Pocket Milling

[Scot]

I'm using version 9.1. The package I have does not include solids. I need to mill several pockets that have islands within the pockets. There are also holes drilled in the bottom of the pockets. I have a converted IGES that has wire frame and surfaces. The method that works best so far is 2D pocket milling, picking chain with plane mask checked in the options. I then select the wire frame geometry inside the pocket. I have been using zigzag toolpath. The tool is jumping all over the place without consistency. Does anyone have a better method or any ideas.

 

Thank You,

Scot

[Thad]

Looks like you're doing everything right. We usually use constant overlap spiral when pocketing. Parallel spiral is our second choice. We don't do too much milling pockets with islands, but I would guess you would just have to experiment with the different pocket types to find what you like. Good luck.

Thad

[Trevor Bailey]

If you have the L3 option, try using surface-rough-pocket. It will get the material out efficently. All you have to do then is add some geometry to do some simply 2d paths for a fast clean up.

[Thad]

quote:

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try using surface-rough-pocket.

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DOH!!! Why didn't I think of that? I'm still new at this 3D stuff.

 

Edited to say that Trevor was referring to mill level 3 when he said "L3." I thought I'd clarify that because I had to look at it twice myself.

 

Thad

 

[ 05-14-2003, 05:23 PM: Message edited by: thad ]

[Scot]

I tried the surface, rough, pocket method while picking surface at bottom of pocket that I wanted to machine, with no success. MasterCam claims "unable to determine a valid machining zone". I'm still unsure about the mill level 3 that Thad translated for me. I will continue to check this option out, but any more clarification or suggestions would be appreciated.

 

Thanks,

Scot

[Steve Landkamer]

Scot,

If you are using surface rough pocket you would want to pick the bottom surface, the island surfaces and the surface walls of the pocket. Then it should find a valid machining zone. You may want to close the through holes in the bottom of the pocket using "Modify", "Trim", "Surface", "Fill Holes" that way the tool won't hop up in those areas. Or you can pick all surfs and have a containment boundry to keep the tool where you want it.

Steve

[Dan Schnars]

When you are running MC9.1 press Alt+V and at the bottom center of the screen it will tell you which mill version you have. Make a chain around the outter top of your pocket and pick it for your containment boundary if you haven't all-ready. That might dump the "valid machining zone" warning...

[Scot]

Thanks Dan, I am currently running level 3. I rid the warning with picking the containment boundary around the top edge of the pocket. Now I am running into problems with the islands. The toolpath disregards the islands, although I don't believe I am picking them as nested containment boundaries correctly. What is recommended to making MasterCam aware of these islands. How is nesting approached properly.

 

Thanks,

Scot

[Dan Schnars]

I've never used nesting for what you are doing... I'm sorry if i missed this before, but are the pockets flat on the bottom or are they a 3-d surface? If they are a 3-D surface try picking the surfaces forming the islands as "Check" Surfaces, this way MC won't machine them. Make sure you delete them from your "Drive" surfaces selection... you can tell if you have them picked as drive surfaces by clicking on the "select" tab in the surface parameters window then click "show" then add / remove as necessary. Do the same for your check surfaces... Should just need 1 containment boundary around the outside of each set of pockets, not around pockets and islands... lemme know if this helps.

[Scot]

Thanks for the reply Dan. The bottom of my pockets are flat. When I try using surface, rough, pocket milling, it does not highlight the check surface option. How do you pick the checksurfaces? The toolpath that I am getting is turning out better each response from everyone, but all I need to do now is prevent the toolpath from milling out the islands.

 

Thanks,

Scot

[Dan Schnars]

If the pockets are flat on the bottom try just a pocket toolpath and forget about using surfaces. Create chains at the tops of pockets and islands using your wireframe and do toolpaths/pocket. If your islands are different heights use toolpaths/pocket and click the box that says pocket type and set that to island facing. On the roughing/finishing window play with your stepover settings and pick one of the spiral / par. spiral / high speed / options to get the best toolpath. Try checking (or un-checking) "keep tool down" to stop it from jumping all around and dump the zig-zag. Lemme know if this helps allright?

[Dan Schnars]

Oh, when it asks you to pick chains, pick the chain around the outside of the pocket, then pick the chains around the tops of your islands. MC will sort it out.

[perseid88]

I've been doing the same sort of pocket lately with varying degrees of success. I can either choose the outer and inner chain (island) or chooses "area". The only problems I've been having is that it does not always clean up all of the material. Why is it that it leaves some areas near the islands?

[Dan Schnars]

If you decrease your step-over percentage it will clean up the areas that you are talking about, also I have good luck if the "finish outter boundary" box checked... Mess around with those 2 settings and see how it works.

[pactec]

For 2-D pockets you want to use Island Facing, it's one of your Pocket Types. For 3-D, Surface, rough, all surfaces done. Set up your tool and on the Cut Depths setting do a Detect Flats. Abs. or Inc. as you want or need it.

 

Take care...

[DavidB]

i found that a 40% step over works best it wont leave any erea's unmachined

[TREV]

in order to get rid of the stock that it is getting left you may want to try spiral clean corners option when selecting type of pocketing path.also turn on finish outer boundary. as far as doing a surf rough pocket i to have noticed occasional gouges with islands, ussually for me if i change my cut angle i can get a clean path.

hth

 

trevor

[pactec]

Constant overlap with allign points for entry works like a hotdamn in 3-D. Which is the prefered way to run cavities, spiral inside to out and optimize cut order, this way you don't need to run around the walls a second time. The last pass is your finish pass. Don't forget to detect flats in the depth cuts. Overlap can be as big as you want since constant overlap is just that, a constant step from one pass to the next. If you think it takes too long versus zig-zag consider the fact you don't need a separate finish pass and also try highfeed, it works with a little set-up. The more we use it the better it will get with input from the community.

 

Take care...

[pactec]

Constant overlap with allign points for entry works like a hotdamn in 3-D. Which is the prefered way to run cavities, spiral inside to out and optimize cut order, this way you don't need to run around the walls a second time. The last pass is your finish pass. Don't forget to detect flats in the depth cuts. Overlap can be as big as you want since constant overlap is just that, a constant step from one pass to the next. If you think it takes too long versus zig-zag consider the fact you don't need a separate finish pass and also try highfeed, it works with a little set-up. The more we use it the better it will get with input from the community.

 

Take care...

[Scot]

Constant overlap does seem to work better. What method are you using to pick the start point of the toolpath?

 

Thanks,

Scot

[jplecan]

Scot,

For the start points, in rgh parameters check box align plunge entries for start holes. After you run this toolpath, run the circle paths, drill start holes toolpath and it will automatically put the drill path before the pocket path. I've learned a lot from reading this thread thanks all you guys for your input.

Jim

[Scot]

I'm with Jim, Thanks to all for the feedback. Much appreciated.

 

Thanks,

Scot