Author Topic: Resurrecting a Stuart 10V Engine  (Read 3338 times)

Online Twizseven

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Resurrecting a Stuart 10V Engine
« on: January 28, 2021, 08:04:22 PM »
Many moons ago I bought a built Stuart 10V on Ebay. When it arrived I had a quick look and due to work commitments it got put on one side. I have recently finished two of the Alyn Foundry engines and then saw a build of his Stuart 10V on another site and this prompted me to take a look at the one bought a few years ago.

I quickly found a few problems. The main bearing bolts on one side were loose, so I tightened them up. Bad move, engine locked up completely.  :censored: Decided to strip it completely, repair any issues, add a few bits and paint it.

The bearings were a major problem, :ThumbsDown: they had been drilled completely out of alignment and needed 25 thou of shims underneath both the flanges on one of the bearings. Also found he had filed the base and the sole plate but not very squarely and the locations of the bolts for the main bearings were all over the place. Some things I would have to live with others would be fixed. New bearings extrusion ordered, along with valve chest cover, drain valves etc. along with small 7ba nuts. Also 5BA and 7BA taps and dies.

Whilst waiting for the bits to arrive I started on the steam chest. The slots in the steam valve for the fixing nut were filed but not square and to depth. Also the nut was tapped at an angle. Bit of work with a 3mm slot mill in the Cowells Mill saw the looking a lot better a new nut was fabricated and tapped. The steam chest had also been fitted back to front and had an out of square piece of gauge plate for a cover. By now the ordered parts had arrived and so I machined up the new cover. Started this on the Cowells mill with a flycutter but it was so chilled around the edges I migrated to the big mill and used a carbide facemill.

The cylinder and end covers appeared to have been made quite well and all I did with these was drill the cylinder for drain valves.

In one of my other post you can see a fixture plate I made to use initially on this engine.  This fixture plate is approx 200mm x75mm with parallel rows of 6mm holes and 6mm reamed holes.   Fixture plate has been designed and made so will always be flat and square when clamped in vice on the mill.  I was able to clamp the soles plate down and face-mill the bearing platforms and the standard mounts to get them all level.

Then flipped the casing over and flattened the bottom. I used the same welded up clamp but filed the bar so it had flat faces that it would fit between the lower inside of the casting and and not be proud of the top of the base whilst being machined.

I felt was going to have difficulty doing the bearings in the normal way by drilling/reaming or boring them in lathe and the turning the bosses down and then trying to fit them onto poorly aligned bolt /stud holes on the sole plate.

I elected to fit and bolt them to the sole plate first, then would rill/ream whilst fitted to the sole plate, then remove and turn bosses to length etc.

I started by putting the sole plate in the vice and using the DRO on the Cowells to locate the co-ordinates of all four existing holes.

When I had noted these down I fixed (I use this word advisedly) the bearing in place with carpet double sided tape and spotted the holes with a centre drill.


All appeared great so far. Removed the bearings and then used 1mm pilot drill to locate the bearings in vice to drill the holes to 7BA clearance.


One worked perfectly, but the rear bearing had moved and one hole was offset by around 1/2 its diameter in two directions. :rant:

I pondered this for a while. Do I get spare casting and start over or attempt repair. Opted for the repair. The 7BA clearance should be 2.55mm but I had done it at 2.5mm. I turned a short brass pin 2.52mm dia, Loctited the hole and used a punch to drive the pin into the hole then left on a radiator to go off for an hour. Reset the sole plate inthe vice and re-checked the co-ordinates of the holes. This time I was able to use one bolt to hole the bearing firmly in place whilst drilling the 1mm pilot hole. Removed when drilled and opened up to size.

Both bearings now fit and are held down by bolts.

Next task is to mount the fixture plate with the ole plate attached vertically on an angle place and drill ream the hole for the crankshaft.

What can go wrong?? :thinking:

Colin

Offline Roger B

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Re: Resurrecting a Stuart 10V Engine
« Reply #1 on: January 28, 2021, 08:16:28 PM »
A Jo style casting rescue project  :)  :)  :ThumbsUp:
Best regards

Roger

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #2 on: January 28, 2021, 08:19:19 PM »
Roger,

I had not thought of it in that light.  :Lol:

Colin

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #3 on: January 30, 2021, 09:32:59 PM »
Was going to use angle plate and mount the fixture to it, but realised did not need the angle plate, just had to but fixture plate on edge in vice. All was square so centred on the middle of the bearing and went through upper bearing with centre drill and then with 3mm drill followed by 6mm drill. At this point I stopped and fitted long center drill and checked was still on centre in lower bearing.

