topic Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc in Fusion Manufacture Forum

Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

M>oolWorks — Sat, 10 Nov 2018 15:08:40 GMT

I do not have much experience in mold work, but have worked in stamping most of my life and have done some pretty complex form tools. Most of this experience, albeit limited, was on higher end machinery, like a Hermle 5ax.

Lately I have been working on some tooling for a customer, which has really given me a run for my money attempting to use Fusion. There isn't a flat or parallel side on the part (except the end), and often times it is a frustrating and time consuming guess and check process to determine what works.

This is not meant to be a comprehensive post by any means, but I just want to share a few things that I have found worked pretty well.

If you have any questions about Smoothing, this is an excellent basis to begin:

https://forums.autodesk.com/t5/fusion-360-computer-aided/understanding-smoothing/td-p/6636189

The part I am working on is a cylinder of sorts, with lots of faces, protrusions, and goofy stuff the customer dreamed up. The model would be excellent to share, because this would all be much more informational, but due to ITAR, customer requirements, and lots of other political BS, it is best left out. And honestly, tying it specifically to a model tends to change people's understanding. The few simple tips I am going to post really apply to any 3D machining.

First, Ball endmills. I see a LOT of people posting using 3D ball endmills for 3D form work. Ball endmills really are not meant to be used perpendicular to the work piece. They are common for form work, but typically in a multi axis machine. The majority of ball endmills are not center cutting, and as at center they are "not" turning, they cut poorly. Ball endmills are best utilized with a 10-20 degree angle (I usually shoot for 15). Easy to do in a 5 axis, not easy to do in a 3 axis. If your part has sloped walls, perfect! Often with 3D forms however, you will transition through many faces, and that is when issues crop up.

Bull endmills, however, are great for form work as the tool is cutting on the outside edge. Typically you can get away (sometimes!) with a bigger diameter tool, providing a more rigid cutter.

Here is what I wound up doing with my recent piece of tooling. Keep in mind, I do not have a full 4th axis, but rotate my work on a dividing head. Works the same, I program in sections, and rotate as necessary. Been doing it this way for years and started out machining manually with dividing heads. So far it has been humorous, at times, it is faster to machine a complex form manually, rather than bicker with Fusion to try and convince it to make what it views as a strange cut. (I don't think Fusion was made by those w/ "old" machining knowledge)

So here is what I found best to work out the tool. I tried many of the other 3D strategies but none seemed to efficiently work. Most of the time, they wanted to cut the part in half.

3D adaptive clearing to rough in the shape leaving .020 stock both radially and axially.

3D Contour to semi finish with a 12mm 6FL 1mm CR .005" stepdown .005 stock both radially and axially.

3D Contour to semi finish with a 12mm 6FL 1mm CR .003" stepdown .002 stock both radially and axially.

3D Contour to finish with a 6mm 6FL .5mm CR .001" stepdown stock both radially and axially.

Normally I would have prefered to finish with a fresh 12mm with 1mm CR, however due to the geometry of the tool 6mm was the largest I could use and still correctly generate some of the features.

To tie into the smoothing aspect, I ran into several issues, one a recurring one I have had with Fusion, and several new ones. The previous thread mentioned above does a great job outlining the variances in smoothing and how to shoot for a target. However, it does not provide much info for higher precision "goals". For example, on my finish pass I ran .0001 tolerance and .0004 smoothing. Which was necessary to get the finish I needed to clean up the part with minimal hand work. This was also necessary DIMENSIONALLY, as I have found the majority of the dimensional error is created out of the programming. Much of this depends on your post and your machine. Sometimes it takes a LOT of tweaking and experimentation to get dialed in.

