I Know Why Your Vacuum Cleaner Died

The machining adventures continue.

I’m trying to make a follow rest for my old Clausing beater lathe. I want to get a bigger (or at least better) lathe, but while I have this one, I’m making the best of it. I’ve seen people say a steady rest is more important than a follow rest, but so far, I’ve never needed a steady rest, but I’ve been bitten in the butt by the lack of a follow rest. Without one, it’s very hard to turn anything long and thin, and that kills a big percentage of the projects I want to do.

A steady rest provides a sturdy support for a big, long, rotating object which extends way past the spindle. Sometimes you can use a live center for this without a steady rest, but sometimes you can’t. I think. I don’t need to turn long, heavy objects. At least not yet.

I’ve been watching my lathe videos this week, and the guy who made them uses a 17″ South Bend with a 3″ spindle hole. I think he bought it because he’s a motorhead. He runs a place called Precision Measurement Supply, in San Antonio, and he sells products for other motorheads. He says he can put a driveshaft through the spindle of his lathe. That’s pretty cool.

Naturally, whenever I look at a lathe now, I think the spindle bore is too small.

My lathe has two flat spots on the saddle between the tool post and the spindle. Each one has what appears to be a 5/16″ threaded hole in it, so at some point, somebody must have anticipated mounting something there. It happens to be the perfect place for a follow rest. The holes are almost 9″ apart, so I’m bridging them with a 10″ bar of aluminum, and I’m going to find some way to put the follow rest on it.

I had a hell of a time (sorry, Christians) getting the bar ready. Back before I knew anything about cutting metal from raw stock, I got some good deals on “drops,” or spare pieces of metal, from a big metal retailer. I bought an aluminum four-by-four, if you can believe it. It was something like 3 feet long. I figured I’d slice it up in a hurry with my dry cut saw, but for some reason I no longer recall, I decided not to do that. I got myself one of those infamous 4 x 6 horizontal bandsaws. Mine came from Northern Tool, but it’s probably just like the Harbor Freight jobs. It looks like they made it on the shift that started on the morning after the Chinese New Year. Pretty sloppy. But it works.

It has always been very temperamental, so I leave the cutting speed low, and I fiddle with it a lot. I decided to use it to cut a 10″ length of aluminum four-by-four, and the blade kept popping off. I got it to stay on, and I made the cutting pressure very light so the saw would stop throwing up. That made the cut take forever, and that made the motor got hot. Well…bad workmanship made the motor get hot. You should be able to run it all day, but it died after an hour or so.

Oh, the misery I went through, getting the saw to work again. I finally learned that it had a thermal fuse inside the motor housing. This is like a little resistor, and it burns up at 268° F, I believe. Let’s see…128 C…262.4° F? Is that right? Too lazy to check. Anyhow, these things are so cheap, they don’t reset, and nobody wants you to know they exist, because if you think the motor is fried, you’ll buy a new saw. Other AC motors have these things, too, so if your vacuum cleaner dies, open it up and look. You have to go to Radio Shack and spend $1.79 on a new thermal fuse (or “cutoff”), and then you have to solder it in where the old one was, WITHOUT getting it so hot it blows again. Don’t ask me how I know.

I got the saw running again, and it blew after 40 minutes of running with no load. I did all kinds of research on things that make motors hot, and I think I know what’s happening.

Typical electric motors have bearings at each end. At one end, they have a bearing which is fixed rigidly in the motor housing. At the other end, they have a bearing which is supposed to be snugly inserted yet able to move when heat makes things expand. My motor, in spite of being made by the finest Chinese prison laborers, had a very tight fit on the bearing that should have been able to move. I think this caused the other bearing to get pulled out of whack. It was proud in the endbell, to put it in engineerese. I’m guessing here, but I suspect that misaligned bearings or bearings under the wrong kind of pressure can make a motor hot even though they don’t resist rotation all that much. Anyway, I can’t find anything else wrong with it. I may open it up and relieve the endbell’s surface with sandpaper. I found some experts yapping about it on a forum, and they claimed you could have .010″ of clearance between the endbell and the bearing without causing it to rot the endbell, as some others claim it will do.

