Day of casting

One of my nephews and my kids and I got to visit Birk the other day and he showed us the ropes of casting aluminum. It was a great afternoon. Here are some photos and video of the day.

Thanks Birk!!
Guy









You can also see the final results of one of the castings here: http://maxbuilds.blogspot.com/2008/06/little-engine.html

Corrugated Roofing

The steam shovel model has progressed to a point where it could have its corrugated roofing installed. But where do you find "scale" roofing?
Make it of course.

Forming roll dies were machined for a hand cranked Chinese built beading machine with an 18" throat. At first it would not work very well because it was not rigid enough and flexed. However machining some of the ridges off the rolls it works much better, as can be seen by the sample tested.

The metal being formed was salvaged from the side of a discarded clothes drier. That is a good source of material. I use it all the time. Now I can proceed and form the roof, and the machine has enough throat that I believe I can do it in one piece if I start at the center and work both ways.
After I showed the sample piece to a friend, he suggested that I could start manufacturing scrubbing boards. That is real good advice, except 100 years too late.
Birk

Spark Plug Boot

This is not my invention, I read about it a number of years ago in some publication, but it is so simple and easy and looks good.
Machine a brass cap to snug fit on the spark plug cap and solder your spark plug wire to it. Slip a small O-ring on the wire, and a larger one on the brass cap near the open end. Plug the opening in the cap and dip the thing in that rubber like compound that you dip plier handles into for grips. You can dip a couple times to build up as desired. Then with a knife trim the hardened dip around the plug and and pull it out, you have your very own custom boot.
Birk

Boiler Boring

Several days ago I started work on the boiler for the model steam shovel. It needed to be 5" diameter to be scale size, and I was able to find a piece of 5" seamless tubing down at the plant where I use to work. Real good stuff. Only the wall was so thick it about broke my arm to pick it up. It would probably withstand several thousand pounds per square inch internal pressure which was also a bit more than I needed, so I decided to bore it out until I had a more reasonable wall thickness and get rid of some of the weight. My standard steady rest would not accommodate the 5" diameter so I rigged up a Rube Goldberg type steady rest from some pieces of flat bar stock that was laying around. I did not even cut the pieces to length. For contact supports I used skate board bearings. (Those kids will learn not to leave their skate boards laying around unattended)



The bottom ends of the bars are bolted to a 3/4" plate that is clamped to the bed, but as you can see the upper ends are just clamped together with some sturdy C-clamps. The boring bar was only long enough to reach half way through, and when this picture was taken one end had already been bored out and the boiler tube flipped end for end and a couple passes had been made in the second end. The whole operation went very smoothly from start to finish, and the thing has been tore down and put back on the metals rack.
It is such a simple thing that I hesitate even posting it, but perhaps someone will pick up and idea that they can use sometime.
Birk

More Rivets

I better bring you up to date on the model steam shovel. As of today I have the bucket complete and operational. I put lots of rivets in it. Hopefully the same number as in the original. Oh!, and it has teeth too. It is always exciting when babies get teeth.


That almost finishes the "shovel" end of the machine, Now I need to move back towards the rear and work on the "Steaming" end.


Rivets really set a model off, and I install a lot of them. There are dozens in that bucket alone. Rarely do I ever set one with a hammer. I always use a rivet press. It is so much faster, and easier, and I end up with a nice looking head on both ends. Shown below is my assortment of rivet presses.


The red one is a commercially built one that my dad once used on the farm on his mowing machines. It will easily squeeze a 3/16" rivet. The gray one is one that I made out of 3/4" plate steel to install 1/8" rivets in the frame of a model steam roller, and I also used it to rivet the frame for the Steam Shovel shown above. The tiny little press was used to install hundreds of rivets in that Hay Press and a model Manure Spreader. For those rivets, snipped off 19 gage wire brads were used. They are about .035" diameter. They have heads that look like finishing nails, until after they are pressed and then they look like rivet heads. The press with the deep throat was made just last Friday, specifically to rivet the bucket together. For that I used 3/32" rivets.
All the presses have cups in the anvil and screw the shape of the head. If it is desired to change the shape of the head, just change the shape of the cup. For screws I use square head set screws or socket head screws because they are a little harder than a regular bolt. The last two presses I used a piece of tool steel for the anvil. That makes changing the shape very simple.
If pressing rivets seems a little strange, dig out your century old history books and see how they did it. Yes, they used jack hammers sometimes, but where ever it was feasible they used a press, big ones!
Birk

