View Full Version : Need help in machining 3d part

08-07-2010, 01:56 AM

Im working with surfcam for quite a while, but generally im new to cnc. I was machining 2d parts and all was fine, but now i experienced a problem, i need to machine this part:


I made it with solidworks. Using SurfCAM 4 sp1. Tried many different ways to machine it, but still cant get desired effect. If i use z rough and z finish option i get this terrible result:


Have no idea why it leaves so much material. As far as i've got here i got some luck with 3axis planar operation, but still no even near desired.

The part will be made from MDF, so it can still be repaired a bit with hand tools. The borders between walls and that rise is 6mm, so i should be able to machine it with 6mm end mill and then end it with like 10mm ball mill.
Could some one help me with this? how would you do this?

Thanks in advance.

08-07-2010, 06:47 AM
Hi, can you zip and upload your part?

08-07-2010, 07:24 AM
i couldnt attach it here so i uploaded it to web:

08-07-2010, 09:46 AM
Have you tried to do a 2D pocket above the part and then use the project routine?

08-07-2010, 10:33 AM
thats a good idea and nice feature. i hadn't idea what that operation does, but now i do.
So i took a try. I created rectangle 50mm above the part, used pocket operation on it, and then projected it onto my part.
it looks like that:

But result is still not quite good.
It doesn't remove alll fragments of pocket. And even removes way too much material on one side. And it never removes material shown in middle rectange i marked in red, there should be 6mm space between that fragment of circle and wall, and i machine it with 6mm end mill (i enter diameter 5.85).

Though that project operation is quite nice, but somehow it doesn't help me much.. If you're not too busy, could you please try looking into my attachment i posted before? im trying to make good machining route for this part for few days already, and thats a good thing for newbie, but im in a dead end really.

I imagined before, that z roughing and z finish operations should do most of work, and those other operations are for some kind of special cases.

08-07-2010, 11:25 AM
I can’t download from the link you posted. I’ll send you my email in a PM to you. I’m at work now but on a hot job and may not be able to help you until next week. Instead of trying to do all the surfaces at once, try to do sections at a time or each surface separately. It may take a combinations of routines to machine this part.


08-07-2010, 12:20 PM
Cha, i've learned how to attach files here :rolleyes: so here it is

08-07-2010, 02:06 PM
Ok, I had a quick look at this, the top surface of the part (marked with green color in attached picture) is not parallel to the bottom surface of the part.
So, my first question is: Which surface do you want to be perpendicular to Z-axis in the cutting operations?

08-07-2010, 03:14 PM
The bottom of part is flat and should be perpendicular to z axis. The top surface is rounded. As shown on pic. 2
I placed axis like that:
and the view from the left to show you the side profile:

As u can see outer walls are faced about 3 degrees.

I tried selecting single surface with planar routine with cutting direction - Flow surface, step type - scallop 0,5mm and 6mm end mill, tried also with 4mm, but result the same:

It removes too much material on sides

08-07-2010, 03:45 PM
Ok, I´ll see what I can do....

08-09-2010, 02:37 PM
I tried using Z finish with a 5mm ball with .2mm stepover. The feature on the left with the curves would need to be done again with a planar finish option to get a smoother finish. You have draft on all of the outside walls so you could use a tapered end mill to speed things up. I only spent about 5 min doing the program so you could fine tune it to what you are trying to achieve but it should be possible to get a nice result.

08-10-2010, 02:30 PM
Here is an example with 6 different operations.

08-10-2010, 02:39 PM
Thank you guys for help. I'm very grateful. Also found many solutions to this, i used surface editing like moldcore suggested and also got pretty good view, but Limpan solution is also very nice i'd even say perfect:rolleyes:

08-16-2010, 03:13 PM
It seems like there may be a bit of confusion on what Z level does. Z level is mainly for machining steep angles on a 3 axis part. Here is an example of Z axis...

Draw a hemisphere sticking up from the table. Do a planar toolpath and then a Z level finish on it. If you look straight down from the top at the planar you will see that the tool is offset in the XY and then projected down onto the part. If you look straight down at the Z level you will see a variance in the stepover. Now look at a side view of the Z level. You will see even steps in the Z direction. This is because in a Z level finish the part is "sliced" in the Z direction and a tool is then run around the perimeter of each slice. This being said, you can imagine that Z level is not very good for shallow angles because when the part is sliced in the Z direction, the "resolution" has to be super fine to machine the surface.

Did I totally confuse you or does it make sense?

08-16-2010, 03:16 PM
another way I would machine MDF back in the day is by applying two planar paths 90 degrees from each other. I would also do the planars from 45 degrees so you dont get big scallops in the corners.

08-17-2010, 12:52 AM
Thats totally clear to me now :) But how can u choose planar operation degree? I'm just selecting surface, clicking start, end points and then offset side where cut will go and thats all. Planar operation does very well for inside contours, but it just doesn't do good for outside walls and top of the part.

As I've already said I've edited surfaces, changed arrows directions, then used cut operation with gouge check. And it went pretty good though i had to make some finishing by hand