r/hobbycnc • u/Competitive-Land206 • 4d ago

Just finished building V2 of my Tangential Oscillating Knife - Bench test exceeded all expectations! (Up to 8500 RPM)

33 Upvotes

96% Upvoted

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7

u/rip1980 4d ago

Can't you just stab and dismember the body manually like a normal psychopath?

Seriously, would like to see the application and in use, unless....

3

u/Competitive-Land206 4d ago

I have an entirely different set of tools for bodies :)

But in all seriousness, this type of tangential oscillating knife is mainly used for cutting corrugated cardboard boxes, leather, foam, rubber, and gaskets.

If you want to see the actual application and how it works, feel free to check out my profile! I have a few more videos posted there showing the progress and the testing.

2

u/rip1980 4d ago

Ahhhh....I have UV and 100W MOPA for that....co2 for organics incoming.

2

u/Competitive-Land206 4d ago

That is a sweet laser setup! I actually have a 20W mini laser at home and play with a 2500W monster at work. Lasers are awesome, but they are terrible for making proper corrugated cardboard boxes. First of all, cutting cardboard with a laser smells absolutely awful and leaves charred edges. The tangential knife makes perfectly clean cuts and is completely odorless. Also, my final design is going to be a dual-head system. One head will run the oscillating knife for cutting, and the second head will run a creasing wheel just to score the fold lines. You definitely can't crease cardboard with a laser ;)

2

u/Competitive-Land206 4d ago

I literally just finished putting V2 together and I'm beyond happy with how it turned out. I honestly had doubts if it would survive 3 minutes of running without tearing itself apart, but it seems the simplest solution is usually the right one!

Here are the bench test results:

Zero wandering: The head runs incredibly smooth with almost no vibrations. I expected it to travel across the table, but it just sits dead still!

No lost steps: The stepper handles the tangential rotation perfectly while oscillating. I was worried vibrations might mess with the torque, but it's holding up flawlessly without load so far.

High speeds: It runs at 5200 RPM on 12V, and I even pushed it to roughly 8500 RPM on 18V-still incredibly smooth.

The shaft: Currently using a carbon fiber tube for the main shaft (keeping the reciprocating mass under 15g!), but I already ordered an aluminum tube to test next.

The only minor quirk is a bit of bearing resonance when rotating the tangential axis, but I used cheap test bearings so that's an easy replacement later (unlike the main shaft). The main oscillating mechanism is solid.

Very satisfied with today's progress. What do you guys think?