Tuesday, January 29, 2008

Spoked Wheels

Today I'm in the process of machining some spokes cable sheaves for the steam shovel. The operations are similar whether your making a sheave, a gear, or a flywheel. I thought that those new to the hobby might be interested in the process. These are fairly small being 2 1/2" diameter and 3/8" thick. First rough blanks were sawed from some plate steel, then blued and laid out. Under size pilot holes were drilled at what would end up being corners. A hole was drilled and reamed in the center. It will eventually be fitted with a brass bushing. Then the blank was put on a mandrel where the O.D. and sides were turned in the lathe. On this particular job I drilled a 3/8" hole in the center of each space after turning, just to hog out some metal. I don't always do that. Then the part is moved to a three jaw chuck on a homemade rotary table on the milling machine. The circular arcs are milled by simply turning the table and leap frogging over the spokes. The sides of the spokes are milled by traversing the mill table, and indexing the table the proper number of degrees for each spoke. Spokes are nearly always tapered from the hub out to the rim. These sheaves have a 6 degree included taper. That needs to be taken into consideration when setting up, but is easy enough to do with the rotary table.

The first picture shows a sheave in the process of milling the spokes, and the second picture shows two sheaves. One after turning, but before milling, and the other one after the spokes have been milled. The spokes come out rectangular in shape, and the could be rounded of with a radius cutting mill, but it is hard to find a cutter the right size to fit those tiny spaces. So I just use a file, and within a couple minutes can have the corners rounded enough to look ok. The rounding is cosmetic anyway, so it does not matter if it is not perfect.
Try it you might like it.

Monday, January 28, 2008

Beam Engine

Although maybe not the most efficient design for a steam engine, beam engines are certainly interesting machines to watch running. Anything they lack in efficiency is more than made up in entertainment. The beam engine posted here today is a little more refined than the Coffee Engine that I posted yesterday. This engine very closely follows the Stuart Turner beam engine drawing, but I made my own patterns and castings, and that allowed me to add a few of my own embellishments.

For a simulated masonry base, I reworked a little cutter similar to a slitting saw. It was put in the mill on a extended mandrel and set at the height of a mortar joint, and then I slid the casting past the cutter by hand to scribe the joint. Then the elevation was changed to the next joint line, and so on. The vertical joints were chiseled in with a graver and a small hammer.
A flyball governor was an optional accessory on the Stuart engines and I had no drawing for that, so I simply designed my own. It works nicely, controlling the speed of the engine. I have it set a slow pace which makes it more realistic. Working from someone else's drawing is sometimes easier, but I spent over forty years working at a large metal fabrication and construction company, much of that time doing design engineering, so it comes quite naturally. The only difference between models and the real thing is simply size.

Half Beam Engine

After building the Beam Engine that I posted yesterday, I built a Half Beam engine. I have no idea why they call the half beam, because they still use the full beam. They have also been referred to a grasshopper engines because the action somewhat resembles a grasshopper leg. It only required making two new patterns. One for the A frame on top the cylinder and one for the rear beam support.

The brickwork for the foundation was cut in the same was as for the beam engine, only on this one, after the brick red paint had dried, it was sprayed with an off white paint and immediately wiped off with a rag. This left some white in the grooves and smeared a bit on the face which gave it a rustic aged appearance that I rather like.
An advantage of making your own patterns and pouring your own castings, is that you can make them unique to your own workshop as seen if you look closely at the rear beam support.
This engine does not have a governor.
Till next time

Steam shovel update

After setting nearly a month being dormant waiting for drawings to be made, and then followed by parts being cut and fabricated, my baby steam shovel sprouted a thing on the front late yesterday. I'm not sure just yet, but I think that means that it is going to be a boy one.

That is hardly a start on the boom, there is so much still left to do on it. In fact right it is now only being held up in place with a piece of wire. It needs to come off to be worked on some more, but I have to do things like that once in a while to spur my enthusiasm. Anyway Wes said he wanted to see a progress picture.

Ball Turner

A ball turner is kind of a unique accessory for your lathe. Most every machinist at one time or another will have a need to turn spherical shapes. The easiest way is with a ball turner. You can buy one, but they are simple enough to make yourself, and there are all kinds of instructions out there on building them. Usually the cutting tool travels in a circular arc in a horizontal plane or else in vertical plane along the centerline of the workpiece. I have built a couple of them, one quite large with a capacity of about 6" diameter and the other smaller, with maybe 2" diameter. I'll just show the small one today. I need to mention this is a demonstration picture. Normally when I'm turning ball ends I hold the work in one of those 5C collet chucks. That way I do not risk having the chuck jaws strike the ball turner, and cause all sorts of commotion.

On this one I used some features of a plan that I found, but modified it so that it would work on the quick change tool post. I have found it handy for making the balls for fly ball governors, ball ends for guard rail posts for railing around models, etc. One use was to form the ball ends on a helping hands work holding fixture for silver soldering.

For this demonstration picture I just clamped three pieces of brass and positioned them together. From here it would be a simple task to daub the joints with flux and silver solder it together. To assemble that same configuration without the fixture would be a difficult task.

