I will be recutting my 3d eagle once again using Basswood versus the Red Oak I have used to date.
For a rough cut leaving .005, I am using a #201 1/4 end mill and a 1/4 extended Jenny end mill with a Fusion 360 Adaptive clearing.
!/4 Jenny is using 13000k rpm, .080 stepover, .125 doc , 80 ipm #201 is using 18000k rpm, .080 stepover, .125 doc , 70 ipm
Why are they different ? IDK, lack of talent. The chips looked ok. I think the Jenny was chunkier.
The Janka value for Basswood is 410 and the Red Oak is 1220.
How to guesstimate a change is which parameter ? Feed rate ?
I’d say that you can push the extended Jenny more than what Cadence has in their guidelines. But also remember that’s a very long tool. You will need to keep an eye on it as can be prone to being pulled out when pushed too hard.
Usual preface, I’m with PreciseBits so while I try to only post general information take everything I say with the understanding that I have a bias.
The reason they look “chunkier” is that it’s a larger chipload. To get chipload: Feed / RPM / Flutes. So the chipload for the Jenny is 0.0030" and the 201 is 0.0019". Both are extremely conservative though that’s probably more needed on the Jenny (See below).
Short version of chipload if you are unaware. It’s the widest part of a chip made per flute per rotation. Or another way to think of it is it’s how far the tool is moving “forward” per flute per rotation. This is probably the most important cutting factor. It’s a big part of determining cutting forces on top of there being a minimum needed for each material and tool geometry combination to actually cut and not rub (using the tool as glorified sandpaper).
Be careful with extended cut/reach tooling (I say this working for a company that makes them). The longer that gets the less rigid the tooling and more likely that it will flex/chatter during the cut. I’m going to use these 2 as an example The 201 has 0.75" cutting length and making some assumptions let’s say that we can choke it up in the collet to leave only 1" of stickout (amount of the tool “sticking out” of the collet). The extended Jenny is 1.5" of cutting length and necked back to 2". So the shortest stickout we can get is 2".
If we model that in a decent carbide this means that the 201 with 1" of stickout will take ~25lbs to deflect 0.001". The Jenny with the longer cutting flutes and 2" of stickout will take ~2.8lbs to deflect the same 0.001". Functionally this means that the extended tooling will start to chatter at much lower chiploads (feed). Again this is modeling like for like other than the length of cut, neck and stickout. Real world will be different from carbide grade and other features. General rule of thumb, every part of a tool will be used, either for or against you. So don’t buy features you don’t need. That being said, it sounds like you need it for part of the cut.
This works for like grain structure and mineral integration. In this case they are not the same but actually even easier going to the basswood. This is also mostly accounting for cutting forces as that is typically the limit you will reach first. In some cases though if you are moving to extremely fragile material you can instead hit a point where you will get tear out due to the material not being able to resist the cutting forces.
I’d say in general you can go a lot faster. However, there’s a couple caveats in there. First, as previously stated you may reach a point of material failure before machine or tool failure. The other is that this all comes down to chipload, stepover, and pass depth. Functionally those are what determine the forces on the tool, material, and machine. Those can get tricky with adaptive as it will often end up with deeper cuts with smaller stepovers. This starts to get complicated with stepovers less than 50% of the tool diameter as this causes you to actually cut a smaller chipload than you think. How much depends on how much less than 50% you are going. No simple answer to this other than either testing or a lot of math.
Hope that’s useful. Let me know if there’s something I can expand on or help with.
Short version. There’s a side and either lifting or pressing force (up vs down cut). The tools contact points will try to cleave/cut a chip. If the force on the contact point(s) is great enough the material behind it will fail and “rip out” instead of “cutting” at the contact point. It can happen on any helix type (flute twist). But is most commonly seen on the top surface with an up-cut. A lot of this also depends not just on chipload and surface speed (feed and speed) but tool geometry (rake, relief, edge radius, etc.).
For quick stuff I use Millalyzer (Link). It’s decent in like for like comparisons, easy to setup, and fairly accessible to most. It’s doesn’t even come close to covering everything. But nothing for less than a small mortgage does. It’s still a good and useful tool for some starting points or to better one’s understanding of cutting forces and dynamics.
Let me know if there’s something I can help with.
I ran the Jenny at the same rate. I ran the #201 at 150% and it looks good.
I was going to increase the DOC, but the part has a lot of small peaks that break off if I have too deep a DOC.
I shorten the Length under collet and most chatter went away ( my ears appreciated that).