SILHOUETTE BOUNDARY

[Tinyfxds]

Question:  When I make geometry for the lathe operator to program, I use silhouette boundary to grab the outside profile of the part.  I primarily use arc fit but I've noticed that spline fit gives me a more consistent curve instead of little arcs along this curve.  Does anyone know what's the better option?  Also what about settings on this page?  I'm not sure I'm seeing a big changed in accuracy by adjusting them.

[djstedman]

I believe spine fit creates splines and arc fit attempts to create arcs where possible, I guess what is best is up to you to a degree, having them be arcs will let you analyze them to get more information from them, but as you said you might end up with a ton of small arcs which can make the geometry rather cumbersome to work with.

 

Im not sure about the accuracy, but I believe what the accuracy actually changes is how Mastercam computes the endpoints of the arcs when creating the boundary, more tolerance allows more error on the endpoints which can allow the geometry to be simplified and therefore use less arcs.

 

Another option which is made specifically for a turning profile is to use Create -> Turn Profile from the menu .. I have used both, but it seems like turn profile tends to give me less hassles with the geometry it creates.

[Tinyfxds]

 

Another option which is made specifically for a turning profile is to use Create -> Turn Profile from the menu .. I have used both, but it seems like turn profile tends to give me less hassles with the geometry it creates.

 

I have never used this before nor did I even know this existed.  Thanks

[djstedman]

Yeah, its a great tool, its essentially the same as using silhouette boundary with spin enabled, If I remember correctly I first saw it in one of those 'what's new' classes when X6 came out.. glad I could help

[Tinyfxds]

I compared the silhouette boundary geometry to the turn profile geometry and the turn profile was more accurate.  I'll be using that from now on. 

[crazy^millman]

I like to use .0001 as my tolerance for this helps in fitting more accurate features. Does take longer, but worth it IMHO.

 

HTH

[JMahon]

I like to use create> curve> curve slice.

[Rick46]

+1 on the curve slice option.. I use it on a daily basis when I need a good boundary to drive my tool paths for outside profiling of a part.

[Redfire427]

Turn profile is garbage, especially if accuracy is required. Create/curve/slice will give you a perfect cross section to turn.

 

Carmen

[Tinyfxds]

Man!! All these new options that I never used before.  Thanks for making me aware of all the different ways to make a profile for our lathe guys.

[Matthew Hajicek - Singularity]

That's one of the things I really like about Mastercam; there are usually several different ways to skin any particular cat.

[djstedman]

Perhaps I'm missing something, but though Curve Slice is nice,  it doesn't necessarily give a turn profile, as an example, think of a yoke (a y shaped part) lets say you needed to turn the part prior to milling ops..

 

Curve slice returns a profile with the same outline as the original yoke, however if you were to turn using it you wouldn't end up with enough stock to finish the part since curve slice simply gives a 2D slice of the object, if you have a part your going to turn you need to actually spin it in order to guarantee a proper profile for turning hence the need for spin in silhouette boundary and in turn profile.

[Redfire427]

You are correct djstedman. Curve/slice only works on round parts, or symmetrical parts where you know where the proper cross section lies. Turn profile gets you close, but that's all.

 

Carmen

[JMahon]

I usually use curve slice and trim the geometry to make it a "turn profile"

 

Much more accurate and predictable.

[crazy^millman]

I usually use curve slice and trim the geometry to make it a "turn profile"

 

Much more accurate and predictable.

 

I have found the Turn Profile since about X6 to be very good. I also like the fact I can pick my rotation axis with it that you cannot with Silhouette Boundary. Silhouette boundary is great in 2d with a Z value set to get a slice right where I want it. If I want a lot of slices I use the Verisurf Slice to Mesh tool in their Reverse module. Make an STL of the part then I can get slices of a part very quick and easy. What is really cool is if you use the spline and number of points then all the splines start and end in aline and have the same number of nodes. This is great for 5 axis roughing of parts where you want a curve to drive the toolpath and get consistent cuts throughout the roughing. Verisurf takes all of this to a level that people who do a lot of reversing every really need, but is nice when doing very complex parts.

 

Side bonus of the Verisurf reverse is the ability to make the stl files translucent. So you can bring in your operation stock model and make it translucent over your shaded part and get a really good idea what you have left to machine.