Carbide Create Photo Tracing

Carbide Create has a facility which allows one to place an image on the background for tracing or re-creation. Any drawing program with layers or the ability to lock an object at the background will afford the same capability (in Inkscape, Layer | Add Layer | Layer Name: Background, Position: Below Current).

Discussion of this project on the Carbide 3D forums: http://community.carbide3d.com/t/carbide-create-tutorial-tracing-a-photo/3986

In this tutorial, we will use this feature to create a French-fitted box for the tools which are bundled with/need for a Nomad.

Arrangement
First, arrange the tools suitably and take a photo of them. It may help to arrange them with a ruler, or on a sheet of graph paper or other square grid.



Another option is to cover a scanner bed with a transparency film (one can use one pre-printed with a grid) and then arrange the tools, and then scan them.

Setup
Scale this image to the actual size in a photo editing or drawing program (the above should be ~8.5" W x 4" H) save as a PNG, BMP or JPEG, and then import into Carbide Create using the command Job Setup | Document Background | Edit --- select the graphic in the resultant dialog and click OK. Set the stock are to match the original size, (in this case 8.5" x 4"). Adjust scaling until the image fills the stock area, and adjust transparency as needed. It may be helpful to set the document grid to the same size as the grid from the photograph (see photo in next section).



Design
Once the image is suitably placed, switch to design mode and draw in geometry which will create suitable pockets for the tools as well as recesses for fingers to grasp them. Belike it will be easier to cheat by strategically placing such recesses at difficult to draw portions of the geometry. Union drawn elements as necessary (and subtract using other drawn parts) until all the needed geometry is drawn --- note that you will need separate paths for elements of the design which you wish to be cut to different depths.

Note that due to how we will be defining the toolpaths below, the geometry will be cut wider all around by half the diameter of the endmill --- adjust the drawing accordingly, but too loose is easier to accommodate than too tight a fit.

You can just draw shapes and then union them together using Boolean Union if desired:



or draw using the pen tool, or use some other vector editor and import as an SVG or DXF, until one arrives at:



(Note that the finger cutouts should be duplicated, one copy unioned into the path for the tool, the other left behind so as to allow cutting a deeper recess.)

Once the geometry is created, it is a simple matter to assign paths, based on:


 * dimensions of the stock --- suggest two pieces, a bottom and a lid --- the placement of the drawn paths may need to be adjusted based on this, especially if you wish for the lid to include magnets
 * endmills which will be used to cut --- suggest using a pair of 1/8" endmills, one ball and one square. Use the latter to cut a square bottomed pocket, then use the former to cut a No offset contour --- this should result in a nicely radiused bottom.



(The above is a pixel rendering of a .svg uploaded to the wiki --- click on it to go to a page which will allow downloading of the SVG.)

Looking at the design, it seems to have a couple of problems:


 * too large for the Nomad bed
 * bottom finger recess for the small Allen wrench too low / close to the edge
 * finger holes for the endmill containers are kind of small
 * who has only two endmills?

There is also no geometry for the outside of the box, and the lid.


 * First, delete the geometry for the endmill containers and their finger recesses.
 * Second, we change the size of the stock to 7" x 4.375" (wanted 4.32623792 but we have to sacrifice a bit for the ease of the next technique)
 * Third, we hide the background image

Before we can start drawing more geometry, or creating toolpaths, we need to select the stock material --- this also raises a second limitation of Carbide Create --- uniform stock thickness for a given file, so we will draw the geometry for the base, save the file, duplicate and rename it, then open the copy and modify it to make the lid.

Stock
We will use two pieces of wood:


 * a piece of basswood for the base, dimensions 8" x 10" x 3/4" (actual, not nominal dimensions --- lumber measurement is a separate topic)
 * pine for the lid, dimensions 5 1/4" x 12" x 1/4"



In setup, set the stock material to match your choice.

Rounded Corners
To create rounded geometry in Carbide Create which will match a desired radius of cut, set the grid spacing in Carbide Create to half the endmill diameter --- in this case we'll be using a 1/8" endmill, so we set it to 0.0625" rounded up to 0.063" since Carbide Create only allows 3 digits of precision:

Setup | Document Background | Edit | Grid Spacing --- enter the desired value, OK

Select everything and drag it to the center, then draw two overlapping rectangles, both centered on the page --- note that you will need to do math to determine a size which matches the number of grid squares

Need an even grid which is about the dimensions we need, so...

