how to get cross section?

[Gary]

I put a file (3000_opt1) on the ftp site in the mc9 folder and would like to have some of you pros take a look and see what method you use on something like this to get a cross-section and geometry for this part, say to turn on a lathe. Any thoughts or suggestion would be great. I think i have what i need on this but it took me some work and time to get and i know there must be better ways. Thanks in advance Gary

[Rick Damiani]

I'd do the following:

 

- Create a WCS that located the part correctly for turning on a lathe/move the part so it is located correctly (whichever is easeir for you). My first couple of attempts are close, but not quite there. I'll fiddel with it a little more and upload it if you need it.

- Use Create|Curve|Slice to generate the cross section.

 

When I did this, I noticed a sizeable undercut in the part. How are you going to cut that? I ask becasue noting is coming immideatly to mind when I look at it.

[Gary]

Hi i'm just cutting the inside profile they outside is made by the cavity and the cores are held in by the top plate. The undercut is actually made by a lip on the cavity top. The outer part of the under cut is on the core side of the plates. I set the ucs also and did a slice but the geo. was a pain to chain. Alot of trimming required. Thanks for the help on this i appreiciate it.

[Rick Damiani]

Look in the MC9_Files folder for 3000_opt1-rick.mc9

 

Apperently, I don't understand the WCS well enough to use it the way I'd like to for this job, so I used Xform|Between Views to position it after turning one of the green NURBS curves into an arc so I could find the center of the ring. Source plane was the converted arc (with Z pointing away from the part), destinaiton plane was the Side plane. The resulting profile was about .0004 behind Z-zero, so I used Create|Line|Vertical to project the midpoint of the resulting arc at the tip to X zero, then used Xform|Translate|Between points to bring it up to Z zero.

 

Hope that helps.

[Gary]

That’s about how I did it also. I made one of the lines into a curve ( the highest one) then did a surface fill holes to pick that face for my UCS source face. Then I set construction plane to 3-d and moved the part from the center of the arc I created to the origin. Then I rotated into a lathe position. The reason for this is the customer supplied a cross section of the part to cut on a print with no dimensions and my boss acts like it is a 20sec thing to do (even though he can't send an email) so I was a little pissed and wanted you experienced users to have a look at the part. I know they were probably using a solid model for there cross section. It is a piece of cake for me a solids but with surfacing it is different ball game. Anyway thanks for all the help Rick it is greatly appreciated. I'll have to wait till I get to work to get the file.

[Rick Damiani]

One approach to this would have been to turn it into a solid, get rid of all the useless clutter, and generate the few entities actually required for the move. Solids|Next Menu|From Surfaces works fine on this file. Look for 3000_OPT1-SOLID.MC9. I would have suggusted that, but I didn't know if you had solids on your lathe seat.

 

Given the messy nature of this file (lots and lots of edges, even as a solid), I'd still create the slicing curve and do the toolpathing from there though.

 

[ 11-29-2003, 01:29 AM: Message edited by: Rick Damiani ]

[Gary]

Cheap boss doesn't know the difference between a solid and a surface model. It looks like a solid with the shading on and that’s all he knows. Solids would be nice for a lot of this type of stuff we're getting into now. Fun but frustrating.