Gallery, Projects and General > Project Logs
The Return of No. 83, a Hot Air Engine
vtsteam:
Here's a pic of the old milling attachment with the new spindle on the homemade lathe. The milling attachment can be used this way with work held in the chuck or faceplate, which can be locked or used as a rotary table for drilling a radial hole arrangement, or radial slotting, or grinding.
The attachment can be mounted crosswise as well. It's held down to the lathe's boring table with tee-nuts.
[ You are not allowed to view attachments ]
In today's work on No.83, I found I'd tapped the displacer rod guide off-vertical :wack:. So I mounted the whole power cylinder/guide mount in the four jaw and very carefully bored the entire displacer guide out to start over again.
I didn't have a reference location for the guide, so it was a matter of taking small cuts on the off center hole with a thin homemade boring bar, checking for concentricity with the walls as the they got thinner, and adjusting the 4-jaw. Finally when I broke through it was just a very thin foil all around and the bore was concentric. One step forward one step back!
The silver lining, or lemonade, or whatever for the messed up tapping is that it will now be a lot easier to make up a new guide and threaded bushing in the lathe before mounting them in the plate.
vtsteam:
Today I turned, threaded, and pressed into place the displacer bearing boss. I used brass, as before. Then I started on the sintered bronze bushing. It was turned from a rough square cutoff piece from the scrap box. By supper time I had it turned to size, but not yet threaded or drilled.
I just received a no-name 1/8" reamer, but I mic'ed it at .1260". I think it will cut larger. I'll have to try it on a test drilling to see if it's worth using. If not I'll make a toolmakers reamer from the pushrod stock. It's .1250"
[ You are not allowed to view attachments ]
vtsteam:
After a test in some scrap material, the reamer worked out as a good fit on the existing displacer rod. That rod was made from 1/8 drill rod stock (silver steel). Recently I received a few pieces of polished stainless rod, also supposedly 1/8" and trying one of them, they were actually too large. But the displacer rod was a nice close sliding fit in the scrap, so the reamer was proven out.
I drilled the bushing in the lathe with a #31 drill (.120"), and then used the new reamer to bring the bore to size. Then it was time to thread the outside of the bushing 1/4-28. I don't have a tailstock die holder for my lathe (yet), and it doesn't have screw cutting capability (yet), so I used the expedient of squaring up one of my tool holders to the lathe ways, and using that to press against the back of a hand held die handle -- which kept it square to the workpiece. I rotated the chuck by hand, and wound in the leadscrew at the same time, which kept up square pressure on the die, and the threads came out nicely.
[ You are not allowed to view attachments ]
vtsteam:
I parted off, then screwed the bushing into in the brass displacer boss for length. A little filing of the of height and depth brought it flush at both ends. Finally I slotted the top with a hacksaw.
[ You are not allowed to view attachments ]
vtsteam:
And here's the finished displacer guide with the displacer in place. Easy sliding, and yet a close fit, with self-lubricating bronze. Now also replaceable if ever needed. I like the change!
[ You are not allowed to view attachments ]
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version