Plugin for AutoCAD and BricsCAD AVC_Chop.
Chop a 3d-solid into many pieces. Make ribs and stair-step.

With this plugin, you can quickly cut the solid into pieces, layers, slices, ribs. This is useful when you are designing products from sheet materials. For example furniture, plywood frames, “chumps” for bending, puzzles, and model of building, ship and aircraft.

The program consists of two basic commands. Command CHOP cuts the solid parallel planes a specified pitch. The plane can be set to the choice flat face of solid or as one of the planes of the coordinate system or by three points. In addition to cutting command can make “stair-step” slices for further 2D milling of sheet material on CNC machine.

Second command ChopEdge. It can cut a solid into a predetermined number of pieces of the same length. Simply select one edge of the solid, along which will be calculated the length of the pieces. And the edge may be arc or spline. Furthermore, the same command ChopEdge can create ribs on each section.

Also the program can:

  • Make gap between pieces.
  • Save source body after cutting.
  • Save or delete stubs.
  • Set special layer for piece and stub.
  • Configure all the options in the dialog box and in the AutoCAD options dialog.
  • Interact with the plugin Names, numbering a piece in the order of cutting procedure.

Plugin can work with 3D-solids only. It not works with Meshes, Surfaces and Blocks. Just like other AutoCAD commands, my program is in most cases not be able to work with the solids imported from other programs.

According to your request I can optimize the command for you. Offer your price.

Download the plugin in the AVC_Chop_nnnn_nn.7z archive. You can use the program for free, but from time to time the activation window will appear. If you donate at least $15, you can disable this window.

Test different versions using commands CHOP and ChopEdge


Designing complex shape reception-table for the layered milling CNC


Designing the podium (stage) with a stop. Used command: AVC_Slice, Stair-Step, Chop with a gap (twice in two perpendicular planes), Cross-piece and Lay


Recensione video in italiano registrata da Paolo Coter.

Design of the bar using the command ChopEdge for a uniform arrangement of the ribs. In addition, used commands AVC_Slice and Lay

Chop command (Ch)

The first thing command asked to specify the base plane. From this plane will be made cutting solid. Cuts are made by planes parallel to the base, evenly spaced. The easiest way to select the base plane as a face of a cutting solid. The surface (solid face) should be flat. AutoCAD is often wrong, and considers the clearly flat faces are not flat. In this case, you need to select another face or select plane by three points.

During the selection of the face, you will see the same options like Slice command: Selection of one of the planes of the current coordinate system or select plane by 3 points. You can assign a user coordinate system (UCS) before call CHOP command and the program will use this coordinate system.  In any case, the solid will be completely sliced in both sides of the base plane.

Next the program prompts you to select the solid for cutting. If you are chosen as the base plane like solid face, then program will use this solid and the request will be ignored.

Next you will need to specify the thickness of the pieces (step of cutting planes). This request contains option Settings. Settings Dialog shared with ChopEdge command. In it, you can configure:

Thickness: the thickness of the cut pieces. Step of cutting planes.

Start from: Default chop begins with zero deviation from the base plane. But sometimes it is uncomfortable. For example, if the base plane is set as one of the planes of the coordinate system, and the solid is located somewhere away from zero. You can move the starting plane at the bottom or top of the solid or on its middle. You can play around with this setting for stubs optimization.

Stair-step: option will be useful to anyone who manufactures frameworks or “chumps” for bending from sheet materials on CNC milling machines. When you enable this option, the program will substitute pieces or ribs on the flat parts with rectified orthogonal ends. Those all inclined ends are cut. And they cut off so that the new solid will not jut anywhere outside source. All recesses in the pieces become through. And the end holes disappear. This is not a failure, so the rectification ends algorithm works.

OutwardMake the steps outward of the original solid, then to whittle away them. Usually the steps are made inside to putty them.

Save source: the default sliced solid will remain in the drawing. Pieces will be inside it. If it is inconvenient - disable this option.

Save stubs: chop command may leave in the drawing residues the size less than the specified thickness. They can be used for cutting thinner slices.

Save gaps: if gap greater than zero, the program can save solid remaining in the gaps. In any case, Stair-step function not applicable on these pieces and the layer is the same as source solid.

Gap: thickness of the gap between the pieces. You can use the gap to accommodate the thickness of the blade or to form a carcass with gaps between the ribs. If this gap is greater than zero, the cutting step will be equal to the thickness plus gap.

