Bug: "Flute" vs "Shoulder" misrepresented in simulation and warnings.

[Sales6QKF5]

TL:DR public service announcement for CAM programmers: FLUTE setup is meaningless, only SHOULDER length actually matters... even if the tool has no shoulder. 

I just experienced a rather significant bug that could have at best broke a tool or at worst ruined a very large and expensive part. Thankfully, I was cutting model board (a hard foam) with a large diameter tool, so it "squished" sufficiently to avoid disaster. Regardless, this should be fixed.

In simulation there are "flute" and "shaft" display options for the tool. However, this is NOT displaying the flute, it is displaying the shoulder. It is also using the shoulder and not the flute for warning calculations. 

This screenshot shows a 1/2" ballnose with 3.5" of stickout and a 1.5" flute. It's currently buried well over 1.5" and cutting with no warnings shown. (the few warnings down there are the "rapid collision with stock" issue on some toolpaths that has been reported for years and never fixed)

Note that "flute" display is selected, but it is showing the entire tool per the "shoulder" length in tool setup. 

Since this tool doesn't have a shoulder stepdown it was entered the same as stickout. However, it seems Fusion ignores flute for everything and ONLY using the shoulder value for calculations and simulation.

Here is the same thing again, but with shoulder length set to 1.5", same as flute. 

Note this contour has LOTS of warnings for shaft collision. Also, "flute" is displaying correctly. 

If I change it to "shaft" that also displays correctly. 

Shoulder should only be relevant if you actually have a shoulder. If I have a 3/16 end mill with a 1/4 shaft then I want to know if that has a collision where it changes diameter. But that is a fairly rare case whereas flute is ALWAYS important. 

If this is intentional behavior and you want shoulder to be used for everything, then at a minimum the language needs to be corrected on the tool setup page, the simulation page, and the corresponding mouseover tool tips.

[engineguy]

@Sales6QKF5 

Hmmm, IMHO it is the correct behaviour and likely intended, the selection of Holder/Shaft/Flute in the Simulation is only for viewing these things and has nothing to do with the dimensions that determine whether there is going to be a collision or not 🙂

I would not expect any warnings/collisions from the Flute length setting for the tool as that is what is supposed to be in contact with the material, I would expect the Shoulder length to be relevant whether there is actually a physical Shoulder (Change of Diameter) or just the point at which the Flute ends in which case the values for these would be the same and there would then be a Collision of the shaft rubbing against the material, if there is no change of Diameter between the Flute and Shoulder then I would normally set them to the same value so that it would show as a Collision in the Simulation, I can`t get it wrong then, I would be looking to set the Shaft values under the Shaft tab 🙂

If you turn the Tool off completely in the Simulation so that there is no selection of Holder/Shaft/Flute available the collisions still show in the timeline so that says to me that what you are referring to is not a bug but the correct, intended behaviour as Fusion is using the Tool information that has been input for the Tool and not the "viewing" selection.

Again, IMHO no "bug" and no confusion that I can see, very logical 🙂

[Sales6QKF5]

I agree with everything you said, but you may have misunderstood my post. The collision calculation is ONLY using shoulder length. Period.

So if you set shoulder and flute the same then you are correct, it will show collisions properly. However, there should really be two collision calculations going on. One collision calc is if there is a true shoulder, like the 3/16 end mill with a 1/4" shaft example I mentioned. The other is if the tool is cutting where no flute exists.

As shown in my screenshots, ONLY shoulder length is used. So in my example 360 was happily cutting material well beyond (over 1/2" of solid shaft) where the flute stopped without any warnings. The noise alerted me to this and the only reason I didn't ruin the part and break the $200 carbide tool was because it was foam.

So yes, setting flute and shoulder to the same value functions as a work-around. But if they aren't going to calculate shoulder and flute collisions as the separate things that they are, then at a minimum they need to state this in the setup tool tip so that users know flute is irrelevant and shoulder is critical.

[engineguy]

@Sales6QKF5

Nope, IMHO it is correct, if I have a tool in my hand that has no actual change in diameter then at the point where the flute stops and the smooth area starts that is the "Shoulder" height and using that method (Which is what I am supposed to do) means that I would never be toolpathing something that would have the Flute going deeper than it should, it would show immediately in the Simulation as the Red lines at the bottom.

I don`t even have to try and measure it as the tool Manufacturer gives me that value in their dimensions/specifications.

