‘Blended’ spline pattern, how to achieve?

[Carbonwerkes]

Howdy

 

Im looking for a way to create a spline pattern. A simple example would be an hourglass, where I would define the outer two splines, and then some mechanism/function would allow me to define the number of splines which would fill that space between the non-parallel lines, with splines that follow the pattern as equal-spaced at any cross-section along the length of the boundary.

 

For people familiar with aero, this would be called streamtubes. Here is a basic example:

I know of one way to do this, which is a huge hassle. Effectively, you take a pair of splines, and create a Blend toolpath, defining tool and stepover to achieve the number of lines you want. Then you backplot that, save the backplot data to a level, then manually edit the plot as required (kill the leadin/out, etc), and then manually convert each path from arcs to a spline.

What I want to know is- is there any native function in MC that can do this with just a couple of splines as the outer boundaries, where it then it generates ‘n’ number of splines which fill that space?

Seems like all the native Curve stuff (Flowline etc) generates just pure parallel line, not the blended style of splines Im after.

This is for patterning- so the resulting splines will be used to project onto a surface etc, but I want to be able to tweak the shape around so the pattern matches the shape of the body in a visually-appealing way. Maybe there is a Chook I don’t know about which will do this?

 

Best

 

[Zaffin_D]

Draw your two outer splines, then create a lofted surface between them. 

With that done, create a curve flowline; that should give you what your after.

[jlw™]

You beat me to it Jeff.  I've actually done that then surface finish projected where I couldn't get blend to work out.

[Carbonwerkes]

Hey guys-

Thanks! I would swear to you that I tried that first thing- and what I saw was just parallel lines which stopped/started at the boundaries as appropriate. But, it is possible there was some other factor in play- as this works exactly as you describe. So- thank you again. I have no idea what was going on with my machine (or my brain!) earlier…

Hope you enjoy the rest of your weekend-

Best

R

[Aaron Eberhard]

The key (which is only obvious in hindsight) is to create a Lofted surface, NOT a Flat Boundary surface.  If you do a Flat Boundary there, it'll create a square surface and "cut" it out at the splines.  The surface UV lines are still going left-right in that scenario, meaning that the curves that follow it will also be parallel.    When you create a Loft, it's creating a surface that stretches from one spline to the other, so the UVs are going to be a transition as well.   You can see this if you switch to wireframe mode after you create the surface.

[Carbonwerkes]

Hi Aaron

That may well be what the problem was. I dont think I used a flat boundary, but it is possible- as it was late The process is working now, but I have a toolpath that wants to drag the cutter across the surface for a couple of repositions. If it were easy, everyone would do it lol.

Incidentally, is there any provision in MC's CAD functionality to permit linkage between steps in a process like this? Practical example- I use SW for CAD, and in this context, altering the spline boundary would alter the loft- which would make tweaking a pattern for projection easier/much faster. Seems like in MC every operation is independent, to the extent that I dont know if I can even resize a rectangle via a drag op or via dimensioning (stretch may work, but that seems sort of absurd, especially if you are just dragging a point in a 6-sided object around for positioning. A rectangle seems to become just 4 lines on a plane, with no relationships established. Im sure my understanding of MC's CAD is as near 0% as you can get, but I have never seen an actual CAD system where a rectangle doesnt retain its basic relationships.

Best

 

[JParis]

11 hours ago, Carbonwerkes said:

CAD system

Right there is your misconception...

[JParis]

Don't get me wrong, there is a lot you can do within the CAD abilities of Mastercam but it is not by any stretch, a parametric modeler

[Matthew Hajicek - Singularity]

Yep, MC's CAD is non-parametric, with the exception of the solid modelling.

[Carbonwerkes]

Hey guys

So, Im having some trouble with the Multiaxis Project toolpath. I thought it was a bug in my install, but I had a buddy at work who is running 2019 (Im on 2017) redo the projection and toopath creation, and he got the same result.

The symptom is that there tends to be one or two reposition motions which should be retracts lefts as cutting passes. This is seen in the posted example here circled in red, where all the Flowline data yields sort of parallel (well, symmetrically spaced) cuts except for one pass. That pass drags along the 3D surface in a path that looks linear from the Top view- bisecting a lot of the patterned cuts. This cut is real- it shows in the sim and in Vericut.

The surface here is a handle, and it is 3D (domed a bit in both axes). The pattern is created as per the above posts suggested- and used as the Projection pattern in the Cut Pattern dialog.

Nothing I do there, or in any submenu, seems to prevent this dragging. The only thing I have found that will change it is to use ‘sort’ on the actual curves within the Projection chain manager window. Except, that yields all kinds of other problems- sometimes including multiple drags, but always a lot of rapids from retract/repositions between chains to be cut…

I would have thought this would be a Linking parameter, where something analogous to ‘keep tool down if within x distance’ was enabled. But, there is no such beast to be found, and the default links are all about gaps in the surface. Even if gaps counted as repositions for the pattern, I have this setup at retract to rapid distance and ‘use leadin/out’ for both small and large gaps- which is clearly being applied here (except sometimes!).

So, maybe this is some strange parameter, or a problem with a subsection of the Linking menu, where perhaps defaulting ‘Gaps Along Cut’ to ‘Use default links’ freaks it out…

Also, is it possible to force one-way cutting on this? I know I can set cutting side- but that seems to have everything to do with the side of the projected spline to cut. Since the system wants to alternate directions (here, in X), that ends op screwing up the pattern badly. I just want it to always cut left to right (or right to left), so that my cutter deflection is consistent- and I don’t get weird pattern changes where reversing parts of the toolpath are adjacent…

Regards,

 

 

 

 

[jlw™]

Could you just use Morph locked to 3 axis?

