Slicing issues

[performancenut]

I am having issues with the slice option on Cut3D (I'm using the trial version if this makes a difference). The object I'm cutting is 5"x10"x4.5". The material I will be cutting on will be 2" thick.

What I want to do: cut 1.5" deep pieces which will start at the bottom of the 2" material and work up.
What is acceptable: two 2" deep pieces and one 0.5" piece (working from the bottom up)
What is happening: the software is giving me 6 2" pieces, 3 top and 3 bottom. Top 1 and Bottom 1 are basically blanks, Top 2 and 3 as well as Bottom 2 and 3 contain the piece. If I ignore Top 1 and Bottom 1, I'm using 8" of material to make a 4.5" piece.

The process I'm using: I used Ventric support tutorial to walk me through the proper way to do slices. I oriented and scaled my model appropriately and selected "Top and bottom" and hit apply and next. After this, I tried 3 things:

• Used the default X,Y,Z values, selected Z zero as bottom and origin as the center. Selected Model Silhouette. Made cut plane equal to 1.5" and the selected slice. Slice setting for depth as 1.5" and minimal material selected. Six files created.
• Same as first except changed the X,Y,Z values as the size of the material I would use if making this a single piece (6"x10"x6") and used 2" slices. Six files created.
• Same as number 2 except deselected model silhouette option. Six files created

So I have tried most of what I wanted to do and got no where close to my ideal or acceptable formats. It seems to be a complete waste of material to cut the fourth piece. From what I can tell, it looks like the software is defaulting in the middle of the object despite where I set cut plane and it is calculating 2.25" above and below. Is this about right?

How do I fix this so I use only 3 sheets and, if possible, make each cut about 1.5" thick?

[tmerrill]

If the model you are trying to machine is not proprietary or copyright protected it would we great if you could post it (may need to zip it first). If you can't post the model a picture of the model would help. Do not waste your time posting the Cut3D .v3d file as only you and Vectric can open files made with a trial version.

Without model or pictures, here are some general thoughts.

1. Is it truly a model that requires Top and Bottom machining?

2. If it is an actual two sided model then the slices work upwards and downwards from the center plane you have set. Be sure in Step 2 you click Apply before clicking Slice Model.

3. When you specify your Slice Thickness, that will determine the model thickness in each of the slice files created. When you later set these up with toolpaths you can specify the actual material thickness you are using. If I read your project correctly, you would specify 1.5" slice thickness and when you toolpath one of the slices you would specify 2" thick material and position the model slice at the bottom of the material by adjusting the Depth of Model below Surface.

4. If your setup is correct you should not have blank slices. However, if you end up with blank slices you can just ignore them - nothing says they need to be cut.

Again, the model or a picture of what you are trying to machine would go great with the dimensions and setup info you have given.

The trial version is fully functional as setup and toolpath previews go, its limitation is it will not let you save cut files except the the sample files provided.
Tim

[performancenut]

The file is attached. My settings:

• Orientation: Front
• X=5"

• [1.]Yes
  [2.]I thought of that and made sure to hit apply after each change.
  [3.]Correct. The files created would have the same depth despite where I set the cutting plane.
  [4.]My only hesitation is if a blank was created, will my models scale properly. When I'm done, I wish to stack the pieces and have the dimensions of the original project. It looks like it will be the same proportions but I wanted to make sure.

I appreciate the help. Again, three pieces of material is the goal and having about 1.5" of the model to cut on each piece is optimal but not necessary.

[tmerrill]

I'm short on time so here is how I would set it up.

Front view as you did. It has to be either Front or Back to prevent undercuts which the program will not do.

In Step 2 I moved the cut plane to 2.0" from the top. This still falls in the central area and prevents undercuts plus the top will only require one 2" slice. See first picture.

I then sliced at 2.0" and ended up with 3 files, Top 1, Bottom 1 and Bottom 2 where Top 1 and Bottom 1 are a full 2.0" and Bottom 2 was 0.5" high and machined at the bottom of the material. See remaining pictures of finish path toolpath preview for all 3 slices.

If I have misunderstood, perhaps capturing screen prints of the first 2 steps would show all your settings and help figure out what is happening.

Tim

[performancenut]

I found something out very interesting. The key here is Z Zero setting. If you set it for the top like you did, you generate the 3 files. But if you set Z Zero for the bottom, you get 6 files as I described. Why is that?

My next question is about zeroing my Z axis now. Shopbot taught me to zero on the table, not on the material I'm cutting. So if I use the top setting for Z Zero and zero the tool out at the table, I'm going to have a broken bit, smashed material, and a gouge in the table I would think. If I zero on top of the material and I have inconsistencies in thickness, I could end up cutting into my table.

Thoughts?

[tmerrill]

Why is that?

Unknown. I had it selected for top in the main file that I sliced, but after slicing each newly created .v3D file is a stand-alone project and you can set Z-zero to the machine bed before calculating the actual toolpaths for that slice.

There is a lot of personal preference in where you set Z-zero and when you understand the differences you can make either work safely. My preference is to set to the machine bed when needing accurate final thickness or working with materials that my fluctuate in thickness like plywood. For toolpaths such as v-carving and models in a dish shape, where the depth of cut is more important and you know you have enough material so you will not machine through, then I set Z-zero to the top of the material.

It is easy to visualize setting your Z-zero to the top of the material where a dado 0.25" deep will be 0.25" deep irregardless of the material thickness (assuming it is greater than 0.25" of course). When you zero to the machine bed (which is actually the bottom of the material) then all toolpaths start at the top of the Material Thickness you have set. So if you want to cut a dado 0.25" deep in plywood and have the Material Thickness set to 0.75", the toolpath will start at 0.75" off the table and cut 0.25" deep. However, if the plywood is only 0.72" thick, your dado will only be 0.22" deep into the surface of the plywood. But, if you want to cut a piece of plywood out without going into your spoilboard, or to leave a precise thin onion skin, then setting Z-zero to the machine bed gets you the most accuracy when the material thickness can vary within a range.

Tim

[performancenut]

Thanks for the help, I appreciate it