Negative wall offset?

[WillRitter]

Hi all,
We recently purchased Solidcam and I've got a few projects under my belt with it. I am running Solidworks 2010 SP5 with Solidcam 2011 SP3 HF2. Lots of things to like with this compared to Gibbs. One thing I do miss from Gibbs is the ability to do a negative wall offset while doing a profile or pocket. My machine parts typically come out oversized, a negative wall offset helps to get them right on spec. I have worked around it by making an offset sketch of my part geometry, but it's a bit of a pain. Am I missing an easier way to do this? I don't want to get into tool offsets as we are running many different production parts all the time.

Thanks,

[dengo]

Hi there,
This is pretty easy to do with a profile op. After setting up your profile/levels etc. click the Technology tab and you will see an area called Modify where you can choose which side of the contour line to place your tool. Click the Geometry button next to it to open more options. The one you need to play around with is the modify Offset figure. You can use a neg or pos offset. Be sure to click apply to all to set the offset and it will show you a little hint to see if you went the right way. This area is also great for extending your contours to allow for a lead in/out.
Pockets are even easier. Again on the Technology tab look at Offsets on the right side of the window. Just set your Wall offsets to whatever you want. I think -1 would cut an oversize pocket and +1 would be undersize.
Hope that is clear for you.

[WillRitter]

Thanks Dengo, I checked my file and your approach should work great. I like the profile one better as it allows you to do a roughing and a finish pass in one operation. I wasn't able to do a negative offset in my pockets until I unchecked finishing on the walls. There doesn't appear to be the same modify menu for pockets, am I missing something?

[dengo]

In the Finish area for the wall finishing pass change from geometry to offset.
Alternatively just save and copy the operation and use the copy for your finishing op.

I think If you have to mess too much to get the outcome you need you have to ask yourself would it be easier to use SW to create the exact geometry required and work from that.

[WillRitter]

Agreed on the save and copy Dengo. Parts are coming out to spec, thanks again for your help!

[mattpatt]

Modifying the geometry with offsets and lengthening and shortening the profiles is a great option. I use it all the time for many different things.

Also being able to choose exactly where to start and finish a profile on a closes loop is very useful as there's areas where I don't want the start/finish witness to be visible, so I can choose where it is. Even though the part is correct dimensionally, and the start/finish cannot be felt, it can be seen and I'd rather it was not on show.

Chamfering edges that are flanked by walls is also a good time to use the length shortening/lengthening option. I cannot get the perfect chamfer with a run of the mill chamfer tool, but by playing with these options I can get it very close without the tool bashing into the wall, which is would do of course if I just left it to cut the whole profile. And with a nice smooth lead in/out it looks good.