Waiting on the Half-Moons

The Upper angle blade and the half-moons

Progress is halted on machining the angle mounts, because I don’t believe the blade and the half-moons match.

The half moons (see this video for visuals) are what push against the upper angle blade. They allow it to rotate throughout the cut to compensate for the rotation of the upper arm. This allows the blade to be parallel to the angle being sheared at all times during the cut.

The angle blade assembly for a smaller Piranha machine

From the video linked above, you can see that in the Piranha version (this is for a smaller machine), the half moons are only slightly shorter than the blade itself. This means the force is being distributed throughout most of the blade.

With the ones I got sent from Piranha, the half moons are much smaller in comparison with the blade, and they are thinner as well.

Side view of the half-moons and the angle blade

It would make sense for them to be the same thickness, and closer to the same overall length. My solution is to order the Half-Moon’s for the next size up machine.

There is a chance that the blade I was sent from the blade manufacturer was the wrong dimensions. The other possibility is that Piranha sent me the wrong parts. They sent me the wrong parts initially, but I caught it on the invoice, and was able to return them. They supposedly sent me the new ones, which I received last week, but I still believe they are the wrong size.

On the new invoice, it says the part is the “P-70/P-90 Angle Knife Block”. This would imply that the P-70 uses the same part. However, the capacity on the P70 is only for 5x5x1/2″ angle, whereas the capacity for the P90 is 6x6x5/8″. A piranha representative informed me that the P90 does have a larger blade. So, it follows that the P90 would have a different set of Half-Moons.

Also, the P90 and the P120 have the same angle capacity, so it would make sense for them to have the same half-moons.

So, I will order the parts for the P120 and suck up the $100 it will cost.

If the part is the same size, I will assume it is the correct size and machine it for the smaller half moons. If not, I’ll sure be glad I ordered the new ones!

If the moons are too small, what could happen is it could compress the part of the upper arm which pushes on it, loosening up the mechanism.

I had initially planned on finishing all the machining on the upper arm in San Diego, but now will finish in Missouri.


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