Unwrap Vectors

This gadget is used to 'un-wrap' a vector to create a profile for a shaped cylinder in VCarve Pro. This is easiest to explain using images, so we will show the steps you would need to take to create a hexagonal shaped column:

If you have downloaded the gadget from the Vectric website, you will need to copy it into your installation of VCarve Pro. The gadget belongs to the 'Wrapping' tools family of gadgets, so we would suggest that you copy it into the Gadgets\Wrapping folder under your VCarve Pro installation. For a normal installation of VCarve Pro [ProductVersion], this path will be

C:\Program Files\VCarve Pro V[ProductVersion]\Gadgets\Wrapping

You will need administrative right to copy the file to this folder.

The Process

The first step is to run the 'Wrapped Job Setup Gadget' to specify the size of the material you are machining and the orientation of your rotary axis (Gadgets - Wrapping - Wrapped Job Setup from the main menu with no file open).

In this example we are creating a job 20 inches long with a diameter of 6 inches.

The cylinder is aligned along the X axis, so we are wrapping the Y values in the job around our cylinder.

The Z origin is set to the cylinder axis (bottom of material)

Most importantly, we are doing a simple cylindrical wrap.

After hitting OK, a new blank job will be created in VCarve Pro.

In order to help visualize the unwrapping, we strongly recommend that you draw a circle the same diameter as you job in the center of your work area to act as a reference for the unwrapping. Go to the 'Draw Circle' tool and draw a circle of the required diameter (6 inches in this case). After drawing the circle and closing the form, select the circle and press F9 to center it in the job.

We are now ready to draw the vector which will represent the cross section we want to machine. Use the 'Draw Polygon' tool and set the Number of Sides field to 6. You can snap to the centre of the circle with the cursor and then enter the radius on the form (2.95 inches in this case as our material is 6 inch dia = 3 inch radius and we want to make sure we stay inside the cylinder). Alternatively, for a symmetrical shape like a hexagon you can center the vector after drawing it with the F9 key.

We are now ready to 'unwrap' the hexagonal vector to get the shape we will need to extrude flat and then wrap back again to get our original shape. With the hexagonal vector selected go to the Gadgets Menu ► Wrapping ► Vector Unwrapper.

If this gadget isn't shown in the menu, please review the instructions above for installing it.

The gadget is unusual as if it works no interface is displayed, the unwrapped vectors and some supporting data are created automatically as shown in the screen shot below.

This example shows the unwrapped vector for a cylinder aligned along the X axis. If your rotary axis is aligned along Y the unwrapped vector will be horizontal. For clarity here, I have also selected the unwrapped cross section and moved it down slightly so that you can see the straight 'legs' which have been added to each end of the unwrapped vector to get the correct height when it is used as a cross-section for the 2 rail sweep command. As well as creating the unwrapped cross-section, the gadget will also automatically create two drive rail vectors on a layer called "Unwrapped Vectors Drive Rails" which can be used directly to create the base shape for our hexagonal column.

The screen shot below shows the vectors selected and the Two Rail Sweep form open.

Press the 'Add' button and you will create a shape as shown below.

Although this may look strange in the 2D view, shown flat, when the toolpaths for this shape are wrapped they will create our hexagonal shape. To show this, in the screen shot below I have created a coarse 3d toolpath over the complete model and switched on the wrapped toolpath visualization (Note: remember to deselect the vectors you used for the Two Rail Sweep before calculating the toolpath otherwise you will get a warning about open vectors being selected as the machining boundary).

However, before creating a toolpath we need to ensure that the model is positioned correctly within our block. When the gadget creates the unwrapped cross-sections, it adds 'legs' to either side of the unwrapped vector to ensure that the swept shape is the correct height from the center of the cylinder.

Therefore when using this gadget you must ensure that the model you create is at the BOTTOM of your block of material. The Gap Below Model field must say 0.0 and the easiest way to ensure this is to just drag the 'Model Position in Material' slider to the bottom of its range.

Once you have set the model position you can calculate the 3D toolpath and view it wrapped as shown below.

You are not restricted to simple shapes for your cylinders. The example below from one of our testers shows a heart profile unwrapped. This example has been created for a rotary axis aligned along Y.

The screen shot below shows the wrapped toolpath - the view has been rotated to show this orientation.

Advanced Techniques

The examples above have shown a single cross-section being used to define your base shape. As we are using the Two Rail Sweep command we can use a different cross-section for the end of the sweep to the one we use at the start. In the screen shot below we have unwrapped two vectors, the heart shape and the hexagon. The unwrapped hexagon vector has been nudged up after wrapping for clarity.

The screen shot below shows the 'flat' model created from the two rail sweep, and you can see the unwrapped heart shape blending into the unwrapped hexagonal shape along the length of the job.

Finally, the screen shot below shows the wrapped toolpath (again with the view rotated).

Modeling 'Twisted' Shapes

A fairly common style of column has a constant profile which 'twists' along its length. The 'Vector Unwrapping' gadget can be used to help with the construction of these models but more work is required to achieve the desired result. We will look at the example of a square column with a 45° twist along its length. The screen shot below shows the two square cross-sections drawn in the center (one rotated 90°) and either side I have placed the unwrapped vectors from the gadget.

