The Workholding Challenge

While the Vice Plate project doesn’t illustrate mass production using the full power of CNC, it does illustrate a couple of important points.

Firstly, speed and efficiency of setup is important.

If we can’t get set up in a reasonable time, enthusiasm wanes, I find. The vice is an ideal way of gripping many pieces of work, so it is worth adding a plate or a tongue to allow the vice to be set on the bed and lines up with the fixed jaw parallel to the X or Y axis with ease.

Secondly, although all we are doing in creating the plate is milling four sides of a square, the problems caused by the plate being awkwardly large are not trivial. They are an example of a very common situation where it is difficult to get the work set up so that we can get a clear run at machining the part. Frankly, it’s a pain.

Sure; if the workpiece was smaller we would be able to zip around the four edges without moving it. Or would we? What about the clamps, I hear you say?. Yes; very true; and another universal problem. The solution lies partly in having enough experience of previous setups to be able to spot a solution. If the material was a little smaller, I would suggest drilling the holes first then using those holes to bolt the work to a packing piece and to the table, using four tee nuts in the mill slots.

But of course the material is inconveniently large.

I sometimes think I should machine smaller things; make smaller models and other things, and be content with the little things in life.

But then again; where would be the challenge?

You now know...

what I already knew; that I can’t tell my right from my left.

I always check my references to right and left quite carefully, but even that, as I have discovered, is no guarantee I won’t make a mistake.

On page 18, third column, about half way down, in the third paragraph, I say “To cut directly down into a workpiece, and end mill needs at least one over-centre tooth like the right-hand cutter in photo 42...” I meant “like the LEFT-HAND cutter in photo 42” but I’m sure you guessed that.

As a special consolation for those of you who were unconsolably perplexed, here’s a close up of the end of that cutter:

Laborious typing

We are headed towards Teach sequences and construction of programmes, both of which will cut down on the typing. In the meantime, I would encourage you to take all the shortcuts you know, like copying and pasting, to cut down the typing.

Mind you; there is some merit in having to think about what you will type next, because it forces you to think about where the CP must move, and that is always a good thing.

Foothills

We are in a slow patch, but we will make progress shortly.

My purpose is to take you through all that I think is necessary, for you to be able to use your CNC machine effectively. Part of that, though, involves things other than diving into programming.

I am aware, too, that not all readers are beginners, so I hope there is something for you even if you are an expert.