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Surfacing Question.


metzenwest
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Hey Everyone, first post here. I need help with a problem I'm having. Attached is a screen shot of my problem while using the Parallel Surface Finish toolpath. I keep getting these fingers that travel up in Z all over the toolpath. I have changed every setting inside the parameters without any luck of getting rid of them. I thought it was a Gap Settings issue, but I tried every setting in there yielding no results. Anyone have any suggestions? my knowledge of surfacing in mastercam is really limited to simple surfaces.

 

Thank you,

Richard Wells

post-48703-0-60068400-1397638955_thumb.png

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Hey Everyone, first post here. I need help with a problem I'm having. Attached is a screen shot of my problem while using the Parallel Surface Finish toolpath. I keep getting these fingers that travel up in Z all over the toolpath. I have changed every setting inside the parameters without any luck of getting rid of them. I thought it was a Gap Settings issue, but I tried every setting in there yielding no results. Anyone have any suggestions? my knowledge of surfacing in mastercam is really limited to simple surfaces.

 

Thank you,

Richard Wells

 

What version of Mastercam are you using? I personally tend to avoid the legacy style tool paths and would use the newer surface high speed toolpaths. I feel you have much more control over things like that. For that you could use surface high speed > raster and get basically the same path, only you would be able to select your containment areas and control the retraction factors much more finely.

 

Anyways, usually when I see that, it's a matter of the gap size being too small, and the tool retracting. Try setting your gap size to something large, like 1.000 just to see what happens. Also, if you have that boss selected as a check surface, the toolpath is looking forward and seeing it intersect, so it pulls up and over to avoid it. Try reducing the amount left on check (so the tool is allowed to get closer), or tweak your containment boundary offset so the tool stays farther away.

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Welcome to the forum, Richard! :cheers:

 

This is a fairly common occurance whenever you have vertical walls perpendicular to a surface you are trying to machine.

 

One of the great things about Mastercam is that there are always several ways to accomplish anything.

 

Both solutions above are good ones.

I tend toward Mike's solution of picking the boss surfaces as check surfaces and adding a little stock to leave.

 

A less elegant solution is to create a temporary surface over the top hole (Create>Surface>Fill Holes) then just run the finish toolpath over the entire part.

Sometimes that is easier than messing with everything else! :cheers:

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Use containment boundary around that boss. Make sure you offset the contour by 1/2 of tool diameter plus a small amount.Addition of .001 +/- usually works.

I also avoid legacy toolpaths, but they ARE still very efficient in many applications

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The boss is selected as a check surface. and i have changed the amount left form .010" to .100" to just see if it would change anything. Nothing, still have the fingers. Seems like that makes more fingers.

 

So I tried containment, With much better results. Are check surfaces broken in Mastercam? Why would a containment contour that does the Exact same thing as a check surface work?

 

Also I'm using version X7 MU2, and High Speed tools paths aren't really an option since the machines I'm programming for have VERY limited memory. There late 80's early 90's machines. so i'm usually limited to 50kb total.

 

I'll eventually get this down, not new to mastercam, just new to doing 3d work.

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The boss is selected as a check surface. and i have changed the amount left form .010" to .100" to just see if it would change anything. Nothing, still have the fingers. Seems like that makes more fingers.

 

So I tried containment, With much better results. Are check surfaces broken in Mastercam? Why would a containment contour that does the Exact same thing as a check surface work?

 

Also I'm using version X7 MU2, and High Speed tools paths aren't really an option since the machines I'm programming for have VERY limited memory. There late 80's early 90's machines. so i'm usually limited to 50kb total.

 

I'll eventually get this down, not new to mastercam, just new to doing 3d work.

 

They're not broken, they're just finicky. Check surfaces and containment are two different things, they don't do the same exact thing. Changing you containment changes the zone your tool can move within; changing the check just means the tool will stay further away. If you increase the amount left on check, you will get huge fingers because the check zone will be violating your tool path, so the tool will retract to get over it. Try making the check surface smaller (change it to zero just to visualize this.) I bet you'll see the fingers disappear.

