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Machining convex corners

Pioneer
Pioneer

Ok, i have only been using NX for almost 2 years now. That is also the extent of my expierience of using any CAD/CAM software.  With that being said I have a question. A customer has presented a model that has multiple convex and concave corners that are modeled sharp. They also have given "call outs "  to where they want corners to be a radius that of various sizes both convex and concave. This is a new customer of ours and they claim that they dont model radii because it reduces machine time (to me this is sounds like utter BS in my opinion, i could be wrong). I do know how to use the flow cutting operations for concave radii. Is is possible to machine a convex radius on a part that is modeled with a sharp edge without remodeling?  Is there a specific cutter that is used ?  This model has no right angles.

 

Thanks for your time!

14 REPLIES

Re: Machining convex corners

Can you post a picture of a typical case? Is this prismatic or contoured? 

Keep in mind that to the system, rounding a convex corner is intentionally gouging the part geometry.

Mark Rief
Retired Siemens

Re: Machining convex corners

Pioneer
Pioneer

there are both prismatic and contoured.

Re: Machining convex corners

Pioneer
Pioneer

There are both prismatic and contoured instances. Each colored curve represents a different radius size.

radius call outs.PNG

 

 

Re: Machining convex corners

Pioneer
Pioneer

We are machining with a 5 axis CNC router.

Re: Machining convex corners

The short answer is that the blends should be modeled.

What is the justification for the customer not modeleing what they want you to produce? Is there a technical reason, or are they just passing the buck? 

The old drafting note "break all sharp edges... " had a place years ago, and may still apply in some cases, but I would expect actual blend radii to be modeled. 

Mark Rief
Retired Siemens

Re: Machining convex corners

Legend
Legend

Sounds like an easy way for your customer to pass this on to you because they cant get the complex blends between all those faces to work correctly >.<

 

NX11.0.1

Re: Machining convex corners

Pioneer
Pioneer

The customer is using Rhino to model, which i hear is fairly difficult to radius with. Still, it is no excuse.  Thanks for your input. I really appreciate the feedback.

Re: Machining convex corners

Esteemed Contributor
Esteemed Contributor

OK, concave corners can easily be done by the cutter radius, but convex corners must be modeled.

If there is something wrong with the radii, who will be responsible?

It is easy to overlook something that is not physically there.

Stefan Pendl, Systemmanager CAx, HAIDLMAIR GmbH
Production: NX10.0.3, VERICUT 8.0, FBM, MRL 3.1.4 | TcUA 10.1 MP7 Patch 0 (10.1.7.0) | TcVis 10.1
Development: VB.NET, Tcl/Tk    Testing: NX11.0 EAP, NX12.0 EAP

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Re: Machining convex corners

Esteemed Contributor
Esteemed Contributor

Often, we don't model blends on our complex parts (just let the ball nose tool form them). 

If we tried to model the blends:

- it can take days(!) to add them

- often, there are blends we just can't blend (NX refuses)

- if we have to edit/change the model, every update we have to spend another 2-3 days fixing all the blends.

 

It's just not worth it to us.

(note the above may have changed - last we tried to do blends, we were on NX7.5, I'm not sure if NX10 would work better)

 

Of course, we then have issues in CAE (if the blends are critical) and inspection, but we live with those issues

 

Ken

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP5 + patch/TC11.2
I'd rather be e-steemed than e-diseaseled


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