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klank:
Thanks Rob and Benni.

Workshop time was reduced today (had to go shopping with s.w.m.b.o. for her wedding outfit - number 1 son is getting married shortly - quite an experience, trying to be tactful, yet positive, whilst standing on razor blades).

Anyway - I started on the main bearing blocks.
The main bearings are solid gunmetal, split, but contain no separate bearing shells
These come as three castings - two separate "bases" and a pair of "tops", joined together. :-

The general quality of the castings was good, apart from the bottom of the bases being canted over somewhat, as can be seen above. Apart from that, they were all reasonably "square and true", although somewhat oversize compared to the plan dimensions.
Minimal dimensions are given - and not really needed - just the bolt hole spacings for both the bottom of the bases and the those holding the two bearing halves together, plus overall thickness and length of the base.
6 BA bolts are recommended to hold the two bearing halves together.

There are several ways to machine these - SB recommends doing them all in the 4 jaw (he did not use a mill at all in his notes), whereas HH recommends using the milling machine/toolmakers' vice.
I went the latter method - quicker set up time.
I have not bothered with mundane photos of doing the basic macining - points to note obviously are to get the centre heights exactly the same for each pair (using a height gauge on a flat plate or whatever), and the vertical faces at right angles to the base and parallel to each other.
Here's one lower bearing half part finished, compared to an untouched casting :-

I macined the top castings together, before separating them. :-

I temporarily joined the two halves together for each pair with cyano., not forgetting to mark each pair for re-assembly later.
Each pair was then marked out, drilled tapping size for 6BA (sufficiently deep to accommodate the supplied bolts - nice to have them as part of the kit), separated and the lower halves tapped, the upper halves opened out to 6 BA clearance, and the top faces where the bolt head will go, spot faced for the diameter of the bolt heads.
Each pair of bearings could then be assembled with the bolts..
I know that some may prefer to use soft solder thinly to join the halves together instead of cyano. - just my preference. It does hold quite well.

I chose to do the boring for the crankshaft pin in the 4 jaw, together with final facing and turning up the shoulder around the boss, which has been previously machined away when bringing the blocks to size.
The centre mark for the bore was measured, checked and centre popped.
I used a chuck back stop for this set up, which simplified matters considerably - you can just see it here behind the bearing casting :-

Slight digression here.
There have been many published plans/articles for making a chuck back stop, indeed Bogs has done a very good thread on this.
A friend put me in touch with a link (I cannot find it at present - if anyone else remembers where it is, please add it) for making a truly simple, effective yet elegant backstop requiring minimal components and machining - the picture here shows it far easier than words can explain - its "inventor" should be praised! :-

Each bearing block was set up as above, to turn true with a wiggler (wobbler?) and clock.
Centre drill, pilot drill, etc. and your choice to use a small boring bar (recommended) or reamer to finish. (Don't forget to withdraw the back stop a bit first!).
At the same time, the boss face can be skimmed and the shoulder turned back using a left hand tool.
The block was then reversed and put back in the same position in the 4 jaw/backstop, checked to run true and the other boss face/shoulder machining done.

The rest of the casting was then fettled and machined with a small end mill to remove the rest of the rough cast finish.
The tops of the bearing blocks were marked/popped for drilling/tapping the hole for the oil cup - but not finished at this stage.

Here is the result, temporarily placed on the base. :-

The overall finish of the bearing blocks needs a bit of fine bench working and elbow grease.

Next up - the cylinder.

Thanks for the support

Best wishes to all

Peter

saw:
You are doing very well, it's a plesure to folow your'e project. :clap: :clap: :thumbup:

NickG:
I think you've done a great job there because I don't know what anybody else thinks but those castings for the bearings look pretty awful to me. The fact that you've had to machine them all over makes it kind of pointless, it would have been easier from solid bar. They look great now by the way! :bow:

Nick

sbwhart:
Looks like you sorted them casting well Peter :thumbup:

Stew

klank:
Thanks again guys - you are very kind.

