Fillet Polyline

The Fillet Polyline (FP) command allows you to quickly draw a radius blend (i.e. fillet) at all corners of the polyline. Of course, you know that for this in AutoCAD and BricsCAD there is the _Fillet command, which even has the _Polyline option, i.e. theoretically can fillet all corners of a polyline at once, too. But Autodesk programmers have not coped with their task and for the past 20 years have not been able to correct errors. The _Fillet _P command produces amazing images that look more like an explosion at a macaroni factory than a smooth contour. And the guys from Bricsys did not strain at all and did not even try to make fillet between arcuate segments. However, this feature is required by users. Especially if you are preparing the contours for milling and want to see how the round cutter passes in the corners. For the inlay of the milled parts into each other, for the luminous letters in the walls, it is also necessary to fillet all the corners, otherwise the parts simply do not fit into each other. Everyone who faced similar problems is intended this plugin.

Features of the program

• • Fillet corners between arcs and lines

  • Fillet all the corners of the polyline from the side of the cutter passage or from both sides.

  • Fillet an corner between two pre-selected polyline segments. Moreover, the segments do not have to be contiguous, and you can skip the chain of segments.

  • The program will increase the radius of all too small arcs of the polyline to the given one.

  • The program itself can skip too obtuse angles.

  • The small trash segments of the polyline at the corner will be absorbed.

  • Original contours can be saved if you want.

  • The program will show on the command line how many fillets are made, how many corners are missing and how many failed to fillet.

  • The program has common settings with all my CNC contour processing commands 

  • You can switch between "CNC styles" (sets of settings) directly from the command line while selecting objects.

  • Outside Loop (OSL) and CNC Prepare (NCP) commands can call the FP program themselves.

Read about downloading and installing the program here.

To run the plugin, you will have to register account and top up your account balance or receiving bonuses.

Then you can activate one of the licenses:

• • Annual license - 10 EUR.

  • Unlimited license - 50 EUR. Free updates for 1 year.

  • The trial period is 20 days.

The FP command is also included in the set A>V>C> Pro. 

As the source data you can select two lines or arcs. The main thing is that they lie in the same plane and have a common point. You can also select two segments of a polyline (straight or arcuate) via Ctrl.

During the selection of objects you will have the following options:

• • Diameter - enter the diameter of the cutter

  • subselectON/subselectOFF - enable selection of sub-objects (polyline segments) in order not to hold Ctrl.

  • MillSide / BOthSide - make fillets only from the side of the cutter's path around the contour, or fillet all corners.

  • SwitchStyle - Quickly switch the style of the CNC direct in command line using the style number.

  • TUNE - call setup dialog

If the diameter of the cutter is not specified in the settings of the current CNC style, it will be requested. You can set any diameter cutter. The default diameter is 8mm or half an inch (depending on the drawing units). While entering the diameter, you can also select the Tune option to bring up the settings dialog.

Note that by changing the cutter diameter in this command, you will reconfigure it in the other contour machining commands (Outside Loop and Dado Loop).

If the option "Both sides" is not checked, the program will ask you to choose from which side of the contour the cutter will go - from the outside or from the inside of the contour.You can set this with the help of layers - if the contour is on the NC_Outside layer, then the selection is done from the outside, if NC_Inside, then from the inside.

The program draws an arc with a diameter slightly larger than the cutter (the gap is also adjustable) tangentially to both segments and cuts the segments for the joint with the arc. The program does not know how to lengthen the segments to build a fillet.

If the polyline segment is too short to mate with a fillet arc, then the program will move the arc to the end of this segment.

If the fillet attempt did not succeed, the program will try to construct a fillet of the following segments. But it works only for short segments, within the diameter of the cutter.

You can configure the program to skip obtuse angles. Making fillet in too obtuse angles does not make sense, since difference from the original contour may be barely noticeable, less permissible variation. The program will automatically calculate the most obtuse angle for which it makes sense to do a fillet. For example, for an 8mm milling cutter and a 0.5mm error, corners that are duller than 122.1° will be ignored. Skipping obtuse angles is configured in the CNC settings dialog.

The program runs in a loop and will request new polylines until you press Esc.

Watch the command line - all messages of the program are displayed there, in particular the number of angles in which it is impossible to construct a fillet.

CNC command settings

You can bring up the settings dialog by selecting the Tune option or use AvcOptions palette on CNC tab. But when called from the command line, all unnecessary settings will be hidden.

All options have a tooltip.

There are many settings and for your convenience, you can use ready-made sets of settings, which I call CNC-Style. You can create up to 9 styles. You can switch the current style in the header of the settings window. And during the work of the command, you can call the SwitchStyle option and select the style by its number.

Attention! The current CNC-style affects all contour commands. Switching the style in one command you will work with this style in all other command too.

The work of the command is influenced by options from the sections Contour optimization (Permissible variation) and Milling, as well as the accuracy settings from A>V>C> Common Options.

You can configure the contour processing commands (Outside loop and Dado loop) so that they themselves call the Fillet command (FP). To do this, tick the Consider diameter and Fillet switches on Exterior and Interior loops.

Limitations and Known Issues

• The Fillet Polyline program looks simple, but in fact it is the most difficult program I've ever written. Despite the 4 months of debugging, it undoubtedly still has errors and flaws. Please send me drawings with outlines that the program could not process. Together we will make the program better.

• There are many cases in which it is impossible in principle to construct an arc of fillet. The laws of geometry cannot be fooled.

• Narrow long "guts" into which a given mill does not pass, of course, will not be fillet - this is simply impossible. To cut off this piece of contour, select 2 non-adjacent segments at the entrance to the gut (by pressing CTRL) and call FP. The program will try to make a arc between these segments and erase an impassable section of the contour.

• The program does not attempt to lengthen segments before fillet. If the specified diameter is insufficient to reach from the end of one segment to the beginning of the second, then fillet will not be built.

• The program does not check the contour for bottlenecks. Perhaps there will be areas where the mill just does not fit. Check the resulting circuit using the _Offset command.

• It is noticed that sometimes the _Offset command cannot process a polyline built by a program. This sometimes happens when the Offset must absorb one of the fillet arcs. Try slightly increasing the radius of the arcs (just pull the middle point to the ends of the arc) - this helps.