All was okay so put 3mm and 6m drill through the lower bearing. Followed this with 9.8mm drill through both together. Followed this with 9/32" reamer. Then tried 9/32" drill blank. It fitted. smiley

Removed the bearings and then made small mandrel to hold the bearing by the bore. Used the Cowells lathe and turned the bearings down to final dimensions.

Refitted bearings to the sole plate to drill for pair of oil cups. Where are the b....y cups. I had them two weeks ago.  :cussing: Searched high and low through workshop and office. No sign whatsoever. Just about to order some and then decided to make my own. Again used the Cowells lathe as can work in the office in the warm at eye height.

When happy with a pair I drilled and tapped the holes in the bearings.

Now to sort a few studs out.

Colin

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #4 on: February 04, 2021, 06:08:23 PM »
I then came across another little problem. Having machined the sole plate flat this has now lowered the cylinder by six or seven thou. The piston now appeared to hit the top of the cylinder and prevents the crank from going over centre. :censored:

I have the "Building a Vertical Steam Engine" book but I think there are a few errors in it. On page 64 it gives the length of the piston rod as 45mm PLUS the 4mm and 6mm threaded portions giving total of 55mm. The plain section on this engine is approx 37mm long. Because of this the piston bottom is 2mm above the inner face of the lower cover. I have a feeling that 45mm in the book is the overall length and the plain section should be 35.719mm (1 13/32" not 45mm.  JasonB confirmed the 1 13/32" for me, so I now had to shorten the piston rod 1.04mm.  Borrowed a friend Hardinge lathe with 5C collets as was able to insert the piston rod complete with piston from the rear of the collet and have enough sticking out to shorten as required

The cross-head was also very close to the bottom of the piston gland. This looks very close.  Investigating the piston gland  and housing showed up the fact that the thread only went half way down the bore.

Fixing someone else's poor work takes a little longer than you would think. :)

With the mods to the piston rod and the gland nut thread in the bottom cover I temporarily assembled the engine. Had a few issues with it locking up when tightening the nuts on the valve chest but eventually sorted this and finally had it running briefly with the air line nozzle blowing into the inlet port.

Gradually speeded up as it freed up. Ran it for about 5 minutes, it was a lot better after squirted some clock oil into the steam chest.
The engine turns over quite easily by hand. It does not appear to be tight anywhere. The piston is very free in the bore (maybe too free). BUT It needs a quite high PSI to get it to run. :ThumbsDown:

Plan had been to now sort out the cladding and pipework. Whilst I am painting it I can continue with the making the reversing gear.

This quickly went out of the window.  Because it did not want to run very quickly, I decided to take another look at the steam ports. The ports on this one I am attempting to resurrect are not cast very well, in particular the left hand one in the photo.  I was not sure how they are would effect the running of the engine if they are left as is and wondered about filling the left hand port with JB Weld and then re-machining to the correct size/location.  Discussed options with several people (JasonB and others) and it came down to fill with JBWeld and re-machine ports, or remove ports in their entirety and replace with brass insert with correct port slots.

Having had a much closer look and spotting some "white stuff" in the miss-shaped port it looks as though there is a small blow-hole between the exhaust port and the miss-shaped inlet port or more likely when drilling the port through from the end of the cylinder it was drilled too far. It has possible had some filler put in somehow. Looks like it will definitely have to be the brass insert.  This insert may have to be at least 1/4"" thick as it is now going to have to replace the port slots in their entirety.

After some thought I opted to mill out the poorly formed ports. In order to do this I needed to remove the studs the previous builder had fitted for the top and bottom covers in order to mount in the vice.

The studs decided to fight back. Well one of them did. Five on the upper cover end came out easily. Four of the lower ones came out relatively easily. The last one fought back and said no way am I leaving this casting in one piece and promptly sheared flush with the top of lower face. Bugger I thought.  :cussing: I actually said something worse.

I knew drilling it out would be fraught as it needed a 2mm tapping drill size and if this wandered being such a thin drill it would go down the casting in preference to the stud.

I set it up in the vice and refitted and bolted the top cover down.

This now gave me a fixed location. I then used my centering scope for the first time in anger to locate on the hole in the cover.

