Metal Head
June 18th, 2009Crack is Cheaper
One of the frustrating things about trying to learn machining is the constant search for cheap metal. You would think metal would be inexpensive, given the low prices of many large metal objects. But you would be wrong. Seems like metal is the only thing that loses value after you use it to make something.
I’ll give you an example of the kind of problem I’ve come up against. I wanted to make some brass knobs for a bathroom cabinet. The best size brass cylinder for my purposes is about 1.5″ in diameter. I need four knobs, so a foot of brass is a good safe amount, to allow for waste and leave a little extra for chucking. Let’s check Onlinemetals.com.
For 360 free-machining brass, which is a brass machinists like a lot, the cost is over forty bucks, before shipping. Add shipping, and it’s over $53.00.
Now, what do knobs cost at Home Depot? I don’t know. But less than $53.00 for four. Granted, you get way less metal, and it’s probably the worst metal available. Still, it takes some of the fun out of making the knobs for myself.
You can do better on Ebay, right? Wrong. Well, okay. Right. But not a whole lot better. Ebay used to be a true flea market, packed with finds. Now, many of the sellers are ordinary retailers who charge near-retail prices. This includes the metal dealers. So it ain’t that great.
Luckily for me, I found a guy who is liquidating the inventory of an aircraft business. Up side: cheap metal, cheap shipping. Down side: metal very weird.
There are certain metals machinists use all the time, like 12L14 steel, T6 aluminum alloys, and the brass mentioned above. Then there are metals from Mars, like “Greek ascoloy,” “Inconel,” 660 stainless, and “Waspaloy.” The liquidation dude has lots of this stuff. If you want to buy from this guy, you have to spend forty minutes Googling each alloy to find out what it is.
I got some good stuff from him. A little tool steel, some stainless, and a mysterious round bar which might make a good tool holder, provided I can machine it. But by the time I found him, the really useful items were gone.
I also found a metal dealer that sells drops. These are like carpet remnants. Example: somebody who makes locomotives orders x hundred feet of mild steel 3″ by 3″ bar, and you buy the remaining 16 inches cheap. You can save maybe two-thirds of the ordinary price. You get dinged on shipping, but if you order a large amount, it still pays off handsomely. I got some mild steel I hope to cut into lathe tool holders, plus the brass I wanted. Plus something else I do not recall.
People say, “Go to the local scrap yards and ask if they sell drops.” I guess I can do that. I already put in a word at a boatyard. But Miami metal dealers don’t seem all that interested in that kind of business. They sell new metal cut to order, and they buy scrap, but if they are letting people come in to wander around and look for goodies, they are definitely doing a bad job of advertising it.
One nice thing about joining forums is that forum members help each other out. I bought a drill chuck with a useless taper in it, and it turned out another guy needed that kind of taper, so I sent it to him for nothing. He’s going to send a mystery package in return. Another member offered to send me some steel rods for nothing, as long as I paid shipping.
So now I will have the beginnings of a useful scrap pile. I won’t be totally helpless.
Steel rod suitable for turning and threading is not readily available around here. A reader recommended a local dealer to me, and they’re great for angle iron and aluminum rod, but they had no idea what leaded steel was. Seriously. Did not know what it was. I had a dowel I got from Home Depot for a welding project, and I tried turning it, and wow, is it lame. Imaging trying to turn cold cheddar cheese in a lathe. The tool jumps. The metal tears. The finish is horrendous. Cutting fluid made no difference. So I guess I can forget Home Depot for turning stock, even in emergencies.
I was using a round-nose tool I made myself, intended mainly for finishing things I make using cobalt. A round-nose tool with a big radius gives a better finish than a pointy cobalt tool. I tried it on the Home Depot dowel, hoping to create a surface I could use as a basis for threading. Upon witnessing the cheese effect, I concluded that I make really bad tools. Then I chucked a piece of aluminum and tried it, and the finish was beautiful. It shocked me. So it’s not me; it’s the metal. Fine for welding. Useless for turning.
I’m keeping an eye on Craigslist. Sometimes a liquidation takes place.
Can you do anything useful with machine tools? Sure. Here’s a link someone just sent me. A guy made a 1/6-scale Chevy 327 that runs. The perfect thing to have on hand when Stuart Little goes through puberty. Or it would make a great power source for a blender.
