The .444 Magnum Oscillating Engine

I got tired of cutting clock wheeels and badly needed a vactaion sooo....

One of the first projects the beginning "model Engineer" does is an oscillating engine. These are very simple engines, where the cylinder oscillates back and forth to expose the intake and exhaust ports. A complete video of a build of an "Ossie" (as these things are called) engine will be found on Emma Ritson's channel on YouTube, if you want  to see a blow-by-blow description.

What had been holding me up was the lack of suitable material to build the cylinder.  But I found, still at Chalupy (which has probably burned to the ground by now, there is  huge forest fire there) an expended .444 Marlin cartridge  case. This is cylindrical, no necking at all, so it seemed like a possible candidate. A test with calipers yields 10.47 mm and the drawings call for 10mm. Close enough. In this build I have followed Mr Stan Bray's book, "Simple Steam Engines" and I must say both the words and the music (drawings and instructions) leave something to be desired.

Anyway, while I was at it I built a finger plate. This is a gadget to hold things down while you drill or otherwise machine them. It is a piece of aluminum with holes drilled in them. I got the idea from Clickspring's Channel on YouTube. It has a 45 deg  groove in it, which I did by tilting the block 45 deg in the vise and using an end mill.

So, a bit of Aluminum later, we have a finger block.

Next thing to so is to mark put the port face, which will be soldered to the cylinder. [In retrospect, I should have not done this. I should have bored out the cylinder and made the piston fit it. I also should have drilled the pivot, but not the port hole. I plead just following directions in the book.]
You see the finger plate in action.

So next we solder the cylinder to the port block. This went very well.

I turned a rod out of a Dremel tool shank. These need to be turned down to 3mm and threaded. They are around 3.2 mm so it is delicate. The only 3mm tap and die set I have happens to be M3x0.5 so that's what it got. Both ends. This is the pivot shaft; the pivot will rock about this.

Next job is the frame. I took some pains to line it up. It is very fortunate that Ossies are very forgiving.

Then I drilled the port hole intake and exhaust ports. They are tiny, about 1.5 mm. Then I made some more little fiddly parts (go see Emma's video) And  then I discovered the holes would not line up. In fact the piston would not go in all the way. I soldered the original port block hole up.




So I had to bore out the cylinder. Of course. It is an expended cartridge. Who knows what egg-shaped sections lurk in the heart of an expended cartridge? Had I done this in the first place, I would have saved a lot of time. In a limp excuse, brass is unobtainium in Alaska, except for cartridger, expended of course. The problem was indicating it. Because the port block has already been soldered I canonly indicate 2/3 of the diameter. I put up the 4-jaw chuck and did what I could.

So I turned a piston and voila, Marlon the .444 Magnum repurposed.

Still not right. Of course. The original called for a much thicker port block than I have. The piston was too short and the port holes would not line up. So I turned a new piston. Here is Version 0.2.

BTW Cecil B. De Mille is excellent for spacing accurately placed holes.

 Today I drilled the hole in the port block. It seems to work.

So here we are. I will return, I hope.

Steady Rest, some more

I have been away in Anchorage for the last two weeks. Although I can post from there, the laptop I use drives me to distraction. Most of this is caused by the touchpad cursor; I suppose I could do something about that -- but the laptop also runs Ubuntu Linux, which I hate. Just me. I could fix all these things, but I don't feel it's worth the effort.

While I was in Anch I did some carving, a pleasant change from machine work. That's a future post. I would like to record progress on my steady rest.  All of it before I left for Anchorage.

I finished milling the dovetail slides and for improvised cutting setup it was a very good fit. I was pleased. I will have to drill and tap some holes for fixing screws, but that comes later.



 Next picture: the body of the steady. It will be screwed to the dovetailed piece.This is just drill and tap. I will not show it.

Now comes the really crucial step. I must put a great big hole (25mm) in the vertical plate. The center of the hole must be exactly at center height on the lathe. Once  you get the hole drilled, the center is gone! So I put a sharp point in the lathe chuck, and located the centerpoint by tapping the work with a hammer. That is center height. (The nominal height is 2.5" or about 62mm, but it is not advisable to rely on this.). we have a centerpunch mark. Right where it belongs.

