Stuart 10V Build Log - Complete Beginner...

Looking great.

This was my first engine build and it was so satisfying seeing it move for the first time.

Looking forward to seeing more.

D

Thanks!

Not quite finished the eccentric strap yet - I’ve got to drill the oil hole, but can’t figure out how to do it:



There’s not enough clearance for a chuck. I was considering putting it at the other side of the stem, at 45 degrees to give myself room for the chuck, but Id like to know how to do it as per the drawing.

So I got on with the eccentric itself. The steel provided in the kit Is the correct o/d, so with that in mind, I faced it in the lathe:



Then transferred to the mill and got the centre with the edge finder:



Then offset the x-axis by the eccentric throw, and centre drilled:



Then back to the lathe and set it in the 4-jaw chuck, centred on the offset hole:



Drilled and reamed to size:



Then turned the spigot with intermittent cuts:



Marked out for the locating groove:



and then cut the groove with a ground down old HSS parting tool:



I started to part it off:



Then realised that because the hole is offset, it would break through at one side, and the process wouldn’t work. So I removed from the chuck and centered it on the hole again, meaning intermittent cuts for parting off:



It worked ok, but I found this material very difficult to work with . It seemed very tough, and turning tended to gouge the surface. I cleaned it up by making a wooden block and coating the face with SiC, and abraded the marks out by turning. A bit like lapping, but on the face.

Finally, the screw hole. I set it up on the mill, getting the high point with a finger gauge:



Then drilled and tapped without any issue:



Finished, although it is a bit crunchy when rotated in the strap. No idea why.





Also tidied up a few loose ends, like making an expanding mandrel and facing the main bearing external faces to length:



Again using the mandrel, facing the flywheel bosses to length, then mounting on the mill and drilling and tapping the screw hole:





And finally, machining the eccentric strap stepped locating bolt:



Not the best fit in the groove -a bit loose - but I found it difficult to get it right. Might have another go at that sometime.

The ideal thing to do the oil hole with is a long series ctr drill, I have an 1/8" x 3" long one which would be just right.

Failing that you can do it at a slight angle to get clearance or make a simple extension for an existing ctr drill by drilling a hole in some rod and using a drop of loctite to retain it.

Thanks, I'll try and get hold of a long series center drill then. The smallest one I have only just fits, making sleeving it impossible.

Re. the eccentric strap locating bolt - even though I've got clearance on teh groove, it still picks up occasionally. I wonder if it would be better made of brass, rather than steel-on-steel as it is now. It seems pretty smooth without the pin in place.

Cheers.

It's unlikely to pick up and gall so I would leave as it is, a small amount of play won't hurt.

Today I re-visited the cylinder, and made some progress with the steam ports.

First off, the pockets adjacent to the cylinder. A depth and diameter is given, but no centre location. I used a 6mm milling cutter, moved to marked-out arcs defined by the gasket cut-outs:





Then the exhaust drilling, to measured dimensions from the drawing. I marked out the projected position of the cast-in ports as a double check. Luckily the drill broke through the back of the port perfectly:



Then opened up the hole for a few mm, and tapped for the exhaust pipe fitting:



So that one turned out ok:





Then the tricky angled ones I’ve been putting off for a while. I started by extending all the port lines to the edge of the casting, and effectively drawing the positions of the ports on the side using the projected lines and measured depths. I then got the tilt angle using a protractor, and made a setting jig from an old plastic card (26 degrees):



The machined port face was located against the gap in the vice bed, ensuring it was square. Then a centre drill was used to start the hole dead in the corner of the milled port:



With the dro zeroed, I moved the casting so I could set the z-stop such that any error wouldn’t result in breaking into the exhaust port, giving me a chance to correct things if necessary:



Then moved back to x-zero and drilled. It broke through bang in the corner of the port, as did the other side. Which was nice:





Next will be the insulation jacket securing holes, and the drain cock holes, but I’m waiting for a tap for those.

This is one of the few occasions when I would suggest drilling the cleading first and then spotting through the hole positions onto the cylinder or simply clamp the cleading around the cylinder and drill tapping size right though both before tapping the casting and opening up the other holes.

Thanks Jason - yes, only this morning I experimented by wrapping the cladding around the cylinder to do just that - hold it in place and drill pilot holes before springing the cladding off and drilling/tapping as appropriate. Then secure through the just tapped holes, re-orientate, and repeat the process.

Didn't you say to use a smaller drill than tapping diameter where it breaks through to the cylinder for the drain cocks though - about 2mm IIRC? I want to do this before lapping, so that I can then make the piston assembly. I need to get it in the right order...

Of course I also need to mill the O/D of the casting a bit using the rod-through-the-hole method you suggested a long time ago, in order to get the cladding to be a perfect fit under the cylinder cap overhangs. I also want it a flush fit to the valve chest - I machined that at the time to have the correct step.

