Splines to arcs

[Thee Rickster ™]

If you have a long continuous curvy spline contour,

can you convert it to a bunch of arcs?

 

Like a 'create arc from spline' type of funtion?

 

Thanks

Rick

[Cuda84]

Yes

 

Edit>>Trim/break>>break many peices>>(either)lines or arcs

[Thee Rickster ™]

Hey Cuda,

 

That worked but it broke it into really tiny arcs.

Is there a way to make them bigger.

 

The contour resembles flames.

 

Thanks

rick

[Mcam Nut]

Did you try edit simplify?

[Don S at Barefoot CNC South]

quote:

---

edit simplify

---

This has not worked here on Cat files converted to X2 no matter what I set the tolerence at it always says 0 splines were converted but if I save the same file in version 9 and use convert to arcs it works fine. Something is not working right I think.

 

[Thee Rickster ™]

quote:

---

Did you try edit simplify?

---

I did,

but nothing happend.

 

tryed it many times, had no result.

i exhausted the avilable options in X2,

it just dosen't function as I would like it to.

 

Don,t sweat it Cuda, I'll just do it in other

software , for now.

 

Gotta get the job done.

 

Thanks

Rick

 

[ 11-21-2006, 03:08 PM: Message edited by: Rickster ]

[Colin Gilchrist]

Rick,

 

Toolpath the spline with contour. Turn Cutter comp off. Turn the filter on, set it to .001 tolerance. Set retract, feed, and depth to 0.0 incremental. Backplot and save the toolpath as geometry. It will now be lines and arcs.

 

HTH,

[Cuda84]

Yes put a number in the # field. Note this is not very acurate. The number would indicat the number of arcs you get.

 

I think the tolerance field works best, only as acurate as you want. The bigger the number the larger the arcs.

[Thee Rickster ™]

Colin,

 

After I save as geometry it does not have entity

properties? Also when I have only that geometry, I

just saved, on the screen it does not do a screen fit.

 

It goes to the corner of geo where the tool path

starts and ends, shows a tiny square and 5 lines (it created). Those are the only selectable entities

on that layer.

 

Rick

[Thee Rickster ™]

I am giving up for now.

 

13hrs is all but enough for me today.

I have In-house soultions for some inhouse training

tomorrow. I ask the teacher.

 

TTYL

 

Thanks ALL

 

Rick

[88Matt]

Having the same trouble with an iges file. used curve on edge of a surface was basically a tapered box with fillets and it created two splines. Simplify should break them into 4 lines and 4 arcs (according to the description). simplify wont convert at all unless i jack the control point distance tolerance WAY up and then it just makes 2 huge arcs.

 

I'm not able to send files to QC for security reasons.

 

PS: MC9 converted them just fine.

[summit fever]

quote:

---

Toolpath the spline with contour. Turn Cutter comp off. Turn the filter on, set it to .001 tolerance. Set retract, feed, and depth to 0.0 incremental. Backplot and save the toolpath as geometry. It will now be lines and arcs.

---

This little trick worked great! I've been having problems breakins splines to arcs too. Every time I input a number or length, an error message comes up: " warning, zero line length".

 

I think I'll use the above process from now on.

[Andy]

Simplify is for circles or close to cirlces only.

Edit/trim /break many is for all non ciruclar contours.

[Colin Gilchrist]

Andy,

 

Edit/Trim/Break will not give you the ability to "break" a spline up into a chain of tangent lines and arcs. Neither will "break many pieces". The method that I mentioned above uses the contour toolpath and backplot to create a tangent chain of lines and arcs. This takes advantage of the filtering options available in the toolpath, which gives superior results when trying to create a chain of tangent entities.

 

HTH,

[Andy]

Colin,

 

Edit/trim/break/break many pieces/ does, in fact, make a continuous tangent line and arc conversion of the spline. Just pick the tolerance and the line type. I use this frequently. It will delete or save the original spline.

The backplot method you mention works also.

Try this with a simple spline (NURBS) and you will see.

[Colin Gilchrist]

Hi Andy,

 

Let me clarify what I meant by my last statement. Break Many Pieces will indeed work to give you a tangent chain in *most* cases.

 

The problem I have found is that you will occasionally get a chain that has several small arc segments, in a place where you can easily see that you could use a single larger arc to make the same move. By adjusting the chordal tolerance value, you can eventually get Mastercam to create a single arc in your chain.

 

The problem is that you may have to bump up your tolerance to such a high value that it compromises the accuracy of the chain that you are creating in other areas of the spline.

 

There will be areas of the spline where the line/arc combination may have shifted off the position of the original spline due to the chordal tolerance.

 

I have seen this happen time and time again. I'm not sure how complex the splines are that you are trying to convert. On very complex splines you will notice the tolerance issue much more than on simple contours.

 

I'm not trying to start anything here. I just wanted to point out that the toolpath method will give you a more reliable and predictable result on complex splines in *some* cases.

 

 

Thanks,

[Andy]

Colin,

I wont disagree with that.

The splines I usually work on are ones I create from raster to vectorization photos. I then create splines to best fit the vectorization geometry. The key here is best fit for "visual" purposes only.

I think it is great that we are able to manimulate splines to tangent geometry at all.

What a powerful tool CAD is.

Andy

[Troy Gossett Indepak Inc.]

Sometimes the splines won't convert because they are in diff views, try combine views, then simplify.

 

I like the toolpath method thanks Colin.