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Determining amount of material that is removed when milling a cylinder

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Message 1 of 65
Hadwood_CNC
1511 Views, 64 Replies

Determining amount of material that is removed when milling a cylinder

Hi,

See attached file. I'm trying to mill the inner and outside diameter of this model which is made of plywood that is precut to match the model displayed (not a solid piece of plywood). My goal is to remove a small amount of material from the edges (1/16" per pass) as the cutter moves in a circular motion around the cylinder. I understand how to control depths of cut for the z axis but how do I determine this for the x and y axis in this case?

64 REPLIES 64
Message 2 of 65
seth.madore
in reply to: Hadwood_CNC

Are you looking at removing material beyond what your Stock and your Model represent?

For that, you would want to use negative "Radial Stock to Leave":

2023-06-13_05h41_18.png


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 3 of 65
Hadwood_CNC
in reply to: seth.madore

That's correct. Your explanation makes sense, however how would I approach taking off 1/8" of material but doing it in multiple passes instead of one pass (taking off 1/16" per pass for example)?

Message 4 of 65
seth.madore
in reply to: Hadwood_CNC

I would actually switch to a different toolpath; 2D Bore. This will give us better control over the stepover and ramp motion:

2023-06-15_06h02_25.png

File is attached 🙂


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 5 of 65
Hadwood_CNC
in reply to: Hadwood_CNC

Awesome! Thanks Seth. I can use this same process for milling the inner diameter of the wood cylinder correct?

Thanks!

Message 6 of 65
seth.madore
in reply to: Hadwood_CNC

 


@Hadwood_CNC wrote:

Awesome! Thanks Seth. I can use this same process for milling the inner diameter of the wood cylinder correct?

Thanks!


Yep!


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 7 of 65
Hadwood_CNC
in reply to: seth.madore

How would you approach setting up a G54 offset for milling the outside of
the cylinder? I’ll have clamps on the inside of the cylinder that the
cutter/z axis will need to avoid.

My current method is to set the G54 offset in the center of the cylinder
and this should work fine for milling the inner diameter with clamps on the
outside of the cylinder but I don’t believe this will work for milling the
outside diameter with clamps on the inside of the cylinder.
Message 8 of 65
seth.madore
in reply to: Hadwood_CNC

Are your clamps modeled in your file? Could you share the latest version of this file?


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 9 of 65
Hadwood_CNC
in reply to: seth.madore

Hi Seth,

I figured out the issue with avoiding my clamps, however when I ran the attached gcode the cutter only shaped one half of my stock and removed about 1/8". I did my best to center the cutter prior to assigning my g54 offset, so I'm wondering if there's something else that I'm missing or if this is purely an issue with centering my cutter incorrectly.

See attached files.

Thanks!!

Message 10 of 65
Hadwood_CNC
in reply to: Hadwood_CNC

See attached files.

Message 11 of 65
seth.madore
in reply to: Hadwood_CNC

What do you mean by "only shaped one half of my stock"
The toolpath (in Fusion) is certainly going fully around the part, so are you saying that it was offset to your stock (at the machine)?


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 12 of 65
Hadwood_CNC
in reply to: seth.madore

Yes. I ran the gcode and the toolpath only cut one side of the
stock/cylinder leaving the other half unshaped/cut. Assuming everything
looks good in fusion is this purely an issue of getting the cutter centered
correctly before assigning my g54 offset?

I used the cutter as an edge finder to establish my center point, but on my
next test I’ll be using an edge finder to establish the center point.

Any best practices for establishing my center point/g54 offset and making
sure it’s exact in this case?
Message 13 of 65
seth.madore
in reply to: Hadwood_CNC

What do you have for a machine/control?
I would edge find on one side, record the X(or Y) value on a notepad, move over to the other side and repeat the process. Take the average of those two values and record your G54. Alternatively, some controls have a "mid-point" option, which does effectively the same thing.

 

Are you certain that the part did not move on you?


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 14 of 65
Hadwood_CNC
in reply to: seth.madore

I'm in the process of milling a new piece of plywood to test on. When creating the test piece I tried to create tabs on the bottom of the work piece, but the spindle ended up cutting through the tabs. What did I do wrong in my setup?

 

When setting my heights the spindle took a long time to contact the work piece when executing the g-code. Is there a way to speed this process up so my spindle makes contact with the work piece immediately without going in circles before making contact?

 

I'm certain the workpiece did not move when I cut out the inner diameter circle, but it's measuring inaccurately. Is there anything I can do in fusion to try and get more accurate results/outputs?

 

Thanks!

Message 15 of 65
seth.madore
in reply to: Hadwood_CNC

How "inaccurate" is it?

As for it poking thru the bottom of the stock, an investigation of your toolpath will reveal the problem:

You have it set to -.100" from the Model Bottom, so it applies the toolpath and the tabs at that point. You should have it set to "Model Bottom" with no additional offset


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 16 of 65
Hadwood_CNC
in reply to: seth.madore

I took some more measurements and it looks like my output is fairly accurate. I ran the attached test and had an offset of -.1 for the hole bottom set in fusion. My machine went too far on the first pass (taking off the first "1/16 of an inch) and crashed into my cnc table. Is there something else that's set incorrectly or will removing the offset fix this issue?

 

I looked at the gcode with and without the offset and it looks relatively the same, so maybe there's something else I need to adjust?

 

Thanks!

Message 17 of 65
Hadwood_CNC
in reply to: seth.madore

I’ve been running into an issue where my bottom offset is set to 0, but the
machine keeps going past the expected end point.

Can you advise what could be causing this?

Thanks!
Message 18 of 65
seth.madore
in reply to: Hadwood_CNC

Would you be able to share your Fusion file here?
File > Export > Save to local folder, return to thread and attach the .f3d file in your reply.

Also, please share your NC code


Seth Madore
Customer Advocacy Manager - Manufacturing
Message 19 of 65
Hadwood_CNC
in reply to: seth.madore

The requested files are attached. Thanks for taking a look! How can I send through the nc code? I'm unable to attach a .tap file in this forum.

Message 20 of 65
Hadwood_CNC
in reply to: Hadwood_CNC

Additionally, the next step in this process is to mill rings that are on the inside of the cylinder. The rings are 1/2" thick and 1" tall. My goal is to mill the top ring and then mill the bottom ring. Will the attached file work or is there something I need to change?

 

Thanks!

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