By the way if you do not want to build your own helping hand fixture Harbor Freight has an in store coupon sale going on right now, till Feb. 11, for $1.97. (normally $3.99) It is smaller and does not have as many joints to move and position things as my home made one, but at that price I could not pass it up, even though I already had one. They also include a magnifying lens. Take that off attach a nice handle and do a little detective work on the side.

In closing I suppose a ball turner could be compared to a bull on the farm. It is not the amount of work it does to earn his keep, it's the occasional service it performs.

Table Engine

Here is a third engine that I built following Stuart guidelines for their series of models that use interchangeable parts. This one comes with several names too. Elmer Verburg built one and called it a mine engine. In the Stuart catalog it is referred to as a James Coombes engine, possibly because of the original builder or something. The table calling comes from the fact that the cylinder sets of a platform supported by four legs like a table. In the Stuart catalog it states that the original prototype engine had a 10" bore and 24" stroke, and produced 20 hp at 40 rpm. It also stated that it was used at a Bristol colliery for more than 100 years. Wow! How many machines now days last that long? A lot of people feel lucky if their car lasts long enough to get it paid off.

Most of my engines are painted gaudy contrasting colors, because it makes them so photogenic, but I figured ant engine that had spent 100 years working a a coal mine would be black. The color might be right, but it sure makes it hard to photograph so that you can see it properly.

There are at least three more engines in this series that I have not built yet. I have to compare myself with a young man on a big college campus with thousands of girls. There is simply no way that all of them can be pursued, You just have to make do with what ever number you can work into the schedule.


Unicycle Dude

At our place I try to have something of interest for every size and age of people folk, so why not a Unicycle Dude. The first picture shows a close up right after he was built. The second shows him on the high wire (cord) in one of the display buildings. One end of the cord is stationary, and the other fastened to a lever that moves up and down. That action causes his little legs to pedal that cycle as fast as he can back and forth across the building. He has pretty good sense of balance. He has only fallen of a couple times when someone bumped him.

What is not shown in the pictures is the mechanism that makes him go. Down on the wall is a little crank that is within easy reach of even little people. That crank is connected to gears and then a drive shaft up the wall to more gears and another crank and finally to the lever. You know, whatever it take to keep it mechanical. I'd post a picture, but that part does not photograph very well.

Lubricating sealed bearings

have devised a pretty slick way (pun intended) of lubricating sealed bearings. It is so simple and non destructive. The bearings are placed in a container just big enough to hold them. In this case, a little plastic cup. Oil is poured over them until they are completely submerged. Normally I use 90W gear oil. Then the cup is placed under the bell jar on the vacuum table, and a vacuum pulled which extracts the air. As you watch you can see the air being pulled out of the bearings and bubbling up through the oil. After a moment or so release the vacuum and oil will be sucked into the bearings to replace the missing air.

I've lubricated lots of bearings this way. Usually they get over filled so they leak a bit until the excess drains out, but that is ok. I've re-lubricated electric motor bearings that sounded like they were wore out. The bearings in my 50 plus year old table saw sounded like a grist mill until I lubed them. Now they are quiet as new ones. One time I ran onto some new-old stock bearings that had set on the shelf so long the grease had hardened rendering them useless. Some fresh oil to soften the grease and and they are ready to roll again.
Not every shop is equipped with a vacuum table and a bell jar, but something as simple as a 1/2 pint canning jar with a hose fitting soldered to the lid would work fine. There are lots of sources for vacuum, some people could even hook it up to their head. A vacuum cleaner would probably not draw enough. You need at least 15 inches. Those hand pumps that are used to bleed hydraulic brakes would work, there are aspirators available. Even condensing of steam in a closed chamber.
Play a little, you will have fun with it.


An easy quick way to build a lively little engine is by using a pneumatic cylinder. Air cylinders can often be found at flea markets and swap meets, etc. The Surplus Center in Lincoln Nebraska has bushels of them. This engine has a simple spool valve and is connected with plastic tubing. The crankshaft bearings are from roller blade wheels. Skate boards, roller blades, and those little aluminum scooters are all equipped with ball bearings, and the bearings usually outlast the treads on the wheels so they are a good source for little bearings for your engines.

Although the cylinder on this engine is not a Bimba brand, I named it that anyway. The Baby Bimba shown below does have a Bimba cylinder. In fact the factory decal is still on it

It is a real little hummer, with a 1/4" bore by 1/2" stroke. I sort of suspect that is the smallest cylinder that Bimba makes.

Wednesday, January 16, 2008

Grasshopper or Half Beam Engine

The engine above is a Grasshopper or Half Beam engine. The one to the right is a Beam engine, and the black one in the background is a Table engine. All three were built from Stuart drawings, and they share a lot of interchangeable parts. (Castings)

Sunday, January 13, 2008

more progress

Here are the latest photos.

Sunday, January 6, 2008

Steam shovel Platform

Birk just sent me this photo and says, "The past couple days I've been extending the platform on the steam shovel. It now has three times the area of the casting that supports the machinery. It is starting to look pretty big, and I have concluded that if the digger does not work I can remove the hoisting machinery and use the thing to haul hay. An image taken day before yesterday is attached. Since then I almost have the deck plates fitted and installed, but their installation has to be worked in with cutting holes for control rods, etc, so it goes slow."