CNC Routed Salt Box #1: Creating the Top

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Blog entry by SPalm posted 10-20-2011 04:38 PM 18499 reads 8 times favorited 35 comments Add to Favorites Watch
no previous part Part 1 of CNC Routed Salt Box series Part 2: New Vacuum Clamp & Ooops »

I will try to describe how I created the design for the Salt Box, and how I told my homemade CNC to cut it out. Here is a picture of the box, and the top. Let’s start with the top.

Remember this is just a router. Almost all the things that the CNC can do may be done by hand routing, maybe with a template or a fancy router table. But for this project, I picked a couple of things that would be quite difficult without the machine control.

Background: In my mind, there are four types of routing that you can have the machine do.

Profile: Cutting on a line. You have it cut on a line, outside of the line, or inside of the line. Different bits can be used to get different effects. These would include a straight bit, a V-bit, and a rounded core box bit. You can also tell the machine how deep to go and whether to go flat horizontal or gradually change the height as it routes.

Pocket: Cutting out a pocket (or mortise). Typically here you select a closed drawing and tell the machine how deep to route it out. The two main bits here are the straight bit and the bowl cutting bit with its slightly curved sides. Typically the bit is plunged to a certain depth in the center of the pocket, and then moved about to complete that depth. Lower the depth and repeat.

Raster: Cutting out a “3D” design. Typically here the router is started at the upper left hand corner and then move straight to the right using a very small bit. The bit depth is constantly changed as it moves. This is repeated hundreds if not thousands of times until the design appears. It takes a long time, and you need a really nice machine to pull off a nice result.

V-Carve: Cutting with a V-bit while gracefully changing the height. This produces basically the same thing as Chip Carving by hand. The design must be carefully chosen to never allow the bit to route too deep. The way it works is the software sees a drawing object (called a closed vector) and will tell the machine to lower the V-bit into the center of it until the depth is such that the sides of the V touch the sides of the closed vector. Then it will instruct the machine to move and raise the bit to keep the V always touching the sides of the vector. A lot of signs are made this way as font characters are closed vectors.

I will cover Profile and Pocketing in another blog. I don’t do Raster. And that leaves me with V-Carve for now.

Here is a picture of the objects presented to the software which creates the design. This should be recognizable to someone who has done Chip Carving. I started with a bunch of overlapping circles. I then trimmed the lines (called vectors) until I had what is shown. Next I used layers in the drawing editor to copy certain elements of the design to end up with 4 sets of closed vectors. I then selected all the little parts and stretched them into an oval. Also pictured is the profile of the design and where the drill hole goes.

And here is a video of it being cut. I edited it down to two minutes. It is worth a look, as I think this is the most magical part of a design. Maybe you should hit the mute button, as you probably are not wearing ear protection right now.

Take care,

-- -- I'm no rocket surgeon

35 comments so far

View jim C's profile

jim C

1472 posts in 4071 days

#1 posted 10-20-2011 04:49 PM

Great explanation Steve

View sras's profile


5761 posts in 4102 days

#2 posted 10-20-2011 05:35 PM

Love the video! Thanks for sharing.

-- Steve - Impatience is Expensive

View Bob Kollman's profile

Bob Kollman

1798 posts in 4164 days

#3 posted 10-20-2011 05:36 PM

I turn with cnc lathe, your home made machine cuts just as gracefully as any of our fadal mills.

An amazing achivment on so many levels for a home wood work shop. Great Video, I would

have liked to seen it all.

-- Bob Kenosha Wi.

View leanne's profile


45 posts in 3385 days

#4 posted 10-20-2011 05:54 PM

loved the video, look forward to more.

-- Leanne, Australia,

View Northwest29's profile


1706 posts in 3463 days

#5 posted 10-20-2011 06:05 PM

Now that’s just too cool! Thanks for sharing the video.


-- Ron, "Curiosity is a terrible thing to waste."

View blackcherry's profile


3345 posts in 4796 days

#6 posted 10-20-2011 06:17 PM

Now Steve this is right out not playing fair 15 yard infraction for not using your hand tools…lol Nice work on the video the CNC cuts like butter…BC

View CartersWhittling's profile


453 posts in 3647 days

#7 posted 10-20-2011 07:57 PM

Thanks for the video.

-- And whatsoever ye do, do it heartily, as to the Lord... Colossians 3:23

View fernandoindia's profile


1081 posts in 3916 days

#8 posted 10-20-2011 08:02 PM

Steve, that’s just too cool! Thanks

THough it may it not be rocket science, it is very close to it. Great job

-- Back home. Fernando

View lanwater's profile


3113 posts in 3907 days

#9 posted 10-20-2011 08:23 PM

Great video Steve.

Your CNC cuts through the wood like butter with excellent precision.

Thanks for the video.

-- Abbas, Castro Valley, CA

View MShort's profile


1798 posts in 4391 days

#10 posted 10-20-2011 08:42 PM

Thanks for the video Steve… What a great toy (tool) to have !!!!

-- Mike, Missouri --- “A positive life can not happen with a negative mind.” ---

View shipwright's profile


8646 posts in 3771 days

#11 posted 10-20-2011 08:58 PM

OK Steve, it’s been suggested several times but I think it’s time to abbreviate your signature.

Steve, rocket surgeon …....................... has a certain je ne sais quoi and would look quite appropriate on your posts.
All those in favor say Aye.

Good video

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese!

View degoose's profile


7280 posts in 4327 days

#12 posted 10-20-2011 09:41 PM

Brain Scientist… nah… I like Rocket Surgeon… awesome… meaning I am full of AWE… great video too

-- Don't drink and use power tools @

View Joe Lyddon's profile

Joe Lyddon

10958 posts in 5025 days

#13 posted 10-20-2011 09:50 PM

That Video is SO COOL!

Just awesome how it can do that!

Thank you for showing…

How did you define your 3D source?

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: ... My Small Gallery:

View GaryK's profile


10262 posts in 4961 days

#14 posted 10-20-2011 09:51 PM

Great looking video!

What kind of wood is that?

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View SPalm's profile


5337 posts in 4855 days

#15 posted 10-20-2011 10:15 PM

Thanks everyone.

That V-Carve stuff always captivates me. Just when I think it screwed up, it fixes it. Like Steve Jobs said “It’s magical”. Of course when things go wrong, it can draw all over the place – with a very sharp and scary tool on expensive wood.

That video is 90% of what happens, and it is running at normal speed. Things get slower when I am hogging out a larger design. I guess that is a duh. Also I took the dust vacuum skirt off for the video.

It is Cherry wood. And there is some double sticky 3M tape underneath because I do not have any tabs. If I did not use the tape, the part would take off flying just after the final profile. And then the drill would just drill into the air. Don’t ask me how I know.


-- -- I'm no rocket surgeon

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