Introduction: CNC Desk Ornament "the Block" (With 3D Model)
This a small Project mostly designed as artwork and a demonstration to clients of what our machine can do.
It's a very simple project that looks hard to make and is quite eloquent.
If you prefer you could bore a hole in the inside center and use as a pencil holder etc.
Maybe a glorified mug holder?
Here is a link to a 3D model: https://cad.onshape.com/documents/e471cd0199b55ab8...
Step 1: Gluing
Cut your stock wood larger than desired size.
In my case I chose Black Walnut and decided I wanted a 4 Inch square final product.
So I cut my wood to approximately four and a half inches.
When gluing I oriented the grain of the wood 90 degrees different to the last piece to increase strength.
On this I used titebound original, but would highly recommend titebound III for its superior strength and durability.
Apply your glue evenly making sure not to miss a single spot, if available a small smooth paint roller works perfect for this. Clamp your wood together immediately after gluing, you should see glue seeping out from the edges if you used enough glue and clamping force.
Leave your wood in the clamps for at least a hour, though of course the longer the better.
Don't do anything with the wood for about a day to insure maximum adhesion before manhandling.
Step 2: Squaring
24 hours after gluing you can precede to the next step of squaring your block.
I have access to a 5 Axis machine so I just wrote a program that cut all 5 sides at once. (excluding the bottom face)
As I am writing this under the assumption that you will be using a three axis machine I recommenced that you use a table saw in conjunction with a shaper to square your wood.
If using a table saw I recommend leaving a 1/32" to 1/16" to sand off saw marks left from the saw blade.
On mine I cut one side to be 1 inch longer so it would have a pedestal.
PLEASE use caution if yours is in the same size range as mine, it is a rather small piece of wood to handle and both these power tools are HIGHLY DANGEROUS.
Also wear your PPE (glasses, ear protection, gloves .etc)
Step 3: Programing
The Second Picture is a larger prototype made of pine with four circles that I intentional broke.
Programming is relatively easy.
It's just a series of Clearing (cut everything inside of) concentric circles (circles centered in circles) that get EQUALLY smaller and deeper.
First Circle radius of 1.75 depth of -.25
Second circle radius of 1.25 and depth of -.5 .etc
Continue making smaller circles till it "looks Right", for me that was Three circles
On the final circle drastically increase your depth to cut through the wood.
I chose to cut a 1/8" short of center on the final pass to leave a small 1/4 X 1/4 square in the middle.
I also programmed to only cut off 1/8 deep per a pass to lower the risk of damage i.e thin areas breaking.
If you can make a 3D model and make sure that the different faces overlap some, this gives the holes at the center quadrants of the circles, i.e the top circles and the front circles slightly overlap.
If you are using a 3 axis machine and plan to leave a base like I did, remember to to program accordingly as your height will not be the same on all sides.
Alternatively you can forgo the base and cut all six sides for a perfectly symmetrical cube.
My tool of choice was a .5 in flat tipped finisher.
Step 4: Executing Routine
Our machine is currently running on vacuum pods. (Building a vacuum table)
so I screwed my materiel onto a piece of mdf to give it a larger footprint for the vacuum clamps.
MAKE sure that you will not hit the screws with your machine.
Please remember to take the height of the mdf into consideration in your programming.
If you are running on a vacuum table, make sure you can consistently tell the machine the exact position of your wood. (maybe use a sharpie to mark the table around the edges of your wood?)
In my case I had my wood on mdf and then used a set of calipers to measure my distance from my corner stops (0,0,0,) and offset the program accordingly.
Run your Program flipping the board for each side if needed. :)
I ran mine at about 1/5 full speed of the machine as this is a delicate item and I did not want to break or mar it.
At that speed it probably took about 20 Minutes to run.
Step 5: Shaping the Base
I took it to the table saw and made a 1/4" wide by 1 1/4" deep slice starting at 4" from the top and descending to make it a cube on a pedestal.
Than I set the saw to a 45 degree bevel and cut about a 1/4" inch off the top of the base to give it a nice profile.
Step 6: Sanding
As you can see in the pictures it came out a bit rough.
I took some 180 and 320 Grit sandpaper to it to sand off all the fuzz.
I took a small chisel to the wood in the middles and oh so carefully chiseled it shorter until it was square.
You can expect there to be slight marks from the tool passes that you might want to sand off.
I was not overly pick and decided to leave them.
Step 7: Coloring and Staining
I used a oxidizer on mine to bring out more of the black walnuts natural color and grain.
I think it was Cobalt something or other. ;)
I used a cotton painting rag (old white t-shirt will do) to carefully apply both the colorant and the stain.
Be extra careful around the edges, there is a lot of different faces and corners, be sure to get them all for a consistent color.
With this oxidizer I had to wait until dry, wash the residue off with water, let dry again and only then was it ready to stain.
For Stain I went with dark walnut, apply it the same as the oxidizer and let dry.
After the stain was dry I added a few layers of clear coat to give it a shine.
Before applying the shellac use a tack cloth (best) or a rag to clean off any dust.
Step 8: Show Your Friends.
I am not one for show, but I was too proud not to take this to a few events and pass it around.
It has made a great conversation starter and received many a great comment and questions from tons (literally) of folks.
This now sits on my desk in a place of honor where I program for a 5 axis Felder profit h50 German CNC.