I managed to get a little bit more time in the shop today, so I made some progress.
The first part of the day was just spent turning and facing brass, and better understanding tool grind details, spindle speeds and feeds, and how they relate to finish.
After a little practice / playing about, I decided to tackle the wobble plate and collar.
These are two simple parts - a 1" diameter disc, which sits at an angle on a simple brass collar. Per Elmers guidance, I made the plate first, and then made the collar to suit.
I had some 1 1/8 brass in stock, so I faced off and turned the OD first.
With that done, I drilled the through hole.
I didn't worry overly about what hole diameter I ended up with, since I knew I was going to turn the OD of the mating part to suit. All I mean there is that I did not feel the need to set up and bore the hole to a close tolerance.
I parted the disc off, and must say I was happy with the finish on side 1 (which I faced earlier).
Oh dear - but not so happy with the finish of the parted side.
I suspect that if I had ground a better relief angle on the parting tool, I could have parted it to the right width, and got a decent finish too. Lesson learned.
Anyway, I decided to try and save the part, since it was on the thick side. I made a simple expanding collet from a piece of leftover brass. It is simply a piece of brass, with a shoulder turned on it to match the ID of the disc. Then, I drilled through and tapped M6 (because that was the size of countersunk screw I had handy), then counterbored, and then countersunk the ID. I then cut (with a hacksaw - quick and easy, but it did the job) 2 slots, to allow the part to expand when the screw was tightened.
Of course, I had to dress the shoulder up to true it, so I'd have been better off not machining the shoulder until this point, but no matter.
The result is this fairly brutal fixture. I had to turn the OD of the screw slightly so that it would fit through the collar hole. No big deal.
With that done, I could mount the wobble plate.
The fixture worked a treat. Admittedly, this is somewhat making mountain out of a molehill, but I saved the part, and learned some stuff. It's all good. I turned the plate to the right thickness, and all was well with the world.
It is a pretty ugly, tarshled screw. I usually throw those out - I'm surprised it was in my odds and ends screw jar, but it did the job.
Next I made the collar. It is a simple part - so not too many pictures here. Basically, the trick is to machine it close to the diameter of the ID of the wobble plate, and then take small finish cuts off the OD, test fitting the plate, until you can get the plate to sit firmly at the correct angle. I suppose I could have done the trigonometry to calculate the required diameter, or even laid it out on CAD (which I know would have met with disapproval), but in the end taking light cuts until the correct fit is achieved works perfectly well.
After that, I parted the collar to length, and added a threaded hole (4-40 rather than the 3-48 on the plans - because I have 4-40 grub screws in stock).
You can see the little remnants of blue that I used to help mark the hole position - that will clean off when I prep the parts for soldering.
Next up - the cylinder.
The plans show a plain brass cylinder, soldered to the cylinder head, of 0.5" OD and .375" ID.
I saw someone somewhere add some fins, just for aesthetics, and I thought that was a splendid idea, so I followed suit. I increased the OD to 0.625", and then cut some grooves, about 0.1" wide, leaving fins of 0.05". The fins should come flush against the side plate, I should not need to increase the length of the valve or the crankshaft to match it - although that is another valid option.
First cuts:
A little further...........
Most of the fins done
After the fins were all machines, and the edges lightly chamfered to remove burrs, I drilled and reamed the bore to 3/8. Then I cleaned up the end, and parted off the cylinder.
The cylinder just needs deburring at the parted end, and then a light face to length, and it is complete, and ready for soldering to the cylinder head once that is made.
Here are the parts so far:
Plenty to do yet, but I am 5 for 5 so far - no scrap on this project yet!
Tomorrow - perhaps the cylinder head and piston. I'll see how I feel.