Stuart 10V rebuild

Hi All,

I acquired a old Stuart 10V and on inspecting it in preparation to run I realised this was not likely to happen due to the very poor workmanship.

I hope to show you all the issues and what I done to rectify the faulty parts, I will welcome advice from you all during the rebuild.

there will be decisions I will have to make in the early stages whether to work in imperial or metric although I think there will be a bit of a mix in the dimensioning to allow me to use available material.

we will see how it goes.

Hi Jim,

I built a vertical steam engine based on the Stuart 10 Standard and Cylinder, see here, that you may find useful. Good luck with the rebuild.

Thor

Edited By Thor 🇳🇴 on 11/10/2022 11:29:17

In the bottom two photos, I have three issues to deal with.

1. The seatings for the Main bearings are hand filed and are oversize, in order to ensure that they are both in line I will probably machine out the seatings so they have square bottoms this will allow me to machine a suitable piece of brass as the main bearing journals.

2. The holes on the seating for the main bearings are not aligned, I will drill these out and plug.

3. On the left side there is a step on the engine standard seating also on measuring the height it has not been filed even giving varying heights, I will re-machine this soleplate just enough to clean it up around .5 mm(.015",I believe this should not make a difference as long as the measurements for the bearing holes are as per the drawing.

Edited By Jim K on 11/10/2022 11:48:05

Edited By Jim K on 11/10/2022 11:48:32

Thor,

Thank you that information will be very helpful.

That plan should work, looks like at least one of the bearing retaining stud holes will need moving over too. I'd plunge out with a milling cutter on the right position and loctite in a plug.

If you go with the square bearings then just some simple flat bar will do for the caps. One I prepared earlier.

Hi Jim,

Your 10V doesn't seem to be machined with much accuracy. I did machine the seatings for the bearings with square bottoms on mine (but I used stock material for the Soleplate, not the Stuart casting). For an engine that is not going to do heavy work brass should do as bearings material, I have used that on several of my models.

Thor

Jason,

Nice one, I was not thinking of that design I was thinking of the bearing including the flange for bolting it down machined into it so it is like a t shape.

Thor,

I want to try and make all parts I replace on the engine just like you have stated rather than purchasing castings.

There is an interesting photo coming tomorrow showing the engine standard it is a mess just like a Swiss cheese with all the holes.

There is a new unused engine standard in the FS section……

I had a similar 10V. If you have a look on Model Engine Maker website you will see the issues I faced and how I overcame them. Follow links below:

https://www.modelenginemaker.com/index.php/topic,10180.msg231644.html#msg231644

• Model Engine Maker »
• Engines »
• From Kits/Castings »
• Resurrecting a Stuart 10V Engine

Best of luck, it will be worth it.

Colin

You will need to register to be able to see Colin's images as they are posted as attachments which guests can't see.

Thank you for that Jason. I had not realised they would not be seen.

Colin

Hi All,

I am including today a photograph of the standard and the cylinder to highlight the issues I have to deal with in these two parts.

The Standard

1 The bore of the standard should be 16mm or 5/8" it also should have 4 holes on a PCD of 28mm 1-1/8" I have 5 slots to deal with on this standard.

The height of the standard is 70mm 2.763" so I have some metal I can remove as the drawing standard height I understand is 68mm 2-11/16"

For the bore I am not sure what approach I should take as there is not a lot of wall thickness to enlarge the bore, I could true it up on the lathe and just ensure it is round and clean it up a little, not the ideal solution.

For the flange, I will either have to plug up the slots or I am thinking to machine remove the flange and turning a spigot with a shoulder to receive a new flange, the new flange could be silver soldered to the standard and then machined to the final size.

The Cylinder

As you can see the cylinder needs some love and care to restore it to what it should be.

The bore has a brass sleeve with a bore of 18.59mm .731" it must have been machined oversize when it was made looks like it could have been 21.35mm .840" before sleeving, wouldn't mind some suggestions on this one.

The length of the cylinder is 30.60mm 1.204" this should be 28.5mm 1/1/8" so I can remove metal from both faces to ensure that both faces are parallel and to the correct size.

For the holes in the cylinder, the best approach would be to mark them up and see if any of the holes are in the correct position the remainder is to be plugged using a threaded rod and the holes are redrilled in the correct positions.

For both these faces due to the current positioning of the holes, I do not see many where the holes will be converging with the newly positioned holes.

For the future i will improove the quality of the pictures.

