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Weird rest machining behavior on 1/32 ball mill

Tbaker25
Advocate

Weird rest machining behavior on 1/32 ball mill

Tbaker25
Advocate
Advocate

I'm machining a mold. I have some complex forms which I'm roughing out with adaptive clearing, first 1 .5" EM, then a .25, then .125, then .03125. I'm doing rest machining for the subsequent passes. It works fine for the larger tools. But when I get down to the 1/32, it will create tool paths for all surfaces, regardless of the value in Ignore Cusps. My plan was to adaptive clearing to get down to 2 thou of stock, then do a finishing pass for a very smooth surface. But adaptive clearing wants to have that tiny bit touch every surface in my bounding area. I just want it to hit the small corners which the previous tools didn't get to.

I've tried stock from previous operations, ignore cusps from 0.005 to 0.1. Same results.

 

Is there a different way I should be approaching this problem? This tool is a mold cutting taper neck extended reach bit, 0.5" long. So the cut needs to be carefully controlled, the EM maker recoomends only 10% DOC and 10% WOC. No other path I've found offers me the control to make sure the bit never gets loaded more than that.

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Tbaker25
Advocate
Advocate

I finally got a pass to work for cleaning out the corners. I had to use a standard pocketing operation. While it can't gaurentee my WOC, I'm using a ball mill so I can controll WOC via DOC.

 

Would still appreciate input from the dev team if this is a known bug.

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Steinwerks
Mentor
Mentor

Out of curiosity, what happens if you create a 1/32 bullnose and define the corner radius so there's a .0002" flat? Not ideal perhaps, but a possible workaround with negligable consequences in terms of actual machined result.

Neal Stein

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Tbaker25
Advocate
Advocate

Thanks for the idea. Jusy tried it, still fails to detect rest areas. 

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jeff.walters
Advisor
Advisor

Can you export the file as a .f3d and send it to cam.support@autodesk.com?

Jeff Walters
Senior Support Engineer, CAM
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Tbaker25
Advocate
Advocate

Sent it. Let me know if you didn't get it.

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jeff.walters
Advisor
Advisor

Im testing it now and will let you know what i find but yes .003 stepdown is extreamly small for Adaptive. 

Jeff Walters
Senior Support Engineer, CAM
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Tbaker25
Advocate
Advocate

I'm continuing to try and refine this problem.

It seems to be mainly be an issue on a 1/32" bit, an 1/8" seems to work okay.

On the 1/32" bit: Square end mill works as advertised. Ball mill continues to mill all surfaces. If I make it a bull nose, the squarer it is, the better the rest machining works. The more rounded it is, the worse it works.

 

Another interesting bit, is that it is actually doing rest machining. It's just doing a final pass over the whole surface, rather than skipping faces which have already been properly machined. But, it doesn't, for example, try to machine the middle of the pocket half way down.

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jeff.walters
Advisor
Advisor

I let the file run and it is working but as i stated above it will take a long time. With Adaptive both 2D and 3D it’s doing basically a rest machining on each cut. That’s how it knows how to “morph” to maintain the constant tool load. And as I said above a .003 step down with the complexity of the part there will be a huge amount of tool paths. Once the actual cuts are created then the system goes back and adds the linking so once again with the amount of cut paths it will take quite a bit of time to connect them all.

 

My point being is this really isn’t a bug but a calculation speed issue that is and always will be an ongoing thing the developers are working on.

Jeff Walters
Senior Support Engineer, CAM
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Tbaker25
Advocate
Advocate

Jeff, thanks for looking into it. Here is an update:

The October 19 release greatly improved the issue. One thing this release did was remove the "disc" which was on the tool with a wider shaft. (An error I'd previously reported, thanks for getting it fixed!!)

Now, for the first time, it is properly skipping areas which don't need to be machined! So it seems to me that that display bug was playing into the issue. While that bug hasn't traditionally affected the calulcation of the toolpath, it DID affect tool holder and shaft (fail on collision, pull back tool). It appears to also have affected rest material detection.

 

Down side- it still hits a lot of areas it doesn't need to. On this picture I have it set to ignore 0.05" of cusps. It skips the steep wall area like it should, but hits the less steep areas. The previous pass left 0.001". 

Just as a point of comparison, this picture is part way through a calculation, and has linking moves set already. It seems to add them per stepdown.

 

Screen Shot 2015-10-20 at 3.14.22 PM.png

 

 

So it is now working well enough for me to use it! Yay! Thank you. I do think rest machining is not perfected yet for this size bit.

Thanks,

Tom

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Tbaker25
Advocate
Advocate
Accepted solution

Update: After that pass finished, it gave me the warning "Warning: Rest material adjustment reduced to maximum limit". So it may actually only be a few thousands, I don't know what the max is. So my previous test is not so extreme as I descibed.

Thanks,

Tom

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