3D Roughing Toolpaths

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_O_blvn
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3D Roughing Toolpaths

Post by _O_blvn »

Hi all, I'm in the process of working through a two-sided 3D machining job and am having a little difficulty with roughing toolpaths and machine time. Simply put I am machining a curved oval leg for a stool with a tenon on it. My biggest issue with the roughing toolpath is the toolpath options, I really wish there was an offset option for roughing toolpaths because using the raster option with an initial pass in use I essentially clear the pocket with just the profile but the tool goes on to very annoyingly make very short raster passes that are simply just cutting air. Also for some unknown reason the roughing toolpath also on cut to a depth of essentially 9/16" when the full depth needed to be closer to 1" so my smoothing pass had to do quite a bit of extra work, fortunately the bit was still large enough to not be broken but the heavier pass depth. The specs of this job are a 1.75" blank with a model of roughly 1-5/8" centered in the stock. two-sided machining option with an overcut depth of 1/8". My roughing tool is a 1/2" endmill with 0.25 boundary offset using the selected model level. My smoothing bit is a 3/8" ballnose with a 3/16" boundary offset using the selected model level.

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Rcnewcomb
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Re: 3D Roughing Toolpaths

Post by Rcnewcomb »

_O_blvn wrote:
Mon Aug 22, 2022 4:46 pm
My roughing tool is a 1/2" endmill with 0.25 boundary offset using the selected model level.
You may need to increase the offset by a little more.

From the 3D Rough Help Page:
Boundary Offset
If you are machining a raised object, often the tool will not fully machine down the edge. This field is used to specify an offset to the selected machining boundary to increase its size to allow the tool to go past the actual edge if needed.

Note
The tool tip (rather than the cutting side) will not leave the machining boundary. This is to help ensure that roughing removes enough material on machining boundaries.
- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop

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adze_cnc
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Re: 3D Roughing Toolpaths

Post by adze_cnc »

 
A couple of things to remember about Cut3D:
  1. The “Machining Margins Around Model” can be set so that the margins exceed the material size. This is useful in that the software will think that it can cut deeper at those parts of the model where the model size is close to the material size (i.e. the software I’ve got this 1/2” bit but since the model is 1.625” at this point an the material boundary is at 1.75” I can’t get in there)
  2. For z-level roughing toolpaths if the amount of material remaining in the Z is less than the pass depth of the tool it won’t cut it. e.g. tool pass depth 3/8” and amount to cut 5/16” it won’t make the cut.

_O_blvn
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Re: 3D Roughing Toolpaths

Post by _O_blvn »

My apologies, I ended up being able to troubleshoot the issue with the depth, I think it just ended up being that my tools diameter reached my machining offset limit and its maximum cut depth within that boundary limit around that 1/2" cut depth that I mentioned. I increased my machining boundary limit from 0.25 (half the bit diameter) to the full diameter and had no problem roughing the part do to its full depth. I also had my pass depth set to 1/16" to really try to minimize the amount of material needed to be removed for my smoothing bit.

The questions that remain are as follows:

1.) Is there a faster/more efficient workflow for 3D roughing toolpaths (i.e. creating multiple roughing toolpaths, increasing the pass depth of the 1/2" bit making fewer deeper passes and then utilizing smaller bits with appropriate pass depth settings to minimize the material needed to be removed for the smoothing bit?) I want to note that even with a 1/2" bit and a 1/2" offset from my model I am at no risk of not having enough material to hold the part in place.

2.) I am still wondering about the travel of the roughing pass in and of itself. As I mentioned earlier with the profile pass running first it clears 100% of the material needed to be removed on each level but after the profile pass it continues to raster within that profile cutting nothing but air and making much smaller jerkier moves that are really unnecessary.

I've has this issue in the past and I am fairly proficient in rhino so I've actually split my model in to 1/16" layer and duplicated each border then offset them by 1/16" so I wasn't cutting in to my finished material with the roughing bit and then created 2d profile toolpaths at each vectors respected depth. It worked well, I just wish there was a better workflow to do this with a 3D model in aspire.

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Adrian
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Re: 3D Roughing Toolpaths

Post by Adrian »

You've posted in the Cut3D section and some people have replied based on that software but you say you're using Aspire?

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