Once located i remove the top cover and the studs. Fitted a 2mm slot mill and very gingerly raised the table to bring cutter and stud together. Ran at approx 1500rpm and worked my way through the stud. Once remnants cleared out was able to run 7BA tap back down the hole. That was quite a relief. :ThumbsUp:

Blued up the port face on the cylinder and lightly scribed a box around the area to be milled out. This was my sanity check to ensure I had my DRO settings correct. Clamped in vice and set level and set up a 3/16 slot mill.

Initially put in four corner holes at 1/8" depth, then reduced the DOC to 1/16" and milled out first layer. Dropped down to the 1/8" point and took out another layer. I was hoping to get away with this but needed another 1/16". Looked good at this point so them went round the periphery with a full depth cut removing final/1/64" all round.

Pleased with that now need to make the brass insert.

I have never used JBWeld before so am not sure how much smaller I need to make the brass insert. I assume I need the JBWeld as thin as possible. Is it fairly thin as soon as it is mixed. I was think that when the brass insert is pushed into place to use, either flypress or arbor press to push it as fully home as possible.

Colin

Offline Chipmaster

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Re: Resurrecting a Stuart 10V Engine
« Reply #5 on: February 04, 2021, 09:14:56 PM »
You're certainly getting some entertainment out of this engine Colin.
Reminds me of some of the bodged motor bikes I experienced as a teenager fifty years ago.

Andy

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #6 on: February 05, 2021, 03:27:39 PM »
Too right.  A little bit more entertainment than  I wanted.

I see now why Jo has such fun on her resurrected / orphan engine castings.

Colin

Offline Bluechip

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Re: Resurrecting a Stuart 10V Engine
« Reply #7 on: February 05, 2021, 07:11:00 PM »

Reminds me of some of the bodged motor bikes I experienced .

Andy

Like the new Triumph 750 Bonnevile I bought ....  ::)  although, to give credit where due,. the back number-plate performed faultlessly in the 15 months or so that I owned it 'cos i got scooped up for zooming as Ogri would have said. Ah well. long gone.

Dave
« Last Edit: February 05, 2021, 07:16:58 PM by Bluechip »

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #8 on: February 05, 2021, 10:03:31 PM »
Cut and squared a block of brass up on the Cowells mill. Then for my own sanity blued it and scribed the port locations.

Having then files the corners ensured it fitted the location in the cylinder and sat flat on the bottom.

Yesterday evening I sat and wrote down all the DRO positions and moves I needed to produce the slots. To make it simple (for me) I worked from centre lines in both X and Y axes.

Used the Cowells mill to do the slots as exhaust port was going to use a 3/32" and inlet ports a 1/16" slot mill. There is a lot more feel on the tiny machine for the little slot mills. But even with this I still snapped a 1/16" as I was half way through the last port.

Once I had finished the two inlet ports I revisited the corners of the exhaust port with the 1/16" and plunged it down to tighten up the corners.

It deliberately sits proud of the cylinder port face as I will face it off when JBWeld has gone of and then lap it.

Whilst I had the 1/16" slot mill in the chuck I centred up the slide valve and opened the recess up to its correct dimensions.

Slowly but surely.

Tomorrows task is to JBWeld it into place and look at top cover.

Colin.

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #9 on: February 07, 2021, 08:44:14 PM »
JBWelded the insert in yesterday morning. Looked at it at 8 in evening and had not gone off. Had left it compressed in the flypress in workshop. Obviously not warm enough. Found suitable machine clamp and clamped it together and left on bathroom radiator for 10 hours. That cooked it.

Into the mill and ran facemill over the top. The drilled guide holes through the brass into the casting at points coinciding with original exit of diagonal hole. Set up at 25 degrees and drilled through from end of cylinder to meet up with drilled hole. I had cleaned the echaust pprt up as much as possible before the JBWeld had gone off and ran a tap back down it. Set it up in mill and ran a long centre drill down to meet up with drilled hole.

Pretty happy with the end result. Just needs lapping.

In the end I opted to use a 3.5mm slot mill to remove the 5 tapped holes for the top cover. Before i did this I hunted high and low for some cast iron remnants to use to plug the holes. Eventually found a 20mm length left over from the spigot on the cylinder for the CHUK2 I had recently made. It was 20mm diameter and had a hole in one end. Was it going to be enough. I slit it lengthways to give me four triangular sections 20mm long. Was able to roughly centre this in the three jaw chuck and the checked whether it would stand a interrupted cut and took one piece down to 5mm dia, Happy I could do this I the set the cylinder up in the mill and because I could not trust that the holes were on an accurate PCD I set each hole up one by one with Isoma optical centre.

