Projecting Path Onto 3D Model ISSUE

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Projecting Path Onto 3D Model ISSUE

Postby SceroGuitars » Tue Nov 21, 2017 1:26 am

Hey Guys,

Im having an issue with the "Projecting Path Onto 3D Model" Function -

I am trying to cut fret slots on a guitar fingerboard, with a .023 bit. I have my model (10" Radius) perfected, and am trying to cut frets slot to cut to the proper depth along the 10" radius, as opposed to just having a flat bottom the whole way across.

Doing the slots with a flat bottom, works fine. But for what ever reason, when I project the tool path onto my 3D model (10" Radius), it cuts them correctly along the radius, BUT it cuts them TOO wide. It's as if the machine is stepping over the tiniest bit each pass (takes 12 passes per slot for the .09 depth I need).

Anyone have ANY insight? I really don't want to go back to cutting them with the flat bottom pocket.
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Re: Projecting Path Onto 3D Model ISSUE

Postby Rcnewcomb » Tue Nov 21, 2017 1:56 am

Is each fret slot a single line vector, and are you using profile ON the vector for calculating the toolpath?
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Re: Projecting Path Onto 3D Model ISSUE

Postby SceroGuitars » Tue Nov 21, 2017 2:25 am

Rcnewcomb wrote:Is each fret slot a single line vector, and are you using profile ON the vector for calculating the toolpath?


Yes, exactly like you just described.
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Re: Projecting Path Onto 3D Model ISSUE

Postby SceroGuitars » Tue Nov 21, 2017 2:28 am

I "thought" it may have been a machine/stepper motor problem, but I have my machine dialed into almost .1mm. It cuts VERY accurately all the time. I'm CONVINCED its a CAD/CAM problem. Like I said, when I cut them normal, with a flat bottom pocket (no projecting onto 3D Model), it cuts to the proper width (width of the .023 bit).
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Re: Projecting Path Onto 3D Model ISSUE

Postby Rcnewcomb » Tue Nov 21, 2017 2:38 am

I'm CONVINCED its a CAD/CAM problem. Like I said, when I cut them normal, with a flat bottom pocket (no projecting onto 3D Model), it cuts to the proper width (width of the .023 bit).

An easy way to check this is to compare the G-code between the two cutting strategies. Just select a single vector (fret slot) to cut, one without projecting onto 3D, and the other projecting onto 3D.

If you wish you can put the two G-code files into a zip file and upload it here. There are a number of people on the forum who are comfortable reading G-code.

You can also mail in your files to support@vectric.com for actual support from Vectric. The forum is predominately other users, though team Vectric does drop in from time to time.
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Re: Projecting Path Onto 3D Model ISSUE

Postby sseale » Tue Nov 21, 2017 2:55 am

Maybe the resolution used when creating the model of the neck can affect the accuracy of the 'Project Path onto 3D Model' strategy? With the requirement for tight tolerances and miniature bits involved with fret slot cutting, the deviation you're seeing might be more apparent than someone cutting a large pocket or profile by projecting onto a 3d model. i.e you may be noticing something which is usually missed...
Did you use very high model resolution when the neck was created?
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Re: Projecting Path Onto 3D Model ISSUE

Postby SceroGuitars » Tue Nov 21, 2017 3:59 am

Rcnewcomb wrote:
I'm CONVINCED its a CAD/CAM problem. Like I said, when I cut them normal, with a flat bottom pocket (no projecting onto 3D Model), it cuts to the proper width (width of the .023 bit).

An easy way to check this is to compare the G-code between the two cutting strategies. Just select a single vector (fret slot) to cut, one without projecting onto 3D, and the other projecting onto 3D.

If you wish you can put the two G-code files into a zip file and upload it here. There are a number of people on the forum who are comfortable reading G-code.

You can also mail in your files to support@vectric.com for actual support from Vectric. The forum is predominately other users, though team Vectric does drop in from time to time.



Here are the two files, one normal ON cut, and the other projected onto 3D Model. Let me know if this helps. TRULY appreciate your help!
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Re: Projecting Path Onto 3D Model ISSUE

Postby SceroGuitars » Tue Nov 21, 2017 4:03 am

So, I just went back and air cut the SAME radiused fret slots, closing watching the X-Axis belt/pulley (This HAD to be the axis that was moving to make em wider), and it did not budge. Almost makes me wonder if the machine was was rattling/moving my wood around during each cut? I "did" cut them after the profile was cut (being held on by 5 tabs), which I normally don't do. . . but ONLY did so I could make sure the depth at the ends was deep enough. Maybe this could be why?
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Re: Projecting Path Onto 3D Model ISSUE

Postby IslaWW » Tue Nov 21, 2017 4:05 am

If the machine is stepping over with each pass there will be a stair stepped edge that will be visible. Is this the case? How wide is the finished cut?

I am sure that you are convinced that this is a CAD/CAM problem. IF so the lateral movement will show up on the toolpath preview. As would the stair steps I mention above. If the results are different on the machine than the toolpath preview shows, then it a machine issue.

The most likely cause is a loss of steps in one of the horizontal axes due to the extra power required to run, not just hold the Z. Have you attempted cutting the file at half the feedrate to see if the results change? My guess is no, because you assumed software. Like I said, its a machine issue. Yours may simply not be able to hold tolerance when 3 axes are engaged.
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Re: Projecting Path Onto 3D Model ISSUE

Postby IslaWW » Tue Nov 21, 2017 4:52 am

Let me add that the material moving in one direction would show similar results to the machine issues above.

I'm most cases, air cutting, or cutting under no load, will usually not help diagnose load created issues
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Re: Projecting Path Onto 3D Model ISSUE

Postby SceroGuitars » Tue Nov 21, 2017 5:46 am

IslaWW wrote:Let me add that the material moving in one direction would show similar results to the machine issues above.

I'm most cases, air cutting, or cutting under no load, will usually not help diagnose load created issues


Well, th I air cutting was to see for a CAD/CAM issue, which it wasn’t. I don’t doubt you are probably correct. I’m going to test cut on a piece in the morning to see if I can find the culprit. I “think”, it may actually be runout in my new MuschleChuck collet.
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Re: Projecting Path Onto 3D Model ISSUE

Postby tomgardiner » Tue Nov 21, 2017 1:49 pm

One new tool in my shop that I find very useful is a 10x magnifier I bought at Lee Valley Tools. With it I can inspect tooling and work. I think it would be valuable in this case to see if you are getting chatter or a clean cut.
I never thought I would use it because it is so small and has such a short focal length but I find I pull it out quite often.
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Re: Projecting Path Onto 3D Model ISSUE

Postby SceroGuitars » Tue Nov 21, 2017 3:49 pm

tomgardiner wrote:One new tool in my shop that I find very useful is a 10x magnifier I bought at Lee Valley Tools. With it I can inspect tooling and work. I think it would be valuable in this case to see if you are getting chatter or a clean cut.
I never thought I would use it because it is so small and has such a short focal length but I find I pull it out quite often.


Yah, that may not be a bad investment.
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