Nick, thanks. Given what you have said about these castings' "quality" and wih great respect and deference to your experience, I feel must have come across some truly shocking castings in the past and treated them as the "norm"!
O.k. my experience is quite limited - I have really only built two and a half engines from castings up to now and compared to what I have been presented with in those, I really thought these weren't that bad - being reasonably "true (ish)" and with no knobbly accretions.
Maybe I have made a mistake in machining all over, but once you start doing shoulders and such, bringing out the "shine" it made the rest of the surfaces look somewhat "rustic?"! So I gave it a shot.
I do appreciate all of your encouragement - compared to the other superb engines currently being built - this is playschool stuff.

Anyway - talking of castings - this is what is provided for the cyl. casting :-

To me it didn't look too bad, having checked its dimensions with those on the plan, and for "trueness" across the various faces. The only real problem side was the base, where it was partly canted from true to the valve port face - marked in felt tip.
Following SB's suggested method, I decided to start with the port face side of the casting as "datum" and set up for machining the base in my milling vice with the datum side against the fixed jaw, and "squeezy" packing against the cyl. body.
Once done, turned around to lightly machine the port face and check the results with a square.

The casting bore seemed reasonably "linear" throughout, and went ahead and plugged the hole at each end with some turned down wooden dowelling (a length sawn off the end of a garden hoe handle - I expect to get "sanctioned" in due course when my wife finds out!).
After a quick facing swipe across the disc sander, I could then mark out the bore faces for the true centre using a height gauge on my Tesco face plate and popped the centre mark.
I didn't bother with any photos of all of the above as its pretty mundane stuff, but here's the result :-

The casting was then set up in a Keats angle plate on the lathe faceplate, using the two finished faces to locate in the larger angle, and some scrap steel packing on the round cyl. body.
It was set to turn true with the usual wiggler from the tailstock and clock :-

Subsequent to this shot, I bolted a counterbalance weight to the face plate opposite the mass of the casting/Keats plate. The lathe would then turn reasonably steadily at about 750 rpm.

After skimming the first face it became apparent that there could be some small casting flaws hidden in the gun metal material. You can just see the "spots" dotted around the face here :-

They don't look to be too close to the bore itself and are very small - so I decided to press on.

The boring operation was quite straightforward and I didn't bother with photos of this.
Pilot drill through both bits of wood (there is quite a large central hole in my face plate), then drill out to 1/2" and start boring with a Glanze boring bar with the tip set on centre (it will quickly remove any residual wood from the plug). I used a bore gauge/micrometer to check the bore at various points down its length as it got close to size (1" bore required) and allowed for "spring" in the cuts.
Obviously, a better way of doing this would have been setting up the casting on the cross slide and boring between centres, but my Glanze bar is pretty rigid, and using very light cuts at the end, I am happy with the resut.
I left the bore a tiny fraction undersize, and finished it with some wet/dry paper and paraffin, wrapped around another length of Garden Hoe handle, turned slightly undersize and kept moving in and out as the casting rotated.

I faced the end (removing 1/2 of what I needed to overall to bring the cyl. to finished length) and cut the shoulder, reversed the casting in the Keats plate and did the other face/shoulder.

Following SB's advice, I checked the valve and base faces for squareness to each other and the end faces by bolting the cylinder to the cross slide, and interposing a 123 block between the valve face and the face plate (the latter having been ever so lightly skimmed) and checking for high spots/misalignement. (Sorry, the top slide toolpost spigot is in the way) :-

There was one slight high spot, and as recommended by SB, I fly cut the two faces ever so lightly from a cutter held in the face plate.

Here is the result :-

You can see the casting spots - enlearged here :-

There do not appear to be any imperfections running through into the bore, and I hope those around the rim side of the end faces will not be a problem, provided a good gasket is used between the end cover/cylinder at this point.

I shall start on the end covers tomorrow (provided I can hide the Garden Hoe again).

Best wishes

Peter

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