The swapped to 3.5mm slot drill and took first hole down to 4mm depth. At this point I finished turning the cast iron down to just over 3.5mm dia and checked fit in hole. All okay so repeated exercise for each hole in turn. End result below.

I turned my bits of cast iron down for each hole in turn. I found that the slot mill cut slightly bigger in couple of cases so took the rod to 3.55mm.

Loctited pegs in place and have left on radiator overnight.

Will clean up (and square up) top of cylinder tomorrow and if necessary make a new top cover. Might bling this up and do it in brass.

Colin

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #10 on: February 08, 2021, 07:44:28 PM »
Left the Loctited inserts overnight on radiator to cook and go off.

In the mill this morning to face down and square the top face to the port face. Then used Bolt Hole on DRO to position the new holes and tap them 7BA. Think they look a lot better. Manage to get the top cover to fit by opening up the clearance holes.

Lapped the port face and cylinder end faces and did a quick reassemble and test run.

A significant difference. Turned the air down to 25psi and would still run. I know this is still quite a lot but not plumbed up properly as yet just using airline nozzle, so losing a lot of air.

One thing interests me. How much of the inlet ports should be exposed when the slide valve is at the limit of its travel. If you look at the picture below I would say that around two thirds is exposed. This is the same for both extremes of slide valve travel. Would I be correct in saying all of the port should be exposed for best performance. My thoughts are that the slide valve is fractionally too long and needs a quick skim of each end.

Colin

Online crueby

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Re: Resurrecting a Stuart 10V Engine
« Reply #11 on: February 08, 2021, 08:33:44 PM »
Before taking any off the ends of the slider, make sure it won't open the port before the crank goes past its extreme travel. Better to have the port partially covered, which won't be a problem, than to open too early, which will keep it from running. Been there, done that! Hmmm, last week, as I recall...

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #12 on: February 08, 2021, 09:09:46 PM »
Cheers Chris,

Will leave as is.  It is to the dimension on the plans.

Thanks,

Colin

Online Twizseven

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Re: Resurrecting a Stuart 10V Engine
« Reply #13 on: February 14, 2021, 09:37:23 PM »
I have now got the engine painted and rebuilt but I am really struggling to get it to run.  I have had it running a couple of times but it did not appear to be running very fast.  Have tried air pressure at anything from 30 to 80psi.

At the moment I cannot get the slide valve in any position where it is 1/2 and 1/2 over the two inlet ports.  2/3 and 1/3 is the nearest I can get.  I will try tomorrow to swap the valve end for end to see if lines up any better.

To set it up I am turning the flywheel to get the piston to TDC.  Undoing the screw on the eccentric, rotating the eccentric anti-clockwise (as I look at it) so it is moving in same direction as the flywheel and rotating it until the slide valve is just starting to drop and uncovers the upper inlet port about 1/2mm.  Then locking up the eccentric locking screw.  Checking that the slide valve appears to be opening at the same time both a TDC and BDC.  Bolt the valve chest cover back down.  Connect to airline.  And nothing.  Twice I did get it to run but as I said to my mind it was slow.  I then released the eccentric set screw and moved the eccentric a gnats whisker forward or backwards.  Then try again.  In some positions you can feel the flywheel want to spin, but it does not.  If I then put the eccentric back to the position in which I had it running (albeit slowly),  It will not run again.

I have spent about 6 hours trying to get it to run and am rapidly losing patience with it.  The couple of occasions it did run I could stop the air, reapply the air and it ran.  But I cannot find that sweetspot again.

What am I doing wrong?  I was under the impression that the eccentric could be moved around a little to and the engine would behave differently depending on how much lead there is on the valve.  This thing appears to want to run in one position only and this has to be accurate to a few thou and I only appear to have found this by a fluke on the couple of occasions it has run.

Colin


Online crueby

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Re: Resurrecting a Stuart 10V Engine
« Reply #14 on: February 14, 2021, 10:05:43 PM »
The half and half is not as important as it opening the port after tdc and bdc,. Are you getting air out the exhaust? If constantly, something is not sealing. If none, and no or very little force on the flywheel, I would suspect that passages are plugged or covered. I had that on an engine where I didn't get the gasket right, so no air made it to the cylinder. Easy way to check a lot of things is to take off the end cap on the cylinder. Apply air, and turn the flywheel by hand. You should get air out the port at the top as it goes past tdc, and that should stop as it gets towards bdc. That should isolate the issues, let us know those results and I can step you through the fix if it does not show itself to you.


Chris
 :cheers:

 

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