The picture of the R is a test piece I tried after I made the sign and it did it again. (The R is actually from the sign. I just set it up separately on another piece of material)
First pass is too deep
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?
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?
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A couple of possibilities. How was the stock held down? If clamped around edge, possibly not flat everywhere or lifting do to upcut. This may be a good application for the blue tape and superglue method.
How did you zero off the top of material? If you use touch off puck, make sure that the thickness is set correctly. Mine seems to have not read some types of bits as consistently, have mine back off to 1", and double check with a 1-2-3 block.
Several sharks that I have seen tend to have a little flex in the gantry do to the unsupported rails, possible that "grabbing" of the aluminum is pulling the entire Z carriage down a slight bit. If you push up or down on the collet, is there any movement?
Do you know the alloy of the aluminum? I have had better luck with harder alloys (6061) than with softer (3003) alloys. The soft ones are gummy and grab more.
When cutting aluminum, I like to lubricate the bit with this spray. Use it all the time, but it seems to make a more noticeable difference with aluminum. May not be as necessary if you were using wd40, I have been cutting dry most of the time (or just air blast).
How did you zero off the top of material? If you use touch off puck, make sure that the thickness is set correctly. Mine seems to have not read some types of bits as consistently, have mine back off to 1", and double check with a 1-2-3 block.
Several sharks that I have seen tend to have a little flex in the gantry do to the unsupported rails, possible that "grabbing" of the aluminum is pulling the entire Z carriage down a slight bit. If you push up or down on the collet, is there any movement?
Do you know the alloy of the aluminum? I have had better luck with harder alloys (6061) than with softer (3003) alloys. The soft ones are gummy and grab more.
When cutting aluminum, I like to lubricate the bit with this spray. Use it all the time, but it seems to make a more noticeable difference with aluminum. May not be as necessary if you were using wd40, I have been cutting dry most of the time (or just air blast).
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Here is my G-Code. I don't see any reason for the first pass to be 0.035 deep. I looked at the entire code and it shows what I should be seeing of first pass depth of 0.010. I guess I need to check other places. Hopefully it's the touch plate calibration.
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