# Carbide Create tutorial --- tracing a photo

Worked up the beginnings of a basic tutorial on re-drawing stuff on the wiki:

http://www.shapeoko.com/wiki/index.php/Carbide_Create_Photo_Tracing

Hopefully someone will find it interesting / of use. Tomorrow’s task will be assigning toolpaths and actually cutting it out.

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“Well, good morning!” (Not dating myself there, am I?)

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?

I also failed to draw in the geometry for the outside of the box, and the lid.

For those, I’m going to add a technique for doing rounded corners in Carbide Create — hang on!

• First, we 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 — anyone else ever watch a black-and-white film on the golden ratio in school? It sounded a bell each time one was identified on-screen by a drawn-in highlight — wish I knew the title…)
• Third, we find out that one can’t remove the background image — suppose one could place a white background or something totally transparent… hang on, gotta send an e-mail.

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.

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"

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" — or we would if the program would allow it, round up to 0.063":

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 — not that you will need to do math to determine a size which matches the number of grid squares

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Will,

Thank you for making this tutorial - so helpful. Awesome!!! I had no idea about these techniques

Martsy

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First off, there is a “Show” checkbox for the background image — clear that and it’s at least hidden.

Okay, picking up where we left off — since Carbide Create won’t cooperate, we have to work out some way to get 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 number 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 open it 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.

Open each file, set the stock thickness to match the desired stock, and do CAM operations for each element.

For CAM, 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.

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Repeat (more-or-less) for the box itself:

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.

Cut a pocket using the outermost and inside path for the lip of the lid, do a follow-path and outside path to trim additional material out of the way, then do an outside path to cut the perimeter of the box (it may be necessary to add an additional bit of geometry outside the perimeter to allow cutting the box free using a pocketing operation rather than a profile so as to facilitate chip clearance).

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 lide 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.

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anyone else ever watch a black-and-white film on the golden ratio in school? It sounded a bell each time one was identified on-screen by a drawn-in highlight

Not black-and-white, but I’m guessing you’re thinking of Donald in Mathmagic Land; I remembered the same scene, and found it on youtube.

-j

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I wonder if they didn’t pull in content from a variety of sources for that — I don’t remember colour, (it was a film, so no need for it to be b/w), and I don’t remember that it was animated (but when I was a kid, I didn’t do so well at differentiating between drawn and photographed reality — not that my Dad helped, let me tell you about the time he let me think The Andromeda Strain on TV was a documentary) — thank you, for solving one of the mysteries of my childhood!

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, adjust for the lid and any lining if necessary and 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 to the proper depths so as to ease the edges and ensure that the tools will fit with any padding which might be used:

Lastly, we select the outermost path, switch back to a square endmill and cut it out using the stock bottom:

Finally we ensure the order of operations is acceptable, preview the file as a final check, then save the G-Code file.

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Last up is the actual machining and finishing.

The lid is simple: nice side down, fix in place and cut:

Use some appropriate workholding method to secure the piece within the machine, load an endmill, and the file, don hearing and eye protection and begin.

I am going to finish the top of the box (using a “hot” finish where a successive coat will bond with a previous one), then cut, (and will be covering the perimeter of the lid and the entire surface of the box with blue painter’s tape).

Rainy, dreary day, so the photo leaves something to be desired:

Apply the finish per the manufacturer’s directions, and allow to dry between coats (an earlier coat went on first thing this morning).

Sprayed two coats, without any prep beyond wiping off, since this is intended to be somewhat sacrificial — the idea is to keep the top surface from splintering (hence the tape) and to prevent the tape from adhering too strongly, and to allow a later operation to be done more easily.