With respect, every machine owner/operator that I have known in many years knows from either their Apprenticeship or On Site Training that the end of the Flute (In other words the Shoulder) that is as deep as you can go so that is what is selected, it is the sort of thing that is "Hammered" into a trainee from "day one" or should be 🙂

The other thing that is calculated is the "Length below Holder" which also is not dependant on the "Viewing" selection in the Simulation.

I am afraid that it is just automatic for me to use the Tool Manufacturers Specifications when creating a tool in Fusion, if I want to create a visual representation of the tool with an actual physical difference in Diameter then I do that in the "Shaft" area but the selection remains the same for the "Shoulder" as the Flute. There may be times where some material has already been removed and the next tool needs to be close to a wall and is going deeper than the Flute of the first tool then the difference in Diameter comes into "play" where it will show correctly any collisions due to the difference in Diameter 🙂

I even use the values supplied to me by the Company that I use for "re-grinds" for the new Diameter/Flute Length, yes I do trust them but I still double check 🙂 🙂

I am not an Autodesk Employee so unfortunately I am not able to apologise on their behalf, hopefully someone from Autodesk will jump in and do a better explanation for you that will help with any confusion you may have 🙂

Yes, maybe the option to set the Shoulder in the same area as the Flute Length should be removed and only be done in the "Shaft" area, that may be easier for someone coming into CAM/CNC Machining that has little/or no Formal Training, nothing wrong with being "self taught" though, it is usually just harder 🙂

[Sales6QKF5]

Again, I still agree with you in every way. There is still a misleading "flute" entry in tool setup that does nothing and will break collision warnings.

The idea of "anyone trained will know...." viewpoint is true. But consider the audience here. Most "professional" machinists I know doing CAM work are using mastercam, not 360. However, I would bet that a huge portion of 360 users, if not the majority of 360 users doing CAM, do NOT have formal training and are likely to mess this up.

I fall into that latter category as a "do everything" small business owner with CAM programming as one of many tasks I handle. If I see two separate entries in setup for shoulder and flute then I am going to automatically assume that the software is figuring cut area for flute and a step out area for shoulder. It is not doing that.

Bottom line, 360 is very clearly not generating warnings for something that will unquestionably break tools. That said, it appears that no one from Autodesk is paying attention and I should probably stop wasting my precious time putting these posts together.

[engineguy]

@Sales6QKF5

Sadly it would seem that my poor attempts at an explanation don`t work, you need to stop assuming that a shoulder is physically sticking out, if I have a straight tool that is the same diameter for all it`s length why would I then "make up" a dimension that is different to the Flute length for a "Shoulder" that doesn`t exist, not logical at all.

As previously explained, if you want a Tool to show an actual diferent diameter "Shoulder" then do that at the "Shaft" tab.

Just because something doesn`t "suit" a particular persons idea of how that person thinks it should be doesn`t make it wrong, everyone is different (Vive la Difference) but no one can make a "one size fits all" software, many thousands of users do not seem to have an issue with this 🙂

Apologies but I do not know how to explain it any better !!

If you look at the lower Right corner of your Screen in Fusion you should see a very small Autodesk Icon, clicking on that will get you the Option to "Chat with an Agent" directly at Autodesk Support 🙂

[Sales6QKF5]

[engineguy]

@Sales6QKF5 

Yep, that confirms it, the key part of the descriptions that applies is the "cutting edge of the tool" so Fusion is correct, it is only your interpretation of things.

The chart only applies to tooling with an actual Shoulder, if there is not one then how could you set a value that is different to the Flute (Cutting Edge) length, eg, cutting edge is 20mm and the tool is same diameter for it`s length why would anyone input say 25mm for the shoulder value, doesn`t make any sense 🙂

In Fusion if there is a physical shoulder then set it in the Shaft section 🙂

So, Yes, OK, to some it may seem confusing but it is quite easy once the user gets used to the way Fusion does it, no one is saying that Fusion is the greatest thing going but if you don`t like it then go try the Demo of  MasterCAM and you will just have to learn a different method of setting up tools and if you like it then go for the Bank Loan/Re- Mortgage needed by a "one man band" to have it 🙂 🙂

[Sales6QKF5]

I have truly tried, but I do not understand how "length above the cutting edge of the tool" means "if this field doesn't match flute length value we won't warn you about crashes and you'll break tools". I know you're trying to help just as I was trying to help by posting this and I'm really glad this makes perfect sense to you.

[engineguy]

@Sales6QKF5 

Just out of interest here are three Tool Creation methods of three different softwares, Fusion 360, MasterCAM and BobCAD-CAM, you can see that one of them does not have a selection for the Shoulder, the two that are the same are Fusion and MasterCAM 🙂

Fusion

MasterCAM

BobCAD