How to cut a dished shape with nothing around it.

This forum is for general discussion about Cut3D
Post Reply
iacomputerguy
Posts: 5
Joined: Tue Aug 27, 2013 11:14 pm
Model of CNC Machine: Shark Pro Plus HD

How to cut a dished shape with nothing around it.

Post by iacomputerguy »

Hi,
I’m new to the whole CNC thing, so please forgive me if this is totally novice. I’ve watched a few tutorials and did a bit of searching, but did not find what I was looking for.

I’m wanting to cut a dished shape out of the top of a board (like the inside of a spoon, see attached file). I created the shape I want and saved it as a 3DS file. I then imported it into Cut 3D. The tool path created attempts to cut out the shape around the dish cut which I do not want. I am cutting this shape into an existing piece so all I want to do is clamp it down, set my xyz above the place to cut and then cut only the dish. If I used the tool path created, it would dig in to the object around the outside of the dish shape.

I tried making a large flat surface around the dished shape and setting my Z0 slightly above the object. This helped, but the router would be goes back and forth like crazy over areas not cutting.

Any suggestions would be appreciated. Thanks!
Attachments
The dish shape
The dish shape

tmerrill
Vectric Wizard
Posts: 4797
Joined: Thu May 18, 2006 3:24 pm
Model of CNC Machine: ShopBot
Location: North Carolina

Re: How to cut a dished shape with nothing around it.

Post by tmerrill »

Try this:

Just model the dish shape and bring that into Cut3D. Be sure it is positioned at the top of the material block (Set "Depth of Model below Surface" in Step 2 to 0.0).

This is normally the key - in Step 2 be sure the Symmetrical box is checked and a very small value in the input box as shown in the first picture below. Do not enter 0.0 here, but a small number as shown.

Set up your toolpaths and both the roughing and finish should stay within the dish. The second picture shows the finish toolpath and it is only over the dish shape.

My example Cut3D file and .stl dish model also attached should it help. The dish model was done it Aspire but that should not make a difference.

Tim
Attachments
dish shape.zip
(2.9 MiB) Downloaded 385 times
Step 2 setup.JPG
Finish toolpath stays in dish.JPG
dish shape toolpath preview.jpg
dish shape stl model.zip
(45.71 KiB) Downloaded 401 times

iacomputerguy
Posts: 5
Joined: Tue Aug 27, 2013 11:14 pm
Model of CNC Machine: Shark Pro Plus HD

Re: How to cut a dished shape with nothing around it.

Post by iacomputerguy »

Thanks a lot tmerrill! :)

steina81
Posts: 8
Joined: Sat Aug 30, 2014 9:01 pm
Model of CNC Machine: Stinger
Location: SC

Re: How to cut a dished shape with nothing around it.

Post by steina81 »

I think this answers my question. I guess the small value needs to be smaller than the cutter. At that point the tool will not drop into the perimeter.

User avatar
adze_cnc
Vectric Wizard
Posts: 4324
Joined: Sat Jul 27, 2013 10:08 pm
Model of CNC Machine: AXYZ 4008
Location: Vancouver, BC, Canada

Re: How to cut a dished shape with nothing around it.

Post by adze_cnc »

I guess the small value needs to be smaller than the cutter. At that point the tool will not drop into the perimeter.
Remember that the larger the value the more the finish cutter (probably a ball-end bit) will "roll over the rim" hence the use of 1/10,000"

Steven

JHSheley
Posts: 10
Joined: Tue May 31, 2016 2:12 pm
Model of CNC Machine: IMSERVICES

Re: How to cut a dished shape with nothing around it.

Post by JHSheley »

tmerrill,

The solution that you posted might be able to help me with a problem that I have. If you have time, will you please comment on the following problem?

I have 7 fractions (images/reliefs) of an original image/relief. For now I will name them A,B,C,D,E,F, and G. Theoretically, I can execute each of the fractions in any order and the original relief is formed.

In practice all of the images have the zero plane included. The effect of this zero plane is that the end mill will remove material from the portions of the block that I want dedicated to the remaining fractions. So if I execute “A”, then A is made, but all of the material above the zero plane is removed and is no material remains for fractions B,C,D,E,F, and G. (GRRRR!)

The desired effect:
When I run “A”. I only want material directly above (z-axis) removed for “A”.
When I run “B”. I only want material directly above (z-axis) removed for “B”.
.
.
.
.
When I run “G”. I only want material directly above (z-axis) removed for “G”.

After "G" has been executed, the original relief is visible.

There is a 2megabyte limit on this web page, so I can not post the miscreant files.

User avatar
Adrian
Vectric Archimage
Posts: 14541
Joined: Thu Nov 23, 2006 2:19 pm
Model of CNC Machine: ShopBot PRS Alpha 96x48
Location: Surrey, UK

Re: How to cut a dished shape with nothing around it.

Post by Adrian »

Tim (tmerril) hasn't been here for over a year now but hopefully someone else will be able to help.

Have you tried zipping the file or putting it on a service like DropBox and linking it to here?

Post Reply