Hey slovdahl. Sorry about the thread divergence.
Itās partially addressed in my first reply. To summarize it, tools that stick that much out of the collet have to be run less aggressively. They are like for like more prone to deflecting (bending). The only ānot likeā part I can confirm on them other than the lengths is that they are a chip broken flute. That will āreduceā āsomeā of the deflection as you are not keeping flute engagement through the whole length (depending on crossover location and chipload). But, itās not a miracle worker that lets you ignore the rest of the physics. e.g. in that other postās example, itās about 3lbf to bend the long tool 0.001" and over 13lbf for the shorter one.
If I look at the feeds and speeds listed for the regular ones in Sienciās chart, they are conservative. However, in my previous example I had to be much less aggressive to what is listed in that chart for reduced speed to keep the modeled tools deflection reasonable.
Hereās a straight comparison if it helps. Keep in mind for the below that I donāt know the geometry of either tool. Iām working off of a āgeneric geometryā and āgeneric carbide gradeā. So basically I canāt guarantee anything / use at your own risk.
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Sienci reduced feed 1/4" UC:
Feed: 1650mm/m (65IPM)
Speed: 12,000 RPM
Chipload: 0.06875mm (0.0027")
Stepover: 2.85mm (0.11") / 45%
Stepdown: 6mm (0.24")
MRR: 43.73 Ā³mm/m (1.72Ā³in/m)
Per flute MRR: 21.73Ā³mm/m (0.86Ā³in/m)
My calculation:
Feed: 1829mm/m (72IPM)
Speed: 12,000 RPM
Chipload: 0.0508mm (0.002")
Stepover: 3.175mm (.125") / 50%
Stepdown: 2.54mm (0.10")
MRR: 22.86Ā³mm/m (0.90Ā³in/m)
Per flute MRR: 7.62Ā³mm/m 0.030Ā³in/m)
If you are trying to slot with this it gets harder. Forces are functionally cubic material removed per flute per rotation. So while not technically correct, you could double the stepover (slotting) at half the pass depth. It changes some as the helix (flute twist) moves some of the force into the Z. But you are also keeping the tool engaged on the other side of the cut while slotting. You are also breaking the flute engagement with the cross cuts in the flute. So best guess, maybe only an 80-90% reduction of the pass depth.
Hope thatās useful. Let me know if thereās something I can help with. And sorry again for the thread divergence.
Edit: Forgot to mention that this is also all dependent on the material being cut. So the harder the wood the more forces. I used paper birch in the simulation.