As you can see, both vectors unwrap to similar shapes BUT the alignment is different as you would expect. If we just try to sweep these sections as they are we get the following result.

The cross sections have blended smoothly between the two ends but we don't get our 'twist' effect because in this case, we don't want the points on the left section to blend into the points the same distance from the start on the opposite section, we want them to blend across to the matching rotated piece.

If both sections had the same number of spans and they matched, we could have used the 'Sweep Between Spans' option on the Two Rail Sweep form but unfortunately they don't.

Although it is a little hard to see from a static view (it's much easier to see when you can twiddle the model), the screen shot below shows that we aren't getting a 'twist' just a blend like the previous example with the heart and hexagon.

There are a number of possible approaches to this problem, and I will demonstrate here the one that needs no node editing. We are going to 'skew' our sweep, which will leave parts of our model uncovered. We will then create another drive rail and 'fill in' the missing portion.

To layout our 'skewed' drive rails we can use the 'Spiral Layout' gadget to do the hard work for us. From the main menu, use Gadgets - Wrapping - Spiral Layout to run the gadget and the form below will be displayed.

Set the Number of Starts / Strands to 2

Set 'Twist Direction' to 'Create Left Hand Twist' only

Ensure that 'Use Spiral Pitch or Spacing' is set to 'Spiral Pitch'

The next part is the important part, The 'Spiral Pitch' edit field should be set to the length of your column * (180 / Twist Angle). So for this example where we are rotating by 45° on a 20 inch long cylinder

Spiral Pitch	= 20 * (180 / 45)
	= 20 * 4
	= 80

Set the offset from start/end to zero and don't create coves.

Press the OK button and two lines of the required angle will be created in your job as show below (the lines have been selected). Note: we are only unwrapping a single cross section as we are doing the 'twist' with the two rail sweep.

These lines are at the correct angle and length for our sweeps, but they are grouped and the upper one needs to be moved to the top of the work area. To ungroup the vectors, make sure they are selected and either press 'U' as the shortcut for ungroup or right click and choose 'Ungroup Objects' from the pop-up menu.

Once the vectors are ungrouped, click off them to de-select them and then click on the upper vector twice to select it and go into 'transform' mode. Click on the vector near the end and drag it to the corner of the drawing you want the end at, it will 'snap' into position when you get the end of the vector over the corner (the cursor will change to the snap cursor when it can snap). The screen shot below shows the vector dragged into position. Note that this example is for a rotary axis aligned along X, if your rotary axis is aligned along Y your vectors will be more vertical and you will be dragging the vector to the bottom right corner instead of the top right.

We are now ready to create our Two Rail sweep the same as previously, but this time we select our angled lines as the drive rails and our single cross-section.

Hitting 'Add' on the form will give us the following shape in the 3D view

As you can see this looks right for the 'twist' that we want but we have a section missing in the bottom right corner due to the 'skewed' sweep. To fix this we need to do another Two Rail Sweep in that area.

To create the second sweep we need another drive rail the same distance below the bottom drive rail. This distance is actually the circumference of the piece and is the height of the job if your rotary axis is aligned along X and the width of the job if your rotary axis is aligned along Y.

To create this line, first make a copy of the bottom drive rail, click on it and select Edit - Copy and then Edit - Paste (or Ctrl+C followed by Ctrl+V). Then go to the 'Job Setup' form (Edit - Job Size and Position), make a note of the Height or Width which corresponds to your circumference (you can just use Ctrl+C to copy the value form the edit field after selecting the text). Close the 'Job Setup' form and re-select the line we are going to move (we copied this above).

Open the 'Move Selection' form ('M' is the keyboard shortcut). We are now going to move the vector a relative amount in the -Y direction (or - X if your rotary is aligned along Y). In the required field type in the circumference we got from the 'Job Setup' form - if you copied this you can just 'paste it into the field with Ctrl+V. Remember to make the value negative. The screen shot below shows the values for this example - a 6 inch diameter cylinder with the rotary axis aligned along X. Note the '-' sign in front of the 18.8496 value and that we have selected Relative for the 'Type of Move'

Pressing the 'Apply' button will move the vector down in Y by the value we entered (or left in X if your rotary axis is along Y).

Your screen should now look like that shown below. Select the upper drive rail, then the lower and finally the cross section and open the Two Rail Sweep form. This time make sure you press the 'Merge' button in-case there are any slight overlaps between the sweeps.

After pressing the 'Merge' button you should see the full model in the 3D view as shown below.

You now have the base shape for your column to work on. Creating a coarse 3D toolpath to visualize the shape will give results similar to that shown below.

Error Messages

If the shape you are trying to unwrap will not fit within your cylinder diameter the following error dialog will be displayed.

To identify the problem, make sure you have drawn a circle representing your cylinder diameter and centered it in your drawing area (use F9 to center it). The above error message indicates that some part of the vector you are unwrapping goes outside of the circle.