[777funk]

I have some CAD that was all splines (had to explode to seperate the geometry). So being somewhat new to CAD (BobCAD is my first real CAD experience) I am not familiar with what they are or what they're for. Will they create a smoother cut than exploded shapes or is it basically the same thing?

Another important question, what is the opposite of "splines"?

[AiR_GuNNeR]

In simplified terms, splines are mathematically smoothed curves based upon a given set of points. With splines you get curved lines between points rather than point to point straight lines. There are different kind of splines, (bezier, cubic...).

[777funk]

In simplified terms, splines are mathematically smoothed curves based upon a given set of points. With splines you get curved lines between points rather than point to point straight lines. There are different kind of splines, (bezier, cubic...).

Thanks Gunner, I'm an Air Gunner myself (assuming that's what your username means), had a few tuned springers and pcp's. Good cheap fun. Quieter and a little safer than the powder burners.

As far as the actual cut, will it create a smoother cut profile if I have splines instead of point to point geometry?

[BurrMan]

As far as the actual cut, will it create a smoother cut profile if I have splines instead of point to point geometry?

Your toolpath will be breaking things up into lines anyway, but, having nice, smooth curves will allow the toolpath calc do that per your parameters, vs. line segment geometry dictating to the toolpath what should happen.

[jrmach]

Burr,would like if person was doing a 2D engraving,would it be beneficial to have it drawn in Corel(splines) versus just lines and arcs?

[777funk]

Your toolpath will be breaking things up into lines anyway, but, having nice, smooth curves will allow the toolpath calc do that per your parameters, vs. line segment geometry dictating to the toolpath what should happen.

So would that mean that the toolpath would be smoother with less stops between shapes? i.e. a smoother motion?

[AiR_GuNNeR]

Thanks Gunner, I'm an Air Gunner myself (assuming that's what your username means), had a few tuned springers and pcp's. Good cheap fun. Quieter and a little safer than the powder burners.

As far as the actual cut, will it create a smoother cut profile if I have splines instead of point to point geometry?

Yep, I shoot air guns as well. Mostly field target. Here is pic of my Steyr LG100 rig with a 10-50x60 scope.

Regarding the smoother cut it will depend on the CAM software. You can often direct the CAM software to use arcs instead of discrete moves. You define the tolerance, and it tries to fit arc moves, (which are very smooth), that are within your tolerance in place of the curved line segments. Point to point moves will only be as smooth as the length of the line segments. You will always see "facets" on the cut surface in a point to point system of curves.

[aldepoalo]

I wanted to touch in on this topic. You machine will only cut G01 G02 and G03 movements. So if you draw with splines or lines and arcs the output to the machine would be the same.

The difference would be how you construct the geometry and using splines will allow you to create complex curves that otherwise would be very difficult to construct.


Here we have a series of points:


photo storage


Using line join and fillet you'll get a result that looks like this:


picture hosting

If you created tool path for this cure and posted you would get code that looks like this:

(TOOL #1 0.5 ENDMILL ROUGH)
T1 M06
M00
S3880 M03
G54 X1. Y1.
G00 G43 H1 D1 Z0.1 M08
G01 Z-0.25 F44.6296
X2.6464 Y2.6464 F89.2592
G17 G02 X3.3536 Y2.6464 I0.3536 J-0.3536
G01 X4.6464 Y1.3536
G03 X5.3536 Y1.3536 I0.3536 J0.3536
G01 X6.6464 Y2.6464
G02 X7.3536 Y2.6464 I0.3536 J-0.3536
G01 X9. Y1.
G00 Z0.1

Now if we take those same point and run a spline through them it will look like this:



image ru


If you created tool path and posted code for this profile it would look like this:

