WillAdams
April 26, 2025, 2:37pm
13
For a CNC, it is usual to cut in multiple passes — remember you’re using a tool which doesn’t have positional feedback — each time it tries to make a motion you have to ensure that the forces involved are such that the machine will be able to make the step with essentially absolute certainty.
Where possible avoid slotting and add geometry and cut as a pocket
While cutting up vacuum extension wands for this is expedient, it’s a bit problematic given that Shop Vac recently filed for bankruptcy, was bought at the last minute, and production hasn’t caught up.
I need a receptacle for the Sweepy 2.0 dust fitting — one option would be to purchase one from Woodcraft, but Carbide 3D sells blocks of HDPE:
which looks to be just barely big enough for things to fit.
Measuring the hose fitting I get a diameter of ~63.5mm — offsetting that twice we arrive at…
and/or
One technique which is often suggested to avoid slotting is to add geometry around a part which one wishes to cut out and cut as a pocket down to tab depth — here’s one technique for that.
In this case, the project is a bevel gauge which will be cut out of 0.0625" (~1.5mm) thick aluminum:
[bevelgauge]
Due to the narrowness of the angles, an 0.03125" endmill has to be used, so after importing and scaling the file (we will be cutting out one which is 3") we select the perimeter and offset it tw…
and consider leaving a roughing clearance and taking a finishing pass.
One which has a cutting flute length equal to or greater than the thickness of the stock — pretty much any tool should work.
Big thing is the toolpaths — if cutting out, rather than just cutting a slot:
[image]
Offset to the outside by endmill diameter plus 10% or so:
[image]
[image]
[image]
Then cut as a pocket:
[image]
down to tab height or the penultimate pass:
[image]
then move the contour down to below the pocket and start cutting at the bottom of the pocket:
[image]
and…
For an example of testing see:
I had one project take several hours to cut so I needed to see how far I could go on Feeds and Speeds to reduce the machining time.
Last night I did several tests (32 to be exact) and found that the Shapeoko Pro can actually cut walnut pretty aggressively; as long as you choose the right operation. With a 2D Adaptive toolpath, I got as high as 150 IPM (3800 mm/min) with a 1/4" depth of cut. That means the test cut finishes in less than a minute; versus just under 4 minutes for a conservative 1/…