More work done on main bearings, cleaned up casting, drilled through 5.9mm as start for shaft and drilled mounting holes and drilled and tapped 8BA for bearing caps. Next job I found a tad scary as I had not done it before, was to use the vertical slide and a slitting saw to slice the caps off the block of bearings. I had to attack it from 3 different angles due to the boss on the slitting saw getting in the way, but got there in the end. Once all the 8BA bolts were in, the whole block was returned to the 4 jaw to be drilled to size ( 1/4 inch ). final operation was to slice off the individual bearings, again, a bit nerveracking as after the first one there was very little to hold on to, but all went off without disaster. I was going to knock off at that point, but couldn't resist finally attaching the bearings to the base, again, all went well, and they were fixed in place with 6BA bolts. The shaft was in the bearings all the time whilst fitting, so all is nicely in line, and once I have sent a long series reamer through, it should turn nicely.
Slitting the cap off
http://youtu.be/qadrC9Ukjk4http://youtu.be/G-y8_X0ffzcVery little to hold on to here
End result
Next job is the crankshaft , it is made from 1/4 dia silver steel with webs from 1/2 x 1/4 gauge plate, apologies for the photo quality, I forgot to charge the camera and had to use my phone.
So, first thing, marking out in the usual way, I made 1 'master' web and spotted through for the other thre, in the hope of getting 4 identical webs, it nearly worked, and luckily I was able to pass a reamer through all 4 while they were clamped together with a pin lining up the other set of 1/4 dia holes, so it worked out ok in the end. I will be assembling all the parts with Truloc 231 and pinning with 1/16th silver steel pins.
Master web marked out
All 4 spotted through from the master
The assembled webs were left overnight to cure and the rest of the shaft assembled earlier today. I set one throw in position and left for half an hour for the 'glue' to grab, then set it flat, supported on two pieces of tool steel across the crank pin and the shaft and set the other against an angle plate, again with a piece of tool steel as a spacer against the angle plate. I left it like that for an hour or so, then, (I couldn't resist it) assembled the embryo shaft onto the bed. I will cut the pieces of shaft out of the webs once all is pinned, which will be when the postman has fetched me some steel. Last thing, I turned up the flywheel, I may, however, fit a spoked one later....
2 complete throws
Assembling the crankshaft
Ta daaaaa, boom tish....
With the lathe now repaired, it is time to carry on with the Alpha Build. I mounted the crankshaft in the vertical slide, (big mistake) and commenced cutting away the pieces of shaft between the webs with the slitting saw, it was a bit springy, but with much care the first one was cut and I turned the job around and started on the second one, it was then it all went horribly wrong, the slitting saw dug in, the shaft bent, then broke, along with the slitting saw. Exit one crankshaft. Lesson learned, If in doubt don't, keep your eyes on the job, it all seemed to happen in slow motion, but what is done is done, so time to set to and make another. I decided to approach the webs a little differently this time, I was not entirely happy with mk 1 anyhow, I had shaped the webs on a linisher and made a bit of a pigs ear of it, so I decided to make a simple jig that would enable me to just turn a radius on the ends of the web, rather than having a complete semi circle. I cut 4 pieces of 1/4 x 1/2 steel, marked out and drilled the holes for the shaft and crank pins then made a fixture from a piece of 1" aluminium bar with 2 pins on which the blanks could be stacked, a slight dimple was made on the last blank for the live center to sit in and machined away the ends until there was a nice finished radius......
The destroyed crankshaft and 4 new embryo blanks..
The jig, loaded with blanks and ready to go....
Stack of nicely finished blanks...Along with mucky tea mug, tea just don't taste the same from a clean mug......
The newly assembled webs, they will sit until tomorrow to allow the glue to cure........
And finally, a short video of the proceedings.....
http://youtu.be/JHJaQg0bkXcNew crankshaft now finished, a much better job than the first effort. Now started on the steam block, This was bought to size in the vertical slide with a flycutter, ( forgot to photograph) The top and bottom (feet) were done in the 4 jaw, as trying to flycut in the vertical slide was decidedly dodgy, I could not hold it securely enough. The 4 jaw was not the ideal way either, but with care and light cuts, all was finished to a niecety.
The new webs
Setting up the Mk2 version
Done, all pinned and cleaned up....
Installed on bedplate, looks much better than the last one...
Machining the 'feet' on the central steam block....
Bringing to finished size....
.....
A bit more progress has been made, I have made the steam chest for the reversing valve, the port block and slide valve, relatively straight forward jobs, although a proper engineer would probably have me banished from the workshop for life, as I tend to work to marked lines sometimes, a bit like the woodworking fraternity, especially when I am on a lazy streak and can't be bothered with mental arithmetic. I have roughed out the two bottom cylinder covers made a start on the A framed and bored and faced the cylinders.
The roughed out cylinder covers
milling out the steam chest
Steam chest and port block
Making the little slide valve
Tha A frames were altogether a much trickier job, the machining notes say to grip them by the boss (about 5/16 long) and machine the inside face with a boring bar, taking care not to clout the tool with the feet. This did work, but I do have a little more metal to remove, so any suggestions for an alternative method would be well received. there was barely 1/4 inch clearence between the feet and the lathe bed.
The A frame casting in the chuck ready to go... ooerr missus, looks dodgy......
Phew,, done, without disaster
A short video of the proceedings.....
http://youtu.be/cyuQCmpbIbMFinally, the cylinders were made, all went well. They came as one casting, fo I faced the portface and the bosses that take the pivot springs while the casting was in 1 piece, then parted into two separate cylinders. These were then set up in the 4 jaw chuck, drilled, bored and faced. I got some excellent tips from one of Keith Appletons videos on You Tube on boring cylinders, including taking the final facing cut with the boring bar to ensure the face was at 90 degrees to the bore. Finally, I made a mandrel to hold the job whilst it was bought to final length and faced off.
Facing the port block on the cylinders before splitting.
Initial drilling of cylinder casting, I used three different sizes of drill before the boring bar...
Final sizing on mandrel.....
An almost identical pair of cylinders The bores differ in size by about 8 thou, I had to make a minute adjustment to the mandrel to get the second cylinder to fit.
Boring.......
https://www.youtube.com/watch?v=uzuDx79M6y8Facing...
https://www.youtube.com/watch?v=rwxslPGWxbwThanks for looking....... :) :)
And rest......