 

The reason you have the retract amount is pretty simple: your tool is trying to follow a very linear path- back to front, move over a step, move front to back, etc. When you have geometry that isn't elementary (such as a boss with fillets) there will be parts that intrude into the tool path. Since Mastercam is trying to keep the stepover that you put it, when it encounters this intrusion, the only thing it thinks is "Oh, I've got to go around this." And the only way it can do that is to go up and over. If it tried to move left or right, it would violate your stepover amount (aka, it's not dynamic.) As you add material to leave on check, it essentially grows the size of the boss, meaning it will make even more violations into your toolpath, thus more retract amounts. Another way to visualize this is to make your stepover smaller: this will reduce the area of intrusions, and you'll likely see the retracts disappear.

 

Containment boundaries are exactly as they sound, like fences around your tool. Increasing the size of the boundary lets your tool move in more area; this means it will let more of the boss into the boundary, thus making more violations, thus more moves. Making the fence smaller exludes more of the boss, so less violations, less retracts. If you make your boundary smaller but increase stock left on check, you're defeating yourself and not making any difference.

 

Unfortunately sometimes the violations are things we can't even see. Imperfections in the solid or a mismatched fillet that is so small only a computer would think it's a problem, damaged solids, slight skewing, etc. This seems especially prevalent when you use surfaces, and not solids. I feel the legacy toolpaths are more prone to this kind of thing.

 

Using the newer high speed toolpaths shouldn't make a huge difference in program size. You can adjust your arc filter tolerance to reduce the size of the NC by huge amounts without necessarily sacrificing surface quality. Sometimes just turning the filter on will reduce the file size by half.

 

If you want to, you can upload or email your file so others can play around with it and show you good tricks to overcoming obstacles like this.

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Yes. The same way that gap settings work on the legacy toolpaths. In the HST toolpaths, on the cut parameters tab, you simply modify the "keep tool down within" value to a larger number. It all depends on which toolpath you are using, but increasing this value will keep the tool supressed to the next cut.

 

Carmen

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Yes. The same way that gap settings work on the legacy toolpaths. In the HST toolpaths, on the cut parameters tab, you simply modify the "keep tool down within" value to a larger number. It all depends on which toolpath you are using, but increasing this value will keep the tool supressed to the next cut.

 

Carmen

 

I don't use legacy paths that often.

 

Doesn't work as well as you think. I have tried to fix that as you state with

almost no difference and if you put 'keep tool down' with 100"s it basically

joins lines of path(using min distance, not vertical retract) in a non

efficient way.

 

when it wants to spike, it spikes and there isn't much of a quick setting

fix to alleviate them.

 

Its like when pencil paths that take 10mins to regenerate and they skip areas

of fillets that clearly they should not. You can spen 1/2hr regenning a few setting

tweaks then BAMMMMMM. a legacy path does it with out tweaking it.

(but you cant work while its crunching)............

 

Time is money

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Yes. The same way that gap settings work on the legacy toolpaths. In the HST toolpaths, on the cut parameters tab, you simply modify the "keep tool down within" value to a larger number. It all depends on which toolpath you are using, but increasing this value will keep the tool supressed to the next cut.

 

Carmen

No, gap setting doesn't work THAT well, if at all using HST with similar protrusions (vertical walls) as in above sample.

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There is a much easier way to solve this problem, on this particular set of geometry. Include the top surface as a Drive surface, then use the Depth Limits function to restrict where the tool can cut in Z. In the Gap settings, use a setting slightly larger than your stepover value, then in the drop-down, make sure you are set to "follow surfaces". (in Depth limits, set the min/max Z value of where you want to cut.)

 

That will eliminate the fingers.

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The key setting for me was to set the "Motion < Gap size, keep tool down" setting to "Broken", and disability the "Check gap motion for gouge". That checkbox was causing the "fingers".

 

I used the top face as a "drive" surface, but set the Depth limits to control where my tool could cut, thereby forcing the toolpath to skip that area.

 

The last (and critical!) setting was "Optimize cut order", which keeps the tool cutting in one spot until that area is finished, then prepositions to the start of the next area and begins cutting.

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  • 2 weeks later...

Thanks for all the replys and help guys. In the end I used containment to stop the fingers and it turned out well. And used High Speed Pencil to do the Radius around the Boss. I saw that one of the Samples Did a contour then surface project. That is an awesome way to do it. and seems to give more control, i will probably do that next time.

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