Chop

Using this plugin, you can quickly cut a three-dimensional body (3D solid) into slices, ribs. This is useful when you are designing products from sheet materials. For example, furniture, plywood frames, "blocks" for bending, puzzles, models of buildings, ships and aircraft. A single Chop command can replace dozens of calls to the _Slice command and do a lot more auxiliary work.

The main mode of the Chop (Ch) command is cutting a solid with parallel planes with a given step. The starting plane can be set by selecting a face on the solid, or as one of the planes of the coordinate system, or by three points. 

The second cutting mode is cutting along a curve along a given solid edge. In this case, the secant planes are placed perpendicular to edge of the solid. The curved solid will be cut into pieces of the same length. 

In addition, the Chop command can be switched to the mode of placing ribs on each section.

You can remove the inclined ends from the obtained slices - make them "stepped" for further 2D milling them from sheet material on a simple 2.5D CNC machine. Stair-steps can be made inside or outside the original solid.

In addition, the program can:

• Cut with parallel planes many solids at once in 1 call of the Chop command.

• Cut with a clearly defined step. You will get a trim (stub) at the end.

• Cut into a given number of pieces (the program will calculate the step itself).

• Cut without stub into pieces  no more than a given length.

• The location of the starting section can be chosen by the user, it can be set at the beginning, end and middle of the solid.

• Make gaps between pieces.

• Keep the original solid after slicing.

• Save or delete stubs.

• Assign special layers for pieces and stubs.

• Give pieces names. The name can be substituted with any properties of the original solid and the number of the piece in the order of cutting. To do this, the Numbering command is called.

• You can set up to 9 Chop-styles with different settings and quickly switch between styles right from the command line.

• You can switch to cutting mode along a curved edge without changing the chop-style. To do this, there is a separate command "Chop Edge" (ChE)

• There is a separate Stair-Step (StSt) command, which removes inclined ends from a flat part.

• All options are configured in the dialog box, in the AVC Options Palette, or in the AutoCAD Options window.

The program works only with 3d-solids, does not work with meshes, surfaces and blocks. Just like the rest of the AutoCAD commands, in most cases Chop command will not be able to work with solids imported from other programs.

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 - 15 EUR.

  • Unlimited license - 75 EUR. Free updates for 1 year.

  • The trial period is 20 days.

Parallel plane slicing mode

In this mode, the program asks to set the base plane. Solid will be cut from this plane. The cuts will be made by planes parallel to the base, with a uniform step. The easiest way is to select the reference plane as a face on the solid being cut. The solid face must be flat. Often AutoCAD makes the mistake of treating apparently flat faces as non-planar. In this case, you need to select another face or define a plane using three points.

When selecting a face, you will see the same options as the _Slice command: Select one of the planes of the current coordinate system or specify a plane by 3 points.

You can assign a user coordinate system (UCS) before calling the Chop command and the program will use that coordinate system. In any case, the solid will be cut completely, on both sides of the base plane.

When the program asks for a flat surface, you can also click on the linear edge of the solid. The secant planes spaced along the linear edge are also parallel to each other. Therefore, the program will not object to such a choice.

This mode allows you to cut many solids at once. Solids must be selected before calling the Chop command. Thus, slicing a large solid along and across (by squares or rectangles) can be done in just 2 calls of the Chop command.

Slicing along a edge mode

This mode allows you to cut the solid with non-parallel planes. It is convenient for breaking curved solids (arcs) into equal sections.

First of all, you need to choose a base curve. This curve will be used to place the cutting planes. To set this curve, click on the edge of the cut solid. You can select an edge on a solid before calling the command.

The program will place cutting planes evenly along the given curve. The length of the pieces is calculated according to the length of this curve (arc or spline), and not as the overall size of the pieces. The planes are set perpendicular to the tangent (first derivative) to the curve at the cut point. That is, for straight lines they are perpendicular to it, and for arcs, the cut planes will be made along the radius.

A solid can be longer than its given edge. The program makes cuts at both ends of the edge, and there may be trimmings (stubs) left behind the ends of the edge, even if you set the program to divide the edge without a remainder.

If you choose something more complicated than a straight line as the base curve, then the cut planes may intersect. The original solid can wriggle and fall under the section many times. All this greatly complicates the work of the program. The slicing algorithm is very complex, it will first try to find such secant planes that cut the solid without touching it in other places. But this is not always possible. And then you get a lot of weird clippings. This is not a glitch. Try to do the same job yourself using the normal Slice command - you will run into the same problems. The program detects multiple intersections and warns you. In this case, I recommend making the first few cuts by hand in order to separate the solid into large pieces. And then use this program for each piece. For some reason, AutoCAD cannot cut some curves at all.

The slicing along a edge mode only works with one solid - don't try to select many solids at once.

Make Ribs mode

If the "Ribs" option is enabled, the program performs a different function. It creates new solids in the places where the cut should have been. Ribs - these flat solids of a given thickness. They can be used as ribs of a three-dimensional frame. Use them to make furniture, puzzles, bending blocks, ship and plane models. After creating the ribs, the program can make them stepped (like stair-step), for easy CNC milling.

Ribs can be placed both in the parallel planes mode, and in the along a edge mode.

Remains of the original solid between the ribs can be saved in the drawing if the option Save Stubs is checked. Of these, it will be possible to model shelves and curved skins.

