THREADING: Try coating the area to be threaded with Crisco. As soon as several threads have been cut, smear some into them to lube the forward drive of the die. It works better than most threading oils I have tried and is especially good on aluminum. Don't forget to reverse every thread or two to break the chips loose. For best lubing, get yourself a couple of sticks of Tap Ease from Enco.
FINISH CUTS: Same story. Try some Crisco. Not only does it give a fine finish, it smells better than cutting oils. I keep a glob in a paper cup near the lathe. It does not spoil uncovered. Another site recommended butter flavored, but I see no difference in the cutting action. Use what your nose likes. Of course, if you want to spend just a bit more, you can buy the vapor cooling kit from LittleMachineShop.com. It is very reasonable, but you will usually need to remove the entire carriage for water clean-out after using. It is very good for cutting hard steels such as drill rod. See WATER COOLING below.
DRILLING ON THE MINI-MILL: If you drill very deep in aluminum you know that the pilot hole bit has a rough time making much distance before pulling out for unclogging. The situation is helped by using fast spiral bits from Enco. They don't cost any more than regular bits, but they only come in HSS versions. The fast spiral carries out the sticky aluminum chips better than the steep spiral of regular drill bits. I have learned a little trick that vastly improves cutting of pilot holes such as 1/8 inch. Set the mini-mill gearbox to high speed and rub the drill with Tap Ease to load up the grooves just a bit. Run the spindle around 2000 RPM. It will go through aluminum like butter. I cut a lot of 1/8 holes at 1-1/4 inch deep and find that the bit usually goes through the block in a single pass without the need to pull back for cleaning.
WATER COOLING: Cutting hard metals, such as drill rod, create a lot of heat. On long runs the heat build-up can take the edge off your cutting tools. The Crisco trick, above, helps, but is not really sufficient for heavy cutting. LittleMachineShop.com sells a vapor cooler for 27.95 and the coolant for 6.95 a pint, but it mixes out to 4 gallons. Properly adjusted, that lasts for a long time since it cools with a vapor spray rather than water flow. I carved small plungers out of 25 feet of 7/16 drill rod and only used a half gallon. The cutting can run faster and is cooler and smoother. An added plus is that you don't get burned handling the chips. You must leave the chip pan on the lathe and I recommend you line the pan with paper towels. The lathe must be thoroughly cleaned after use to get out all the water, especially the carriage. A drain hole or two can be drilled in the gap between the pyramid front rail and the flat faced area behind it. I used an eighth inch bit and countersink in two places angeling in toward center from the middle of the non-machined area. Now excess water drains down to the pan rather than running under the spindle head.
POINTED STICK: Sharpen a piece of 1/8 inch hard rod (preferably drill rod or stainless) in the lathe to insure the point is dead centered. Fitted into an 1/8 inch collet, in the milling machine, it is often handier than an edge finder and I find it far more useful setting up for drilling operations when the positions have been center punched. A six inch piece can just be a handy pick for many uses. It is an invaluable aid when setting the center position of a new cutter. Chuck it up close to reduce flexing and crank the cutter up to the point. It is easy to see when the cutter tip matches the center of the pointed rod.
KNURLING: Keep a can of keyboard duster or an air hose handy. If you keep the powder the operation generates blown out of the working area, you get a much cleaner knurl. Knurling to tighten a press fit? Use a straight rather than a diamond pattern knurl. The straight knurl cuts and then lodges into small grooves as it is pressed into the receiving part. The diamond knurl scrapes small amounts of metal out of the hole as it is pressed in, possibly causing a faulty fit that will work loose. If you have several knurl sizes (and you should), make a sample rod with all your sizes side-by-side about a half-inch wide for each so you can easily select the one you want for an individual project without messing up metal for testing.
CALIPER: Get yourself a digital caliper while they are still cheap. You won't know how you ever got along without it. Besides being a great measuring tool, they can be modified for use as precision scales on many of your special projects. I have found these to be so accurate that I rarely use a micrometer. Harbor Freight often puts the 6 inch model on sale for $9.99.
MASKING FOR POWDER COATING: The companies that sell high temp masking tape will tell you that you must not use regular masking tape. Bull! I have used it for some time with no problems. A couple of things you must do are to use fresh tape (not 5 years old) and peel it as soon as possible after removal from the oven while still hot. A glue gunk will be left behind, but it is easily removed later with a bit of naptha after the piece cools. A cheap supply for naptha is Coleman Camp Fuel or the cheap Wal-Mart substitute, Ozark Camp Fuel. I usually cure at 375 deg. so I cannot vouch for the tape above that. Expect it to turn a bit brown, but it has never caught fire on me. If you don't mind a little extra expense, Caswell Plating sells high temp masking tape that tolerates 400 deg.
DRILL ROD CUTOFF: Drill rod is very hard and cutoffs by parting tool are done with great difficulty and a good deal of noise. If you hold a hacksaw with a good sharp blade at the cutoff point while turning in the lathe you will cut off sooner than a parting tool anyway. Don't stay in one position. Saw the blade back and forth several inches or it will clog with chips and stop cutting. The end of your work may have to be faced, but I have broken parting blades and eardrums trying to use a parting tool.
SCRAPE THE WAYS: When turning drill rod or any tool steel small bits of swarf get between the bed and the carriage causing binding. Often the carriage is removed and cleaned only to find it did not fully eliminate the problem. I keep a razor blade scraper handy and periodically scrape the rear way. Being the flat portion of the bed, tiny pieces of metal get in the way and are actually driven into the metal. It is cast iron and not hardened. Left alone, these particles can damage both the ways and the underside of the carriage and will most certainly be dug in deeper. Held at a low angle, the blade will easily dig out these particles restoring the free travel and reducing wear. To reduce the necessity of this scraping, see the item below about adding a swarf guard.
SWARF GUARD: Cut a piece of 1/16 or 1/8 inch thick flexible plastic or neoprene (preferred) to about 4 X 5 inches and attach to the two screw holes on the carriage base intended for attaching a follow rest. Best method is to cut a couple of pieces of lightweight sheet steel to span the holes at about 1/2 inch wide and sandwich the material between them. The flap extends out over the bed under the cutting area and keeps it fairly clean. A good screw to mount this is a socket head screw, 6 X 1 mm, 1/2 inch long. UPDATE: I have found that LittleMachineShop.com sells the accordian neoprene used on the mini-mill as a chip guard. It comes as a 12 X 7.8 inch sheet for under $10 (Part #1431). It will make several guards of the size needed for the lathe.
METAL BAND SAW: Toss out the factory blade and get a vari-tooth, bi-metal blade. They cut 4 to 5 times faster than the typical spring steel 18 tooth blade that comes with most small saws. I use a 10-14 pitch Kennametal blade from Enco although it now appears that Kennametal has stopped making these blades and so Enco has switched to Erwin blades in this size. An aid to cutting aluminum is the use of Tap-Ease, mentioned in item one. bump the running teeth now and then while cutting aluminum to reduce clogging of the teeth. It speeds up the cut noticeably.