[Carbonwerkes]

Maybe so- I suspect there are a number of alternate paths (no pun). I just had hoped to apply this (Projection) path since it worked well for some variants of earlier patterns. It just seems a bit buggy with some patterns- where often the drag is actually a move to an end retract position. I dont know why it would complete the entire path, then drag the tool half way along the surface lengthwise to some edge position, then retract as end-of-op... I dont have any specific start/end point defined, as that wasnt needed for earlier attempts, and I dont have to navigate around a jig etc here. So, it is a littl,e bizarre that it is so intent to exit at some random edge position that it would create a path to that position (without a retraction even) following a 3D surface...

This is literally just a very simple cut, which I can run 3 or 4axis on a trunion. Neither variant changes the basic toolpath pattern; the drag of the tool remains when 4-axis is enabled...

Ill see if Morph works- I have little experience with it for this type of operation-

Best

 

 

[jlw™]

Can you share a file?  There's so many of us here with so many different points of view that some one can likely put a path on it that will be exactly what you want.  It appears as though you didn't get the exact curves you were wanting either.  I would think that blend, morph, project would all work.  I've done similar but I would like to see what you're actually after to be able to give you a good path.

[Carbonwerkes]

Sorry, I cant- it is a proprietary part/NDA. I may be able to send just a surface along with the curves Im projecting, since untrimmed it isnt that useful or indicative of what the part is. I know it is hard to diagnose based on an image, and I wish I could send the model; Im sure there are many paths possible that would work.

Where Im coming from on this is that, if I have a setup that works for the sort of simple example image above (the Venturi type thing), I was hoping that I could use that as a baseline and just focus on the curve geometry- since everything else is the same (MC is creating the projected lines on the same surface after all). I didnt want to get into a scenario where a small change required me to switch toolpaths and go through all that config headache, where there can be problems synchronizing parameter values (especially where the toolpath types use different functionality for a given result). This current approach works almost correctly- it just tends to drag the cutter for the last motion (between the final cut, and some random place it selects to retract, or between a mid-body edge and some center-dome (shallow) generated path in the pattern, where it never seems to want to just cut bottom to top etc, but always circular in groups (ie low to high, breaking that into two machining slices and then dragging the cutter between end of phase 1 and start of phase 2)...

Im going to try Morph now. I work stupid late (graveyard) hours, so I tend to rely on emails from guys on other shifts, since we are all under the same NDA for these files. But none of the few others knows much about texturing.

Thanks so much for your help jlw- I truly appreciate it. I wish I were more creative with surface texture approaches, but this one seems more like a bug than a parameter config error.

Best

 

[Carbonwerkes]

Well, blend doesnt seem to work. it doesnt want to maintain the pattern closely for whatever reason.

It does seem however the core problem with the Parallel projection pattern is related to a containment curve. By toggling that around a few times, and eventually trimming all ops except this core texturing op, the pattern compiled cleanly. Nothing had changed, so seems like a bug. Anyway- at least its not dragging the cutter diagonally across the textured surface... Not sure I can force it to cut only right to left bottom to top- maybe with manual edits to the  paths in the Chain Manager within the operation, but at least the pattern is clean. I hate intermittent bugs... Not sure if this is closed- maybe just luck for a particular projection effort. But, it seems to illustrate that it isnt a parameter config, and has more to do with a functionality with MC.

[Aaron Eberhard]

From the picture, I'd look at your linking parameters for that toolpath.   It looks like it's trying to keep down between regions.    Of course, best would be to post the toolpath, but it looks like you're not trying to contour/morph from the outer shape?  In that case, you may have better luck with a Parallel toolpath, since that will offset one shape across the whole part.

[Carbonwerkes]

Hi Aaron

I doubt it is a linking setting I control- not only have I tried basically every variant, but they are all conservative (i.e. all in testing were set to retract to rapid distance for any gap  etc). And, the fact that it works for 98% of the 50 splines that define the pattern suggests to me there is something awry. I did find that changing (removing) the 3D/2D containment did often help, but not always.

For my application, the goal is just to be able to define any sort of winding river type pattern of lines along a handle- where the inter-line gap is not fixed (i.e. it might expand out- as with a river flaring at a corner, etc). At present, the pattern is defined by 2 splines and a surface in a single plane parallel to the top plane- connected by a loft, which then serves as a surface for a wireframe->Curves->Curve Flowline path, with 50 curves defined. That is then the pattern for a Project Curves path onto a 3D surface (a surface created in MC as a create-from-solid from the imported solid- to make sure this was all native geometry).

I suspect this has something to do with the body geometry being a shallow dome, where the system determines that even a ballnose will have more engagement on the right/climb side if the body is sloping upwards on the right side of the cutter, I notice that the toolpathing is always +X to -X on the near side, and -X to +X on the far side, and that midline it zigzags. This seems to be related to the probem, because the drag tends to be related to this segmentation along the Y axis (3 regions). That is, the origin always seems to be at a transition of these regions on the -X side of the body, and exits at some max or min Y position mid X along the body.

I dont know if there is a way to just force the toolpath to always move from +X to -X for each curve in the sequence. I cant seem to force this, even by screwing around with the direction or side of the chans in the chain manager...

Any idea on if this is possible to implement in 2017?

Ill look at parallel, but I dont know if that allows me to apply a pattern which has a source component which fans outside the physical body to be cut...

Regards

 

 

[Fred @ Slate Industries]

Mc2019's new " scallop even "passes toolpath