Phlatboyz plugin “tab”

phlatboys tab

Here is a default tab from Phlatboyz plugin for Google Sketchup. Here I’m cutting 1/4 inch aluminum with a 1/8th inch endmill. The default tab is 1/4″. I’m supposing I need to make it wider since it seems to be all used up by the endmill. It looks like it is measured from the “outside of the endmill” rather than the “inside”.

I have been meaning to figure out how to do 2.5D with MeshCAM. Perhaps that’s worth doing instead of worrying about the phlat tabs.

Phlatboyz plugin for Sketchup: Order of cutting

I was just doing some test cutting of a new model plane design on a CNC machine.

I was having some problems because the toolpath made by the Phlatboyz is pretty efficient but it was not optimal for permitting my tabs to hold the material. I knew a different cut order would be better and I could save material and have smaller tabs.

The manual says to just group the items. It didn’t say when to group them. I tried to make groups assuming that meant I could then add the cuts to the groups in order. That didn’t work. After making all those groups, I could not add a cut.

So I added all the cuts, then added the groups. The cuts where done to each group in the order that I made the groups.


Machining an XL timing pulley

timing pulley

I made my first attempt at machining an XL pulley this morning.

I decided that a 6 inch circumference would have 60 groves since an XL timing belt is 5 groves per inch.

I divided  by pi and got 1.9099 inches for diameter.

I then drew a 1/16″ x 1/16″ square which was the right distance from the center of the pulley. This would be a grove. I then copied it to 6 degrees and then replicated it 59 times (since 360/60=6).

I drew a circle and then erased the extra lines so I was left with a circle and the groves cut in it. I changed the circle to 300 segments from the default 24 segments.

I added a circle to the middle for the bearing and then some circle to create spokes. I changed all the inner circles to 200 segments.

I set the material thickness to .125 and the mill size to 1/32 and generated the g-code using phlatboyz plugin.

timing belt

The g-code came out to 7 Megs! It took about 5 minutes for it to load in Mach 3.

I used too many passes as it took about an hour to cut. I’ll know next time.

Also, I made the mistake of using the diameter as the radius so it came out twice as big.

I measured the bearing OD and got 1.255″. So that’s 1 1/4″. I made the center hole radius 5/8″ which is half that. The actual hole measures 1.245″ so it’s a little small.

The grooves are also a little small. I found a real sketchup of an XL timing pulley. I’ll open it up and steal the grove profile.

I was doing some research and lots of people are using a 4th axis for cutting gears and pulleys.