Cutting the bottom surface

[lilricky2]

I'm starting to catch on a little I think. I've drawn a small rectangular part. I have even managed to generate the tool path and g-code for 5 sides. I am having trouble figuring out how to get the bottom contoured. I am trying to generate the tool path on the bottom by boundry geometry but I am doing something wrong. What is the Z dimension on the translation table taken from? Are the X and Y rectangle values the same as your part dimensions? Any help on this would get me over the hump and into parts production. I made some practice runs with acrylic blocks and it looks decent. Just this and a little tweaking and I'm onto cutting aluminum parts.

Thanks,
Rick

[tjones]

Sounds like you are asking how to pocket but I am not sure what exactly you are asking. Is this a solid part with uneven surface or a standerd pocket? A contour is just that a contour around not a pocket or surface.

[lilricky2]

It's not a pocket, just a dropped surface. I am making a rectangular charging handle about 2.5 inches lond and .620 wide. Most of the contour is on the top and I was able to gat Bobcad to produce the toolpath and g-code for all the sides except the bottom. The bottom runs parallel to the top, but it drops downward about ,260 at an angle then runs parallel and then notches out about .080. Sort of a step down and then part of the way back up. Anyway, I only have the version 19 manual and it shows that you can create a toolpath and g-code for a surface or face but I have not been able to figure it out. I don't know how to post an image or I would.

Rick

[CNCdude]

Rick,
If you are working with a model, select it, extract the edges and then use the boundary geometry for the pocket area and use that to generate toolpath from the Solids menu: Generate Toolpath. If you have island geometry you will need to select that as well. Or you can extract and keep the geometry you need to create the pocket and simply use the pocketing function from the "Other" menu if you know the exact depth of cut. However, it would be easier to use the boundary machining options if it is a solid model. That should do it.
CNC Dude

[tjones]

This does sound a bit like a solid but you could post a picture or file if you like. Use the solids menu for toolpath if you have a solid.

[lilricky2]

O.K. I extract the lines and go to generate the the tool path. I fill in the fields and set my Z top and bottom. I hit generaye and then it tells me so select geometry and turns the cursor black. At this point any thing I do clears the cursor and sends me back to selection mode. I've tried setting the surface. unstitching the face and using a rectangular boundary to highlight the face. So far I am still lost. I can render it after I highlight the face and it shows the correct fae is selected, but I still can't generate the tool path. I will try to attach a picture.

[Jim Estes]

Most of the time when I have trouble getting lower surfaces to generate toolpaths it is because of: 1-the cutter is too large to cut the surface, 2-I chose use cutter edge instead of cutter tip and also chose the cut to part edge (this effectively increases the cutter size for calculation purposes.) 3-I used a positive integer for cutter depth in the Z depth window.

Getting all these setting correct can take some real thought sometimes, especially when you are working with several different cutter styles. I have had lots of trouble figuring out how to cut surfaces in my molds. I like to start by roughing out the cavity with a 1/2 carbide endmill, but many times the toolpath just won't go to the bottom because one or more setting prevents it. I sometimes have to use 3-4 different cutters and 3-4 different tooplaths to cut the cavity completely.

Jim