Monday, April 6, 2009

carbide/ceramic tooling

I am developing a real love/hate relationship with insert tooling.

* perfect geometry out of the box - no special tool grinder or skill required
* no sharpening - if a point gets dull, turn the insert to one of the other points. With carbide, and given what I usually machine, it is more likely an insert will get a point or edge chipped before it gets dull. I've chipped several insert edges so far - mostly from trying to turn hardened steel, but long before any of them got dull.
* relatively inexpensive if one shops carefully. Keep in mind that each triangular insert (one of the insert choice I've already made and committed to) has three cutting edges. Some styles (which would require me to have different tool holders) can be turned over for three more edges. You can get the price down to about $0.25 a point if you dig around for good prices.

* holy fuck are there ever too many standards, industry codes, shapes, geometries, coatings, mounting methods, materials... finding the right insert is like looking for a specific piece of hay in a haystack.
* you have to buy at least ten from any vendor before the price-per-insert approaches reasonable.

So last week I ordered what I thought was a package of ten new inserts, this time with a very sharply pointed geometry intended for cutting threads, and at a very good price. My package arrived today. Inside was a single insert, with no chip breaker on the edge and no hole for mounting. Can't be used in my tool holders at all. It turns out I mis-read the online catalog - easy to do with several vendors who sell this sort of thing because their websites were implemented in a way that bases them on their dead-tree catalogs. Enco always willing to take returns if the customer screws up, but at $3.71, it's not worth the cost of shipping it back. I'm marking this one down as a $4 experience point.

But in searching again for the right insert, I can't seem to find what I want out of the thousands of inserts that are available. It's starting to look as if I bought the wrong tools. Grr. I can always get another set of insert tools, I probably would have had to do so eventually anyway, but it's annoying to have to do it earlier than I had expected, since even the consumer/hobby-grade tools are kind of expensive. However, it now appears that the use of cheaper inserts might eventually "pay for" a set of different insert tools, and will allow the use of inserts which offer more variety & selection.

Toward that end, this guy has a great page for the hobby machinist. His budget looks to be a little higher than mine, but he's still limiting himself to mostly import tools similar (in some cases identical) to mine. He's also got lots of good ideas for home-brewed tools and accessories, many of which I plan to duplicate or emulate, as well as advice, tooling nomenclature, look-up tables and useful data.

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