Hey All! This week we have created a plants stand project to demonstrate the basics of
CNC joinery and an introduction to the design to fabrication process and
vectric software. Stay to the end for a walkthrough and VCarve and learn how we
created the vectors and tool paths for these joints. This project is a great
opportunity to focus on the design and evolution of a project rather than the
materials or the machining aspect of it. Starting with the fairly basic project
and sheet goods such as plywood is a great place for anyone to begin. This will
allow you to make several test joints and adjustments depending on the
material thickness until you get the dimensions just right. Doing a smaller
scale project and then taking those techniques on to larger builds is a
smart way to scale with less risk. For this project we decided to use a double
sided tape approach for the workholding method. Check out the description below
for a video on this. Prototyping your project before jumping into final
materials is an essential step in most projects. One has to make adjustments for
varying material thicknesses, material behavior such as plywood versus hard
wood versus soft woods. It's a great way to catch mistakes to check for the
functionality of an object as well as the aesthetic outcome. While we all love
watching the CNC run, let's focus on how the parts in the project come together.
Out of six, we have three types of parts, two of each. This is a simple design and
we have two different joints. First, we have a half lap dovetail which is a nice
alternative to the classic CNC joinery aesthetic. If we pocket both the female
and male sides of the joint to half the thickness of the material, when inserted
the surfaces should match up flush.
After a dry fit we'll apply glue and insert our piece. When you're creating
your design the trick is at the pocket in which the dovetail sets into should
be slightly larger or offset than the exterior profile cut of the dovetail.
You may or may not have to clamp this while drying depending on how tight the fit is.
We'll assemble the parts into two "H" shapes. The most important thing to
remember is to have one notch on the top side of the cross bar and have a notch
on the bottom side of the cross bar on the second "H". The second type of joint
we have is a cross lap joint with t-bone fillets. Once the dovetail lap joints are
dry you can slot these together. Depending on the snugness of the fit you
can glue this join or leave it as a modular design. After some finished
sanding I applied a few coats of wipe on poly with scotch brite in-between. This
type of joinery is easy to do and can be used in many ways in a variety of scales
on all sorts of furniture and projects. Thanks everyone for watching! We can't
wait to see how you use this technique in your own work. See you on the shop!
Welcome to our VCarve walkthrough! I'll set my material dimensions. The most important
dimension to be aware of here is the thickness of the material we recommend
you taking an accurate measurement of this when setting up your file as this will
affect the fit of your joinery. I've drawn out a dovetail shape on the ends
of the cross beams and we'll get back to this. We'd like to create two slots for
the cross lap joint. I'll make a box, the height of the box should be the
thickness of the material and the width should be half the width of the part so
that when you slot them together the heights should match up and should add
up to the total width of the part. We'll add some t-bone fillets to make sure
that the corners are cleared out. The joint would not slot together otherwise
due to the radius of the router bit. Also, for this particular joint I prefer
the t-bone over the dog bone fillets because when the parts come together
they're hidden.
Now let's talk about the dovetail you can draw the shape out, the angle does
not have to be a specific measurement. The only thing that matters is that the
pocket matches. I'll take my vector, it would be advantageous to make a copy at
this point. I'll hit "N" to turn on my nodes, I'll right-click on the corner
points to cut the vector.
After turning off node mode I can delete the extra vector then I'll go back in
with my line tool to close the shape.
These are two separate vectors so we'll join them together. Now, at the top of the
dovetail pocket we'll need to have a fill at corner clear so that the
dovetail can sit into it and not be limited by the radius of the router bit.
If we pocket the design before the fillets you can see how the part would
not fit. Let's add those T-bone fillets on the top here. We can click the
calculator to recalculate our tool paths.
Now, we can rotate this vector and reorient it where we'd like our parts
to join.
The shape is the exact profile of the shape that will fit into it. We can
offset this vector so that the parts have a little space to slot together.
We'll offset it outward, about 10 to 20 thousands of an inch usually works
fairly well though we'd recommend you do a few test fits first. We'll delete
the original. As you can see, the offset line gives us a little bit more room for
the parts fit together. Great, now let's create some tool paths. Now I'll go to my
layers tab and right click on the "half depth pocket layer" and select layer
vectors. I'll create a pocket tool path be sure to note the actual thickness
your material and adjust this number is necessary. I'll set my depth to 3/8 of an
inch about half the thickness of my material. I'd like to run all three tool
paths with the same router bit. I'll select a quarter inch end mill. I prefer
to use the offset option for pocketing odd shapes like this. Finally, I'll name
my file "pocket _halfthickness_0.25down spiral" and
calculate. Now we can select our cross lap joints and pocket those to the full depth.
We can type "Z" for cut depth and it will reference the material thickness from
the material setup. I'll use the same router bit as before and I'll rename
this pocket "full thickness_0.25down spiral"
Now, let's create the exterior profile toolpath. Same as before we can go to our
layers tab right click and select layer vectors and set the cut depth as Z
thickness. Let's select an outside of the line cut and we'll skip the tabs
because we're using double sided tape. Or add tabs if you're using an alternative
hold-down method. Check the description below for a more in-depth video on tabs.
We can calculate and preview our parts. Thanks everyone for watching! We look
forward to seeing what kinds of CNC joinery you come up with for your own
projects. Stay tuned for more videos on fabrication techniques software
tutorials projects and build videos soon.