Roughing w/ V bit

[NewCNCguy18]

Greetings all,

I'm trying to mill a brass brand, with some fairly intricate details. It's a diamond shape, inside a rectangular piece of brass. I'm using a 3mm endmill for one roughing strategy, and it basically mills out everything outside my "diamond" shape, but the 3mm is too large to mill out anything inside. I don't have anything smaller than a 3mm for brass work.

Now, if I immediately start a finishing pass with my 60 degree V bit, this does produce the final result I'm looking for. However, we all know that the finishing pass will follow the contour of the model, and there will be portions of the model where the v bit is carving into 1.5m of brass. This won't work. So I'm attempting to perform, essentially the finishing pass, but as a roughing pass... where I can set the "depth per pass" to .1mm a pass in the tool specifications. However, I continue to get the error message "Check that the pass depth for the tool does not exceed the depth of the model being machine......." when I try to run the path.

When I increase the offset to anything above 4mm... the toolpath will calculate, but only create a profile around the model. I have tried each of the four model boundaries, vector boundary options... I have even tried making a square vector around certain areas. None of them allow a roughing strategy around my model that gets any of the detail. And I'm positive that my model shape allows for a 60 degree bit inside.

Also. I imported a picture. Traced it. Created a "flat profile", raised at 1.5mm... then created a 30 degree draft around everything. It looks exactly like a "stamp". I've even tried it at 32 and 35 degrees to see if that was causing any issue.

To summarize. How can I create a toolpath similar to a finishing path, but "step down" gradually so I don't destroy my 60 degree bit?

Thanks for any help.
Bill

[JimmyD]

There is no reason you can't use the finishing tool path. Adjust your depths to accommodate what you want to do.

[martin54]

Hard to say without a picture but can you run 2 different roughing passes using vector boundaries? One for outside the Diamond shape with your 3mm endmill & one inside your diamond shape with either a ballnose or Vbit? Never tried a roughing pass with a v bit but if the inside shape were roughed with the 60 degree then you would still only need one tool change.

[NewCNCguy18]

There is no reason you can't use the finishing tool path. Adjust your depths to accommodate what you want to do.

Jimmy when you say adjust the depths, how? That parameter is removed in the tool specs on a finishi nut toolpath. It will only follow the _3D shape of the model

[Leo]

Change your Z-zero for the 60 degree tool. Set it to .100 higher than the correct Z-zero and it will leave .100 material. Re set it as many times as needed to achieve the results you want.

[jimwill2]

Could you set your z-zero higher than your surface for the 'roughing' pass? Then change set the true z-zero to the surface. Just a thought... I could be wrong.