Stuart 10V Build Log – Complete Beginner…

[Mick B1Participant @mickb1]

Posted by Dr_GMJN on 23/07/2020 09:24:55:

…

Your 10V looks fine to me, I'd be more than happy with that, the main thing is that it runs well.

Wing and prayer job, really – with a Unimat 3 and a cheap Chinese bench drill I still use. Couldn't swing the eccentric with its arm in the tiny Unimat for boring, so I had to cut it off and attach a separate turned arm instead. I interference-fitted a bronze tyre to the flywheel – but I can't remember all the other dodges I used.

Edited By Mick B1 on 23/07/2020 11:00:06

[JasonBModerator @jasonb]

It is very common to use a 5BA thread straight onto 1/8" nominal stock (which can be a bit under size) and I expect just about all the 10V & H engines built do that, 2BA also goes onto 3/16" nominal and 7BA onto 3/32" even though they sizes are not what you will find on most charts.

[Cabinet EnforcerParticipant @cabinetenforcer]

Hi Dr_GMJN, I was sure your username rung a bell when you started posting but I couldn't place it, didn't realise it was from PH until I saw the Stuart build thread pop up in recent posts there.

Nice engine build so far, hopefully she'll run like a chipped 330D .

Re your post on the previous page about indexing, would highly recommend getting both hex and square Stevenson collet blocks from Arceuro, makes jobs like that really easy.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Cabinet Enforcer on 23/07/2020 15:09:09:

Hi Dr_GMJN, I was sure your username rung a bell when you started posting but I couldn't place it, didn't realise it was from PH until I saw the Stuart build thread pop up in recent posts there.

Nice engine build so far, hopefully she'll run like a chipped 330D .

Re your post on the previous page about indexing, would highly recommend getting both hex and square Stevenson collet blocks from Arceuro, makes jobs like that really easy.

Thanks, yes those blocks look good. Spending money is going to be a bit tight next month unfortunately though!

[Dr_GMJNParticipant @dr_gmjn]

So tonight I re-set the scrap valve rod in the lathe and sawed the threaded end off. I found that putting it in a collet gave me 0.0015” runout, so I stuck with that rather than messing about with the split bush and 3-jaw chuck:

Centre drilled, and turned down to size with a DCGT insert, then tried the 5BA die. This time it worked. I needed to turn a pointed grub screw to open the die though (it slid on without that, but I wanted to make sure, as suggested, it wasn't undersized):

There was about 1mm to spare. Flushed with success, I milled the valve plate to size:

And drilled and tapped it after centering using the edge finder:

Fit on the rod was spot-on.

So then onto cleaning-up the valve Itself and the rest of the parts. The sliding fit of the rod in the chest is pretty good, if a tiny bit sticky at the very top of the travel (but only in one orientation). Might need a bit of lapping or something to get it perfect. I think it’s Probably fine as it is though, becasue it shouldn't ever get to the very top of the bore I guess.

All seems to fit together well:

And I think the travel is OK for the ports too:

Just need to make sure the eccentric throw is spot-on.

[Dr_GMJNParticipant @dr_gmjn]

So I made a start on the valve rod fork end:

Full disclosure:

I chamfered the end, drilled, tapped and lightly screwed the rod in with Loctite. Then brought the tail stock chuck in, and gently nipped it around the end of the rod to keep it aligned while the Loctite set.

Turned the chuck Slowly by hand to make sure it was true, the Tailstock chuck grabbed, and twisted the end off the rod.

I think I may take a week off from this project…

[Mick B1Participant @mickb1]

Posted by Dr_GMJN on 26/07/2020 11:59:09:

….

I think I may take a week off from this project…

No. This is Victorian tech, so do what they did when they fell orf their 'orse.

Get straight on again, and ride!

[Dr_GMJNParticipant @dr_gmjn]

Posted by Mick B1 on 26/07/2020 12:15:48:

Posted by Dr_GMJN on 26/07/2020 11:59:09:

….

I think I may take a week off from this project…

No. This is Victorian tech, so do what they did when they fell orf their 'orse.

Get straight on again, and ride!

If I had any spare rod I would! I was still congratulating myself on saving the first screw-up (by about 1mm).

Ill send for another rod next week.

I have a rule when modelling or whatever, that I correct screw-ups before moving on.

[mechman48Participant @mechman48]

Hi Dr_GMJN , it's looking good. have a look in my album for some pics of my build, also my final run video..