So today I tried to mill the outer cylinder concentric with the upper cylinder, using a method suggested here on the forum. This involved positioning a rod in the bore, putting it in the vice and milling a series of flats all around:



I might have misunderstood the method, but I must admit I found it hard to position correctly - it was easy to get it into a position where the o/d wasn’t at its lowest point relative to the cutter. This culminated in it grabbing, and damaging the casting:



Maybe it wasn’t orientated right, and I guess the vice should have been tighter, but either way it’s not a process I was particularly happy with.

Anyway, luckily the damage was only cosmetic, and some epoxy metal and flatting and re-priming (for the next stages of marking out) resulted in the desired outcome, ie a consistent step to the end caps:





I profiled the cladding using an 18mm socket, and test fitted it. It still needs trimming a bit:



But so far, so good:



Not sure if the cladding is some kind of anodised metal, but the finish is slightly flawed at one point. I might spray it satin black in the end.

Also painted the box bed and screwed it to the wooden base:

Yes you can use 1/16" or 1.5mm holes to drill the last couple of mm.

It is anodised

Ok.

Are the holes in the cladding for the exhaust and drain cocks meant to fit around the parts? The exhaust in particular would appear to want to distort the cladding when tightened, because it’s at an angle to the surface. Also the drain cocks fit to a curved surface - should the seats be spot-faced and clearance holes made?

Thanks.

I think you would to cut a channel for the exhaust port. If you try to distort the cladding when you tighten up the exhaust the cladding will just buckle.

Is the cladding aluminium? If yes I am left wondering why the anodising did not crack when you formed the curve. What gauge is it, can you put a Mike on it to find out, I'd be interested to know.

Also can you give more details about how you formed the curve. Was it as simple as you make sound to get such a neat curve, no clamping involved?

Thanks geoff.

Great work doc, once again I admire your attention to detail

Cheers Geoff,

Yes, it's aluminium, about 0.5 mm thick. The coating is extremely thin, to the extent that it fades away in certain areas, so it's unlikely to crack.

Initially I just wrapped it around the casting by hand, forming it around the block with my thumbs, while making sure it wasn't skewed. There was some spring-back, so it needed over-bending slightly. I found that gently forming it around the socket (again by hand) eventually gave it the correct radius. Obviously I didn't go further than the straight edges where it tangents back to the valve block.

The drilling may, or may not work out, but I kind of see it as a challenge to get it fitted properly without damaging the coating...

A step drill is handy for cutting clearance holes for drain cocks

I finished my 10V earlier this year, and the cladding was the only part I managed to scrap. My mistake was to drill the holes as per the dimensions on the drawing and not having the presence of mind to remember that the (already drilled) exhaust port on the cylinder was not dimensioned. Still - at least it was an easy decision to chuck it in the bin when the holes didn't line up!

Second time I measured from the job and using a 1/8 BMS drilling jig, as per Harold Hall's instructions, produced nice clean holes.

For the drain cocks I spotted the holes and drilled clearance. For the exhaust port I drilled 1/4 and turned the exhaust pipe out of hex stock to produce a tube with a nut part way along it - just a little further up from the end of the thread. The exhaust pipe could then be screwed into the cylinder and tightened up without the nut crushing the cladding. Not sure if this is the "correct" solution - but looks Ok to me.

Dom

Thanks both - I’ll get a step drill from Arc.

Dom - I might steal your idea for the exhaust. I considered doing something similar, but with some shallow flats milled on some brass tube, with the end threaded.

Could you by any chance post a picture of your 10v?

Thanks.

I don't have any pictures to hand just now - but here is a video of its first run on steam that gives a pretty good view of the exhaust. I threaded the other end of the tube also to connect to the elbow connector.

https://www.youtube.com/watch?v=xCclavQAQjA

Very satisfying when they run for the first time! It has run in since and can run quite slowly now.

The boiler is the ME vertical boiler which was serialised in the magazine last year and was also fun to make!

Regards

Dom

Edited By Dominic Bramley on 30/09/2020 16:04:29

Thanks Dom - it looks like a very nice 10V build, and setup with the boiler too.

Eccentric strap. Started by mounting the stamping into the 4-jaw chuck, using a tight fitting spigot in the tailstock chuck as a guide:



Then bored the hole:



Transferred to the mill and faced the main bore sides with the fly cutter:



The shaft was bent:



So I straightened it the best I could using a screwdriver and spanner as levers:





Then milled the flats and corners level:



and drilled the clamp hole:



and then the tapped locating pin hole after first milling a bit of a flat:



Cut the slot using the 0.8 mm slitting saw:



Then drilled the small end for its bolt. The specified clearance hole sizes on the plans are all way too big for a good fit:



and milled the faces symmetrical and to be a sliding fit in the fork end of the valve rod: