DtD Update: machining soft jaws

So I'm starting this Day to Day (DtD) Update thing so you can see the drudgery associated with the bright lights and big city stuff. 

I had to have some bearings replaced on my mill before I could get to making actual parts. That was finished last week and I've been doing the last of the programming. So far I have about 70 separate programs to make this little light. That means there are 70 "operations"...not including the manual operations. For example: cutting all of the stock to length, sanding down the edges so they are smooth and even, etc. More on that in a future post. Suffice to say, there is a lot of work to do outside of the actual machining. Most of it is manual, and this is the kind of labor that kills product margins.

Soft jaws before machining

So yesterday and the day before I have been cutting the "soft jaws" that will hold my components that need to be machined. They need to be extremely precise and one mistake means they are ruined. Each jaw will have five separate locations machined...so that is five chances to wreck the whole thing. Ask me how I know.


Soft jaws are (most often) made of aluminum and are meant to be machined to the size and shape of the part being held. They are the best solution when holding parts that are irregular in shape, or as in my case, multiple parts in one vise. This type of machining is relatively high stress because you only get one shot to get it right. Normally a CNC routine has had hours of optimization so all you have to do is press the button. However, running a program for the first time can mean disaster. There is a whole lot of steel and horsepower and extremely sharp things moving around inside the cabinet.

Thin wedges are clamped between the jaws while they
are machined, to maintain a small gap.

So, we are pretty much ready to go! I'll shoot some photos of the finished jaws today. I mucked up one set already. When you are making a round hole the program needs the tool number, length offset, and diameter offset. Normally all of these are supposed to be the same. For example: T5, H5, D5. However, it's common practice to have different settings (T5, H15, D25) so the software doesn't let you know if they are different.

Shims are clamped and ready to machine! Or royally mess up in my case.