Machinable Jaw Blanks or “soft jaws” are a repeatable and effective work holding solution for odd-shaped parts. In this article I will discuss a simple but effective method in CAMWorks for getting toolpath to cut your jaw blanks for most parts. When I say most parts, I mean any part that only requires the outer profile to be cut into the jaws. For really nasty parts that require more advanced fixturing, you may want to actually create a 3D model of your fixture and get toolpath like you would any other part. However, this method is so simple that it doesn’t require any additional modeling and can be performed on your original part file.
Okay, so let’s dive in how to do this. I have an oddly shaped part that after the first operation looks something like this:
In order to complete the part I am going to have to hold on to the profile that has been cut during the first operation. So rather than square jaws, I need my vice to have jaws that look more like this:
The first thing I need is a plane to sketch on that represents the depth that this part will sit inside the jaws. In this case I have .0625” that I can hold onto, but I like to leave a little clearance between the tool and the vice, so I will offset a plane .05” off the face that will eventually sit flat on the bottom of the finished jaws.
Now I will need to capture the part profile on a new sketch on this plane I just created. There are lots of ways to get this job done, in this case I used the Intersection Curve sketch tool (completed sketch shown in blue).
Once the sketch is completed I will switch over to my CAMWorks feature tree and create a new configuration. You don’t have to do this, but I like to do it to ensure that I keep the toolpath for my fixture separate from the toolpath for my part.
In this new configuration I will create a setup that references the plane I created moments ago. I will double check the direction to make sure it points towards the face I referenced when I created the plane. On this new setup I will define a pocket feature that uses the sketch I just created a moment ago as my base entity. Then I will choose the bottom face of the part (again, the one I used to define my reference plane) as an up to face end condition.
That’s it! Now just create toolpath for this pocket like you would for any other pocket. You will probably want your Z=0 point to be on the reference plane somewhere; that way you can index off of the top face of your jaws. Keep in mind that if you simulate toolpath, the simulation will be inaccurate because your jaw blanks look nothing like the stock used to machine the part from. Here is an image of the part in the completed jaws after a roughing operation has been performed to remove the stock that would hide the part from view:
Like I said before, this method may not work for all situations, but it is quick and easy, and I find it to be acceptable for most parts. Take a look at the video below if you would like to see this process in action. Happy Machining!