So we can drill a pilot hole on the punch mark.  Now if I could chuck this in the lathe I'd be in clover. I could bore it out with a boring bar. But the upright will not "swing" in the lathe. Obviously -- it is at center height. So we will have to mill it out. The big boys do this on a rotary table. I have no such animal. It costs almost as much as the mill! So instead I built a fixture.

 Somewhere on my walks I found a very heavy piece of steel; whence it comes I know not. But I drilled my work something like 6mm and also my fixture, more or less in the middle. I pushed the work on to the pin. Then I could rotate the work around the pin, with my hand. So the cutter cuts a circle. Keep increasing the Z axis till you go through. This is definitely the pauper's rotary table! But it works. As Tom Lipton says, "we're all heroes in Aluminum".

After this, all that remains is to screw the upright back on, drill and tap the fixing screws, and make the fingers. 

Bought some aluminum to make the fingers. Haven't done a thing yet; busy carving. At least next post will be a relief from all this machining.We'll be doing some carving in wood for a change.

Milling around

 Looking at my labels I am surprised I don't have a label for "milling." But I do have a label for "Proxxon mill". The only mill I have, in fact. A mill holds the work still, and a cutter revolves. In a lathe it is the other way around. Both are very useful in my miniature machine shop. I have been milling (and turning) for quite a few days now, in fact is quite an obsession. My first attempts at milling have been documented. But now I want to cut flutes on the clamp bolts on my digital indicator stand.Ideally, in machinespeak, these would be knurled on the lathe. But I don't have a knurling wheel set.

 
 Instead, I took a  hint from Tom Lipton's oxtool videos and cut flutes instead. Very nice. I decided to use 8 flutes. This required making the fixture shown above. A square piece of aluminum. I scribed one line at 45 deg. By simply flipping the fixture around I can cut four flutes. Then I carefully align any one of the flutes I just cut. And I then, by flipping, cut four more flutes. My steampunk dial indicator stand is really beautiful now. And I can adjust it with my fingers. Should have a pic of it, but omitted to get one.

However, today I decided to make a fly cutter for the mill. I had a piece of very nice steel, taken from a defunct printer. It made the clamp bolts. Now I want to make a fly cutter out of the rest of it. A fly cutter is used to level out rough surfaces. I did some internet research. There is always myfordboy to the rescue. Another good reference is Dean. From these two references, I extracted the fact that a fly cutter must be angled to the work. I picked 45 deg per myfordboy. OK, I have this piece of 13mm (more or less) round bar, and I have to drill a 45 deg hole in it. How do I do this? I spent the entire morning working this out. I am no professional machinist! I finally cobbled up the setup shown below.

  
I held the round in the vise.  It is pure serendipity that the Taig milling vise (Imperial) fits the Proxxon mill (metric).  I propped it the round bar on a step block kindly provided by Proxxon. Thanks Proxxon! I packed things up with stray aluminum scrap and it all worked, a miracle because the mill is metric and the rest of it is all Imperial. But Aluminum has a bit of squish in it, so the thing was well held.

Next problem is to drill the hole. Were you to simply bear down with the drill, it would skitter all over the place. This is not wood, it is metal. So I had previously made a 2mm or so end mill out of a broken drill. Ground it to shape. I ran this end mill so it made a little step in the round bar. The step gives the drill something to bite into. So I went through with a small drill and then a 3.2 mm drill (0.125") which is a collet size I have -- standard Dremel size shank. I had very carefully drawn out the thing to scale, a very good idea.

Next step was to turn down the shank to something that would fit a 3.2 mm collet. Straightforward turning. Now I have to make a setsrew hole in the thing to hold the cutter bit. Not to mention grind the cutter bit itself! That's another day's post.

Now I have to figure out how to get a setscrew in there to hold the cutter bit down. Later.