Stuart 10V Build Log - Complete Beginner...

OK guys I'll have a think about it. I don't have a rotary table, and I don't trust my three jaw chuck.

Anyway, I didn’t have much time this evening, so I just squared and flatted the valve chest cover. First job was to mill the edges; first opposite pair I face-milled vertically, then clamped those faces horizontally and side-milled the other two. I made sure the “S” Circle was central:



Then fly-cut the faces to the right thickness:



The finish using the power feed is really nice - the leading cut obviously takes the majority of the material off, and the trailing cut just skims the surface. I think this must mean that my tramming efforts weren’t so bad after all. I finished by lightly rubbing on wet and dry on the surface plate:





It’s a shame that to *just* completely clean up the side edges, it went undersize. I’ve tried to make the gap equal all around. Not to plan, but there was no way around it I could think of:



If Im careful, I can get the cover to stick to the chest on its own:



The gasket is not a great fit, and I suppose I may have to re-position the holes very slightly, but it shouldn’t be a big issue.



I’ll try to get the cylinder caps done next, then spend the weekend’s workshop time drilling all the mounting holes. I think calculation of all the co-ordinates will be at least a two-mug-of-tea job.

IIRC the calc's on the back of the Zeus booklet. I made my top end cap out of phosphor bronze - I thought it might look nicer. It did for a year or three - now it looks like lightly-rusted steel. But the phosphor bronze tyre I shrink-fitted on the flywheel still looks good.

Thanks, yes, I used the booklet to get the co-ordinates for the motor mount plate PCD holes.

The valve cover plate will need to be re-calculated because of it's smaller size, or at least they need carefully checking.

I notice there is no oil hole for lubricating the big end on this model, yet there is one for the eccentric.

This seems like a potential issue - are there any neat ways of incorporating a method of lubricating the big end?

I was also told that the cylinder drain cocks aren't needed, becasue the floating valve allows excess condensed water out. Not sure how, just asking the question. The drain cocks commonly used do look a bit over-sized. Any comments?

Also, for the steam inlet and exhaust, can anyone recommend some neat looking brass fittings? I'd like to fit a short exhaust stub - perhaps some thin walled brass tube, and a connection for compressed air. Ideally the pipe connector for the air would be removable for display, perhaps just leaving a threaded or plain bore fitting. I don't want to drill the holes before having the fittings.

Thanks.

Think of them as pre-heating vents rather than as drains. You can allow steam to flow through and get everything hot before running so there will be minimal condensate in the cylinders when first run. It's probably important on a large scale steam engines, not so much on a model that is not really required to be a working engine.

You can make your own brass fittings for pipework quite easily. Solder a small ring on the outside diameter near the end of the tube for retention of the tube. Thread the end of a piece of hexagonal brass and drill through for the tube OD and part off the hex bar. If required you can also recess the nut to suit the retaining ring outside diameter. P

Martin C

For air you also need to think about how you will control the volume particularly if your compressor does not have a pressure regulator.

I use the push fit fittings for PVC pipe and depending on size of engine will use 4, 6 or 8mm OD pipe. You can either tap the chest and exhaust to take one of these fittings or tap to take a short stubby length of tube and use a double ended connector to push over the metal stub, tube could simply be a rod with hole drilled. Other end of PVC pipe goes to a suitable push fit connector that has a thread to suit your compressor usually 1/* or 1/4 BSP. If you intend to run several engine sthen you can make a manifold.

Failing that a simple fitting can be turned up with a barbed end to push a bit of tube on and flow "adjusted" by kinking the tube

Kinking the tube is not very engineery. mole grips are far more impressive

Martin C

Those of us from a sciency background would use a tube clamp:

Rod

Thanks for the ideas all.

I've got a compressor and regulator, and a cut-off tap at the end of the pipe. I use it mainly for airbrushing, so need a controlled supply.

So I made a start on the cylinder covers, firstly the top one, because It’s much less critical than the lower. The only feature that’s important is the spigot that fits into the cylinder.

I chucked the cast iron bar in the three jaw, faced and turned to size:

Then turned the inner spigot, to be a good fit in the bore diameter:



I started to part-off the job, with the intention of reversing it in the chuck and turning the top features. It seemed to be going well, so I decided to part it in two stages- the first to form the upper boss, then move the tool back and part off from the stock:



It actually worked pretty well, but some clean-up was required anyway, and due to this the top boss is a bit short (not that it matters). On balance I should have parted off long, reversed and just turned the other side as normal. In the end my initial method could have worked, but as usual didn’t quite.

