- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Please Bring back Funcinality of Avoid Machine Surfaces
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Hi tommyscustomsho
Could you elaborate more on what you feel you can't achieve with the new machine avoid table? Which toolpaths are you using where you feel you can't reproduce old behaviour? It would be useful if you could send me an f3d file with an old toolpath and the new version after the machine avoid table was added that is different.
It sounds like you would like to select one face and set that to machine, with all other faces set to avoid. To do this, create a new face selection group in the table using the plus button, select the face to machine and set the group to machine (that should actually be the default). Then set the model in the table to avoid.
We made some changes to how machine and avoid tolerances work on some of our toolpaths, because we wanted to instate a consistent system where they work the same for all toolpaths. So there are some toolpaths where the behaviour has changed by design. It would be useful to know which ones you are having problems with and see the specific examples.
All the best,
Tessa Colledge

Tessa Colledge
Senior Software Engineer
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Old way pick these surfaces and boom off to the races it would only machine these surfaces by picking only these 3 surfaces. (Parallel,Scallop, Steep and shallow all use to work very well)
New way Result next photo
Here picking avoid surfaces
Here's result we never use to get the waterfall now we have to use slope and trim toolpaths
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Yes, it is more work up front as it works more like other software so you can have multiple surfaces with different amounts of stock to leave in the same toolpath. When you create the toolpath and go to the touch avoid part just right click on it and edit it to red(avoid) now create hit the plus and pick the surfaces you want to cut(green). I attached a simple sample
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Yes PowerMill has had that feature that you are talking about and it is bulky just like Fusion's version now, can it be separated out so we can get the original functualy back? I do not think Fusion realizes how valuable its original functionality has been. Working on complex molds and having to only pick a few surfaces makes calculating times go fast..
Your Fusion is updated beyond publics versions for download (See photo)
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Change the whole model to check and a second group of what you wanted to cut.
Fusion had always checked against the whole part in the setup just in the background unless you checked the model
checkbox and told it to ignore setup model. at that point you better use containment and watch lead-ins
or it can violate neighboring surfaces.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Thanks for the further details tommyscustomsho
I am still concerned that I don't understand the 'waterfall' effect you are seeing in the toolpath. If you could send me the f3d, we could check whether this difference in toolpath behaviour is by design, or if it is a bug.

Tessa Colledge
Senior Software Engineer
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Hello Thank you for the reply. Here is the link https://a360.co/48Lo3us . I do understand to pick entire model the link here is just a simple slide entire model is picked to Avoid Surface (Red) and the (Green) is Set to "machine surface" and we end up with toolpath waterfalling over edges even with "Contact point Boundary and Contact only" Checked and also unchecked either way tool path still falls over this stands true for all other 3d toolpaths now. If you guys have access to the old way please pull this slide in and program a parallel pick machine surface and you will see the results.
One other thing to consider is this is just a simple slide. When programming large molds such as large headlight lenses with many many multi faceted surfaces each time you are picking the entire model to add to a toolpath we are slowing processing time down.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
I see steep and shallow works the best but you are right it shouldn't be rolling those corners. The other thing I noticed is what happened to tangential extension for parallel and contour
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
So if you look you will see it happens in the rest of the 3d toolpaths with the Avoid and machine surfaces.
One other thing to consider is that we struggled in Powermill that does the same thing, One toolpath leaving more stock in one area then another. When an employee calls in sick or moves on to another shop or has a bad memory it is hard to find out what material is where and how much, so instead of copying Powermill come up with a much improved solution. So I only ask that we keep what really works well. I can't stress enough Fusion 360 is an absolutely awesome software with great feedback and solutions.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Hi tommyscustomshop,
Having taken a closer look at the file, another colleague and myself both believe the heart of this problem is that a change was made to allow the toolpath to 'touch' an avoid surface with a clearance of 0 on it. This can have the undesirable consequence that on vertical walls in 3-axis, the toolpath sometimes spills over. However, unfortunately, if we return to the previous way of internally defining a small avoid tolerance, there are other common and fairly simple cases that go wrong. We do not yet have a solution that solves both cases.
To overcome the waterfall effect, add a tolerance or fraction of tolerance sized avoid clearance on your model surfaces. Adding 0.0002 inch avoid clearance gave me the following result.
I hope this helps you overcome some of these challenges. We have taken notice of the fact that you find the waterfall on vertical walls problem significant, and that the lack of a simple workflow to select a small number of machine surfaces is undesirable. We generally allow feedback like this to direct our decision making processes, so thank you for engaging with us.
All the best,
Tessa Colledge

