First pass was too deep!

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OCEdesigns
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First pass was too deep!

Post by OCEdesigns »

I have not noticed this before but in this project it was my first attempt at milling Aluminum. The plate is 1/8" thick (0.125) and 18"x18" I set everything up to use Virtual Zero. I'm running V-Carve Pro 9.5

I set it to a maximum cut depth of 0.030 and the end mill set to maximum pass depth of 0.010 for a total of 3 passes. See pics

The problem is the first pass was 0.035! The next 2 passes were correct at 0.010 each. I ended up with 0.055 total depth. The total depth I was OK with because I had enough material thickness to work with but the initial pass of 0.035 caused the end mill to "Dig" in or be pulled down into the material which caused a few imperfections in the sign. I checked a few tutorials and they all have the Start Depth at 0.0. And I did set it up to use the material surface for starting point.

Any ideas why my first pass is going way beyond the set point? What am I missing?
Attachments
CNC Pic 4.jpg
CNC Pic 2.jpg
CNC Pic 1.jpg

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Adrian
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Re: First pass was too deep!

Post by Adrian »

Your first picture you don't have the passes set. Is that the same toolpath as the other ones?

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Re: First pass was too deep!

Post by OCEdesigns »

Yes it is all from the same program. The first pic doesn't show number of passes because the check box for Show Advanced Toolpaths is not checked. That is why I did the second pic just to show it.

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Adrian
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Re: First pass was too deep!

Post by Adrian »

That doesn't mean that the number of passes was three when the toolpath was originally calculated though.

My guess would be that the z-zero was off on the machine giving the impression that it was the first pass that was wrong, perhaps something to do with the virtual zero thing?

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Re: First pass was too deep!

Post by OCEdesigns »

Adrian wrote:That doesn't mean that the number of passes was three when the toolpath was originally calculated though.

My guess would be that the z-zero was off on the machine giving the impression that it was the first pass that was wrong, perhaps something to do with the virtual zero thing?
I'm not sure what you mean by your first sentence. Could I have done something wrong in the program?
And I did another test after I made the original sign and I did not use Virtual Zero since it was just in a 3x3 area and it did the same thing.

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Adrian
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Re: First pass was too deep!

Post by Adrian »

I can't think of anything that would be causing that other than the z-zero being wrong. Are you using a touch off plate or doing it manually?

As to the calculation the passes are reset when you redo the calculation. You could set them to anything, switch the option off and on and they will reset. That's what I was getting at. That won't be your issue though as it wouldn't be doing three passes. I was just pointing out that you can't assume it was always the same as there are quite a few settings that will reset the passes.

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Re: First pass was too deep!

Post by OCEdesigns »

Adrian wrote:I can't think of anything that would be causing that other than the z-zero being wrong. Are you using a touch off plate or doing it manually?

As to the calculation the passes are reset when you redo the calculation. You could set them to anything, switch the option off and on and they will reset. That's what I was getting at. That won't be your issue though as it wouldn't be doing three passes. I was just pointing out that you can't assume it was always the same as there are quite a few settings that will reset the passes.
Thanks for the clarification!
Yes I'm using the touch plate. I can double check the calibration of it.

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Re: First pass was too deep!

Post by Leo »

Did you place the touch plate on the material - or on the machine bed?
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Re: First pass was too deep!

Post by OCEdesigns »

Leo wrote:Did you place the touch plate on the material - or on the machine bed?

On the material surface.

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Re: First pass was too deep!

Post by mtylerfl »

Double-check your Material Settings to see if Z-Zero is set at the material surface.
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Re: First pass was too deep!

Post by OCEdesigns »

mtylerfl wrote:Double-check your Material Settings to see if Z-Zero is set at the material surface.
I did and it was set to surface.

Can I open up the .tap file in something like Word or Notepad to see what it shows for the first pass?

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Re: First pass was too deep!

Post by Adrian »

OCEdesigns wrote: Can I open up the .tap file in something like Word or Notepad to see what it shows for the first pass?
Yes you can.

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Re: First pass was too deep!

Post by OCEdesigns »

Adrian wrote:
OCEdesigns wrote: Can I open up the .tap file in something like Word or Notepad to see what it shows for the first pass?
Yes you can.
Thanks! I'll check the G code when I get home.

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Re: First pass was too deep!

Post by OCEdesigns »

I checked the G-Code of it starting (and the rest as well) and it looks correct. Shows Z at .0100. I guess I need to look somewhere else. Thanks for the replies so far!

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Re: First pass was too deep!

Post by WNC_Ed »

Try setting your Z zero manually
The Z plate on the shark is a convenience but I have found it to be a tad bit “unreliable”.
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