Working out some kinks — Grazer


This week was spent working on the same fixture components as last, and I think I’ve begun to uncover some issues.

Here’s a link to last weeks post to reference. In summary, last week ended in an uneven failure. This week, I put a similar procedure to use, except I actually did it “right” this time, in an effort to eliminate variables, and uncover why I my part was so uneven. To begin, I borrowed something called parallels from a friend. Parallels are exactly what they sound like: parallel. They are actually a collection of very flat and straight pieces of steel.

They look like this:


These are used to allow a flat piece of metal to rest on top them, at the parallel’s specific height, flush with the existing step.

The next precaution was to make sure the piece of stock was square and flat with the vice. This means getting the same finish throughout the piece with a flat endmill. Ends up looking like this:

The two final precautions were to accurately find a corner point for the part by touching the side of the part with the endmill on the now straight x and y axis of it, and subtracting the radius of the tool from that zero point.


Touch points, x and y. Someone else used the machine between sessions, so I had to zero everything again. 

Lastly, since the parallels only came in specific sizes, and since all of the milling rode low to the vice, I needed to zero the z axis above the part to give more room so the endmill didn’t crash into the vice.

After being very careful about squeezing the piece of stock in the vice, hammering it down every so often during vicing, so as to seat the part correctly.

I milled it again, and got a part back that had the same type of inconsistency as the last attempt:


Bottom half = new part. Notice how flange depths change across the part. 

So, I definitely have a problem, if I want to make an even part. It’s not in the code, I already checked it. I doubt it’s because the machine isn’t level, since the cuts would slant down from one side to the other, not go up and down like a cosign curve.

Therefore, I think this happens because the forces that the part undergoes as it’s cut shifts and tilts it in the vice. To remedy this, I plan on make the program as least aggressive as possible.


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