The high tolerance also presents another problem on the machine side that you need to be cognizant of. Two fold issue really, the size of the program and the number of lines of code. They go hand in hand but they are two separate issues. If I want to mill a PRECISE 1" square, it is necessary to set both the tolerance and smoothing to an exceptionally SMALL setting, which produces an ENORMOUS amount of code, for four linear movements. This is doubly important if you want high surface finishes. My machine will for some reason, error out at 100,000 lines of code. I am working with the machine tool manufacturer to change this, but for this part, it required me to break the programs into 15 degree segments, and then work all 8 segments to blend in correctly. This is frustrating, especially with the particular segment is a linear 1" cut, swept into a radius, and about 3/4" length of cut. Fusion produces 8 lines of code to output one pass, which to me, should be 3 lines. Part of this is due to Fusion wanting a radius move at each linear segment, which you cannot seem to turn off in 3D contour. An issue in this case, because I want crisp sharp corners.

One last issue to consider when you are doing 3D surfacing. On one segment the tool nicked a corner for some reason that I could not track down, and it required re-running all 8 segments. This, to me, is frustrating, as there is no cutter comp for 3D Contour and you must manually input -.0005" into stock to leave, then repost, reload, and rerun.

Certainly don't take this as a be all end all. I have been using fusion for a little over a year. It has to be the most frustrating and irritating modeling and CAM system I have used in my career, so my hope with this post, is to pass some of that hard won knowledge onto others.

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

LibertyMachine — Sat, 10 Nov 2018 15:21:53 GMT

First off, great post. 3D Surfacing is certainly a small amount of black magic....

Second off, sorry to hear that you've found Fusion to be the most frustrating experience. It is certainly a different approach in some areas, but quite similar in others. I remember when I first started with the software, I was always comparing it to Esprit and MasterCam, pulling my hair out in frustration. Once I "forgot" everything I expected and knew, I found the learning curve to be more tolerable.

Yes, there are certainly holes in the software that we can only hope will improve by time. There IS currently an issue with Smoothing where it's less effective in some applications. The dev team is working on a fix for this.

I don't do mold work (although I'd like to take a crack at it), but I do a fair amount of 3D work to blend in radii I can't reach in another setup or similar work. I prefer ball endmills where I can IF (and that's a big IF) it doesn't involve the tip of the tool. You mentioned 10/20 degrees, and I fully agree with that. I will often get in with as large a ball endmill as possible and blend the very last bit with a bull nose tool (where it approaches being a horizontal surface)

On the clipping bit, are you on a Haas by chance?

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

M>oolWorks — Sat, 10 Nov 2018 15:51:28 GMT

Thanks.

I do not know how to best explain the majority of the frustration. It is Fusion doing completely counter intuitive actions. Like this morning I scrapped a part I was machining due to Fusions ??? I don't know what the word is. I ran the part with a -.001 stock radially and axially, changed the stock to -.002 and re ran it. The first batch of code was great. The second batch of code has a random tool movement where it plunges right into the side of the part.

Same area of frustration. I have "avoid surfaces" selected for this face... yet the faces I select to avoid, it still posts code and machines them. I tried doing the opposite, and selected "touch faces" for the faces I want machined, but then it still machines the other faces I do not want it to machine.

Really angering when I have about 8 hrs of machining already in this part, and on the finishing passes it makes a random cut like this. Changing the stock to leave offset should not drastically change the code. Again, a great place to be able to run cutter comp!

I am running a brand new Brother S1000X1

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

HughesTooling — Sat, 10 Nov 2018 15:53:32 GMT

@M&GToolWorks wrote:

So here is what I found best to work out the tool. I tried many of the other 3D strategies but none seemed to efficiently work. Most of the time, they wanted to cut the part in half.

Can you knock up a example file with this problem as it sounds like you're doing something wrong, like using model selection within an op. If you're not doing something wrong then a sample file for a bug report would be good.

It has to be the most frustrating and irritating modeling and CAM system I have used in my career, so my hope with this post, is to pass some of that hard won knowledge onto others.

What software where you using? I used to use Rhino\Visualmill then RhinoCAM and SprutCAM but would not go back. These are all lower end software, if you were using megabucks software I guess Fusion is a stepdown.

Mark

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

HughesTooling — Sat, 10 Nov 2018 16:07:03 GMT

@M&GToolWorks wrote:

Thanks.

