Thanks Stew
- no worries about posting your engine at all mate
- and many thanks for the link! My guess about them using gas for the burners was obviously wrong - I should have guessed they would have used something like naphtha back then.
Carl, thanks for checking in
- things were a bit slow actually... I got caught up in a bit of work, but at least it was on very interesting projects. No Tornados here - not even Fords or Oldsmobile Toronados
- right boring innit
Thanks Don
- I'm really enjoying the build
- It's all Stew's "fault"
.
- I had a nice shop session today - so this will be quite a lengthy update...
The bearing columns had quite a bit of excess stock left on them, so I crudely hacked off some of that of it with a junior hacksaw:
Rather than faff around setting up a rounding-over jig on the rotary table, I just used a 6mm drill bit to mill the curves to approximate dimensions - there's no real need for accuracy here and it's just quicker for me to do it this way:
The cylinder end bearing block needed some additional work for the cross-head mounting; I just used a small square to set it up in the vise to mill to the line:
Milled to width, and to length on the top:
After a minute or fifteen spent with files and a bit of emery, the two bearing columns turned out OK There's still some fine blemishes left on them, but that will disappear (hopefully) when I paint them:
So far, the engine bits looks OK on paper (remember that I said that the "on paper" size inspired this build), and the bit of rod above the bits is a bit of 18mm printer shafting for the next bit to come:
With a suitable section of the printer shaft chucked up, I turned the OD down to 17.4mm to match the OD on the inboard cylinder head, and faced the end off:
This shafting comes from a C.Itoh 5000 printer - it is a bit soft to make tooling from, but machines absolutely fantastically. As it is used as the main head traverse shaft in combination with bronze bushes on those printers, it is also ideal for use as a cross-head guide with a bronze or brass cross-head
.
The end was then center drilled, and then peck-drilled about 90mm deep with an 8mm drill. The peck-drilling (about 2mm at a time with the 8mm drill) helps to keep the hole true to the lathe center axis, and as this shafting is very uniform without hard spots that could cause deflection, the hole came out very nicely indeed. After the 8mm hole, I followed through with a 9.8mm drill, and then reamed it out to 10mm:
Next, the hole was drilled out to 13mm diameter, 18mm deep, and then a section bored out to 16mm x 2.5mm deep to be a snug fit on the boss on the inboard cylinder head:
Important: I was working quite a bit away from the chuck here - about 80mm (3
1/
8")away on 18mm (just under
3/
4") rod. This is a
lot for an unsupported workpiece, especially with a hole down the center. The rules for me for doing this successfully are good quality and easily machinable stock, a super-sharp honed cutting tool, and fine cuts and feeds. I was confident in all these regards to turn that end section - if I had any doubts at all, I'd rather have broken out the fixed steady and added that for support.
A bit more work on the exterior - turned down to 15.5mm OD as close to the chuck as I felt comfortable with:
The bit in the bore where I just drilled out to 13mm looked like crap, and after more machining that would be visible (clicky-photo):
So I bored it out a bit to smooth the inside, as that would be visible once the engine is done. Crappy photo as I didn't get a nice angle to show the bore:
It's a lot smoother though
OK- post-break - to be continued...
Arnold
