Try to Contain Your Excitement

I keep learning things about tools. It’s astonishing how much there is to learn about using the few simple items I have in my garage. People who really know tools must have stores of knowledge comparable to engineers.

A week or two back I created a new handle for my blow gun. Then something happened that required me to switch a tool from one air compressor to the other, and I realized I had a male fitting on the end of one hose and a female fitting on the end of the other. I could not switch tools without switching the fittings on tools.

This one left me scratching my head. Surely there was a right way to do this. Everyone else uses male or female fittings, but not both.

I kept thinking about the pluses and minuses, and I realized female was the way to go. If you put a male fitting on the end of a hose, the compressor will discharge every time you remove a tool. A female fitting will have a valve in it that shuts the air off.

Here’s the question: why did I have a male fitting on one hose? I must have asked about the correct fitting a long time ago, when I got my first compressor. I must have had the right information. My best guess is that I installed a new hose, ran out of fittings, and used what I had. Then I forgot to get a new fitting.

Anyway, whatever the explanation is, here is the answer: put a female fitting with a swivel on the end of your air hose.

In researching this, I also got into the subject of different types of air fittings. I know of three types, offhand: automotive, industrial (I think it’s also called “mechanical”), and universal.

In the past, I never thought about the type of air fitting I was buying. I just assumed they were the same. Then I found out about the different types, and I had a new research project on my hands.

Which is the best kind? NO ONE KNOWS. People do whatever they want. Believe it or not, there are regional preferences. In some areas, you want automotive, because that’s what everyone else has. In other areas, you want industrial.

To make things worse, there are rarer types. Some are supposed to provide superior flow.

A guy on a forum provided a great solution to my problem: universal female coupler and industrial male couplers. A universal female coupler will work with all male couplers. I went to Home Depot last night and got me a universal female coupler.

The replacement hose I bought is a Flexzilla. I agonized about which brand to get, and finally I decided to give Flexzilla a try. It’s bright green, so if you step on it, it will be a choice and not a mistake. It has no memory (I can relate). It’s light. I like it. If I hadn’t gotten a Flexzilla, I would have gone with rubber. Poly is too stiff.

I found out that machining coolants are more complicated than I thought. When I started, I learned to use WD40 on aluminum and Ridgid threading oil on steel, and that was about it. The other day I picked up a fantastic indexable end mill from Shars (where low-budget machinists shop), and I found that the finish varied, so I started looking into the problem. That’s how I ended up reading about coolants.

First, let me say the cutter is great. The big gripe with indexable cutters (cutters with several carbide inserts in the end) is that they give poor finishes due to minor differences in the heights of the cutting surfaces. I cut a piece of mystery steel, and the first 75% of the performance gave me an astonishing silky surface. Better than I could ever get with an end mill. The problem is that the finish got worse after that.

I am not knocking the product. It proved it can do a great job. I recommend cheap Shars indexable end mills. I paid a little over $30 for a 2″ mill complete with three no-name inserts, and it works. Check prices on American indexable end mills and see why I’m so happy.

I was cutting with a light application of Ridgid oil, even though a lot of people don’t use oil with carbide and steel. I read up on it, and I found a couple of sites that said interesting things. First, coolants and lubricants may be counterproductive. Second, it may be possible to grind HSS tools for aluminum that require no lube at all. Two different subjects (aluminum and steel).

One site said that liquid coolants chill carbide edges as they land on them, causing tiny stress cracks. Then the edges break down prematurely. The site suggested that the wear you avoid by using coolant is outweighed by the damage the coolant does. It said something about commercial shops spending 16% of their machining budgets on cooling and only 3% on tooling, which suggests the coolants cost way too much.

I don’t know if it’s true. I plan to throw some steel on the mill and find out.

Another site said clearing chips was the most important part of preventing finish issues. That sounds likely to me. The part I was machining had little swirling scratches on it, and I know they weren’t caused by the inserts. I think they were caused by bits of metal caught under the inserts. If that’s true, then I can get a beautiful finish on steel simply by blowing air on parts as I cut. It will blast the chips out. I think the oil may have made the finish worse by making chips stick to the metal.

