Hi! Sami here from CNC Router Parts. This is a Pro-Tip video about tabs,
how to place and program them into your tool path and strategic placement of
tabs regarding wood grain. Let's back up for a second. Tabs are the little bridges
that hold your final piece to the drop material. They are simple and easy to
program in Vectric's Vcarve or Aspire programs. Stay to the end for a
walkthrough on how to program settings for your tabs. This is what it'll look
like when the spindle is performing the profile cut. It's a little obscured by
the material but if we remove this you can see the full tool path operation
where the router bit will lift up to accommodate the height and width the tab.
We'll attach our material to the bed, here I'm using composite fasteners. Check
out the description below for a link to a video about this work holding
technique. I'll zero the machine to the top of the workpiece in the front left
corner using our touch plate, we also have a great video that goes into
details of using this tool as well as the fundamentals of zeroing. Then we run
our program and pull out our pieces from the material to see how grain affects
the tabs in the final product.
Here, if you watch closely you can see the spindle lift up for the tab.
Let's touch on how grain affects tabs. One should consider the grain direction in
the initial setup of your file until paths. In general, when you cut wood with
the grain it's more likely to split on the grain and cut cleanly, whereas, if you
cross cut a piece of wood it is more likely to tear out. This concept is
relevant on a much smaller scale of tabs. In order to prevent your tabs from
tearing out on the back of your piece or on the veneer consider the placement of
the tabs. Putting them perpendicular to the grain will make it so the grain goes
across the bridge rather than lengthwise with it so when you go to cut the tab
it'll split across the tab nicely. However, if you want a really strong tab
you can consider placing them parallel with the grain this will be less likely
to break out when cutting on the machine. Just take care when cutting or flush
trimming them later on. There are several ways to separate the piece from the drop
material. This might include using a mallet and
chisel which works well if you have a large sheet that's difficult to remove
from the CNC bed or you might use a small hand saw, the bandsaw or jig saw to
cut the tabs. All of these techniques work better in different circumstances
and the same goes for cleanup using a flush trim bit is a great way to remove
tabs. Though if the tab is parallel with the grain is so possibility for tear out
and you're more likely to avoid this if your tabs are parallel to the grain.
Alternatively, using a belt sander is a nice option for flat and convex curves
and it will be less likely to tear out. A spindle sander might work well for
concave curves.
Thanks everyone for watching. Stick around for the Vcarve walkthrough if you
like. We'll have more pro-tip, project and build videos coming your way soon!
See you in the shop!
This is our Vcarve walkthrough about how to place edit in program tabs. I find it
helpful to label the direction of the grain in your file to assist when
placing your tabs.
We'll go into our toolpath, scroll down to the tabs box and check the box
for "add tabs to toolpath." We have a few options at this point, we can edit the
size of the tab for the width and height. I prefer using 3d tabs for wood and wood
products. The triangular shape makes it easier to remove them from the drop
material as well as to flush trim later on. 2d tabs are slightly more difficult
to clean up but they do work really well for acrylic and tend to chip out less.
Now if we click "Edit tabs" it will bring us to this dialog box.
Now you can hover over the selected vectors with your cursor and left-click
to add tabs wherever you'd like. Or we can use the program to auto place tabs
based on a few parameters " how many tabs per vector," "distance between tabs and
start points." Click Add tabs. As you can see it's distributed them evenly but it
has put some of them in inconvenient places such as the corners of the
vectors and parallel with the grain. The auto place tab feature works ok for
primitives but you're a much better tab placer than the program. This way you can
have control over how to place them in relation to grain and the geometry of
the shape. For this first rectangle I'll place all four tabs perpendicular to the
grain this will leave a much easier to clean up edge but sufficient enough to
hold the piece in place. On the bottom rectangle I'll place two tabs parallel
with the grain which will be extremely strong but more likely to tear out later
on. I'll do the same thing for placing tabs on the top and bottom circle the
bubble design while an odd shape has surfaces on the top and bottom of the
design that will likely clean up easily. Now we're faced with a little bit of a
challenge as we look at the zigzag shape. The grain is at an angle but generally
closer to parallel on all edges of the part. Looks like we don't have too many
options here so we'll just have to take care when removing this piece from the
drop material.
Now you might imagine that it's a little frustrating to have to add tabs to every
individual vector. If you're making an array or several copies of an object
consider creating a tool path of that vector and then calculate.
Then make copies of that vector when you reopen the toolpath and select those
vectors you won't have to replace the tabs on the vectors.
I call this tab memory.
Depending on the size of the object two to four tabs is generally a
good ballpark, however, I would add more if it's a complex object. In regards to
size of tabs smaller tabs are easier to release later on but a little bit more
risky because they could break out and get caught up in the spindle. When
programming multiple profile paths or tool paths that are overlapping
they will not recognize tabs that are on other vectors so you must align the tabs
on the two vectors to preserve them. Or one tab on the drop material between the
objects rather than tabbing the objects to one another.
Preview the toolpath in the 3d rendering in order to catch these mistakes.
Thanks everyone for watching, we have a couple more great videos coming out in
the next few weeks so stay tuned and I look forward to seeing you in the shop!