The Sabino Compound Engine

[RReid]

That really is beautifully executed Chris, very very well done! So which one of those guys is Steamer?

[crueby]

Chris--you have moved beyond mechanical models, and are now creating mechanical art. A totally awesome build, from beginning to end.---Brian

Thanks very much Brian!  This build did combine my engine and ship model hobbies, really had a lot of desire to get the little details in.

[crueby]

Wow - simply just stunning work and details - of corse, it being a Labour of Love, makes so much sense        

Per

 

[crueby]

That really is beautifully executed Chris, very very well done! So which one of those guys is Steamer?

Thanks Ron! 


They are Elfric and Bob. The  Steamer that I've referred to is the other forum member here, aka Dave, who was an engineer on the Sabino and gave me tons of information on the engine. I'd never reduce him to shop elf status, regardless of how much time he spends in his own shop on great engines.


 

[cnr6400]

Re the shop elves enjoying the "cruise" - I guess if you have enough Elfensteiner stubbies and Navy rum the lack of a lake river or sea becomes less critical to the event.....    

[Michael S.]

Hello Chris,
I am very impressed with the oil lines. I know what the pipes, no matter what size, always means work.
I like the machine a lot 👍.
It must be an experience for everyone to be able to marvel at this ship's steam engine in real life.

Michael

[crueby]

Hello Chris,
I am very impressed with the oil lines. I know what the pipes, no matter what size, always means work.
I like the machine a lot 👍.
It must be an experience for everyone to be able to marvel at this ship's steam engine in real life.

Michael

Thanks Michael - yeah, watching this engine in person as a little kid is to 'blame' for me being here building steam engines, I was hooked watching it puff away!

[crueby]

While waiting for the parts to show up in the mail (from tracking it looks like they have actually made it here to Rochester on time!) I took the time to make up something that I've wanted for a years but never got around to - a radius turning tool. Sherline makes one for their lathe, but I never really liked the look of the design, and I have also seen posts online of people who have used a boring head to make one, though the cutter geometry is a bit odd in that configuration. Wanting something that could use the same insert cutters that I use, I had the idea of rigging up a holder on the vertical rotary table on the mill.
Using the mill has the advantage of adjustability for the cutter position in each axis, and using the rotary table would allow nice smooth feeds around the arc rather than having to hand-hold/move a lever attached to the cutter head like most radius tools do. So, took a little time and drew up this in Fusion - the large disc represents a faceplate that would be attached to the center post on the rotary table, and the angled chunk represents the cut-off end of an indexable lathe tool (had some extras of those). The hieght of the tool holder is to allow the lathe chuck holding the part to clear the faceplate - wanted to be able to turn very small ball ends/arcs so the cutter has to be able to reach in close to the centerline of the chuck.


I made up the pieces from some 303 stainless bar stock left over on the shelf. One block is bolted from underneath to the faceplate, and has a notch taken out of the side to form a rail. The other block has a channel cut in it to fit over that rail and keep it from twisting, the other end has a 45 degree channel to hold the lathe tool. The slot in the bottom of the holder allows the holder to slide in and out to adjust the radius to be cut.
Then came the first trial run. I took a piece of 1/2" round bar, and used a parting tool to make a notch 1/2" from the end to give the cutter clearance to come around the center and keep going. The piece was chucked up on the mill, ready to line up the tool. First needed to adjust the height of the part and the position of the cutter - took a little back and forth adjusting. With the rotary table cranked around to put the cutter at the bottom, the mill table was moved to put the cutter on the center of the part, that should align the center of the rotary table with the center of the mill head.


Then backed the mill table off to the left so I could crank the rotary table 90 degrees to put the cutter up to the midpoint, moved the table back over to the right to put the cutter on the center of the part, and made two adjustments - moved the mill head up/down the column to put the center of the future ball on the center of the cutter, and moved the cutter in/out (by loosening the screw in that slot in the bottom of the holder) till it just touched the part.

Now, if I had made the tool holder with a screw adjustment for in/out like a boring head has, I could have started with the cutter farther out for the first few passes and gradually moved it in. Instead I started out with the mill table moved over to the left, started the motor, and slowly brought the mill table back to centerline while moving the rotary table through the arc - this knocked off the corners of the part and started to round it. Not ideal geometry for the cutter, but for soft brass it worked fine. For steel, on a large diameter, it would make sense to either do passes with the cutter moved out farther, or take off some of the excess on the lathe first. Here it is after the first couple of passes, moving the table a little to the right, making a pass with the rotary table, repeat...


and after getting all the way to centerline:

It took a few attempts, adjusting the cutter position and part height, the first attempts I had the tip of the cutter too far out, but got a decent result eventually. I like being able to make a slow even rotation through the arc with the cutter, gives a smoother finish than the ones I've watched videos of where the cutter was moved by hand with a long handle. Here is a wider shot of the setup:

and the ball end it produced

Overall pretty happy with how it works. One thing this setup doesn't allow for is to do a radius in the middle of a longer bar with the end supported, like could be done on the lathe with the tailstock. Also, to come around onto the shaft next to the ball does require the part to stick out from the chuck a little ways, but thats true of most radius cutters.
Anyway, a nice diversion, and a new tool added to the box!   

[cnr6400]

 

Nice addition to your custom tooling Chris!

[mklotz]

Additionally, that tool should allow you to form ogives, which were frequently used as terminators in early industrial designs.

This reference...

https://en.wikipedia.org/wiki/Nose_cone_design

covers many nose cone designs but also contains the equations for tangent and secant ogives, the most often seen types.

[crueby]

Additionally, that tool should allow you to form ogives, which were frequently used as terminators in early industrial designs.

This reference...

https://en.wikipedia.org/wiki/Nose_cone_design

covers many nose cone designs but also contains the equations for tangent and secant ogives, the most often seen types.

Ah, yes! That explains the first result I got, where the cutter was too far out and I got a stretched curve.   

[mklotz]

To turn true spheres the axis of rotation of the tool must intersect the axis of rotation of the workpiece.  If it does not, some form of an ogive will be generated.  If it does, the center of the resulting sphere will be at the point of intersection.  The equations I referenced allow the user to calculate the offset of these two axes as a function of the desired dimensions of the resulting nose cone/arrow head/etc.

[crueby]

Couple bits of good news. The pipe castings made it to the local post office this afternoon, will be delivered tomorrow. And things are going well for the next event at the logging museum in Maine in a couple weeks, so more fun driving Lombards.    Got a couple rc boat days this weekend too.  So, looks like I'll get the last pieces on the engine Monday, and wrap up the build. Wish there was a lot more to do on this one, been a great build!

[cnr6400]

 

Glad to hear the pony express got the castings within range!

Re the RC boats - hope the surface ones stay on the dry side of the water, and with the subs, everything that goes down comes back up! 

[crueby]

Glad to hear the pony express got the castings within range!

Re the RC boats - hope the surface ones stay on the dry side of the water, and with the subs, everything that goes down comes back up! 

Yeah, am happy that they got through the UPS to Post office depot in Ohio in a day, in the past I've seen it take two weeks.


The boat run tomorrow should be fun, its at a boat show, full size boats, down near the Curtis museum, which is an amazing place. Curtis was into lots of fun things, motorcycles, cars, boats, planes...