Material Setup Using Machine Bed as z-zero

[mplsartist]

After reading many posts about using "machine bed" for z-zero to cut a profile all the way through the wood, and not carving up my spoilboard, I still have some procedural questions.

I've set Material Setup in Vectric Cut2D Pro with the z-zero dot at the bottom of the material (or top of machine bed) at the lower left corner (x=0, y=0).
Do I then move my router bit to the top of the spoil board and then designate that as z=0 in my CNC Control Software?
Do I then move my router bit to x=0, y=0 on the top of the material and then designate that as x=0, y=0 as usual in my CNC Control Software?
Do I then move my bit down to barely touch the top of the material before starting the program?
Will Cut2D Pro then automatically start cutting at the top of the material and gradually work its way down to the bottom of the material (top of spoil board)?

Thanks for the help.

[IslaWW]

Do I then move my router bit to the top of the spoil board and then designate that as z=0 in my CNC Control Software?
Yes, assuming it has been surfaced

Do I then move my router bit to x=0, y=0 on the top of the material and then designate that as x=0, y=0 as usual in my CNC Control Software?
Yes, just like you normally would

Do I then move my bit down to barely touch the top of the material before starting the program?
There should be no need for this, unless your control or the program sets something from that position

Will Cut2D Pro then automatically start cutting at the top of the material and gradually work its way down to the bottom of the material (top of spoil board)?
Yes. Exactly the same as when you zeroed from the top

The only difference between zero to top and zero to bottom (machine bed or spoilboard) is that you 1) Set Machine Bed in your design 2) You zero the Z to the Spoilboard.

That's all there is to it!

[mplsartist]

Gary:
Thanks for confirming my steps. Unfortunately, when I completed all the steps, I ended up cutting air. I noticed that Safe Z was set at 0.916 (normal: 0.201) and Home Z was set at 0.92 Should I be over riding one of the values and enter a negative value?
Steve

[IslaWW]

Steve...
Since you mentioned it, (move to touch surface prior to file run) I think your control system sets the Z there.
Try moving the bit down to the spoilboard, off the side of the material, then start the file. What control software are you using?

There may be a line in the post that sets the XYZ zeros at the position where the files starts, seems messed up, but that's the way some programmers think.

[mplsartist]

Gary:
I did touch the z to the spoilboard (on the other side of the bed where I had an open area sticking out from beneath the material) before starting the file. After touching Z to spoilboard I then designated that as zero in my controller software (CNC X-Pro V3). I then moved the router to its home position in the lower left corner, x=0, y=0, and desginated those in my controller software. I then positioned the z on the surface of the material. After starting the file, the router went to the proper spot on the material but too high and started cutting air.

Unfortunately, I can't start the bit at the spoilboard because it is pocketed into the MDF Spoilboard and then my material sits into that for a consistent snug fit.
Steve

[Frunple]

Unfortunately, I can't start the bit at the spoilboard because it is pocketed into the MDF Spoilboard and then my material sits into that for a consistent snug fit.
Steve

You just answered your own question I think.
If the material is pocketed in the spoilboard then you should be setting your z at the material top before toolpathing.
If you set the z to the spoilboard, the software accounts for the thickness of the material and starts cutting at that height.

[kaetamer]

Can you set Z zero at the bottom of the pocket?

[mplsartist]

Kaetamer:
I have been setting zero at the bottom of the pocket. It's the same as my spoilboard and/or machine bed. I've tried leaving the bit at that depth after setting my x,y in my controller software, but I still get air cuts.

Frunpie:
I was originally setting my toolpaths at the top of the material but was getting inconsistent depths of cut through on my profile cuts. It was suggested that I try setting my toolpath on the machine bed or spoilboard to ensure even depth of cut through without cutting into my spoilboard. That's where all my head scratching began. No matter where I start my x,y,z and try to over ride what my controller believes, it continues to auto find where the bit truly is and I end up cutting air.

Gary:
I'm using Universal G-Code Sender on an OOZnest 1500x1500. It seems as if the UGCS is automatically finding where the bit's x,y,z is in real time vs. what I've tried to designate in Vectric and I end up cutting air.

I tried manually entering a negative z location in the UGCS but that caused the router to move in a negative y direction

I also started a new Vectric file from scratch thinking that my current file that had been changed so many times, became corrupt. No luck there either.


I'm going bald with all this head scratching

[kaetamer]

Not familiar with your control software but your machine acts as if it thinks your material is thicker than it really is. I'd check your material thickness settings (critically important if zeroing on spoil board, not important if zeroing on surface).

[Frunple]

When you say "pocketed in the spoilboard" is the top of the material even with the top of the spoilboard?
If not, how deep is the pocket? That would change everything. Are you zeroing to the bottom of the pocket? That actually becomes the top of your spoilboard at that point.

[Adrian]

That was confusing me as well. The only way the bottom of the pocket can be the same as the machine bed/spoilboard top is if the pocket is a hole not a pocket.

[mplsartist]

My machine-bed/spoil-board is 54"x56" MDF. Since I use 48"x48" Baltic Birch for my material, I have leveled the middle of the spoil board to about 1/8" depth to ensure a level surface and provide for a consistent and snug placement of the material. The top of the material therefore, is above the non-leveled surface of the machine bed. I'm setting z=zero at the bottom of the pocket.

kaetamer: You're right, it does seem to be thinking it's thicker because I noticed that the air cutting is occurring about 3/4" above the material. This is what got me thinking about entering negative numbers etc. Perhaps I should think about entering a thinner material thickness to fool the controller software. Thoughts? Hazards? Anyone?

[Adrian]

So in that case the pocket terminology is irrelevant really. The top of the spoilboard is the top of the spoilboard. What is outside of it doesn't come into the setting of the z-zero.

Easiest way to see if your control software is working properly is to zero to the spoilboard then move the z axis up and finally tell your controller software to move to 0 on the z axis.

[mplsartist]

Adrian:
You are correct regarding the bottom of the pocket and the top of the spoil board being the same thing.

I tried your idea of setting zero, moving the router, and then giving the return to zero command to test the controller software. I tried it several times, adding an additional axis movement each time. Each time the router returned to the zero point in all axis.
Steve

[mplsartist]

I did some further contemplation regarding what kaetamer has said about my controller software thinking the material was thicker that it actually is and the result being the air cuts. I went back into Vectric and set my material thickness, start depth, and cut depth all to the same dimension of 0.716" (See attached images). I then used a piece of cardboard about the same size as my router bit and taped it to the router collet instead of using the actual bit for safety reason.

It worked!

It should be noted that I tried to enter a negative number in the Start Depth but Vectric didn't accept it.

Later today or tomorrow, I'll try an actual cut.