Piece Layer: the program can assign layer to piece or rib. If this field is left blank layer is the same as that of the original solid. The program creates a layer if necessary.

Stub Layer: the program can assign layer to stub. If this field is left blank layer is the same as that of the original solid. The program creates a layer if necessary.

Numbering: for the product assembly convenience, you can give names to all the cut pieces with the numbers in order of cutting. In contrast to the Numbering plug number in the name does not depend on solid size, only by cutting sequence. Identical segments will have the same name. Stubs and gaps are not numbered. If one cut will give several pieces (the solid was divided into separate bodies), then they, too, are different numbers in a random order. The name of the solid, you can see only if you have installed the plug-in Names. Names are available in all of my plugins: Lay, Sawing Table, Smart Leader.

Numbering format: string of solid name. Must contain symbol # like the place where the substitute number. Read more about numbering formats in Numbering plugin description.

Show dialog: the settings dialog will appear every time you invoke the command CHOP and CHOPEdge, without the need to specify options in the console. It is possible to enter the thickness and piece count. But to set the thickness by mouse click in drawing has not come out.

After specifying the settings, the program will start cutting the solid. If in the process of cutting an error occurs, the program will ask you whether to keep trying to cut. There are many places of solid where AutoCAD is unable to make the cut. In its work, the program moves solid to the zero of WCS, and next return pieces to source place. But if an error occurs, you may find pieces at the origin WCS.

Settings are stored in the Windows registry under current user.
Follow the messages on the console. There may be program messages.

Chop Edge command (ChE)

Unlike conventional CHOP command, this command can cut the solid of non-parallel planes. It is convenient for splitting curved solid into equal sections.

The first thing you need to select the base curve (edge). This curve will be used for alignment of the section planes. To select the curve Click on the edge of the cut solid.  You can select edge before command calling.

Next You will then be prompted to enter the number of pieces. Enter an integer not less than 2. The program itself can choose the required number of cuts based on the maximum length of the section. To use this, select the option MaxLength and enter the length. You can also select option Settings. General settings shared from CHOP command but there are add-ons:

Count: Specifies how many pieces should be cut in the solid. Close to this option, you will see the total length of the base curve and the length of the resulting piece.

Ribs: Changes the program. Now the program will not cut the solid and it will create the ribs desired thickness on those places where cutplanes passed.

Thickness: This parameter is only available when enabled Ribs mode and gives their thickness.

Cleaning ribs: Remove unnecessary ribs that do not relate to the basic curve. I recommended to enable this option when the edge is strongly curved and planes intersect the solid repeatedly.

Stair-step: Ribs with rectified orthogonal ends.

Command does not work with gaps. The other parameters are similar to the command CHOP (Ch).

The program then starts to set clipping planes uniformly along a given curve. The planes are placed perpendicular to the tangent line (the first derivative) to the curve at the point of cut. That is for the straight lines are perpendicular to it, and for arcs cut is along the radius.

The program makes the cut at both ends of the edge. Therefore it can stay stub. Stubs can be saved in the drawing and assign them to a separate layer.

If the option RIBS is enabled the program performs a different function. It creates new solids in those places where it should have been cut. Rib - the flat solid given thickness. They can be used as a surround frame edges. Use them to make furniture, puzzles, “chumps” for bending, models of ships and aircraft. After creating ribs program can make their stair-step for the simple milling on the CNC.

The remains of the source solid between the ribs can be saved in the drawing if you check «Save stubs».

Command may be numbered segments or ribs in the manner of the cut. Identical segments will have the same name. Stubs and gaps are not numbered.

If the base curve you chose something harder straight line, the cutting plane may intersect. The source of the solid can wriggle and fall under the cross-section many times. All this greatly complicates the work program. Slicing algorithm is very complex; it will try first to find such section planes which cut the solid without touching it in other places. But this is not always possible. And then you get a lot of strange stubs. It's not a glitch. Try to do the same job yourself, using the command Slice - you will encounter the same problems. The program detects multiple intersections and warns you. In this case, I recommend doing the first few sections in the manual, in order to divide the solid into large pieces. And then use the program for each piece. Some curves for some reason AutoCAD cannot cut.