June 18th, 2009 at 9:46 AM
Ignore the “green” theme, is this a viable alternative? Og, your thoughts?
http://www.sdearthtimes.com/et0799/et0799s16.html
June 18th, 2009 at 10:18 AM
I’m not very scared of lead. I was in my thirties before I realized I should stop opening split-shot sinkers with my teeth. They have a pleasant flavor, especially when seasoned with salt water.
June 18th, 2009 at 10:22 AM
Not the safety aspect, but maybe the availability is better. The article also implied it is easier to machine.
June 18th, 2009 at 11:09 AM
My first machining experience was using a Unimat lathe we had at the Research Lab where I worked to build a little hobby steam engine from a kit they bought me to fool around with.
Of course not understand turning speeds and tool feed rates I ended up with a finished product that was so sloppy that it never ran on steam or compressed air.
I’ve made parts and misc BS in school machining class and on borrowed lathes and mills through the years but since I don’t own your garage and my shop is more wood working than metal working I’ve had to put off the desire to build one of these scale model radial piston engines:
http://www.agelessengines.com/
from their raw casting and stock kits.
Regarding steel stock, try talking to the metal fabricators (instead of the metal suppliers) in the area who should have tons of bits and pieces laying in bins and dumpsters to be shipped to recycling.
Most welding shops won’t bother fooling with something like bar stock less than 12″ long or sheet/plate less than 12″ square (unless it’s stainless or some other exotic alloy) because their plasma tables and other tooling isn’t set up to handle those small sizes.
June 18th, 2009 at 12:24 PM
Brass knobs are cast – at least the cheap ones (and the really cheap ones are brass-plated cast zamak).
Not only are they not made from the finest machining-alloys of brass, but they can be made from ingots rather than finely-formed precisely-sized rod stock.
Thus, they cost very little.
June 18th, 2009 at 5:44 PM
Virgil, I have never understood why hobby machinists insist on building engines, but I think it’s becoming clear to me. You have to have something to build, and an engine is as good as anything!
June 18th, 2009 at 7:47 PM
Hobbyists build engines because it is hard.
1/5″ diameter brass? Do you mean 1.5″ diameter?
June 18th, 2009 at 8:26 PM
Uh…NO. I just like really small knobs.
June 18th, 2009 at 10:53 PM
http://www.govliquidation.com/scrap.html?cm_mmc=CJ-_-Scrap-_-Sky-_-1&AID=10529071&PID=3449007
The downside is that you have to buy a whole lot (as in sale unit) of whatever, and supply your own truck. The upside is, this is the leftovers from whatever they did with everybody’s tax money. And by truck, this usually means an open top 40 footer. If you’re looking for 50 drums of assorted pistol brass, this could be the place for you.
June 19th, 2009 at 2:12 AM
Since screwing up that little steam engine kit I’ve made a couple of tools…machinist clamps… and a jack stand with an ACME screw in my college machining classes that gave me enough knowledge to want to do more than just making static parts.
I’ve designed and built and had built (by others) a bunch of brackets and thing-a-ma-bobs which worked and made a little money through the years but I’ve never personally taken a pile of metal squares and cylinders and turned and milled them into something which moved smoothly under on its own power. It was always just funny shaped metal blobs with a couple of threaded holes.
I think that making a “machine”, even something like a manual crank or lever system that actually DOES SOMETHING is the ultimate goal of being a machinist. If it is gas or diesel or steam powered all the better.
Guys are even making their own minature turbine model airplane engines all the time and it’s all I can do to keep from spending too much money on a kit and parts and a garage full of tools like you have just so I can hear the whine of a real turbine engine I built all by my lonesome.
You have the intellect and the time and the financing to do some really cool stuff with the equipment you have put together and if you ever again give an average Christmas or Birthday gift to someone important to you you’re not thinking.
Candle sticks, metal tumblers and shot glasses, coffee table doo dads like 3-d puzzels, yours is an infinite horizion of things you can make as you learn to master the craft of machining.
Imagine the guy that made the first lathe that was accurate enought to make another lathe that was even more accurate?
That question to me is almost as hard to understand as quantum physics.
Sort of a Chicken or Egg situation?
June 19th, 2009 at 2:19 AM
OH I forgot to mention…og…I think knobs for doll house cabinetry are currently bringing premium dollars.