My new (really, new) Logan Model 820

While waiting on the painting to move forward (recoat windows are a pain, sometimes...) I have been borrowing a mill to complete the A-11 Cross Slide casting from Metal Lathe Accessories to fit the Logan.

Because the mill is borrowed, and is not well fitted out, and there are strict rules in place about removing the mill vise (a cheap Shars that has not been fettled...) some of the photos are going to show suboptimal setups...but this is what I have to work with.

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First things first-a piece of card stock against the rear jaw, after dialing in the rear jaw of the vice, and an old diesel wrist pin for a cylinder jaw, and now I can setup and face off the "lead" side of the casting-this is the face that will be used as the square reference for all operations. You can see the cored-in T-slots...I would almost have preferred they weren't cored in this particular casting, as cores were close but just not quite square-this caused issues later.

The face mill in the photos here is a cheap chinese copy of a Techniks face mill, and did surprisingly good for the 32$ for the cutterhead, the arbor, and the four mitsubishi-reject inserts that were shipped with it. I say reject because they look identical to the Mitsubishi APMT1608PDER-VP15F inserts that I used to use at work-identical markings-but they had tiny, tiny chips in the edges of the coating. Not in the actual carbide, but just the coating, and I'd never have seen it if I hadn't be suspicious of them to start with and gotten out the microscope. The APMT inserts are widely toleranced, so I had to play with the position in the cutter to get them all cutting in a balanced fashion, but after measuring the insert pockets and then the inserts, it's just that two inserts were 0.0008" longer than the other two. Another mark pointing to these cheap chinese import inserts being factory "seconds" or rejects-but they worked very nicely and after tramming out the mill, left an excellent finish on the cast iron.

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After the lead side was cut, the casting was set up on the same cylinder square underneath, and the lead side was set against the rear jaw of the vise. After the vise was carefully tightened and checked and re-tightened and checked a few more times, the top of the casting was faced off to clean a casting flaw (bit of sand fell in the mold and left a pit) and then faced flat and square to the lead side. I'm still at 1.160" thick after the final "finish" cut and the drawing calls for 1" thickness. A little thicker is fine, I think-and the T-slot nuts I bought are so tall that I can't go any thinner without re-cutting all the T-nuts. They aren't particularly well made anyway...I may just have to make some better ones. I was hoping to just buy them and use the same T-slot cutter for all the slots on this machine...but the T-slot cutter didn't last.

It's a Shars Tool T-slot cutter, high-speed steel and was 20 bucks. I didn't expect the world, but I didn't want to pony up for a carbide tipped cutter because T-slot cutters have a hard life-they don't ever last too long. On first T-slot, which was slotted with a 3/8" two flute, then followed through with the T-slot cutter, it did very nicely-good chip ejection, nice sharp clean corners. The second slot is where the problems started. Due to the T-slot cores having shifted a bit, they weren't particularly square to the long axis of the part. The first core was good, but as I went down the part they got further and further from square. This meant the t-slot cutter was having to work harder on one side of the slot than the other, and I had to really slow down on the feed rate to stop the chatter and vibration. Slowing down, and the T-slot cutter only barely cleaning up the bottom of the cored T-slot, meant that the very hard skin of an iron casting was all that was being cut on the bottom of the slot-and it started eating the corners off the lower three flutes. The slow feed rate excaberated the issue, by allowing a lot of the chips to be re-cut by the lower flutes...this wore them down even faster. In the end, all the slots were cut, but the T-slot cutter is done. The bottom flutes would need to be reground, even though the top flutes (which were cutting in clean iron most of the time and the chips fell away from them) are in perfectly fine condition. The cutter could be re-ground into a woodruff key cutter if I can't think of another use for it.

On other fronts, the motor acquired the other day has been cleaned, both bearings replaced, and the windings washed, baked out, re-varnished, and baked again, even though it tested good for shorts/ground faults and hi-pot prior to the rebuild. Good practice is only good as long as it's followed, and I don't want trouble from the motor-even if I did only spend 25$ on it. (Between the cost of the motor, the bearings, and the glyptal)

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