Stair-Step command (StSt)

The command should only be used for parts of the sheet materials. In these parts there are always 2 large flat parallel surfaces - those that are left over from a raw material sheet. Often such details are made on CNC milling machines are not able to tilt the cutter. Therefore, the ends of the parts must be perpendicular to the main plane. This command is just for modeling these parts. It works like this:

  • Find the main (largest) plane.
  • Lay the solid in XY plane (so the part will be on the machine).
  • Make two sections - one at the origin on the Z, the second-most solid top (in fact, the program deliberately shifts the section at 0.00001 inside the body, but it is almost not noticeable)
  • Extrude two sections in the new solids towards each other.
  • We find the intersection of these solids.
  • Voila! We got a brand new solid that can be made on the milling machine. It all ends perpendicular to the main plane. And it never put out the original solid. Is that, in the middle of its thickness at baseline solid could have concave ends.
  • Expand the new solid back to the old place.
  • Removed old solid.

Now you can understand some of the oddities in this command.

Command takes on the job is not one detail, and all that you have chosen. You can select the details before call STST command. Initial solid always removed.

Follow the messages on the console. There may be program messages.

Known Issues

Not processed imported solids in AutoCAD:

As a rule, solid imported from other programs, AutoCAD considers defective. Such solid not cut by Slice command and my program too. Or are cut only in certain places in certain directions. You can check that AutoCAD rejected Solid: Call SOLIDEDIT command, select the BODY and CHECK options. Click on the solid and look at the console. Most likely, you will see the sad message «Solid is not valid». I do not know ways to restore such solid and can only recommend to redraw them again with minimal use of splines.

Not processed complex geometry solids in BricsCAD:

If you work in BricsCAD and you get messages that the program can not cut solid, then you can try to fix the solid using the DMAUDIT command. This great command helps in many cases.

CHOP: The first piece disappears:

The first piece cut CHOP command may disappear or turn into a microscopic bar. This happens when the solid end has no a flat surface in the cutting plane. If you have configured the program to do the satir-step segments, the program will work with a piece of the algorithm described for the StSt command. Read the description and you will understand why the piece was gone. I recommend that in such cases, to indulge in the setting "Start from". It move the base plane of the cut, so that the last piece has turned non-standard thickness. It is enough that the program wrote the last piece in the stubs and does not cause Stair-Step feature.

Stair-Step: removes the insides of piece:

If you first make a hole in the solid, and then made a Stair-Step all internal cavities disappear. So runs an algorithm for obtaining Stair-Step. Do inner holes later.

Stair-Step: Slots have become cross-cutting:

If you have made slots, grooves, quarters in the details, and then cause Stair-Step, all the slots will be cross-cutting and the detail will break up into several solids. So runs an algorithm for obtaining Stair-Step. Do slots later.

Stair-Step: Result solid may go beyond the dimensions of the source solid, if the solid indentation between the planes of the cut:

The Stair-Step  program tries to make a new detail not more than the original. But sometimes this is not possible. The error always occurs when the solid has a concave end face. It is an irreparable flaw of the algorithm. But usually, furniture parts and skeletons are so thin that the concave end is almost invisible and there is no problem.

ChopEdge: Unfinished sections, extra cuts, extra ribs

If the base curve for the ChopEdge commnd is more than 180 degrees arc, circle, closed curve, a winding spline, then in these cases the clipping planes will cut solid in several places. This causes a lot of problems. Unfortunately, this problem cannot be solved even in theory. The cut plane is infinite. The first cut on the start of the solid may cut off its tail. Tail will record in stubs and the last sections will be nothing left to cut. Program will attempt to miss sections which intersect the base curve several times. Program will first cut the solid in simple places, and then return to the complex, in the hope that large piece not already so bent. But often such simple places do not exist. Then the program will alert you that something was wrong. And if you will not stop cutting, then inevitably arise extra slices and incorrect stubs. I recommend that in such cases, make the first cuts alone, ordinary Slice command. And then call ChopEdge for each piece.

ChopEdge: Do not cut the whole ellipses and closed splines

Somehow, AutoCAD cannot be cut in half whole ellipses and closed splines. Do not select such edge as the base curve. Maybe I'll find workarounds in the following versions.

Chop: All pieces mark as Stub in AutoCAD 2015

AutoCAD 2015 measure spline-base-solid with errors.


    Stair step outward option
    Updated dialog window localisation
    AutoCAD 2020 compatibility
    New Activation method
    AutoCAD 2019 compatibility
    BricsCAD Pro compatibility
    Cosmetic updates in the command line parameters
    Fixed: StSt error (from tolerance)
    Autocad 2018 compatibility
    New activation dialog
    New version numbering
Fix: NullReferenceException in StairStep
Options dialog replaces invalid symbols in layer names
Added Tolerance options box to AutoCAD options dialog
First public version