Search found 182 matches

by xo18thfa
Tue Mar 19, 2024 9:35 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

With the math done and verified, time to start on the eccentrics. The basic engine plan calls for the single eccentric or the slip eccentric collar be fixed to the crankshaft with a grub screw. Makes for an easy adjustment. The 5a Stevenson plan calls for the eccentric to be keyed to the crank. The ...
by xo18thfa
Fri Mar 15, 2024 4:26 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Today is the start of the Stevenson reverse for the Stuart 5a engine. The basic 5a engine plan includes two types of valve mechanisms. One is a single fixed eccentric, and the other is a slip eccentric. The plan for the Stevenson is sold separately. Stuart sells a casting kit for the Stevenson, but ...
by xo18thfa
Mon Mar 11, 2024 1:22 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

The valve chest, valve and valve spindle are next. I did not take a whole lot of pictures on this because it is all straightforward machine work. Nothing remarkable. The packing gland for the valve spindle is the same general design as the cylinder lower cover. It involves a ½” British Standard Pipe...
by xo18thfa
Wed Mar 06, 2024 5:57 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Back on the cylinder with some work on the portface. Use parallels to set the portface horizontal to the mill table as closely as possible. Cylinder 7.jpg Mill the portface clean and tap the bolt pattern for the valve chest. Cylinder 8.jpg And then there was trouble. There is a difference between 1....
by xo18thfa
Sat Feb 24, 2024 5:14 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Starting on the cylinder today. The Stuart 5a cylinder casting is wonderful. It is spot on in dimensions and is wonderful to machine. The steam ports and exhaust are right on dimension and very sharp. The cores are clean and uniform all the way thru. No work at all was needed on any of that. The fir...
by xo18thfa
Sat Feb 10, 2024 5:19 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Today are the top and bottom cylinder covers. These are a fairly straight forward turning process. The covers are cast iron, with no cast bosses to help in the turning process. However, there is enough material to grip during the machine steps. As with all the other castings, they are way over size ...
by xo18thfa
Sat Feb 10, 2024 4:20 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Hi apm. The crank rod itself was soldered together from ¾” diameter stock. The web pieces and wrist pin were turned to final dimensions. I covered the wrist pin in flux as much as possible to protect it from oxidation. After soldering, the crank rod was turned between a collet and center on the tail...
by xo18thfa
Wed Jan 24, 2024 5:47 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Thanks Andy. Gotta get busy. Next for the piston rod is get it between centers with the dividing head to shape the crosshead portion. Mill the crosshead to the final width on both sides. Piston Rod 6.jpg All of the nice-looking cast features on the crosshead are gone. Start profiling those shapes ba...
by xo18thfa
Mon Jan 15, 2024 12:11 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Hi Harold. That's what it must be. The chips from the rod have a bit of a curl. The other casting chips were dust and very messy.

Thanks, Bob
by xo18thfa
Fri Jan 12, 2024 7:45 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

The piston rod and crosshead are one single casting. As with many of the castings, this one is way oversized. The casting has a very nice profile, but it will all go away during machining. I’m not sure what Stuart uses for the connecting rod and the piston rod castings. It turns like some kind of st...
by xo18thfa
Wed Jan 03, 2024 9:44 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Thanks Jack. Today is a short update to finish the connecting rod. Round over the end of the con rod on the rotary table. Center the rotary table directly under the mill spindle. Clamp down a slab of aluminum and drill for a 3/8” pin. Secure the connecting rod on the pin and round over the end. Con ...
by xo18thfa
Tue Dec 26, 2023 9:43 pm
Forum: Build Log
Topic: Stuart Turner 5a Build
Replies: 48
Views: 203734

Re: Stuart Turner 5a Build

Going to get started on the connecting rod today. The connecting rod is a very oversized casting, fully half the mass machines away. As with most of the castings, there is no way to easily grip it for machining. So, the first step is adding a chucking spigot. Con Rod 1.jpg The spigot is a brass ball...