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saw:
Well done. :clap: :clap:

arnoldb:
Thanks Chaps!

Dave, how's the weather over there in "Gauteng" - I see there's a massive cold front moving through Southern RSA, so your cold spell might be on its way...

:lol: Robert, maybe you need to stop taking "tumbles" and just get on with the base...

Jack, I'm just taking the parts from the plans top-to bottom - hence the weird order of fabrication. I must give Elmer Verburg his due credit for that; his plans are complete enough to allow one to make the parts in any order; if they are made to the sizes specified, things will fit and the engine will run - there's no need to fiddle around with bits to make things fit later on.

Yesterday, I f@rted around with a block of aluminium. The markings on the 1" square bar are indicative that this is an extrusion, and I expected it to be a bit gummy while machining:

It was gummy, and left a lot of burrs from fly-cutting:

Even though not ideal for the job, it's what I had available, so I carried on trimming it down to size with a 16mm end mill:

I ended up with the cylinder block and marked it out for the cylinder bore:

Then I spent quite a while mentally running the machining processes through my head. I was spoilt for choice on machining the bore; it could go on the 4-jaw on the lathe, or I could do it on the mill using drills and a reamer or the boring head. Even though the aluminium was gummy, I opted for the easy way of drilling and reaming, with lots of meths for lubricant while reaming:

If the reamer left a bad finish, I could have bored out the cylinder with the boring head in the same position, but fortunately it came out OK with just the reamer.

Before starting on the top of the cylinder, I drilled the exhaust passage on the side; it just makes it easier to drill the exhaust port on the top to the correct depth:

Then I started on the top. Drilled the exhaust port through, and milled the steam passages. The plans call for 1/8" passages 1/16" deep. I don't have a 3mm slot mill, so I used a 2mm one and to compensate for the width, I milled the slots 2mm deep rather than the 1.6mm called for:

With the ports milled deeper, I had to calculate new angles for drilling the ports through to the bore; a quick bit of rough sketching and trigonometry sorted that:

Come on daddy; the maths is boring:

With the new angles marked, I started off the passages with the 2mm center-cutting slot mill:

That was followed with a 2mm drill.

Came out spot-on:

After a quick rub-down on emery, the cylinder block looks fairly presentable:

Two bits of brass plate and a bit of perspex followed:

The thinner brass plate is for the valve face, and the perspex and thicker brass plate are for exchangeable valve chest covers; the perspex for running on air and showing off the valve mechanism, and the brass one should I run the engine on live steam at some future point.

I machined the three down as a sandwich, with the perspex clamped between the brass plates, and the thicker, sturdier brass plate at the top, as end mills are inclined to want to pull up work pieces. With the perspex in the middle, it would be less inclined to want to crack or break:

Shop time ran out yesterday before I could carry on; I'll continue today:

Regards, Arnold

saw:
Beutifull :clap: :clap:

arnoldb:
Thank you Benni :beer:

I spent six hours in the shop today, and don't have too much to show for it ::)

Stacked up the valve- and cover plates on the block in the mill vise and clamped the lot up with a business card folded double to take up the minute difference in size between the parts, and coordinate-drilled the screw holes - first with a center drill to start each hole accurately, then down to threading depth in the cylinder block with a 1.6mm drill for M2 tapping, and finally 2mm clearance just through the loose plates to the top of the block :

Then I started milling out the port holes in the valve plate with a 1.5mm slot mill:

The valve plate after a bit of flat lapping. I'm not happy with it; I think I used over-heavy cuts while milling the slots, so they are very untidy. I might just re-do this part to make it better:

The steam chest followed from some 8mm aluminium plate. Fortunately this is a better alloy to machine than the bit I made the cylinder block from. I finished the block to near-final dimensions on the width, and chucked it up in the 4-jaw on the lathe to turn the round bits on it, and also to drill the holes for the valve rod. The hole in the back must be 1.6mm, with the one in the front 2mm. I drilled deep enough with the 2mm drill through the block to just reach the point where the 1.6mm hole had to continue - that's about 28mm deep. Then I had to drill the last bit with the 1.6mm drill, whis is fairly short, so I barely had 6mm of it's shank chucked in the drill chuck:

My old girl (the ML7) is a bit slow for these small drills at max 800RPM, so it takes peck drilling at a slow feed and frequent cleaning with a drop of meths on the drill tip each time it comes out. This is where I really find an advantage using meths as lubricant on aluminium over WD40 and such; the oily cutting fluids tend to make the swarf cling to the drill bit, thus clogging up the flutes more quickly. The meths just make it slide past, hence I can take deeper pecks while drilling - 3 to 4mm deep pecks are easily done with a 1.6mm drill.

A bunch of milling followed to clear out the hole in the steam chest. I roughed out most of the material with a 4mm 2-flute slot mill, and then followed with many fine passes with a 2mm end mill to get it to size and sort of neat-looking:

I used the brass valve cover as a template to drill the holes through the steam chest:

All done with the steam chest. After a couple of minutes of rubbing over sand paper to tidy it up; it came out satisfactorily :) - unlike the darn valve plate ::) :

Regards, Arnold

DaveH:
Arnold,

Damn cold thanks, :coffee:

Tis looking very good, like the interchangeable Perspex valve chest cover. :D

The valve plate looks good to me from here. :)
:beer:
DaveH

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