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View Full Version : Slicing: concentric circles/ neatest-most efficient way to get / fails and tales



jeric_synergy
11-14-2015, 03:04 PM
Here's the situation:
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I'd like to SLICE the concentric circles of the 'flat cone' into the chamber.

My first use of DRILL, with the cutter in the background, not as pictured, resulted in no change at all. (that seems familiar). However, that's not what I want anyway. I decided to make a circle, use strandmaker to get a nice 2pt polychain out of it, and then CLONE it with a scale factor to get concentric circles.

THAT didn't work, because I want even spacing between the circles. :grumpy:

Went back to the flatcone, selected the circle LOOPS, copied them to an empty layer, MERGED points just in case, and attempted to use DRILL. Got this error:
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UNDO, selected JUST the top polys, checked for flatness, they're all 3 points, DRILLED again, same error. Decided too many POINTS in the drill were falling on line segments, rotated it slightly, SUCCESS!

So, there's a tale of mild perseverance for the noobs.

My question is: is there a more elegant/efficient way of creating the concentric circle cutter? All that loop selection is tedious

ernpchan
11-14-2015, 03:08 PM
I'd use bevel with a shift value of 0 to make the smallest ring. Then Bandsaw to make the even spaced rings.

jeric_synergy
11-14-2015, 03:17 PM
I'd use bevel with a shift value of 0 to make the smallest ring. Then Bandsaw to make the even spaced rings.
:foreheads: Of course. And now that I'm thinking along THOSE lines, CUT would probably be easier than constructing a cutter too. Geeze. :redface:

Thanks for the nudge. --::tries:: But of course you meant 'multishift', right?

jeric_synergy
11-14-2015, 03:28 PM
OOOOOooooo, now, here's an interesting thing:

You CAN use CUT in this situation, and it very neatly adds uniform cuts and has a button ('Uniform') to make it simple. BUT, as you use it, you see this scarey thing: :eek:
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As you add/subtract cuts, the cut seems all wonky and wrong. BUT, once you hit 'Uniform' the discrepancies disappear.

EDIT: I see the 'error' has to do with non-uniform cuts, but I'm not sure why it results in a key-hole shaped slice. Mathematically it is probably not an error, but from a user point of view it looks like one. It also probably has something to do with triangles vs quads.


Thanks again for pointing me down the correct road: that DRILL procedure was an awful idea.

gerry_g
11-14-2015, 03:42 PM
personally I would have gone back to your original cutter, deleted every alternate ring then used SHIFT+E to extrude to a 3D cutter making sure it intersects the item you want to cut then used solid drill to cut it, although I can't see you have in your instance, n-gons or non planer geo can be an issue for stencil and I have often found a solid objects cut better

jeric_synergy
11-14-2015, 03:45 PM
Interesting thought. But every ridge would define two lines..... ::muttering::....seems complicated. But no doubt will come in handy someday.

I was hoping a bunch of 2pt polys would avoid any non-planarity issues.


Here's the object if you want to play with it: 131016

EDIT: one more oddity: if you attempt to CUT both the ceiling and the floor simultaneously, things get weird.

EDIT2: hitting 'uniform' repeatedly alters the cut, although (obviously) it should not.

JoePoe
11-14-2015, 04:01 PM
If you're not picky about the exact # of concentric circles....

How about hitting "l" two or three times (with ring of pie pieces selected of course)?
You can do top and bottom at same time.

ernpchan
11-14-2015, 04:03 PM
:foreheads: Of course. And now that I'm thinking along THOSE lines, CUT would probably be easier than constructing a cutter too. Geeze. :redface:

Thanks for the nudge. --::tries:: But of course you meant 'multishift', right?

I would use bevel but that's only cuz I use that more than multishift. I use BandsawPro a lot where I have a preset set to cut at 20-40-60-80 (assuming that's the spacing you want). So that's just where my brain automatically went.

I've never used the Cut tool, never even knew about it till now tbh.

jeric_synergy
11-14-2015, 04:11 PM
How about hitting "l" two or three times (with ring of pie pieces selected of course)?
You can do top and bottom at same time.
I've reassigned "l" (lower case "L") to "Loop".... because I could never remember the original SELECT LOOP keystroke. Are you referring to Subdivide?

:clic clic clid: Ohhhh, "CONNECT". ---I never, connect, that tool with its function because that name just doesn't work for me.

jeric_synergy
11-14-2015, 04:24 PM
I would use bevel but that's only cuz I use that more than multishift. I use BandsawPro a lot where I have a preset set to cut at 20-40-60-80 (assuming that's the spacing you want). So that's just where my brain automatically went.

I've never used the Cut tool, never even knew about it till now tbh.

I tried Bevel but all the pie wedges beveled individually. I guess I don't know what function the bevel is supplying in this context.

ernpchan
11-14-2015, 04:31 PM
Oh sorry, I would have started with a disc. Then used bevel on the one end with an shift of 0 and inseted down to the smallest ring. Then use BandsawPro with the new loop to make your additional cuts.

So with what you have in your first picture, I'd merge all your pie wedges to a single poly. Then do my bevel operation.

JoePoe
11-15-2015, 12:54 AM
All that loop selection is tedious

Why?

1) Select one loop (select one edge > right arrow)
2) Select Ring

jeric_synergy
11-15-2015, 08:31 AM
1) Select one loop (select one edge > right arrow)
2) Select Ring
Huh. :stumped: I guess I have a fundamental misunderstanding of what Select Ring does.

That's going to be handy.

:reads dox: BeeVee should put in a little more info: I would never have predicted this behavior from the dox, and it's pretty valuable.

EDIT: perhaps "Select Sideways" would convey the selection action better. Not really suggesting a name change, but just included in the description.