Splines MastercamX mr2

[danhaskell]

Can anybody tell me how to take a cam thats made-up of splines and convert it to arcs. Having trouble with my cutter comp on machine using splines.

[John13]

Will edit..simplify give you what you want.

 

 

BTW, Welcome to the Forum

[danhaskell]

No, I want it to do arcs instead of splines, but can not figure out to convert splines to best fit on arc. if that makes sense.

[Pete Rimkus from CNC Software Inc.]

Edit->Break->BreakManyPieces. Make sure you click on the button to the left of the check to make sure you're getting arcs and not lines. Also, you need to enter a non-zero value in the field next to the 'Tolerance' button.

[Tom Brown from Stork Inc.]

Pete,

I do break splines into many pieces like your saying to do, but somtimes I'll end up with literally hundreds of arcs (some of which are smaller than my cutters rad). I currently go through the geom and create a new arc via 3 pts. but constantly have to keep measuring my variance from the origional geom. Inorder to make a lesser number of rads, I have tried to set the tolerance higher, but in some cases it becomes too liberal to the origional. What would be your suggestion around my problem? Thanks, Tom

[danhaskell]

Peter, I have tried that but doesen't seem to work.I have a cam about 2.5 in dia. made up of 2133 splines but i need to convert to rads. for smoothness.

[Pete Rimkus from CNC Software Inc.]

Dan,

So your real problem is that you've got 2000+ splines that need to be converted (and we only work on 1 at a time)? Did you try Create->Spline->CreateCurvesSpline? It'll convert a chain of curves into a single spline - and maybe then the BreakManyPieces will work to your satisfaction?

 

Tom,

I think you're just running into part of the problem with trying to convert a spline to arcs. If you Analyze->Dynamic the spline, you'll probably see its radius of curvature changing constantly. That's the problem with trying to find a good multi-arc approximation.

 

Both of you,

You may both be also running into a bug in this function that we are not aware of yet (hey - it happens!). If you really feel this can/should be working better, send a sample and explanation or two to [email protected].

[edmBosto]

Did you ever try filtering the toolpath to .00005

or at .0001 creating arcs in xy. This works for wire. If your splines are 3D I'm not sure if you can set your configuration to create arcs in Z.

I'm in wire so I don't need to do the latter of the 2.

Breaking many pieces at a tight tolerance seems to be a real good way to go also.

 

Watch your backplot against the filtered splines at a tight tolerance and you'll see it follow it real well.

[John Summers]

Dan,

At some point, you might as well go linear. If the arcs are short as linear segments would be, you would be better off linear. When we make cams at 1 degree intervals, they look pretty good. I'll send you some cam generators. They make very good cams. You might want to start from scratch with them.

[Thad]

I highly recommend using the Keep option when using Break-Many pieces. The default is Delete. Change color before breaking so you can analyze the difference. Then delete the spline when you're done.

 

The new lines/arcs will be created in the blink of an eye and you'll never know (until it's too late) if new geometry is as good as the old. I found this out the hard way.

 

Thad

[Tom Brown from Stork Inc.]

Good point Thad! I usually kept the engineers forms on a different level for "safe keeping", but your method would work out quicker! Thanks

[danhaskell]

Thank you all for your help but still can not get it. It should be simple as take average of so many splines fit the best arc to it.

[danhaskell]

Is ther a way to have the tool it self when posting to do just arcs.

[Storkman]

filter

[edmBosto]

Filter

[danhaskell]

I used the filter, works but not great. Thanks for all the help and have a wonderful 4th.

[edmBosto]

Dan, If it doesn't work that well I'm just curious what tolerance you are using in the filter

and also in your linear tolerance?

[New Job]

IF the problem is faceting on part, you may need to set linear tolerance to a smaller setting.

[Ying Jiang]

Pete,

 

For years we do this work around:

 

- Contour the splines

- Turn ON filter setting in contour parameters

- Turn OFF cutter comp and lead in/out

- Backplot the toolpath and save geo

 

The saved geo is what works best. Could you add it as a Mastercam spline convert function (without have to do a toopath)?

 

It would be great if you could make "Edit" -> "Simplify" to do this.

 

Thanks!

[Pete Rimkus from CNC Software Inc.]

But, remember, all Edit->Simplfy does is convert round splines into arcs/circles and straight splines into lines.

[Storkman]

Ying, that is the same exact way we have been doing it for years.

[Ying Jiang]

Pete,

 

Ok, fine, maybe "Edit, Simplfy" is not a great example, however, what we are asking is to add a function that would get the same results as the "toolpath way", it doesn't matter whatever you call it. What do you think?

 

Terry,

[Pete Rimkus from CNC Software Inc.]

Ying,

 

It's a pretty good idea, especially if people are already doing it by way of a clumsy workaround.

How are your C-Hook skills?

That might be quicker...

[Colin Gilchrist]

Hi Pete,

 

We use that work around as a standard proceedure here. It sounds clumsy, but the toolpath filter gives a much better result than Break-many pieces. The real goal is producing a closed chain that consists of lines and arcs from a spline. Not just arcs or lines, which seems to be what the Break-many pieces algorithm kicks out.

 

How about creating a new utility called SPLINE-2-CHAIN?

 

We actually do this very proceedure using the Surface Finish Contour Toolpath to get a true 2D profile of a part from any toolplane, because the Silhouette Boundary doesn't work correctly. We would like Silhouette Boundary to give us a true, ACCURATE 2D profile of a part that is trimmed and chainable. We create a Surface Finish Contour toolpath with a .001 diameter end mill, Set the Maximum Stepdown to a value larger than the depth of the part(usually 20"), In the cut depths dialog box set the min and max depth of cut to a Z depth that is below your part. When the toolpath generates you will get a true 2D profile of the part (I know its off by .0005 when you back plot...) but its good enough. Its certainly more dimensionally accurate than Silhouette boundary can be.

 

I typed the word accurate in caps for emphasis Pete, I did not mean to yell, so please don't take it the wrong way.

 

Thanks guys,

 

Colin

[bryanfx]

dont use splines.i mean what do they really need to be used for anyways...lol