**LINK**

George

[Dr_GMJNParticipant @dr_gmjn]

Posted by mechman48 on 26/07/2020 15:12:26:

Hi Dr_GMJN , it's looking good. have a look in my album for some pics of my build, also my final run video..

**LINK**

George

Thanks George, your 10V looks beautiful and runs as well as it looks.

One question though – unless I've misunderstood the concept of how the slide valve works (which is quite possible), I thought it needed positive pressure in the valve chest, ie the air/steam feed would go into the valve block, to keep the sliding faces together, but you've got the exhaust there.

Is this correct – does the valve work with the inlet either side? I'd have thought the positive pressure acting on the pocketed side of the slider would tend to push it away from the valve port face, causing leakage?

Cheers.

[mechman48Participant @mechman48]

I would have to look at the drawing again to clarify what 'guzinta' & what comes 'outa' where. My grey matter is decidedly slower than it was when I built it. I'm just pleased it still runs great.

George.

[Dr_GMJNParticipant @dr_gmjn]

Yesterday morning I got a new rod (and some oilers and drain cocks from Stuart Models) and put it in the parts box. This evening took it out and started to machine it. Then test fitted it to the valve block and found I’d picked up the piston rod stock by mistake, which is too thick for the sealing gland. So started for the third time, this time on the right stock. Turned, lapped, threaded and re-set into the brass block. I didn’t turn the chuck this time. So back to where I was on Sunday.

[Neil WyattModerator @neilwyatt]

Posted by Mick B1 on 23/07/2020 09:16:59:

My 10V's a crude job in comparison with yours, but it's worked very nicely for 25 years.

Crumbs! It's a shock to realise mine is 20!

Neil

[Mick B1Participant @mickb1]

Posted by Neil Wyatt on 30/07/2020 22:04:57:

Posted by Mick B1 on 23/07/2020 09:16:59:

My 10V's a crude job in comparison with yours, but it's worked very nicely for 25 years.

Crumbs! It's a shock to realise mine is 20!

Neil

Creeps up on yer, don't it?

[Dr_GMJNParticipant @dr_gmjn]

Valve rod forked end finished at last. I made some Hardened filing buttons to profile the end. Worked a treat:

Might have a go at the bearings next.

[Dr_GMJNParticipant @dr_gmjn]

I got a bit distracted with other projects recently, but today I fitted the main bearings to the sole plate.

I set it up so that the plate would remain fixed to the mill bed when the bearings were un-clamped. This was so I could drill with tapping drills, clearance drills or whatever, then remove the blocks and go back to exactly the same co-ordinates for tapping.

I used the plate flange edges as datums, because that’s where the nuts and oilers will be viewed relative to. If there was an error in how central the bores are, and I took the bore centreline as a datum, the whole lot would look off.

Started by drilling through everything with a tapping drill:

Then opening up just the flanges to clearance:

Then removed the bearings and tapped the sole plate:

Then re-fitted the bearings using studs and nuts, and tapped the oiler holes:

I’m not sure if I should have gone all the way through to the bore with the tapping drill, but too late now. The oilers themselves have a constriction in them. I’ll have to find some fibre washers because they protrude into the journal. Good job I spotted that – could easily have caused some confusion/damage on test assembly:

I didn’t notice that the bearing mount holes were relieved under the sole plate. It looks like everything is on the right place though, so I’m confident the blocks were the right size, and were aligned properly in their pockets:

So that’s that:

[Martin ConnellyParticipant @martinconnelly55370]

Brass spacer under the oilers maybe?

Martin C

[Dr_GMJNParticipant @dr_gmjn]

Posted by Martin Connelly on 05/09/2020 19:06:11:

Brass spacer under the oilers maybe?

Martin C

Could do, or shorten the threaded bits. I just thought a fibre washer might look OK, and make a decent seal.

[Dr_GMJNParticipant @dr_gmjn]

Next job I think will be to mount the standard to the sole plate. I’ve had to make an extension for the spot-face tool I made previously. I drilled and turned some brass bar to be a fit on the spot-face tool shank, and put a thread at the end to secure:

Seems to run true enough for the job.

[Dr_GMJNParticipant @dr_gmjn]

After a lot of pondering I started on fitting the standard to the sole plate. I wanted the cylinder bore axis to precisely intersect the crankshaft axis.

