Hi all, this is Sami from Avid CNC
and this is a quick Pro-Tip video on how to run an air pass on your CNC machine.
First of all, what is an air pass? This is when you set your Z Zero
a few inches above your workpiece and then run your g-code program to preview how the
toolpath will overlap your material.
This can help you ensure that the toolpath will land
on the desired location and avoid any work holding features or knots.
We have an additional Pro-Tip video linked below demonstrating how to work around knots and clamping fixtures.
Let's attach our material to the spoil board.
I'll opt for metal fasteners as screws are super strong and ensure that my workpiece won't shift during the machining operation.
The trade-off with this work holding strategy is that if any of my screws
overlap the toolpath this will likely ruin the router bit as well as my work piece.
While I'm confident that the locations of the screws are safe,
let's run an air pass to ensure that the tool path is centered on the material.
In VCarve I have two tool paths programmed to cut this wooden dish.
This includes a pocket and a profile toolpath.
You could use these toolpaths to run your air pass but it would take quite a bit of time to run.
Instead, I'll program a second profile tool path
which is only an 1/8" deep and I'll use the same settings of the final profile tool path. This way
when we run the toolpath as an air pass it will follow the outside of the shape we're cutting
and provide us with all the information we need in a short amount of time.
We just like to ensure that we aren't colliding with any clamps,
metal fasteners, or knots in our material.
Let's export this tool path separately and name it air pass.
In Mach4 we'll go ahead and use our Auto Z Corner Finding touch plate to set our work offset.
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Great, once we've set our X, Y, and Z zero let's take a look at our Z location.
The tip of the router bit is two inches above the material surface which was our z0 reference plane.
We can type in 0 to the Z text box or click Zero Z and now we've reset our Z datum location.
The tip of the router bit is where the machine thinks the material surface is.
Then go ahead and load your air pass g-code program
We'll take a look in the g-code window. If you use the most up-to-date
If you use the most up-to-date Vectric Avid CNC post processor this will include information on machining extents.
We can see that our Z - extreme is about an 1/8"
so since we're actually two inches above our material surface we can be confident that we
won't accidentally cut into our material on the air pass
I'll leave the spindle controller turned off so that our spindle won't turn on during the program. Go ahead and click cycle start.
Great, we can re-run the air pass a few times to ensure its location or make adjustments to the toolpath if needed.
Once we're happy with the location of our part on our material
let's reset the Z offset to the material surface.
If in Mach4 our Z location now reads one inch.
We know that this is actually three inches above the material surface so you can change the one to three in the z location text box
or go ahead and use the Auto Z and corner finding touch plate to reset the Z offset.
Next, we'll turn on our spindle controller we'll load our final g-code program with the pocket and profile tool paths.
Go through the 10 step cycle start checklist and then click cycle start.
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That's all for this Pro-Tip video we've linked a few more helpful tips and processes in the description below.
Thanks, y'all for watching I can't wait to see what you make and I'll see you in the shop
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