Fast CNC & WD

I mostly cut dry on my Bridgeport. I find Kroil works well for tapping in aluminum, for tapping in steel I use regular cutting oil.

I usually cut dry too , but I've been machining some pieces I recently cast from aluminum scrap (car wheels) and it's pretty gummy . Since I have a case of NAPA penetrating lubricant (thanks son!) I decided to try it ... worlds of difference ! I think almost any light oil/solvent would give the same results - haven't I heard of people using diesel fuel or kero as a cutting fluid ?

WD-40 works great with AL. The problem is that it's flammable. Nobody wants their $100k CNC mill to go up in a cloud of flame and smoke.

Were the wheels gummy, or did they have a nice heat treat to them? I have heard that there's a world of difference to be made in the machinability of cast aluminum just by proper heat treating. I would assume, however, that (a) you have to start with the right stuff, (b) you have to know what to do.

It'd be nice to know how easy it is to start with scrap aluminum that is obviously able to take a heat treat, melt it down, cast it up, and heat treat it. Clearly buying blocks of ready-to-cast alloy is the 'real' way to go, but the notion of buying mowers or broken wheels for a buck a pop and melting them down has lots more appeal.

(...)

I am talking an order of magnitude difference. We aren't talking

The active ingredient in WD appears to be Mineral Spirits available in

1 gallon jugs for less than 10 bucks from the big box stores.

So less than 8c/oz vs 30c/oz. for WD.

I would be very interested in your test results using Mineral Spirits as a cutting fluid for aluminum.

Thanks Bob!

--Winston

I didn't try to machine the wheels ...

The alloy of these wheels is unknown , but they were probably an a356 type alloy . They were almost certainly heat treated , just about all aluminum is . The exception is extrusions . Chilling the casting fresh from the sand helps , but without the proper equipment there's small chance that a home shop will successfully heat treat aluminum .

I'm kinda choosy about my melts , I try not to mix sources . Every batch of ingots is identified as to source . So far Old Chevy Head is my favorite for post-cast machining . Extrudium is the worst ... But it all cuts better with some lube .

Kerosene will work equally well.

John, I think I remember you're a pro machinist from AMC. I used to lurk there till the OT made it useless. Anyway, I use toilet water (water and 6% soluble oil) on AL - flood on the CHNC lathe and heavy zero fog mist on the mill. I used to use oil in the CHNC but didn't like the mess in the shop. Just curious, does anybody use kerosene in machines like this? It would slowly evaporate and not leave an oil film on everything.

Karl

Vegetable oil or, if you can get it, real cutting oil.

See Vascomill 22. It's one of the premium cutting oils for milling machines these days. You can't really convert a machine from soluble to oil, however. Not without some major contortions. Even then, a big milling machine will take a couple hundred gallons and VM22 is expensive, about $20.00 per gallon. You would want to clean it and dry everything our disassembled just to get started.

Wes could probably tell you what they use on his job.

Never thought of using Kroil as a _lube_ :(

Thanks for the idea! rgentry at oz dot net

Not the strangest lube... I forget what its used on, but the hot-ticket for lubing some type of metal was carbon-tet... tapping aluminum? Milk is another good one for some op on some metal (memory not good before the coffee does its work...)

Dave

Does that mean I could use diesel fuel at < $3.40 a gallon (or less than 3c per oz.)?

--Winston

Yes, it does. The smell is awful because of the volatile's however and there is "stuff" in fuels that can be problematic in the long run.

What you can't do is use this stuff either pumped or misted. Brushing it on or squirting it from a bottle is fine. You will be making a bomb if you create a mist cloud in your garage.

Sinker EDM machines used to use Dielectric Kerosine.

(Cheap substitutes for WD-40 as a cutting oil for aluminum)

I had no idea there were so many. Wow!

I shall try deodorized kero in a squirt bottle next time I am sawing aluminum.

Thanks!

--Winston

Oil will work better with a saw because it stays with the blade better. Sulferized cutting oil is the best, lard based is pretty good and even plain motor oil works pretty well.

Cool! Thanks!

--Winston

You mean like this...

They're lucky the pretty white vaporized kero after the first flash didn't ignite.

Dave

FWIW, and in general terms, lubricants for machining aluminum are used mostly to improve surface finish. A rigid machine with any horsepower at all doesn't need the lubrication for the purpose of reducing cutting forces -- although a small or light machine may.

And using a flood of miscible oil, while a common thing, is done more for chip control than for cooling. It can improve finish, especially when you're using low- or zero-rake carbides.

The really old, traditional cutting fluid for aluminum is kerosene, although it was typically brushed on or dripped, not flooded. It does make a mess but, again, it can improve surface finish.

I use lard oil when I need a good finish, on my 65-year-old South Bend 10L. Like most old toolroom and small-shop operations used to do, I brush it on. I also have a homemade drip can, but I seldom feel the need to use it. More often, I machine it dry with HSS cutters.