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Author Topic: When I set the depth of cut, my CNC does not cut to that depth.  (Read 702 times)
huntleybill
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« on: July 13, 2018, 17:00:53 pm »

I have attached a file I am trying to mill out. I have the target depth set to -4mm for the first operation. When the machine is done with this operation, the actual depth that was milled is -1.6mm. It should be -4mm. I have re-looked at all my settings, I have tried different depths but always get the same result.

I calibrated my Z axis and it is spot on. In other words, when I set the Z to drop 50 mm, it drops 50 mm. So I don't think it is the machine

What am I missing? Is it the file?
Thank you for your time
Bill

* Bejandj7_13.rar (544.23 KB - downloaded 23 times.)
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EddyCurrent
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« Reply #1 on: July 13, 2018, 18:14:24 pm »

The surface is bad, it's true Z depth is -0.2 to -1.369
Also in the 3DSurface MOP you have, Stock Surface = 0 but it's actually -0.2

 
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huntleybill
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« Reply #2 on: July 13, 2018, 18:46:38 pm »

Thank you Eddy,

I'm not sure I understand. I get the part that the surface is -0.2, so I need to reset my stock surface to -0.2. but why then does the milling operation not go down to -4 mm?
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huntleybill
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« Reply #3 on: July 13, 2018, 19:52:39 pm »

Under Cutting Depth, I changed the stock surface to 2 from 0. Now, when I mill the file, the initial plunge goes to -2mm as it should, BUT, when the first pass in completed the Z axis does NOT move down to -4mm. It stays at the -2mm depth.

I am really confused why this is happening. I hope you can help me.
Thank you
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lloydsp
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« Reply #4 on: July 13, 2018, 20:59:14 pm »

If you supply also the .cb file, folks will be better able to help.

Lloyd
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huntleybill
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« Reply #5 on: July 13, 2018, 21:16:16 pm »

I supplied that in my original post
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Bubba
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« Reply #6 on: July 13, 2018, 21:34:10 pm »

First select solid click on 'get object extremas' then change view to Z-X. You can clearly see the top surface is below Z-0. Using transform function raise the solid 0.25 mm in Z axis, and you can see the top of the surface is in line with Z-0.
Hope this helps.
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lloydsp
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« Reply #7 on: July 13, 2018, 22:04:14 pm »

Bill... why as a .rar?  Why not just post the .cb file?  It's permitted.  (Or, was it too big?)

Sorry.

Lloyd
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huntleybill
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« Reply #8 on: July 13, 2018, 22:12:08 pm »

its too big. So I zipped it .

Thanks Bubba but that gets the surface to 0. How does that explain why it won't mill down to the -4mm depth? I don't understand.
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EddyCurrent
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« Reply #9 on: July 13, 2018, 22:18:03 pm »

Bill,

If the surface has a depth less than 4mm, which it has, it is not possible to mill to that depth.
The only way forward here is to generate a new surface from your image and make sure it's depth is 4mm
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huntleybill
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« Reply #10 on: July 13, 2018, 22:36:21 pm »

I set the surface to 0 as Bubba suggested. What does that have to do with the 4mm depth. I have the final depth set to  -4mm. I guess I still don't get it. Can you generate the new surface and show me what you mean? or is that an issue with the file itself? I have attached the original file if that helps.


* benny.stl (1192 KB - downloaded 12 times.)
« Last Edit: July 13, 2018, 22:43:33 pm by huntleybill » Logged
dh42
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« Reply #11 on: July 13, 2018, 23:10:01 pm »

Hello

The total height of the shape is 1.169mm ; on the picture, the 3D shape is aligned with Z = 0 and as you can see on pic1, the lower position is -1.169... so you can't machine to -4mm ; it's the 3D shape that limit the depth.

in pic2, you can see that your STL certainly have a problem somewhere because the yellow marks in the corners show a shape that is 7.22mm of total height ... (and also 3DSmax return a warning > incorrect STL format)

To solve the height problem: select the 3D surface > explode > joint (done in the file in attachment)

++
David




* pic1.png (29.31 KB, 1161x605 - viewed 34 times.)

* pic2.png (36.62 KB, 798x697 - viewed 38 times.)
* benny2.zip (438.22 KB - downloaded 46 times.)
« Last Edit: July 13, 2018, 23:11:50 pm by dh42 » Logged
huntleybill
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« Reply #12 on: July 13, 2018, 23:29:22 pm »

OK...I see what you mean. Before I milled it out, I resized the .stl file to approx 127 x 127 mm and a depth of 5mm. That is why I thought I was milling 4mm in the first MOP. Did I do something wrong in the resizing?
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dh42
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« Reply #13 on: July 14, 2018, 01:03:35 am »

Did I do something wrong in the resizing?

I don't know, I can't open you .rar file ; only the STL ; and it's size is 15x15mm ... maybe you forgot to click on Apply in the resize window ?

Quote
...and how did you set it to mill only the figure and not the whole piece?

Use boundaries in the 3D MOP. You can use a negative margin to avoid that the tool go down on sides.

++
David
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huntleybill
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« Reply #14 on: July 14, 2018, 01:43:22 am »

ok...I'll try it. Thank you all for your help.
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