The program always puts two ribs at the ends of the original solid (or at the ends of a given curve), and in such a way that they do not protrude beyond the limits of the original solid. That is, the thickness of the rib is formed inside the solid from the cutting plane. And all intermediate ribs are formed in both directions symmetrically from the cutting plane. Therefore, the extreme ribs and stubs near them may differ slightly from the rest of the intermediate ribs and stubs.

Program settings

You can configure the program in the _Options dialog of AutoCAD, or in the AVC Options Palette, or in the dialog box called by the TUNE option from the command line, the Chop command.

• Program operation mode:

  • Parallel planes - a way of arranging cutting planes parallel to a given one. We get flat slices.

  • Along an edge - a way of arranging cutting planes perpendicular to a curved line. The curve is set as an edge on the same solid. We get the division of the arc into equal segments.

• Step:

  • Fixed step - the exact size of the pieces. Since the solid is not required to be completely divided by this size, trimmings (stubs) will remain somewhere. Where stubs are formed depends on the "Start from" setting.

  • Number of pieces - Specifies how many pieces the solid should be cut into. The piece size is calculated. Stubs can still occur if the solid extends beyond the base curve (cutting along edge mode).

  • Not longer - The maximum allowable length of the pieces is set, and the program selects the length by less, in order to divide the solid (or the base curve) without a remainder. This mode is convenient when you don’t care how many sections a table | cabinet will have, but you can’t make shelves longer than 800mm (they will sag). Then you set the maximum length not longer 800, and the program itself will divide all the blanks of tables / cabinets into suitable sections.

• Start from: Select the position of the starting cutting plane. It only makes sense when a fixed step is given. Specifies where the stubs will remain. You can play around with this setting to get optimal stubs from the solid.

  • Specify: You specify the first cutting plane as the flat face of the solid, or as the plane of the current coordinate system, or as a point on the base curve. Stubs may remain at both ends of the solid.

  • Minimum and maximum: The starting cutting plane is placed at the very end of the solid or at the very end of the base curve. Minimum - at the nearest end to the base plane, maximum - at the far end. Accordingly, there will be only one stub at the opposite end of the solid.

  • Middle: The starting cutting plane is placed exactly in the center of the solid or in the center of the base curve. You will get a symmetrical cut and two identical stubs on both ends.

• Ribs: Changes how the program works. Now the program will not cut the solid, but will create ribs of a given thickness in those places where the cutting planes have passed.

  • Rib Thickness: This option is only available when the Ribs mode is enabled and sets the thickness of the ribs.

  • Ribs cleaning: Remove extra ribs that do not touch the base curve. It is recommended to enable this option when the curve is strongly curved and the cutting planes intersect the solid multiple times.

• Stair step: the option will be useful for anyone who makes frames or blanks from sheet materials on CNC milling machines. When this option is enabled, the program will replace cut pieces or ribs with flat parts with orthogonal ends. Those all slanted ends will be cut off. Moreover, they are cut so that the new solid will never protrude beyond the original. All recesses in the pieces will become through. And the end holes (latteral drills) will disappear. This is not a glitch, this is how the edge straightening algorithm works.

  • Outward: Make stair steps outside of the original solid. So that you can then grind off with a file. Usually the steps are made inside so that they can be puttied.

• Gap: The thickness of the gap (clearance) between pieces. You can use this gap to account for the thickness of the saw blade, or to form a framework with gaps between the ribs. If the specified gap is greater than zero, then the cutting step will be equal to the size of the pieces plus this gap.

  • Save gaps: the program can save pieces of solid remaining in the gaps or between the ribs. In any case, no stepping function is applied to these pieces and the layer remains the same as that of the original solid.

• Save Source: the cut solid will remain in the drawing. And the slices will be inside it.

• Save Stubs: leave in the drawing the remnants of cutting at the ends of the solid, smaller than the specified size of the piece. Also, stubs remain when cutting along the edge of the solid, when the solid goes beyond this edge. Stubs can be used to cut into thinner pieces.

• Piece Layer: The program can assign a layer to piece or ribs. If this field is left blank, then the layer of pieces will be the same as that of the source solid. The program itself will create a layer if necessary. But if the color of the layer is important to you, then create it in advance in the drawing or in your DWT template.

• Stub Layer: You can assign a separate layer to the stubs. Leave the field blank so that the stubs remain in the original layer. The program itself will create a layer if necessary.

• Numbering: for ease of assembly of the product, you can give names to all cut off parts with numbers in the order of cut. Identical pieces will receive the same name. Stubs and gaps are not numbered. If one cut gives several slices at once (the solid is divided into separate bodies), then they will also have different numbers, in random order. You can see solid names only if you have installed the plugin A>V>C> Properties Palette. All numbering settings are the same as for the Numbering program. This means that you can use any substitutions of the properties of the source solid and the properties of the drawing in the name template. For the number itself, use the %row% substitution. If Through numbering is not configured, then when cutting each next solid, the number will be reset to 1.

• Show Dialog: The settings dialog will be displayed each time you invoke the Chop command, without the need to specify options in the console. You can also enter the cutting step here. But you can no step set the length by clicking on the drawing.

• Request the step or number of pieces: if you want, the program will ask you for data to calculate the cutting step each time you call the command. Depending on the settings, the step of cutting, or the number of slices, or the maximum allowable length will be requested. But if the configuration dialog is set to show, then there will be no request.

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.

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.

Chop along edge: Unfinished sections, extra cuts, extra ribs

If the base curve 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.

Chop along edge: 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.

All pieces mark as Stub in AutoCAD 2015

AutoCAD 2015 measure spline-base-solid with errors.