far i've built a dc (both hip and valley) with sub components that are planes that rotate about with in the 'container' component. there are guidelines at the peak where this would potentially miter. the foot condition changes too much - so i usually do some solids work or intersecting with the model down there.

here's a snap of the attributes (runs off the bottom of the window):

Screen Shot 2012-04-30 at 1.29.59 PM.png

and the component:

Screen Shot 2012-04-30 at 1.28.44 PM.png