To hold the sole plate, it seemed easiest to fit it to the box-bed and secure that to the x-axis. I aligned the sole plate to the axis by touching-on the sides of the standard pads. I also fitted the bearings and slid a drill through. By touching-on each side I could easily find the axis, and zero the x DRO Then halved the widths off the standard pads to get the y centreline and zero the DRO:

It was then a very simple job to co-ordinate drill and tap the four holes:

Then the standard itself. I mounted it upside down to make drilling easier. Then aligned the foot pads along the x-axis with the edge finder:

Then got the centre of the slider bore:

Zeroed the x and y DROs on the centre axis, and again drilled to the same co-ordinates as the sole plate holes:

Then inverted it to use the extended spot-face tool. I aligned it by eye to the holes:

Still works perfectly despite it being covered in surface rust:

The sole plate with studs fitted – I messed up and put a deep score across one of the faces by not fully retracting the tap holder…

Quick test assembly of everything so far seemed to indicate it’s all square:

Might have a go at the connecting rod next.

[Dr_GMJNParticipant @dr_gmjn]

I thought I’d have a go at the crankshaft next, because the connecting rod needs to be fitted to it in terms of width, and the bearings also need shortening to suit it.

Started with the bar, and steel strip:

Cut the bar in half and soft soldered it together, so that the drilled holes will be perfectly aligned:

Then milled to the correct overall web length:

Put in the vice again and checked it for level:

Centre drilled:

Then drilled to pre-ream size…but the solder broke:

So I bonded them with retainer, using the pre-ream drill to align the halves (and clamped them in the vice to keep them square). Then reamed for the shaft:

And drilled for the crank pin:

It turned out that the crank web end radii are centred on the opposite holes, so I clamped them with a close fitting bolt and nut, and turned the radii in the lathe:

The hole axes appear to be parallel in two planes, and the webs normal to them and parallel to each other:

But unfortunately the crank pin holes are offset in the webs to one side:

I must have made an error in getting the centreline of the web assembly when drilling.

Unfortunately, despite the error having no effect on the function of the crankshaft, I’ll have to get some more material and start again I guess.

[DiogenesIIParticipant @diogenesii]

Can you not re-profile them so that they taper slightly – if you set them up (perhaps with pins/rods through the holes) in the vise and touch off on the "thin" side and then flip them over to reduce the "thick" side to the same dimension..? ..as the end radii are generated from the opposite hole, they won't look out of square – the eye won't have anything to pick-up on..

[Dr_GMJNParticipant @dr_gmjn]

Posted by DiogenesII on 10/09/2020 06:30:16:

Can you not re-profile them so that they taper slightly – if you set them up (perhaps with pins/rods through the holes) in the vise and touch off on the "thin" side and then flip them over to reduce the "thick" side to the same dimension..? ..as the end radii are generated from the opposite hole, they won't look out of square – the eye won't have anything to pick-up on..

I’d have to take the new line from the corner of the radii though, which would a) make the wall thickness next to the large holes very small, and b) make the two opposing sides non-parallel (I do understand your point about the radii making this less obvious though). I think it would probably just look wrong in a different way.

To be honest it only took a couple of hours to do, so I might as well do it again. The error resulted – indirectly – from the failed solder joint. Initially I marked the holes out as a check, second try I didn’t bother, and relied on the DROs and edge finder. I must have caught the rounded edge of the stock when using the edge finder I guess. Strange though because edges look consistent, and I measured at the same height side to side.

[JasonBModerator @jasonb]

Posted by Dr_GMJN on 10/09/2020 06:45:35:

I’d have to take the new line from the corner of the radii though, which would a) make the wall thickness next to the large holes very small, and b) make the two opposing sides non-parallel (I do understand your point about the radii making this less obvious though). I think it would probably just look wrong in a different way.

If you forget the shape of the ends and round them over then the "flats" will be tangental to the end radii so no loss of metal around the holes.

[Dr_GMJNParticipant @dr_gmjn]

Posted by JasonB on 10/09/2020 07:10:33:

Posted by Dr_GMJN on 10/09/2020 06:45:35:

I’d have to take the new line from the corner of the radii though, which would a) make the wall thickness next to the large holes very small, and b) make the two opposing sides non-parallel (I do understand your point about the radii making this less obvious though). I think it would probably just look wrong in a different way.

If you forget the shape of the ends and round them over then the "flats" will be tangental to the end radii so no loss of metal around the holes.

Thanks Jason. Yes, that would work. However I think to profile it would possibly – for me – take longer and be more prone to error than just making a new pair. I’ll see if I can source some 3/16” mild steel locally. If not I’ll try to re-profile the originals.

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