7" ÷ 0.0625 == 112 squares 4.375 ÷ 0.0625 == 70 squares

112 × 0.063 == 7.056 70 × 0.063 == 4.41 --- since we'd liefer 4.32623792, we'll instead use 69 which equals 4.347

So, change the stock size to 7.06 W × 4.35 H and set the grid spacing to 0.063.

Select the rectangle tool, click somewhere in the center of the drawing and then at an edge to get two rectangles which can be easily selected, then select each in turn and change their position (starting from the bottom left corner) and dimensions to:

X 0.063 Y 0.000 Width 6.930 (110 × 0.063) Height 4.347 (the full height)

and

X 0.000 Y 0.063 Width 7.056 (the full width) Height 4.221 (67 × 0.063)

Note that since Carbide Create seems to work from the center of a selected object even when a corner is set as the origin it will be best to set the size first, then click Apply, then set the values for the origin, then click Apply a second time.

After all this, you should have a screen something like to:



Then, select the circle tool and draw a circle at each corner, snapping it to the square intersection left or right or above or below (not to the diagonal) --- each circle should have a radius of 0.063 inches:



Then select two of the circles and the two rectangles and perform a Boolean Union:



and



Repeat with the resultant shape and the two remaining circles, then draw in the geometry for the lid.

(In retrospect, it would've been easier to've rounded 3.175mm up to 3.5 or even 4 or 5mm and used metric)

To save everyone else the math, the numbers are:

X 0.189 Y 0.126 Width 6.678 Height 4.095

X 0.126 Y 0.189 Width 6.804 Height 3.969

Draw in circles and union as before to arrive at:



(Arguably the outer rectangle should have a slightly greater radius)

Save the file, and duplicate it in the filesystem, (or Save it, and then and do File | Save using a new name) --- there will need to be two files, one for the box itself, and the other for the lid.

CAM
Once all the geometry is done, and two files have been saved, open each file, set the stock thickness to match the desired stock, and do CAM operations for each element and export the GCode.

Lid
First, open up the file which you wish to be the box lid.

In the setup pane, set the stock thickness to match that of the piece of wood selected to be the lid (6.35 mm).

Delete everything but the two outer rectangles (if desired)

Create a toolpath using Tool #102 (1/8" square endmill), a cutting depth of half the thickness of the lid (3.175 mm) using Offset Direction: Pocket and name it Inset.



Repeat for the outermost path, but use Stock Bottom (6.35 mm) and Outside Profile and name it Profile:



Set the Toolpath Simulation material appropriately, then click "Show Simulation":



If all seems reasonable, click on the "Save GCode" button and name and save the file appropriately.

Box
Open the file, measure the thickness of the tools, decide if one will be lining the inside of the lid (natural felt would work well and the natural oils in it inhibit rust --- if using the plastic felt made from re-cycled bottles, wash in baking soda first to neutralize the acid which is used in the manufacturing process), or the bottom of the compartments, and set the depth of each bit of geometry suitably as a pocket.

Okay, to do the CAM for the box in detail:

Open the file which you have chosen to be the box bottom.

Set measurements to mm

Select the paths which make up a given tool and its finger recesses and duplicate them (control c --- probably command c on a Mac):



With the paths still selected, union them together:



The paths were offset up and over by 5mm, so change the X and Y coordinates to be 5mm less each:



Measure the tool thickness (be sure to measure the thickest part of the tool), adjust for the lid and any lining if necessary, and cut the path to that depth as a pocket:



Select the finger recess circle and cut it to a reasonable depth (which is less than the total stock depth):



Repeat for all the other tools.

In the course of doing this, I became concerned that the Allen wrench pockets were too wide, so narrowed them a bit:



In the course of doing this, it may be helpful to temporarily move paths out of the way.



You will want to take note of the depth to which each feature is cut for the step after next.

Next, we select the outermost two paths and cut them as a pocket to half the thickness of the lid stock to create a rebate for lid:



Penultimately we will switch tools to a ball-nosed endmill and cut follow path (No contour) operations along the paths of the tools to the proper depths so as to ease the edges and ensure that the tools will fit with any padding which might be used (do not include the finger recesses):



Lastly, we select the outermost path, switch back to a square endmill and cut it out using the stock bottom (it may be best to add an additional element of geometry and cut this out as a pocket rather than a slot since it is so deep):



Finally we ensure the order of operations is acceptable, then save the G-Code file.

Machining and Finishing
Then, finish at least the top of the box if desired (if using a "hot" finish where a successive coat will bond with a previous one), then cut, (you may want to cover the perimeter of the lid and the entire surface of the box with blue painter's tape). After cutting, clean up the cut edges, sand, apply grain sealer, stain if desired, and your choice of finish.