Tessa Colledge
Senior Software Engineer
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Hello, so when we add .0002 or even .0001 this is what happens the tool rises off the surface as seen in photo (This part is just an example) For some people this will not be an issue But in building silicon mold our vent depth is .0002 so you see this is an issue. Is there a way for me to roll Fusion back to previous version?
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Hello dames123
The whole point of this feature is not to have to pick or build boundaries when Fusion 360 introduced it we were excited because it was a much better way of doing this than their competitors but with this update it is a big step backwards, Boundaries limit the toolpaths in a lot of cases when dealing with many multi faceted parts the photo is just a very simple example.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
I think that was the point of the old functionality. I agree that was nice, but this new way serves many more functions, such as the ability to leave stock on one surface but not another. Perhaps they should have left both options in the software. This may be a "big step backwards" for you but not for others.
That being said, @tessa.colledge if you can fix the waterfall issue that would be amazing. This was never addressed in PowerMILL as it does the same thing.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Adding rads to rapid repositioning moves would be amazing.
- Apple M1 Max rMBP A2485 // Latest MacOS // Latest Fusion
- Usually working off files uploaded to Fusion as: Step, STL, SLDPRT. If it matters ask me.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
Yes Autodesk already owns PowerMill so they know what to do. We just need them to know this is a need. If they ran cnc centers day in and day out they would know how much this would benefit machining and the longevity of the machines so it is up to us to make it known.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
I will try to address multiple things here as clearly as I can:
1. tommyscustomsho
I apologise, I gave you slightly the wrong solution to reproduce old behaviour. Just add a tiny tiny radial clearance, not axial clearance to the avoid model surfaces. It should work with a very small value, and if it's only radial, the passes shouldn't lift off of the surface the way you describe.
2. dames123: Perhaps they should have left both options in the software
We are realising that we underestimated the impact the total change would have on customers. We are working with a workflow designer to see how we can improve things in this area, but we can't make any promises at this stage. We are aware of the issue of not having a simple workflow anymore and will try to address it.
3. tommyscustomsho
I started my career as a programmer on powermill toolpath algorithms, so yes this is familiar territory :-). Unfortunately, this is a case where tuning things in one direction causes the waterfall problem and tuning them away from that causes surfaces to not be fully machined in other common cases. You probably agree that is not a good situation to be in. It is one thing having to trim the toolpath away, but when the toolpath falls just short of the edge of the surface, it is fairly useless. If we knew how to tune things to prevent both problems occuring, we would certainly do that.
4. tommyscustomsho
We actually have a machine shop on our site, which has done commercial consulting work for decades, using our software in all sorts of industries. Lately it has reduced the consulting work and is focussing heavily on testing the software. The machininsts have decades of experience, which we can leverage to make the software better. Unfortunately, the toolpath algorithms have to serve customers doing every different geometry under the sun, and sometimes we hit problems that are very difficult to resolve. In this case, solving the waterfall problem causes another worse one and we can't see right now how to fix things so that both go away at the same time. We are still thinking though, and your feedback is immensely valuable to us. If many people report a problem, we will put more resource towards finding a solution, so thanks again for speaking up.
All the best,
Tessa

Tessa Colledge
Senior Software Engineer
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report
tuning them away from that causes surfaces to not be fully machined in other common cases.
Just reduce the size of those rads in those areas or omit them where needed? This wasn't an issue with PowerMill but is with Fusion?
- Apple M1 Max rMBP A2485 // Latest MacOS // Latest Fusion
- Usually working off files uploaded to Fusion as: Step, STL, SLDPRT. If it matters ask me.
Fusion