Spiral Option in Scallop Strategy

[michaelmoe]

I would like to see a spiral option added to the Scallop strategy. I know that the initial though is, "Isn't that the same as Morphed Spiral?". To that, the answer is no. Morphed Spiral has the occasionally fatal flaw of not stepping over at a constant distance, or in other words, morphing. In some cases, that's great and it's the strategy to go with, but in others, it's less ideal than having a constant stepover distance such as that produced by Scallop.

If a spiral option were available in the Scallop toolpath strategy, the stepovers would remain constant as it does normally in Scallop, but with a spiral pattern to the toolpath, there are many applications where a continuous motion would produce a superior finish to the current model, which is to produce links between passes. Those links can in some cases be a visible line, like a witness line. If the pattern for Scallop were a continuous spiral, either conventional or climb milling in direction, these lines would not be produced and a higher quality finish would result. 

[michaelmoe]

Just to elaborate a little more on the idea, it would also be just as useful to modify the Morphed Spiral toolpath to have a "Suppress Morphing" feature, where the stepovers would be come a constant as they are in Scallop. This would provide the same functionality, just in a different strategy, so it really would come down to which method is easier to implement from a development standpoint.

I've provided a very basic example of the difference below. Sometimes the difference would be unnoticeable, other times there would be an even more significant benefit than this example shows. Every project is different, so more options are always better.

The first image is an example of the current "Scallop" strategy applied to a basic roundover in Fusion. The second image is an example of the current "Morphed Spiral" strategy applied to the same roundover, again in Fusion. The third image is the Bobcad equivalent to "Scallop", but they do have the option of a spiral, so that has been applied. What you will notice is that like the "Morphed Spiral" toolpath, the Bobcad toolpath maintains a continuous spiral from start to finish with no need to retract and re-engage the material, and there are no links between laps around the part, again same as Mophed Spiral. However, the difference is that like the Scallop example, the Bobcad version never steps over any more or less, the steps are always equal which should provide a very uniform finish. The Morphed Spiral example starts to spread the cuts further appart before it reaches the bottom of the roundover, or in other words "morphing". If that morphing could be supressed, and a constant stepover maintained like it is in the Bobcad example, the result will be a much more consistant toolpath for this kind of application, as well as any other application where you would prefer a spiral to links, but encounter transitions from horizontal to vertical machining areas that tend to elicit the morphing component of Morphed Spiral. Again, whether the option is generated via a modification to Morphed Spiral or Scallop, I would just like to see the ability to spiral without morphing the stepover distance, maintaining the stepover exactly the same as Scallop does. 

A quick note on the toolpaths. They were generated with the same model and the same tool. Since the tool is a ballend mill, it must travel down until the side is engaged with the bottom of the roundover, or 6.35mm past the bottom of the roundover. While the toolpath may look deeper than the roundover, the tool would not be cutting deeper than the lowest point of the roundover. I think it's pretty obvious from appearance that the sprial toolpath with constant stepover would provide the most uniform finish, while also providing a smooth operation with no need for unnecessary Z lifts. Hopefully others will agree and vote for this feature to be added!

[HughesTooling]

I think you should put this Enhancement Request on the Autodesk CAM forum as well as I guess it would be an enhancement to HSMWorks and Inventor HSM as well.

Forum Link.

Thanks Mark.

[michaelmoe]

Thanks Mark,

I'll post it over there as well. It's a feature I use a lot, but when migrating and getting used to Fusion, it seems to be a more significant missing feature to me than others. Perhaps others have never had the option available and have no reason to miss it, so it seems more like minutia in their point of view. From my point of view, it's a pretty significant difference in approach which produces superior results that you can visibly detect, so more than just minutia.

On some parts, Morphed Spiral is so close that it doesn't make any difference, but on others the morphing gets pronounced enough that it has a negative effect on the finish compared to a constant stepover, especially when it nears an outside vertical wall and start to jump around erratically instead of following a more smooth path around the geometry. A constant stepover constrains the toolpath into a smoother motion in those cases. Morphed is great on shallow areas, but flawed on heavy 3d areas.

-Mike

[Laurens-3DTechDraw]

I'm pretty sure that this is something that is being solved as wel speak.

I have no vision on ETA but there should be new version of the flow operation in HSMWorks.

[al.whatmough]

Laurens is correct.  

This is something that is beeing sovled. 

It will be based off of a new morph toolpath that can mantain a constant step-over.

[al.whatmough]

As an update, this is still in progress.  It still looks to be a few months out.

[michaelmoe]

Thanks for the update Al. Will there also be a morphing between 2 curves (drive curves) type of toolpath coming? This is another feature that I think is useful more often than not on real world parts. A "Flow" style toolpath with constant or morphing stepover options and the ability to use one or two drive curves at the users discretion would be awesome. Not sure if that's what is being worked on, but if not I'd be happy to make another request with diagrams showing the difference in approaches.

[michaelmoe]

Is there any update on this being added to the CAM? Has it already been added and I don't see the option? This is really one of the go-to operations for any mold making or similar projects and one of the things that continues to keep me from really adopting Fusion over other products. 

One of the other go-to operations is morph between 2 curves, and I'm curious if that is on the roadmap. Whether you have 3 axis or multiaxis, these features are really critical to avoiding witness lines and other ugliness. 

[michaelmoe]

Here we are near the end of April 2017 and I'm still looking for a solution to this. I still don't see it in any of the toolpaths and unless I'm blind I don't see the Flow feature added either. Will this be addressed at any point in the near future?