Mystery File Challenge

Whats in the File?

MysteryPenny 031 (1.2 MB)

I love the idea of being able to share files, to celebrate the ability to upload .nc files I am creating this Mystery file challenge.

Who wants to find out whats in this file?
No G-code simulation, you have to run the job to find out.
You will need a 1/32 ball endmill (#121) and a penny.
The Origin is the Center of the penny, on the top surface.

To participate:
Engrave the file into a penny (or other surface!), post a picture, take a victory lap in this thread.
(File will work with the Nomad and the Shapeoko.)

To win:
First 2 people to make one are going to win something,… not sure what yet.
Something worth more than a penny, probably a value of around 2k pennies.

Every one who participates wins a custom penny they made!.

You could make a jig to hold the penny or just machine a .745" pocket in some scrap material.
A shallow pocket and some blue wax would work also.
The main concept being that you use the same XY origin for the pocket as you do for the Engraving of the Penny.

Heres a Carbide Create file for making a Soft Jaw for the Low Profile Vise

Vice insert for Nomad.c2d (10.4 KB)

Or you could use the Soft Vise

Good Luck!

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OoooH, How exciting, a mystery. Mine is cutting now. Hope it holds. This is my first time to cut with fixture wax.

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Almost done…95%…

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Yummm, Yummm, Yummm… Did someone say Cookies?

And yes, that is the outline of the Wrench project in my waste board, along with a few other things.

Maybe I won a 10 pack of new waste boards…or even better yet, a flip jig so that I can do 2 sided pennies (wink wink).

Thanks for posting this challenge Apollo. This was super fun.


Chips ahoy, That was fast!
Congrats @Design_Make_Test
Glad you got a chance to use the blue wax!

FYI: A pre 1982 penny will appear to be solid Copper.
But personally I like the look of the zinc core that creates a color break on this design.

Smallest I have is a 1mm and it’s a flat not a ball…


You can still participate, If your curious what will happen.
However, there is a chance you could break your tool.

The Larger diameter will result in some loss of detail since the Gcode file was created for the smaller 1/32" bit.

Since you sound interested, Do you have a project or challenge idea / theme/ material request?

I didnt have the right bit but it was still fun trying,Thanks Apollo :slight_smile:

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Fun, Thanks Apollo.

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Let me think on it for a bit.

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Looks much better cleaned up.


A Foam Soft Jaw insert, cool.
Nice Cut @FlatBaller

Looks like you tried a flat end mill, interesting result.

Do you have a request for a type of project?

It was a diamond dremel engraving bit.ill have to get back to you on a request for project type,Im down for anything though,I just want to learn :slight_smile:

@ApolloCrowe This little file has me hooked for 2 reasons. First, it is a good piece to have in my pocket to just give away, as it is a great conversation starter. Second, it mills quick enough to be a demo piece at a Maker Fair event.

Ideally, you could make another design that would mill faster, be just as easy to recognize <cough>C3D logo</cough>, and still use the penny as the raw stock, and be ever further ahead in having a marketing masterpiece.

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I took a break from the Power Hack Saw project this afternoon when I saw that the mailman finally delivered my Makita 1/8 Collet.

Method of securing the penny? Yup, a drop (or two) of hot glue. Important lessen I learned many many moons ago, no need to re-invent the wheel.

EDIT: Added a non LED lit photo once I realized that it washes out a lot of the details.

Now if you’ll excuse me, I hear a bag of cookies calling me…


The Mystery File Challenge Awards have been shipped
Congrats to @Design_Make_Test @orlrobinson and @FlatBaller

I have updated the Cookie Monster file and added the Carbide Logo.
ChipsAHOY 031 v4 (1.5 MB)

Here is how to set up your own Penny Engraving.

STEP 1: 2D art

This is the JPEG file I opened in MeshCAM
I have done some editing in photoshop to get the image to read at a small scale by adding the black and white outlines for example.
Note, I added a white transparency layer on top of the image, I found this helps blend the tones and levels.

Step 2: Scale the Art

Upon opening a JPEG or PNG file in MeshCAM you will have to define the XYZ dimensions and choose Z + or Z- direction to pull the image. Here are the settings that worked for this job:
X .735"
Y .735"
Z .017"
Black = -Z

Step 3: Smooth

In the Relief Controls you will see the Smooth option, I turn it all the way down to 1 becuase i dont want to lose detail, i just need less spikes in the Fur for this peice in particular. Its a very cool feature, check it out with some black and white art, you will be amazed!

Step 4 Define Stock

Engraving Tip!
When defining the stock size on an engraving job you can set your Z position to -.001(!)
Since I dont want to engrave the top of the surface, I pull the art work above the bounding box by .001",
This way the top surface of the Art is not read by MeshCAM.
Only the parts that are below the top surface will have a tool path created.

Step 5 Set Your Zero

Round objects get center Zeros in my book, especially if you need it to be concentric with the pocket fixture you are using to hold it.

Step 6 Define Region

If it doesn’t need to be machined, then MeshCAM doesnt need to process it, so I use the circle tool to define the area to machine within.

Step 7 Tool path

In this case the material and program is shallow enough to not need a roughing pass.
The very fine stepover of .002" lets the cut be as deep as .016" in places and move at 13 ipm with the tiny 1/32" cutter.

Some time can be saved by eliminating the pencil pass, but I think the extra details are worth the 2-3 minutes it adds.

Heres the TPS file for engraving with the #121 ( 1/32" ballend) on Copper and Zinc pennies.
cookie penny settings.tps (2.1 KB)

Chips Ahoy!


Awesome! Thx Apollo :slight_smile: :slight_smile:

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Great write up Apollo. This gives me some ideas to try in the future. :slight_smile:

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