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Author Topic: Inscribed circle, what am I missing?  (Read 29026 times)

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Inscribed circle, what am I missing?
« on: December 02, 2010, 07:58:01 AM »
From the definition in the manual, I expect the tool definition "Inscribed Circle" to be the radius of a circle that will completely envelop the tool. Or it stupid person terms for me, how big of a snow angle would the tool make if spun in a circle.

So using that definition, I created a tool in LazyTurn that is a 55 degree diamond tool that is 3/8" long on its longest axis. So I set the inscribed circle to 0.1875. Attached is a screen shot of the result. LazyTurn creates a diamond that is 3/8" on its short axis and about 0.8" on its long axis. There is no way that a circle of radius 0.1875 could inscribe the tool that LazyTurn created.

What am I doing wrong?

-Jim

Offline Dan13

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Re: Inscribed circle, what am I missing?
« Reply #1 on: December 02, 2010, 09:19:01 AM »
Hi Jim,

Tool inserts are defined by the inscribed circle. i.e. the circle inside the insert and tangent to all its sides. From your description I think you were defining a circumscribing circle.

Dan
Re: Inscribed circle, what am I missing?
« Reply #2 on: December 02, 2010, 12:52:16 PM »
Hi Dan,
Thanks for the help. When I read page 16 of the manual, it's pretty clear that LT's definition of inscribed circle is not the same as the standard definition for inserts. The verbage straight from the manual says:

"2. Inscribed Circle - Defines a circle, which when drawn about the center of the tool insert, will include the entire tool insert."

However, the actual behavior of the program is working as you describe, a circle that fits completely within the insert.

-Jim
Re: Inscribed circle, what am I missing?
« Reply #3 on: December 02, 2010, 01:02:09 PM »
http://www.machsupport.com/forum/index.php/topic,5767.msg69856.html#msg69856
I thought that was corrected in the manual .... I'm sure it soon will be.
Re: Inscribed circle, what am I missing?
« Reply #4 on: December 02, 2010, 01:26:34 PM »
Excellent. Thanks for finding that Overlord!

Offline RICH

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Re: Inscribed circle, what am I missing?
« Reply #5 on: December 02, 2010, 05:36:03 PM »
The definiton is as stated and shown in the link by Overloaded in the manual. Not sure if Art ever checked and answered my question definitively.
Good grief i only have 375 pages of notes...........!
There seems to be some contradication and will need to look thru a lot of the posts and then check each tool out which LT creates.
Thanks, till then,
RICH

Offline RICH

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Re: Inscribed circle, what am I missing?
« Reply #6 on: December 02, 2010, 05:48:16 PM »
The problem discussed was that if  you use the "standard definition" ie; inside of the insert then the manufactures tolerences come into play as compared to actualy measuring  the insert.
So that is where the answers and contradication comes into play.   
RICH
Re: Inscribed circle, what am I missing?
« Reply #7 on: December 02, 2010, 06:21:11 PM »
Hi Rich,

Quote
"The definition is as stated and shown in the link by Overloaded in the manual."

I guess I'm confused now. The definition in the manual, is very different than the post linked to by Overloaded. The manual says the EXTERNAL circle radius is used. However the most recent version of LT clearly uses the INTERNAL circle radius.  See the graphic I attached in the first post for proof.

-Jim

Offline RICH

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Re: Inscribed circle, what am I missing?
« Reply #8 on: December 02, 2010, 07:23:31 PM »
What is the revision of the manual you are looking at?

I have rev8 of the manual, and on page 16 of the manual ,the figures from the link are the same used in the manual.
No where on page 16 are the words "the external circle radius is used". The latest manual can be found in Members Docs.

What LT shows on the screen is a related but different matter i will address at a later time.

RICH
Re: Inscribed circle, what am I missing?
« Reply #9 on: December 02, 2010, 07:58:08 PM »
Hi Rich, I'm reading from rev 8 as well and I quoted it in the third post in this thread. Does that quote match the current wording? To me rev 8 goes out of it's way to very clearly state that the external circle is the correct measurement. Your right that the figures posted in the thread linked to by Overloaded are exactly the ones used in the manual. Art says right underneath that the figure is incorrect. in the manual I have the text says the red circle is the circle used by LT. From my use of it so far, and from Arts post, I don't believe it is. 

Unless of course I am being dense and don't understand the manual and have very clearly read the completely wrong thing.
-Jim