Job Setup Z zero position machine bed

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Jota
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Job Setup Z zero position machine bed

Post by Jota »

Hi!
Can someone help me understand my post subject ?
In what situations we use this configuration in Job Setup?
I would like same examples.
What's the difference in relation to Z zero position Material surface?

Thank you!
Jorge

I apologize for any error in my English.

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FixitMike
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Re: Job Setup Z zero position machine bed

Post by FixitMike »

Material surface: When the depth of cut is important.
Machine bed: When the thickness of the material that is left is important.
Good judgement comes from experience.
Experience comes from bad judgement.

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adze_cnc
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Re: Job Setup Z zero position machine bed

Post by adze_cnc »

Material surface: If you have the same design that you want to cut through on multiple sheets of material (of varying thicknesses) you'll either need to create a separate file for each sheet thickness or create one file using the largest thickness of the sheets.

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Re: Job Setup Z zero position machine bed

Post by SteveNelson46 »

There are a lot of specific used for both but the bottom line is that it really doesn't make much difference as long as it is set the same on the machine and in the software. Cabinet makers use the spoilboard (bottom of the material) most of the time because it only has to be set once and then used in multiple projects. Modelers and hobbyists like to use the top of the material so depth calculations are easier. Lots of other reasons for both but it's largely just a matter of preference and how you want to measure the thickness of the material. From the top down or from the bottom up.
Steve

Jota
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Re: Job Setup Z zero position machine bed

Post by Jota »

I understand all your comments. But there is still something missing.

In my situation, it`s the thickness of the material that is left that is important (as FixitMike said).

This said, I`m going to clarify what I pretend:
I have several pieces of wood that I want to face to a final thickness of 2.5mm.
The wood have a maximum thickness of de 3.3mm.
My dought is what values I must insert in Pocket Toolpath cutting Depths, to achive the 2.5mm thickness?

Thank you all.
Jorge

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Re: Job Setup Z zero position machine bed

Post by Rcnewcomb »

I have several pieces of wood that I want to face to a final thickness of 2.5mm.
The wood have a maximum thickness of de 3.3mm.
My thought is what values I must insert in Pocket Toolpath cutting Depths, to achieve the 2.5mm thickness?
I would:
  • Create a project where the material thickness is 2.5mm
  • Zero to the machine bed
  • Create a rectangle slightly larger than the project dimensions
  • Use a pocket toolpath with a cut depth of 0 mm -- which will flatten the piece to 2.5mm
  • Run the flattening toolpath first
  • Then run your other toolpaths
- Randall Newcomb
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Re: Job Setup Z zero position machine bed

Post by adze_cnc »

If you really are adamant that you need to use z-zero at the material surface you could do so by replacing the instruction "Zero to the machine bed" above with:
  • Zero to the machine bed
  • manually move the z-axis up to 2.5mm
  • reset the z-zero to this point
and continue with Russell's method but setting the z-zero in Cut2D to material surface.

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Re: Job Setup Z zero position machine bed

Post by Jota »

adze_cnc wrote:
Thu Feb 29, 2024 8:57 pm
If you really are adamant that you need to use z-zero at the material surface you could do so by replacing the instruction "Zero to the machine bed" above with:
  • Zero to the machine bed
  • manually move the z-axis up to 2.5mm
  • reset the z-zero to this point
and continue with Russell's method but setting the z-zero in Cut2D to material surface.
I'm confused.
I would like to clarify that I want more than one pass because I think it will minimise tearout.

So, my confusion is
you first instruct:
● "zero to machine bed"
●...
● ...and then continue with Russell's method but setting the z-zero in Cut2D to material surface.

My confusion is between the first and third point. They seem to me, contraditory.

Can you join and list your instructions with Russell's ?

Thank you!

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Re: Job Setup Z zero position machine bed

Post by Rcnewcomb »

I would like to clarify that I want more than one pass because I think it will minimise tearout.
If your thickest material is 3.3mm and you are aiming for 2.5mm, then the deepest cut is only 0.8mm. (That is 0.0315" for those who use inches). I'd be surprised if 2 passes of 0.4mm gives less tearout than 1 pass of 0.8mm. Has that been your experience?


Since your material starts with an uneven thicknesses and you want multiple passes, then do the following:
  • Create a project where the material thickness is 3.3mm
  • Zero to the machine bed
  • Create a rectangle slightly larger than the project dimensions
  • Use a pocket toolpath with a cut depth of 0.8mm and specify a pass depth of 0.4mm
    (There will be air-cutting on pieces that are less than 2.9mm thick)
  • Run the flattening toolpath first
  • All your other toolpaths must have a start depth of 0.8mm

(My name really is Randall) :D :D :D
- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop

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Re: Job Setup Z zero position machine bed

Post by Jota »

Rcnewcomb wrote:
Sat Mar 02, 2024 6:56 pm
I would like to clarify that I want more than one pass because I think it will minimise tearout.
If your thickest material is 3.3mm and you are aiming for 2.5mm, then the deepest cut is only 0.8mm. (That is 0.0315" for those who use inches). I'd be surprised if 2 passes of 0.4mm gives less tearout than 1 pass of 0.8mm. Has that been your experience?


Since your material starts with an uneven thicknesses and you want multiple passes, then do the following:
  • Create a project where the material thickness is 3.3mm
  • Zero to the machine bed
  • Create a rectangle slightly larger than the project dimensions
  • Use a pocket toolpath with a cut depth of 0.8mm and specify a pass depth of 0.4mm
    (There will be air-cutting on pieces that are less than 2.9mm thick)
  • Run the flattening toolpath first
  • All your other toolpaths must have a start depth of 0.8mm

(My name really is Randall) :D :D :D
Until this date, I only had tearout with a hand plane on the same wood.

With cnc I had any tearout because I only flattened MDF. This is my first attempt at real wood. I bought the Cnc 6 months ago.

I will flatten the wood, then I give you the feedback.

Thank you!

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Re: Job Setup Z zero position machine bed

Post by Jota »

And in the Cnc control software , I also set z zero on the bed?

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Re: Job Setup Z zero position machine bed

Post by Rcnewcomb »

And in the Cnc control software , I also set z zero on the bed?
I don't have your machine, but on my machine, yes, I would set Z0 to the machine bed/spoilboard.

Also, using a downshear (downcut, downspiral) bit will reduce tearout because it pushed the wood fibers down while it cuts.
Example bit: ->Link

UpcutDownCut.jpg
- Randall Newcomb
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Re: Job Setup Z zero position machine bed

Post by Jota »

Thank you all, for your help.


Jorge

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Re: Job Setup Z zero position machine bed

Post by Jimcad »

I'm very new to all this but I love compression bits.
You have upcut forces where it cuts through and downcut forces at the top which helps to reduce tear out.
I'm using quite a bit of 9mm "cheap & nasty" ply with a 4mm carbide compression bit zeroed on the bed. No need for tabs in my case as the shavings hold it all in place.
I'm using the Vectric box creator gadget.
Climb milling leaves a rough finish and conventional leaves it clean so plan your cutting direction.
Jim

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