Ballnose not cutting to depth

Ballnose not cutting to depth

Postby nickgless@gmail.com » Thu Feb 02, 2017 4:53 pm

Yesterday we experienced a challenge when cutting a pocket using the pocket toolpath using a larger area clearance tool (.5 endmill) along with a .5 ballnose to finish with a radius in the inside corner. The ballnose is not cutting to the specified depth. The endmill (clearing tool) cuts to correct depth. Aspire 8.514, WinCNC

I will try to attach photos of the setup and resulting cut.

This morning we did some testing to try and isolate the cause for the issue:

same file, same board, no clearing cut

Cut 4 pockets 1.25" in diameter at .3 deep (Z at bottom of material)
.25 endmill cut to .3
.25 ballnose cut to .28
.5 endmill cut to .3
.5 ballnose cut to .25


Repeated the test using same file and parameters cutting with the Z at the top of the material:
.5 endmill cut to .3
.5 ballnose cut to .27

Any ideas on cause/resolution?

**It has been suggested in another forum that Aspire Pocket Toolpath with large area clearing tool is only for flat cutters and cannot work with a ballnose. Is this true?
Attachments
Capture.JPG
Toolpath settings
Cut.jpg
Resulting cut
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Re: Ballnose not cutting to depth

Postby Leo » Thu Feb 02, 2017 5:51 pm

How are you touching off the cutters?
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Re: Ballnose not cutting to depth

Postby nickgless@gmail.com » Thu Feb 02, 2017 6:00 pm

Leo,
We are using the fast tool change on our Camaster. We just spoke with Vectric support and they verified our g-code is correct, so it looks like the next step is to contact Camaster.

Thanks,
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Re: Ballnose not cutting to depth

Postby dwilli9013 » Thu Feb 02, 2017 6:02 pm

nickgless@gmail.com wrote:Leo,
We are using the fast tool change on our Camaster. We just spoke with Vectric support and they verified our g-code is correct, so it looks like the next step is to contact Camaster.

Thanks,


I would check the lengths of the bits in your tool holder. Is is possible maybe one slipped? Just a thought.
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Re: Ballnose not cutting to depth

Postby Mobius » Fri Feb 03, 2017 4:04 pm

It is hard to judge scale from the picture, but where does the center line of the ballnose bit end up with regards to the lip you see in the picture? It should be dead center on the edge of the end mill cut, otherwise the cut will start to move up the radius of the ballnose and create a lip.

Something like the picture? Have you tried offsetting the cut inwards? Or is the opposite true? Is the center line of the cut too far inboard?
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ballnose.jpg
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Re: Ballnose not cutting to depth

Postby SteveNelson46 » Fri Feb 03, 2017 4:59 pm

I have never worked with a tool changer so I'm kind of stabbing in the dark. Is it possible to swap the position of the bits in the changer to see if the problem is the changer? Of course you would have to change the tool number position in the tool setup also.
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Re: Ballnose not cutting to depth

Postby adze_cnc » Fri Feb 03, 2017 5:52 pm

nickgless@gmail.com wrote:It has been suggested in another forum that Aspire Pocket Toolpath with large area clearing tool is only for flat cutters and cannot work with a ballnose. Is this true?


I would suggest they are in error.
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Re: Ballnose not cutting to depth

Postby Olle » Sat Feb 04, 2017 6:56 pm

Mobius wrote:It is hard to judge scale from the picture, but where does the center line of the ballnose bit end up with regards to the lip you see in the picture? It should be dead center on the edge of the end mill cut, otherwise the cut will start to move up the radius of the ballnose and create a lip.

Something like the picture? Have you tried offsetting the cut inwards? Or is the opposite true? Is the center line of the cut too far inboard?

That's what I was thinking when I saw this: It may be cutting to the right depth, but a bit offset. There is no reason for the cut depth to change just because you change tools, unless you're using a quick change system that's not properly set up and don't zero between the tool changes.

I have run into similar problems, and it's almost always turns out being me screwing up by specifying an offset somewhere, picking the wrong vector etc. Like you said, I would go back to the drawing board and make sure that the center of the cut is located at the edge of the end mill cut before doing anything else.

BTW: I have a cheap depth gauge I use to verify depths and trouble shoot problems like this: http://www.ebay.com/itm/SHARS-0-4-Elect ... xykmZTK0Qc . It's a very handy tool when you run into problems with multiple cuts, or when you need to verify cut depths in general. If you have one of those, run the ball nose cut only and check the depth, then run the end mill cut and check again.
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Re: Ballnose not cutting to depth

Postby M Queen » Wed Feb 15, 2017 7:35 pm

Fast tool change isn't really a tool changer. With this method, it allows the user to output files using a tool changer setup (multiple tools in the same file). When one toolpath finishes, the machine moves to a set location and prompts the user to put in the next tool. Once the user changes out the tool and hits Enter, it moves to a touch off switch or measuring pad, measures the tool, and continues with the file (sets a spindle speed, starts the spindle, and sets a feedrate just like a tool changer). It is quicker than creating and loading multiple files to do the same job.
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Re: Ballnose not cutting to depth

Postby Pete Cyr » Thu Feb 16, 2017 12:41 am

Are you sure you spindle is trammed ? (the axis of the spindle must be perpendicular to the table in the X and Y axis)
If it is off axis I could see a flat end mill and a ball end mill measuring differently on the FTC. I would not expect to see as large a difference in the depth of cut you listed but I would expect to see the different profile measuring differently.
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Re: Ballnose not cutting to depth

Postby ChrisInEstes » Thu Feb 16, 2017 6:12 pm

I saw the OP's post on a Vectric related Facebook group asking about the same issue, & I believe they found their issue to be a loose Z axis coupler nut.

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Re: Ballnose not cutting to depth

Postby nicksilva » Sat Feb 18, 2017 1:48 pm

when cutting a vector you get to choose whether to run ON the light or INSIDE or OUTSIDE. Since a ball nose curves rather than cut on a flat that could be affecting the cut.
Try cutting outside the line and see what happens.
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