Here’s a digression. I’m considering getting a surplus 3-phase motor and wiring it up to one of my existing machine tool VFDs. I realized I can run more than one motor from a VFD, and since my VFDs are bigger than 1 HP, they’ll be big enough to run anything I put on the saw. I can put a switch on the wall, selecting a machine tool or the saw. Pretty neat.

I got the saw to cut the four-by-four, and I faced it on the mill, but then I had to cut out a piece about 1.5″ on a side and 10″ long. I considered using the table saw, but I chickened out and used a big end mill. Man, what a job. It took something like an hour, and I made piles of chips. I Googled around and saw that knowledgeable people weren’t afraid of using table saws on aluminum, so I got out the WD40 and the featherboards and went to town.

It’s amazing how well a table saw will cut aluminum. I was done in five minutes, and I’m slow. The cut was beautiful, I didn’t waste nearly as much metal, the chips vacuumed up in a few seconds, and the cut was so straight it was within a thousandth or so of perfect. Incredible.

From now on, the table saw will be my first choice for aluminum. I have plenty of surplus triple-chipped Corian blades, and my time is worth something, believe it or not.

Here’s the aluminum after I cut it out.

After that, I used the mill to make it pretty. Here it is, as of last night.

Today I used a radiusing end mill to round it off and make it even prettier. I hate this end mill, because the manufacturer gives you no clues on how to locate it on the work, but if you bump the outside of the fat part, set the DRO, and then go in about .125″, you’ll be close enough for government work. Once you get the z measurement dialed in, you lock the quill and worry about the x and y.

I keep looking at lathes. There are some real deals out there. A guy who sold me some mill tooling had a beautiful Clausing 8015VS 13 by 50 on his site for a price which escapes me. Under ten thousand. It looked brand new. He also had a Chin Hung 16 by 67 for a similar price. Both of these things looked unused. I would never consider a lathe that big under ordinary circumstances, but the clean paint and unscarred ways made my heart thump. I started measuring in the garage. Thank God, after I emailed him, he took the Clausing off his site. I guess it’s sold.

I could put the Chin Hung in my garage, amazingly. But it’s just insane. It’s about 110″ long and 40″ wide.

It’s a wonderful machine. Tons of speeds, great rigidity, and quality construction. The same lathes are sold under the Kingston name.

I’ll try to forget I saw it. But it sure is beautiful.

I am starting to think I need a tool post grinder. Because they’re cool. My lathe DVDs feature a tool post grinder segment. You can use these things to put perfectly round points on things like scribers and centers. You KNOW I can’t live without that. Come on.

I highly recommend the DVDs. The series is called “Lathe Learnin’.” They run $125. I think Smartflix has them, but I don’t believe in stealing intellectual property, so I don’t keep copies of rented DVDs. I wanted something I could keep and watch over and over.

Some DVD machinists are extremely fastidious. Rudy Kouhoupt is an example. He must be the best machinist who ever lived, because I was watching one of his disks today, and I think I’m about 20 minutes into the discussion of punches. Seriously, I know every type of punch, and I know exactly how to sharpen them, and the video isn’t even about punches. He did a video in which he ground lathe tools, and before he even got started, he milled out a special adjustable grinding table with a sliding rest.

The problem with the super-persnickety machinists is that they will teach you to sit on your butt doing nothing, unless you can do everything perfectly. The Lathe Learnin’ guy is the other type of machinist. His motto ought to be, “OPEN A BEER AND GO FOR IT,” because all he cares about is getting it done. He shows you all the tricks a real machinist will use when he has deadlines to meet, customers to please, and less than twenty million dollars in tooling financing.

I tend to get caught up in trying to do things too well, so his approach is really helpful.

I want to finish that follow rest, but the mill power feed has gone nuts again. Something funny is happening inside it. I better call the importer and see what they can tell me.

Anyway, I feel like I’m finally getting somewhere with my tools. It’s a great feeling. God really does give you the desires of your heart, once you agree to do things his way.