Anyway, it fits the cylinder, and it’s gasket, and it looks ok:









I was hoping the overhang would be concentric around the circular portion, so the lagging plate would be a flush fit. Unfortunately it’s not the case:



So some filing will be needed. Pretty sure I set up the casting pretty much as good as it could have been, so I wonder if the cast surface is slightly bulged? No big deal.

So next the lower cover. I still don’t really know how to reverse and hold it. I don't have soft jaws, and the three jaw chuck isn't great (it didn't matter for the top cover). I'm still wondering if turning a socket in some brass to a press-fit around the gland boss would do, then superglue the half machined cover onto it. If I used my previous double parting off method, then I'd only be cleaning up the face, spigot diameter and depth using very light cuts. All the drilling, tapping and reaming would have been done on the other side already.

Edited By Dr_GMJN on 19/06/2020 17:52:36

Another option is to make a split bush. Take a short length of stock about 6mm larger diameter than the cover and turn a spigot on the end about 5mm long. Reverse the bush in the chuck so that you are now gripping by the spigot and the larger dia is pushed back against the front of the jaws. Bore right through a couple of mm less than cover diameter and then for about 2mm deep open up to a snug fit on the cover's outer edge.

Mark the bush in some way so it goes back into the chuck in the same position before removing and cutting a slot right through it. You can now slip the cover into the recess, put bush into chuck and pushing both back against jaws and step in the bush tighten the chuck.

As the recess was turned it will be concentric so provided you put it back in the same position the hole will remain concentric and therefore hold the cover concentric and as the back of the cover has something to register against it won't wobble either.

I did think of something like that - but my thinking was as soon as I removed it from the chuck, the precise concentricity might be lost. If it works, I am much happier making that, than the other methods.

I suppose I could check concentricity by putting my dial gauge on the outer diameter of the fixture ring? Combined with the the undersized thread...I think this might actually get done this weekend after all.

BTW, At some point very soon I'll be drilling all the holes for these components. Some of them have good surface finishes - is it acceptable to put paper between these surfaces and the vice jaws for protection, or shouldn't it matter too much becasue of the polished finish on the jaws?

Cheers!

Edited By Dr_GMJN on 19/06/2020 21:08:51

Should not matter as machine vice jaws are smooth so won't mark like a bench vice. Just make sure they are clean of swarf.

For a beginner this is an excellent build log.

Thank you very much for posing all the details Dr_GMJN

BTW, I often use a slip of paper between vice jaws and the work. Not so much to protect the finish though as it really improves the grip between the components

* Danny M *

Dr G

You can mill the rough cast outer rim of the cylinder concentric with the bore

Pass short length of silver steel about 8mm diameter through the bore.

Clamp the cylinder in a machine vice but push the bore down on to the s.s bar which will be resting across he top of the vice jaws

Take a light skim of the rim with the cutter and lock the cutter

Rotate the cylinder a few degrees at a time and take more skims making sure for each skim the bore is resting on the s.s

Keep rotating until the whole rim is skimmed and finish with a flat needle file

Sorry no photo

Geoff

Thanks Geoff - I understand. Might give that a go - better than filing from the start.

Thinking more about Geoff’s cast O/D machining method:

Am I right in thinking it would work better for a symmetrical ring than an asymmetric cylinder casting?

Because of the port face bulge, it won’t hang vertically on the bar (or at least only at one point), so it would be an estimation job to get the orientation correct to achieve a consistent wall thickness?

But if the bar was a fit in the cylinder, all rotational positions around the arced portion would give the correct thickness?

It does not have to hang vertically, just ensure the work is pushed down against the supporting rod to get a constant thickness. The wall thickness is set by the cutters height above the support bar which remains constant whatever angle the work is at.

Here I was making a cylinder from solid and used the method on the smaller diameter, you can see the facets that the method produces.

Quick bit of filing to blend them in.

Hi Dr G

Trust me and Jason, last post, the method works.

Here is a photo of an inverted engine, same one as Jason's which uses a 10v cylinder. You can see the machined outer surface is concentric with the lower cylinder cap. The tapered section is held horizontal in the vice but still with the bore resting on the s.s. bar

Also did the con rod using the same method, 3mm bar through 6.5 hole

Thanks Guys - what I meant was this:

If the part touches the bar at it's apex, then no problem:



But if the part is clamped in any orientation where the contact isn't at the apex, then the wall thickness will be less. This diagram is obviously exaggerated, but shows what I mean:



I thought with an asymmetric part, it might be possible to get the orientation wrong if you happened to roll the part slightly when applying downward pressure.

It seems like it works fine in practice though, so I'll give it a go.

Cheers all.