(TOOL #1 0.5 ENDMILL ROUGH)
T1 M06
M00
S3880 M03
G54 X1. Y1.
G00 G43 H1 D1 Z0.1 M08
G01 Z-0.25 F44.6296
G17 G03 X1.0151 Y1.0169 I-0.1855 J0.1814 F89.2592
X1.0385 Y1.047 I-0.5542 J0.4545
X1.0859 Y1.1139 I-1.8793 J1.3809
X1.1534 Y1.2144 I-7.4759 J5.0986
G01 X1.2498 Y1.3599
G02 X1.3991 Y1.582 I16.9347 J-11.2204
X1.6047 Y1.8736 I9.3942 J-6.404
X1.8229 Y2.1589 I6.1987 J-4.5169
X1.9743 Y2.3394 I4.3253 J-3.4731
X2.1162 Y2.4937 I3.2624 J-2.8558
X2.2602 Y2.6342 I2.3723 J-2.2883
X2.4111 Y2.7615 I1.5999 J-1.7438
X2.5157 Y2.8364 I1.0613 J-1.3706
X2.6042 Y2.8903 I0.7633 J-1.1533
X2.6893 Y2.9333 I0.5409 J-0.9677
X2.7881 Y2.9709 I0.3643 J-0.8077
X2.9103 Y2.997 I0.2006 J-0.6386
X3.0601 Y2.9934 I0.062 J-0.5257
X3.1433 Y2.9727 I-0.0924 J-0.5498
X3.2491 Y2.9275 I-0.2188 J-0.6589
X3.3336 Y2.8767 I-0.4189 J-0.7923
X3.4183 Y2.8131 I-0.6355 J-0.9359
X3.5362 Y2.7052 I-0.9939 J-1.2038
X3.6572 Y2.5726 I-1.6665 J-1.6426
X3.772 Y2.4292 I-2.621 J-2.2141
X3.9094 Y2.2392 I-4.3442 J-3.2881
X4.0323 Y2.0574 I-8.5333 J-5.8989
X4.1404 Y1.8925 I-24.6847 J-16.3037
G03 X4.2459 Y1.7315 I29.198 J19.0062
X4.3386 Y1.5931 I8.8531 J5.8327
X4.4307 Y1.462 I4.707 J3.2083
X4.5321 Y1.3288 I2.7818 J2.013
X4.6368 Y1.2086 I1.5064 J1.2062
X4.7086 Y1.1387 I0.8709 J0.824
X4.7697 Y1.0891 I0.565 J0.6321
X4.8271 Y1.0514 I0.3619 J0.4896
X4.8812 Y1.0248 I0.2269 J0.393
X4.9412 Y1.0062 I0.1327 J0.3223
X5.0202 Y1.0008 I0.0585 J0.2738
X5.0927 Y1.0153 I-0.0221 J0.3005
X5.1578 Y1.0431 I-0.1307 J0.3952
X5.2152 Y1.0783 I-0.2652 J0.4974
X5.2709 Y1.121 I-0.4404 J0.6311
X5.3367 Y1.1815 I-0.6762 J0.8019
X5.4359 Y1.29 I-1.175 J1.1742
X5.5442 Y1.4277 I-2.2166 J1.8539
X5.6594 Y1.5901 I-4.2467 J3.1348
X5.7818 Y1.7736 I-9.495 J6.4704
G01 X5.9199 Y1.9847
G02 X6.0563 Y2.1894 I11.3931 J-7.4477
X6.1903 Y2.3788 I5.1394 J-3.4938
X6.2858 Y2.5034 I3.2189 J-2.3686
X6.3784 Y2.6138 I2.3368 J-1.8654
X6.4904 Y2.7315 I1.566 J-1.3786
X6.5764 Y2.8088 I1.0509 J-1.0816
X6.6536 Y2.8679 I0.7522 J-0.9034
X6.7321 Y2.9173 I0.5341 J-0.7616
X6.8099 Y2.9553 I0.3682 J-0.6555
X6.8986 Y2.9848 I0.2392 J-0.5711
X7.04 Y3.0005 I0.1288 J-0.5143
X7.0914 Y2.9968 I-0.0128 J-0.5418
X7.1893 Y2.9775 I-0.0772 J-0.6466
X7.2965 Y2.9395 I-0.224 J-0.8026
X7.4003 Y2.8879 I-0.4367 J-1.008
X7.4971 Y2.8279 I-0.6974 J-1.2343
X7.6116 Y2.7437 I-1.0157 J-1.5016
X7.775 Y2.6015 I-1.5665 J-1.9646
X7.9568 Y2.4162 I-2.5151 J-2.6495
X8.1438 Y2.1999 I-3.8334 J-3.5027
X8.2998 Y2.0018 I-5.4059 J-4.4191
X8.4628 Y1.78 I-7.0554 J-5.3543
X8.7088 Y1.422 I-11.0518 J-7.8581
G01 X8.8012 Y1.2828
G03 X8.8956 Y1.1411 I16.7154 J11.0303
X8.9552 Y1.0555 I2.5732 J1.7296
X8.9819 Y1.0204 I0.7083 J0.5116
X9. Y1. I0.2214 J0.1776
G00 Z0.1

You might ask yourself when would be a good time to use a spline? For me I use spline most when tracing images. I load the image up in the back round trace around the image using the spline and deform it to get as close to the shape as I can.

Another case where you would want to use a spline is when creating smooth curves for more organic shapes.

Burr has a thread where he shows how to draw the profile of a base ball bat using splines. A great example of how to use splines and a reason to use them. To create the sample profile with out splines again would be extremely difficult.

[aldepoalo]

Here is an example of using splines to trace around an image. I've attached a color image of a dragon fly.

Let's say you wanted the outside profile, using line and arc to trace around the image can be done, but would be very difficult. Using the spline feature it's much easier.


How to Video Link >>>>>>>>>>>> Spline and image tracing - adepoalo's library



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Now using these profile and the BobART Embossing feature we can create a 3D shape. Maybe not what you are after but definitely cool!


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