I do not know how to best explain the majority of the frustration. It is Fusion doing completely counter intuitive actions. Like this morning I scrapped a part I was machining due to Fusions ??? I don't know what the word is. I ran the part with a -.001 stock radially and axially, changed the stock to -.002 and re ran it. The first batch of code was great. The second batch of code has a random tool movement where it plunges right into the side of the part.

Same area of frustration. I have "avoid surfaces" selected for this face... yet the faces I select to avoid, it still posts code and machines them. I tried doing the opposite, and selected "touch faces" for the faces I want machined, but then it still machines the other faces I do not want it to machine.

Yes there is a problem with negative stock and touch avoid surfaces. I've seen this a few time but always too busy at the time to report it. I've ended up not using touch\avoid and use boundaries as much as possible. If I can come up with an example file I'll make a bug report.

Mark

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

HughesTooling — Sat, 10 Nov 2018 16:08:41 GMT

@M&GToolWorks wrote:

. Again, a great place to be able to run cutter comp!

How's cutter comp going to work on with a Bull\Ball cutter on a 3d surface?

Mark

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

M>oolWorks — Sat, 10 Nov 2018 16:20:56 GMT

At some point I will put up a part that I have the issue and can give as an example. Could you expand on what you mean by "model selection within an op"? Are you not supposed to select the model in the operation? I thought that was the purpose of the model driven geometry?

I've used several in the past, the majority of my experience for modeling is Solidworks. I used HSM in solidworks and Mastercam.

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

M>oolWorks — Sat, 10 Nov 2018 16:24:26 GMT

Ha! I can't keep up, you post too fast.

I have the same problem. The part I was making this morning is due at the end of the month. I still have quite a few operations to do yet beyond the mill. When something happens like this and I wind up with a screwed up part, then I am doubly in a hurry and cannot take the time to further deal with the issue.

This time I deleted the operation because I could not get rid of the bad tool movement. Made the same operation over, with the same settings, and now the movement is not there..... ???

Similarly I often using a 3D Adaptive strategy with stock from previous operation, and Fusion does not recognize the previous operation. Delete the operation, input the same settings, and it magically recognizes. Just frustrating to have to do it multiple times, or when it just won't work at all.

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

M>oolWorks — Sat, 10 Nov 2018 16:28:04 GMT

I don't know, that's above my pay grade. How do other systems work with 3D cutter compensation?

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

HughesTooling — Sat, 10 Nov 2018 16:31:33 GMT

@M&GToolWorks wrote:

At some point I will put up a part that I have the issue and can give as an example. Could you expand on what you mean by "model selection within an op"? Are you not supposed to select the model in the operation? I thought that was the purpose of the model driven geometry?

I've used several in the past, the majority of my experience for modeling is Solidworks. I used HSM in solidworks and Mastercam.

Generally you should only use model selection within an op to add surfaces to the model selection from the setup, adding a patch to cover a hole for example. You should not just select the surface\surfaces you want to machine as the rest of the model will then be invisible to the op. I guess if you have a large model and you're only machining a small area within a boundary and you select all surfaces within the boundary you might be OK and it might speed up toolpath calculations but you'd still run the risk of a rapid going through surfaces you've not selected.

Mark

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

HughesTooling — Sat, 10 Nov 2018 16:44:13 GMT

@M&GToolWorks wrote:

I don't know, that's above my pay grade. How do other systems work with 3D cutter compensation?

I've not used\seen any software that allows cutter comp for 3d ops. I think the control would need to support it in some way as well for it to work.

There is a request on the ideastation for cutter comp with 3d contour but restricted to vertical faces only.

Mark

Re: Surface Finishing Strategies - 3D Contour - Smoothing, Tool Offsets, Etc

M>oolWorks — Tue, 13 Nov 2018 19:02:11 GMT

Not sure how it works. I ran 5-axis for some time and as I remember (it has been awhile) we could compensate length and diameter. Maybe it is my poor memory? Maybe that is not feasible with Fusion?