One of the tasks that I have to do fairly often is squaring up aluminum blocks prior to milling. The best way to do this is with a large facemill. You can take multiple passes with a normal endmill but the surface finish isn't great and it takes a while.
It doesn't help that you can't really tram the Smithy mill head, so whatever amount the head is out of square shows up in the surface finish, and multiple passes magnify the effect.
Large diameter face mills cost upwards of $300 though. That's a lot of money to shell out on something that might not work.
So I was browsing eBay and found a Chinese company selling a large-diameter, 6-insert facemill for $40 and free shipping. That's "Chinese" as in "the seller is based in China" not "North American company importing Chinese goods". That price is amazing! You can't ship anything out of the US for less than about $30, and it isn't unusual to see shipping prices in excess of $60 - and that's before UPS tacks on their bullshit import fees if you make the mistake of shipping UPS. So what the hell -I bought it. At that price, it can be junk and I'm not really out that much.
I also bought some Korloy aluminum-specific inserts at the same time. Both orders showed up in a week.
I discovered that adding more inserts is designed to allow you to push up the feed rate, that is, a 6 insert mill can be run faster than a 3-insert mill. You'd think that more cutting edges would produce a better surface finish, but actually the more inserts the more opportunity there is for variation in insert height and thus uneven surface finish. My machine is nowhere near powerful enough to drive this mill with all 6 inserts full speed, so I run it with only one insert, making it a giant flycutter.
This works great:
This cutter leaves a mirror finish and those inserts shear through the aluminum like it wasn't even there. If the mill head was more square and there was less wobble in the spindle, the finish would be flawless. As it is, there are some small tool marks but they are on the order of a couple of ten-thousandths high so that's more than good enough.
It's just so useful for quickly squaring up stock and putting on a final finish - so much faster than back-and-forth with a regular endmill.
It absolutely blows my mind that I can get this part delivered from CHINA, this cheaply, with only a week's shipping delay. The part arrived in a package with Chinese postage on it, so it really was shipped direct from China. I don't know how they can possibly be making money doing this. The cutter head is machined aluminum, it is anodized and laser marked, and the insert heights are within 0.001" as far as I can measure (I need a surface plate...). Really, it is absolutely astonishing that I can get this stuff at this price this quickly.
Upon a time, "Chinese" meant "shit". There are still quality vs price tradeoffs made when buying Chinese tools, but that quality gap has been vastly improved and the price delta is still there. What a time to be alive!