Bog's Paddleduck Engine

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kvom:
I ground the tip off the tap and was able to get the threads deeper into the gland.

Unfortunately I discovered that one of the screws goes in slightly crooked, so I'm pretty sure that means a redo on that one. And then I screwed up the straight one milling the side flats, so that's a redo as well. :hammer: I think it's going to be preferable to mill the flats before parting off the screw, as then I can mount the rod in a 5c collet in the square collet block for milling.

I did find one more piece of brass big enough for a crank web, so now I have three - one to go.

kvom:
A little progress this afternoon:

Reading through the book I noticed that the valve packing gland is almost identical to the piston gland (flange is a bit smaller). So since the 1" round stock was still chucked in the lathe, I turned two of these. I left the flange diameters to be turned down when the boss for the bore is turned.

I found out that my class is cancelled for tonight, so I won't be able to get any more brass material until Thursday, unless UPS arrives with the 1/2" bar I ordered.

I decided I could make the plain pipe flange from the 1" round stock. I chucked the bar in the billing vise using v-blocks and cut the flats wide wide enough for two flanges. Then I chucked the bar in the lathe and drilled it assuming 1/4" pipe.

Then it was just a matter of turning it down to the correct diameter and parting off.

Looking at the photo it seems they're slighly unbalanced, but I can correct that when it's time to drill the mounting holes.

Given the larger size, I'm wondering if brass will be strong enough to make the long flanges. I may try to make a couple.

kvom:
Spent the evening making 4 identical packing gland screws. Mounted a 1/2" brass rod securely in the square collet block in the milling vise. This allowed me to mill flats on opposite sides for all 4 screws. The flats fit a 3/8" wrench.

Then I chucked the bar in the lathe and turned the OD to 15/32. Then for each screw:
- turn the end section to be threaded to .370" for 3/8-16 threads
- undercut the end of the threaded section at the head
- single point the threaded section on the lathe to a thread depth of .06"
- finish the thread form with a die
- test fit to a gland for good measure
- part off

Took about 1:15 for the 4 pieces

kvom:
After lookomng at the drawings and measurements once more, it looks as if the 1.5x goal has put me into the "expensive materials" category, as the block will be just over 3" long and 2" high. Trying to find brass with those dimensions doesn't appear straightforward.

I am thinking it should be possible to make two separate cylinder blocks. Any reason that won't work?

DavesWimshurst:
Kvom,
I'm building the same engine in approximate 1-1 scale with colonial imperial threads.
Perhaps cast iron for the block would be possible using 1 inch thick bar stock which is a little thin
http://www.mcmaster.com/#cast-ductile-iron/=1qzvag
or use brass or bronze liners in an aluminum block.
Dave

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