Edited By Jim K on 13/10/2022 04:25:10

For the standard I would consider removing the flange completely. Then from CI or steel machine a solid insert with integral oversize flange. JBWeld that into the existing oversize trunk guide and when set proceed to machine it as a new casting with the additional operation of milling two slots in the sides. At a little over 1.3mm wall the insert will have sufficient strength and as it is "held" by the casting won't distort during machining. There is an option to do this in two, ask if you want details

As for the cylinder that bore looks to be well off to one side so I think I would sit down and have a good measure and marking out session to see if it can be pulled into the right place, if not get a bit of CI bar and care a new one from solid or fabricate from bronze and brass

If it can be pulled over then I think I would set it up with the existing bore running true and bore out the brass sleeve to leave a clean surface so a turned solid plug of CI can be loctited into place. Then set the cylinder to run with it's bore properly centred and take out to 3/4" skimming the flange end of the cylinder at the same setting. Then clamp that end down to the mill table and square the other end to it.

As for the holes I'm not keen on pluging and drilling close to the edge of a plug particularly if different metals as drills can wander. I would clock in the now trued bore and plunge cut with a 5mm milling cutter at each hole position and JBWeld in some 5mm brass inserts which have previously been tapped 7BA or M2.5 as you prefer.

What is the port face like?

Jason,

The port face looks OK except that the holes are drilled in the wrong positions, as you can see in the picture below. these will be easily plugged and repositioned.

As for your suggestions in your post, I believe your idea will work, I was a little bit concerned about the wall thickness of the standard guide, about using JB weld which I had not thought of as I thought it was an American product.

All in all, I will work on your approach to correcting the casting.

Regarding the JBWeld, just make sure you get the "original formula" not the rapid or marine as they don't have such a high temperature rating should you want to run on steam.

Another option for those stud holes for the valve chest would be to just fill them and drill in the corners as per the drawings. Only downside to that is if you want to use the same chest cover you will see the plugged holes in that.

Jason,

Looking closely at the options for the standard, I can get a small dia cast iron rod which can be machined to suit the standard bore and as I believe it is better to keep it as cast iron, I would like to hear your suggestion for machining the insert and the flange separately.

The standard measures 70mm 2.759" in height, like you have stated new insert, New flange and start out as if a new casting would be the way forward.

Following this thread.

There are a couple of options for the two part repair, one can be done with a single glue up session the other will need a second dose of the JBweld or could be Loctite but does offer a larger surface area to bond.

On the left the standard has had the barely skimmed and the flange turned off flush. A n approx 18.75mm cylinder of CI inserted that extends say 5mm above the lower flange height. A ring of iron or steel 5mm thick is bonded to this protruding section and the top of the standard.

On the right the standard is prepared the same way but a shorter CI plug added and when set bored out to 5/8" or 16mm as you prefer. After that a 5mm flange with a 6mm long spigot is bonded into the bore of the guide and to the top of the standard. I would have this spigoted gland turned ready to bond in once the standard has been rebored to save having to rechuck (faceplate) it so everything stays concentric to the standard's bore.

You can now bore the one on the left out to 5/8" or 16mm and face the flange back to thickness I would aim for this to leave the standard 0.5mm over height.

The one on the right can again be faced back to the +0.5mm and the hole opened up to 12mm*

I would then clamp the flange to the mill table and skim 0.5mm off the feet to true them up and bring the standard to height. Complete by milling the side slots and drilling the FOUR holes 7ba clear in the flange

* the spigot on the lower cylinder cover will need to be reduced from 5/8" to 12mm to fit this hole. Assuming the cover is as well made as the rest then a new one will be wanted to ensure the piston hole and gland hole are concentric to the spigot that fits the cylinder bore.

Jason,

The LH option was what I had in mind, although the RH one looks stronger,

Another issue I have found that the cylinder appears to have been machined presumably on a rotary table (don't know what possessed the builder to do that) the cylindrical dimension on the cylinder is now 33.51mm 1.319" and I presume it was originally 35mm 1.375" approximately as it is a casting. This should not affect the build other than making the top and bottom covers suit the cylinder diameter keeping everything uniform.

I keep wondering as I go through this rebuild if I will ever find anything that is a correct dimension, well I suppose if it was easy it would be no fun.

Currently I am waiting for delivery of a rotary table (should arrive today) and some other bits and pieces i require for the project, I also have to get BA taps and dies, as i am in Thailand it will be easier to buy a set on ebay and get my mate to bring out end of next month.