?? templating large irregular radii / elipses

[ChrisYaughn]

How would you guys shoot/template this? I did a three point arc based on the inside wall of the block. Then offset enought to get the max out of the slab and clear the stones. Problem is, the actuall shape doesn't seem to have a predictable geometry. No surprise, given that it is an eyeball laid out block wall.

I figured jacke dup overhangs but a clean geometry would be the best compromise.

The wackiness nearly caught me short to where I couldn't cover the stone veneer in one or two places.

[DavidL]

Chris - In my cases with these types of objects I forget about doing a radii on the laser. Instead I shoot a group of points. For something as large as that is I would look for like six points on each long side, two on each short. Then in autocad (or wahtever cad you are used to working with), I would go over those points with a "spline" (autocad) or a "Nurb" (a lot of other cad softwares). What you will typcically get is not a true arc but rather a clean piece of geometry. The biggest issue is that it isn;t a true arc typically. Once you have your geometry, offset for overhangs as desired and you should be good to go.

[Carmine Pantano]

I would do the same as David except we use a Proliner.

[clhilde]

i just found out you can scribe in the arch mode then you can offset a scribed wall

[DavidL]

Chris - When you scribe in ARC MODE does it create a series of arcs or does it create one "scribe" piece of geometry? For me having the one piece of geometry is very nice in the way that my CNC runs. When I have a series ARC's connected the machine will leave a little mark at each start stop (beginning/end) of each ARC. IF you are fabbing manually not a big deal, but from a CNC standpoint (at least mine) the cleaner I can make my goemetry the better the final finish.

[clhilde]

It depends on how far you try to scribe i just did that big pool we were talking about and if i did 3 ft sections with out starting a new line it was a nice arch but if i did to big of a step it looked jacked up.It took some time to figure it out but i had a little clean up to do.To clean it up i just went back to arch mode and made certain points of my scribed arch and filleted accordingly

[Mark Meriaux]

Another way to skin the cat:

1) Shoot a series of whatever (could be lines OR short arcs) to get a true reading of the shape.
2) To simplify the geometry (for CNC cutting), draw a 3-point arc using the line/arc points to "approximate" the shape
3) Compare the new arc to the physical shape, you'll see where it might miss
4) If you can't get a decent approximation with a single arc, break it into two (or three maximum)
5) Once you get simplified geometry that closely models the actual shape, then do your offsets
6) Where I have intersecting arcs, I sometimes add a radius/fillet (another arc) to blend them for a better transition

Call me if my description isn't clear.

[Matt Lansing]

If I were to do it I would make it as a perfect three point arc covering the rocks that stick out the farthest as these are the sight lines that people will judge the quality of the work off of. Then I would offset the line to the backside of the arc taking my overhang off of again the rock that sticks out the farthest.

[Todd B]

If I were to do it I would make it as a perfect three point arc covering the rocks that stick out the farthest as these are the sight lines that people will judge the quality of the work off of. Then I would offset the line to the backside of the arc taking my overhang off of again the rock that sticks out the farthest.

Same here but in KIWI that does not make much sense

I Use proliner would do 3 point arcs like matt says
Always bigger than smaller............People like BIGGER not smaller who knows why.........I guess they think they have got more for there $$$

[Paul B.]

...or just throw some sheets of coroplast over the thing and trace it




...or not ...a proliner will trace the darn thing and clean in cad w/ a 3 point arc as close to original lines.