A company called Kool Mist makes little devices that blow a mist of air and coolant on parts as you cut. I’m thinking I may get one and omit the liquid. It would blow chips away from my cuts. I’m positive I don’t need anything other than a light squirt of WD40 for aluminum, and it may be that I don’t need any liquid at all on steel.

I read that stainless is too gummy to cut without coolant, so I guess you just have to accept that.

To get back to the HSS/aluminum thing, I find it hard to believe that it’s possible to machine aluminum dry. It’s impossible with carbide in a mill, because the aluminum welds itself to the cutter instantly. I’ve never tried HSS dry on a lathe, but you can get away with carbide, although the finish is bad if you don’t lubricate.

I’m wondering what kind of rake I need to machine aluminum dry with HSS. Maybe I can find the info online.

I don’t think I want to machine that way as a habit, because I love carbide. You don’t have to grind it. Grinding lathe cutters takes a long time. Carbide inserts last forever in aluminum, and you can get a very nice finish. If I start messing with additional HSS tools, I’ll want to get more tool holders, and they weigh about ten pounds each. I feel like HSS is an answer to a problem I don’t have.

Why did I get into this quest? Because I failed at fly-cutting. A machinist I respect told me to fly-cut with high RPM’s, so that’s what I did with my mystery block. The edge of the bit kept wearing down as I cut. I had forgotten this crucial information: he was referring to aluminum, not steel. When I finally did it right, I had to turn the mill at about 100 RPM, which is ridiculous, and the finish was not that great. The end mill flies through work, and the finish is superior. Done deal.

Remember the treadmill my neighbor threw out? Probably not. I have the motor out, and I may want to machine the shaft to take a new pulley. A forum guy warned me about a potential problem. He said that if you take the armature out of a permanent-magnet motor (like a treadmill motor), the magnets will instantly demagnetize, resulting in reduced performance. Like life wasn’t complicated enough. He said you have to put a piece of steel between the magnets when you take the armature out.

This led to more research, and I learned some stuff.

In the dank, dreary past, many magnets were made from an alloy called Alnico (aluminum, nickel, cobalt, iron). If you shake it too much, it loses magnetism. If you drop it, it loses magnetism. If you take an armature out of a motor with Alnico magnets, it loses magnetism. Engineers designed iron objects known as “keepers” to insert in motors to prevent demagnetization when motors (or similar devices) are disassembled.

I found a couple of sites that said that Alnico is history (unless you play the guitar). Now cheap magnets are made from barium-ferrite powder, which can be cast in useful shapes. Barium-ferrite is supposed to be way less snowflaky than Alnico. More than one website told me it does not require a keeper.

The motor I have almost certainly has barium-ferrite magnets, because the next step up is rare earth, and rare earth magnets cost a lot. So I should not need a keeper (not the magnet kind). But the forum guy claims he ruined three treadmill motors just by removing the armatures briefly. So now I’m thinking I should find a piece of pipe and make a keeper, just to avoid the issue.

My small belt grinder has an armature that has been removed, and it works fine. I asked some electronics nerds on a forum, and they claim no keeper is required.

My advice: if you take a treadmill motor apart, use a keeper. Maybe it’s unnecessary, but it definitely won’t hurt, and it will cost you nothing or about two bucks.

What else have I learned? Let’s see. Belt grinders are fine for grinding HSS bits, but the bench grinder is faster, and it’s probably cheaper. Belts wear out fast.

Deburring…I learned about deburring. This means the removal of sharp burrs from metal parts. I have a worn-out belt on my small belt grinder, and I’ve been using it for deburring. It’s fantastic. One or two five-second passes will put a beautiful soft edge on a part. Try it. Don’t even bother with files. They’re for losers.

That’s all the earth-shaking information I have at the moment. I’ll leave you with a video of a guy using an indexable end mill to make a giant steady rest.