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Stuart 10V Build Log - Complete Beginner...

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Martin Connelly05/09/2020 19:06:11
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Brass spacer under the oilers maybe?

Martin C

Dr_GMJN05/09/2020 19:40:35
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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_GMJN06/09/2020 21:00:21
720 forum posts

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_GMJN08/09/2020 21:35:30
720 forum posts

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_GMJN09/09/2020 22:03:34
720 forum posts

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.

DiogenesII10/09/2020 06:30:16
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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_GMJN10/09/2020 06:45:35
720 forum posts
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.

JasonB10/09/2020 07:10:33
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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.

crank web.jpg

Dr_GMJN10/09/2020 09:34:59
720 forum posts
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.

crank web.jpg

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.

Dr_GMJN12/09/2020 22:30:40
720 forum posts

So...crank webs part deux. The spare material from Stuart Models is £10.46 (delivered) for a 2” length. My local materials company supplied my 1/2 metre for £1.20. I’ll not comment further on that,

First job - Loctite two pieces together:



Then fly-cut the edges to clean them up a fraction to be perfectly flat and parallel:



Mill the ends to be square:



Mark out, then put in the vice and check for level:



Co-ordinate drill/ream the holes, having first used the edge finder to get the datums. This time I used the marking out as a double-check:



Then used the nut and bolt method to turn the end radii:





Then machined the main shaft. Not sure why there’s a hole in one end, but it’s on the drawing:





Main components ready for assembly:



And Loctited together:



Now re-set in the vice and check for level:



And co-ordinate drilled the pin holes:



Tapped the Loctite-coated pins in with a hammer, and flatted and polished back:





Then put back in the vice, dropped onto a pair of parallels. The sacrificial part of the main shaft was then carefully milled away:





That completed the crankshaft:







So second time around it worked fine.

Dr_GMJN12/09/2020 22:32:11
720 forum posts

Then straight on to fitting the crankshaft to the bearings.

Began by aligning the assembled bearings into the vice using the drill I used to bore them undersized:



Then substituted it with the pre-ream drill:



Then the reamer:



Then sized the bearing thrust faces by trial and error turning in the lathe. I should probably have used an expanding mandrel, but the collet chuck seemed to work well enough. The crank pin is now central in the sole plate (let’s hope it’s also aligned correctly under the cylinder bore axis):



It all fitted together well enough:



No side play, and after test-fitting the flywheel, it spins as smooth as silk:



I’m pretty satisfied with today’s progress.

JasonB13/09/2020 07:02:08
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Some good progress over the last few days, I seem to recall that the hole is so that a smaller shaft can be soldered/Loctited in to extend the shaft should you want to fit a boiler feed pump or coupling for a prop shaft.

Dr_GMJN13/09/2020 08:54:49
720 forum posts
Posted by JasonB on 13/09/2020 07:02:08:

Some good progress over the last few days, I seem to recall that the hole is so that a smaller shaft can be soldered/Loctited in to extend the shaft should you want to fit a boiler feed pump or coupling for a prop shaft.

Thanks. OK so the shaft hole isn’t that important.

I think I’ll need to turn some square cornered features in the piston (oil retaining grooves), and around the eccentric (for a locating pin) Are specific tools for this available? I’ve got a parting tool which I guess is similar, but it’s too wide for these jobs I think.

Cheers.

Martin Connelly13/09/2020 09:19:44
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A good reason to keep pieces of broken tools is to use as material for home ground grooving tools. A damaged milling cutter of reasonable size can often be ground to leave give a 1mm (or less) wide grooving tool, they usually don't need to stick out much. The other option is to have some HSS blanks of different sizes handy to grind into a suitable tool. Making a suitable holder is also a simple exercise.

Here's an earlier thread on this subject

Martin C

Link added

Edited By Martin Connelly on 13/09/2020 09:21:44

JasonB13/09/2020 10:10:11
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Piston oil groove son this engine are usually just shallow vee shaped ones, if you mappen to have a threading tool about that will do or even a DCMT or DCGT insert with a small end radiu will do just fine.

The groove for the eccentric would be done with a narrow parting type tool which can either ground from a bit of HSS or narrow ones can be bought, 1.5mm wide are readily available from the ME suppliers quite cheaply or you can pay a lot more for insert grooving tools. that go down very thin and have a range of size inserts

Dr_GMJN17/09/2020 07:48:06
720 forum posts

I'm now part way through machining the connecting rod. I need to hold the big-end in the lathe chuck, to turn the cheek bosses. Would an expanding mandrel be OK for this, made from some spare crankshaft rod? I don't want to damage the reamed big end hole. I'd also use it to hold the main bearings, to finish machine their outer boss faces.

Thanks.

JasonB17/09/2020 10:29:19
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Yes, or you can turn a spigot onto the end of some bar and tap say M3 then retain conrod with screw and washer.

Dr_GMJN17/09/2020 11:20:11
720 forum posts
Posted by Dr_GMJN on 17/09/2020 07:48:06:

I'm now part way through machining the connecting rod. I need to hold the big-end in the lathe chuck, to turn the cheek bosses. Would an expanding mandrel be OK for this, made from some spare crankshaft rod? I don't want to damage the reamed big end hole. I'd also use it to hold the main bearings, to finish machine their outer boss faces.

Thanks.

Hmmm that might be better for the connecting rod - rather than a standard washer, I could turn some bar to the required o/d of the boss, and use it as a guide for turning the diameter as well as a retainer.

Will need an expanding mandrel for the bearing blocks though.

Thanks for the suggetions.

Dr_GMJN17/09/2020 11:59:45
720 forum posts

One other question: The forked end of the connecting rod is threaded 5BA at one side, and a plain diameter (larger than 5BA, but can't remember the size) at the other, so that the slider pin can locate and be secured. The drawings call for the plain hole to be reamed, but I don't think there's enough room for the tapered part of the reamer to fully complete the hole, before it hits the smaller threaded side.

Question is, does it really need reaming? I'd have thought that so long as the pin in a good fit with no play, it wouldn't matter too much.

The only issue is possibly that the pin dimeter itself does need to be a good fit in the slider hole, and the slider hole perhaps needs reaming, making the pin size important. That would have a knock-on effect to the fork end.

Any thoughts? Thanks.

JasonB17/09/2020 13:18:52
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This is where machine reamers have their advantages as they don't have the taper like a hand reamer. You may be OK as you ideally want the pin a firm fit in the fork but a looser fit in the crosshead so the slightly smaller hole may be an advantage. You can always just open it out a touch by hand with a scraper, needle file or home made reamer.

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