Steam engine (Tiny vertical w/reverse)

[gbritnell]

With a little polishing and fitting the rods fit nicely on their journals. I had made the crosshead and connecting screws so I assembled the parts to check the fits. Once all the parts are made they will be properly radiused and cleaned up.
gbritnell

[Don1966]

That is some awesome bit of work on the small scale. You just  keep inspiring me every time I read.
Now I have enough on my plate now and this is one I need to try. Thanks George for you continued photos and documentation.

Don

[zeeprogrammer]

Beautiful work George and as usual a thread full of excellent information.

Hope you don't mind a couple of questions...

You used a jeweler's saw to cut the cap off. Could this be done using a slitting saw in the lathe?
After cutting the cap off, did you (re)drill the holes in the cap?

Thanks

[b.lindsey]

It just keeps getting better and better George. Thanks for all the updates and excellent pictures.

Bill

[gbritnell]

Hi Zee,
When I cut the rod from the bar I used my bandsaw. This left an uneven surface. I then put the rod in the vise and squared it up. I then took a clean up cut on the end so that the surface would be finished and square to drill the holes for the screws. The lower end of the  rod was around .200 long at this point. It would be .15 when finished. After drilling through with the tap drill I counterbored with the clearance drill. With no good way to hold the rod to use a slitting saw to remove the cap I just used my hand jewelers saw and cut the .200 in the middle. Cleaning up the cap wasn't a problem. It needed to be .075 wide so I put a thin parallel in my vise that allowed .062 clamping surface and milled it to thickness. The rod on the other hand posed a problem. I couldn't clamp it on the wide surface because the yoke end is wider. I couldn't clamp it one the narrow surface because I was afraid that there wouldn't be enough friction and the part might move when milling. What I ended up doing was to take a piece of square brass bar, reaming a hole through it lengthwise, splitting it with a .015 slitting saw and then using it to clamp the shank part of the rod in the vise. I made sure that the end mill approached the rod from the narrow surface thinking that if I came in from the long edge there would be more leverage applied to the rod and it might twist in the little fixture block. It worked fine.
I apologize for not giving a more descriptive explanation but it takes a lot of time to make parts, take photos, edit photos and post the text and pictures so some of the machining steps are overly simplified.
gbritnell

[zeeprogrammer]

Thanks very much George. This was very helpful.
No need to apologize. I'd rather you keep doing what you're doing.

[NickG]

George, I didn't get the sense of the minute scale until you showed the coin! I would love to try one of these but think it's beyond my skills. I like the way you did the cylinder though, drilling the angled holes is always something that puts me off a bit - having them straight and milling a pocket makes more sense to me. 

Nick

[gbritnell]

Today I made the eccentrics. I reused the fixture block that I made for the crankshafts. I moved the set screw hole to the edge so that once set to the proper offset I could rotate the part without having to remove the block.
I turned and reamed the stock for the crankshaft diameter and the nose boss. I then offset the fixture block .032 (total of .064) in the 4 jaw chuck. The part blank was mounted and the set screw tightened on the first flat. (one flat for each eccentric offset). The first eccentric was turned to size.
The stock was then rotated to the other flat and the rear eccentric was cut with a small parting tool. The piece was then cut off the bar. The set screw hole will need to be drilled and tapped.
gbritnell

[gbritnell]

The 'D' valve was machined on the end of a piece of .25 round stock. I faced and center drilled the stock on the lathe. The recess is .031 deep so by putting the recess in with the center drill it kept me from having to plunge the .062 cutter into the stock.
The part was then indicated to center.
The first cutter was the .062 end mill. I went right to depth and walked around the inside cavity staying .004 away from the finished size.
The second cutter was the .031 end mill. It only needed to clean up the side walls and reduce the fillets in the corners. I have a high speed spindle for my mill but the setup time for a small job like this just isn't worth it. My mill will only spin 2600 rpm so a gentle touch was needed with this cutter.
The third cutter was a .125 end mill for qualifying the outside of the valve. The overall size of the valve is .175 square.
Once the part was milled the valve rod and set screw holes were put in.
The last picture shows the valve chest assembled on the cylinder.
gbritnell

[Don1966]

Looking good George, I am still following with interest here. I wish you would have put a penny next to the eccentric, it has got to be little. Making an engine of that scale has to work on the nerves. Don't you get some ???%# moments?

Don

[gbritnell]

There's good things and bad things about working in this size. The bad thing is the size. The good thing is the parts are so small that if you mess up something you just make another.
For instance. I had made 2 'D' valves. They have a .037 diameter hole for the valve rod and a 1.0mm tapped hole to secure the valve to the rod. While trying to make the small set screws to hold the valve to the rod I must have lost 3 of them. (.039 dia. x .07 long) It was then that I decided to open up the tapped hole to 0-80 because I have some stainless set screws that size. I drilled the threaded hole bigger by hand, stepping up to the tap size for the 0-80 thread. The first one went fine and when I started on the second valve I had one of those senior moments. The holes are so small that it was hard to tell the difference in them so when I started to open one of them up for the 0-80 tap I had picked the wrong hole. Time to make another valve!
I only have a few pieces remaining but the only part I'm cringing at is the final tapping. I have 2 - 1.0mm taps, high speed steel, 2 flute, one starter and one plug. The only place that I can find them is through Travers Tool and they're $32.00 each and it's not even so much the cost of replacing the tap it's having to make a new base if one snaps off.
gbritnell

[Jo]

George,

You have my sympathy, your taps are the same size as the 14BA's I have had the missfortune to have to use from time to time. Thankfully their use so far has been with success. When I use these small taps I use my pillar drill, with a pointed sprung loaded plunger, as a tapping guide and a very small flat light weight tap holder.

I also have some 16BA , which so far I have been able to avoid by using alternative fasteners.

Jo

[gbritnell]

Gentlemen,
I have the first of the two new engines finished. I found a few drawings disparities along the way, have fixed them and will be reposting the new files.
The engine runs well so the new owner should be pleased. I have taken a few pictures of the new along with the old from several different angles.
About 2 more hours and I should have the second engine finished.
Thanks for watching.
gbritnell

[Don1966]

George that is some superb craftsmanship. Thanks for sharing you work in progress with us. I loved the photos. They look great for being so small. All of the engine that I have seen of yours are superb in all respects.

Don

[gbritnell]

I finished up the third engine this morning. I thought I would take a picture of the trio before I send two of them off to a good home. One is already spoken for and the other is listed on Ebay.
gbritnell