Machining Helical Gears

A little over a year ago I built a scale model Gatling gun. For this project I needed a pair of helical gears. They could have been purchased from a bearing supply house, but there is not much satisfaction in buying something that someone else has made when you can do it yourself.
If you think about it, a helical gear is a short section of a vary course pitch screw with multiple leads; as many leads, as teeth in the gear. Theoretically you could machine a helical gear in a lathe, but actual practice and theory do not always coincide. However if you set up a work holding spindle on the mill table, that represents the lathe spindle, and gear it to the table traversing screw, that represents the lathe lead screw, the theory works great. By the way I did not invent this idea, I just adapted what others had already done to my own mill.



A bracket was built and several gears machined that will remain a permanent part of the fixture. Note that I even installed reversing gears, just like on a lathe, so it will machine both right and left hand helix. Then change gears are needed in order to get the proper ratios, and I just used the gears from an old antique lathe in my collection. It took an extra pair of reduction gears more than used on a lathe, but that was worked in too. When it was all put together the counterbalance knob on the regular mill handle hit the gears so I had to make a new different shaped handle.



To figure the ratio, you need to determine how far the mill table would have to travel for the work piece to rotate one revolution. Then divide the the table screw pitch (mine is .200") into that, and that is your ratio. Simple as that, well almost. The gear I was machining was specified as 1" pitch diameter, therefore the long travel at 45 degrees would be equal to one times pi. Now pi is not a very nice number to try and factor into a nice ratio. I had several choices. I could machine a couple more change gears of the desired ratio for a one time use. I could change the helix angle slightly so the long travel would come out to a nice even number, or I could change the pitch diameter to make the long travel come out even. I chose the latter, as it only required changing the pitch diameter by a few thousandths of an inch. (I cannot remember for sure, but it was about .015") The housing holding the gears had not been made and so when I got to that part it was only a matter of spacing the center distance of the gears a few thousandths different than what the drawing specified.




The mill head was tilted to get the cutter in the same plane as the helix. I used a hand ground one tooth cutter for this job. The big work holding spindle drive gear had a multiple number of teeth of the blank I was working on. One grove was cut, Then the gear train carefully loosened and the big gear turned the proper number of teeth and re-engaged, and the next grove cut, and so on.



The last picture shows the gears after I finished cutting all the teeth. The gears were installed in the gun and it functions beautifully.

Now I have the means to pursue one of those little side shaft engines that I have wished for, for so many years.
Give it a try, you might surprise the heck out of yourself what you can do.
Birk

Cutting Gears

This morning I went out and machined the teeth on a couple pinions. This is the last two of twenty three gears required for the model steam shovel presently under construction. These two will work in unison to push the dipper stick out and in.

I do not know how many viewers of this blog machine their own gears, but it is not a difficult task. When you look at all the charts, tables, math, etc. it is scary. But I have taken the attitude that if the early settlers could make working gears for their grist mills and sawmills, etc. by pounding pegs in a log, then shame on me if I cannot make a gear on my milling machine. Over time I have collected a few commercial gear cutters, and they are nice, but most of the time I do not have the right one and end up grinding a lathe tool bit for a single tooth cutter. You can use a gear of the same pitch and very near the same number of teeth as a template to fit the cutter bit to. Most often I make a layout using the drafting table, and grind a bit to fit my layout. The small paint brush is wetted with cutting oil and held next to the cutter so the bit wipes through the brush providing a film of lubrication each round. It is a lot cleaner than a flood system, for such little jobs.
Birk

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.
Birk

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.
Birk

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.
Birk