Search found 183 matches
- Thu Mar 28, 2024 8:20 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
Re: Stuart Turner 5a Build
Time to machine the Stevenson eccentrics using the custom stub mandrel from last time. Chuck the stub mandrel in the four-jaw and center one of the eccentric lobe centers. Fix the eccentric blank to the stub a screw and washer. Turn the first eccentric to final dimension. Eccentric 7.jpg The key in ...
- Tue Mar 19, 2024 9:35 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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 ...
- Fri Mar 15, 2024 4:26 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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 ...
- Mon Mar 11, 2024 1:22 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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...
- Wed Mar 06, 2024 5:57 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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....
- Sat Feb 24, 2024 5:14 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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...
- Sat Feb 10, 2024 5:19 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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 ...
- Sat Feb 10, 2024 4:20 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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...
- Wed Jan 24, 2024 5:47 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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...
- Mon Jan 15, 2024 12:11 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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
Thanks, Bob
- Fri Jan 12, 2024 7:45 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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...
- Wed Jan 03, 2024 9:44 pm
- Forum: Build Log
- Topic: Stuart Turner 5a Build
- Replies: 50
- Views: 204154
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 ...