Stuart Number 9 Engine

[jcreasey]

Today I finally made a start on my No.9 I have had the castings for a few years now but I wanted to finish some other projects before starting it. Also to be honest I am always very nervous about starting a new engine and I have been procrastinating quite a lot!

Here are the castings. They are very old. No sign of the original packaging (they arrived in a wooden box!) but I do have the plans and the book. The plans are dated 1975. Some rust on the fixings but nothing too major. I also have a set of castings for the governor (bought separately) if we get that far. The crankshaft looks to be cast. It includes piston rings and the keyway key for the flywheel.

I decided to start with the base. First cleaning it up with files till it sat flat with no rocking. Then I put it in the surface grinder and made both sides flat and parallel.

I am very lucky to have this wonderful machine in my home shop.

Next came the very tricky part of the sole plate. This is quite difficult to hang on to but I eventually managed to get the bottom to sit flat using my files.
Once that was done I bolted it down to my milling machine and flattened the crosshead ways with a 12mm end mill. Once I had that as a reference surface I could flip it over and bolt it down using a 123 block as a spacer. The photo below shows my clamping arrangement. The casting is supported by the block on the left and the block on the right is just there to provide some bracing using a couple of adjustable parallels as machinists jacks sitting on top of a second 123 block. The rear support for the strap clamp is sitting between the bearings and is supported by the second 123 block also. A bit precarious but it seemed stable enough and I took light cuts to remove all traces of my terrible filing skills! It seemed to work out ok. So far everything is flat and parallel.

Ok that's it for week one. Now I am thinking about how to machine the rest of the sole plate. Right now the current plan is to bolt it down to a hefty lump of aluminium which I will square up. Then I should be able to attack it with the boring bar. Stay tuned for further instalments!

 

[Sprocket]

I have some castings that have been aging for a while too. Maybe not as long as yours, but you really have to let them age .
Doug

 

[trlvn]

Looking good! We'll be cheering from the sidelines!

Craig

 

[peterl95124]

possibly my favorite of all the Stuarts !!!

be very careful with the sole plate and don't make the mistake I made, be sure that the crankshaft bearing mounts are machined so that the cylinder will be centered in its mount at the other end, mine is off by a bit, not enough to be noticeable by the casual observer, but noticeable by me, and in retrospect it could have been off by much more because I was just eye balling the lineup when machining the bearing mounts first without much forethought about the cylinder mount !!!

also, if like mine yours came with a cast-iron cross head, you might want to toss that and make one from bearing bronze, I did because this is a sliding part (and it also looks better).

finally, I made a new crankshaft with tungsten counter weights so the engine doesn't try to walk across the table when its running !

if when you're done you want to pair it up with a scale Edison Bipolar Dynamo let me know and I'll try to figure out how to share my plans.

PS, if you don't want to paint (I'm not a fan of paint) then you can get a great looking and somewhat rust-preventing finish with "naval jelly", its got phosphoric acid in it and creates a phosphate coating that is grey and very durable, in fact its what is in primer paint to improve adhesion.

 

[jcreasey]

possibly my favorite of all the Stuarts !!!

be very careful with the sole plate and don't make the mistake I made, be sure that the crankshaft bearing mounts are machined so that the cylinder will be centered in its mount at the other end, mine is off by a bit, not enough to be noticeable by the casual observer, but noticeable by me, and in retrospect it could have been off by much more because I was just eye balling the lineup when machining the bearing mounts first without much forethought about the cylinder mount !!!

also, if like mine yours came with a cast-iron cross head, you might want to toss that and make one from bearing bronze, I did because this is a sliding part (and it also looks better).

finally, I made a new crankshaft with tungsten counter weights so the engine doesn't try to walk across the table when its running !

if when you're done you want to pair it up with a scale Edison Bipolar Dynamo let me know and I'll try to figure out how to share my plans.

PS, if you don't want to paint (I'm not a fan of paint) then you can get a great looking and somewhat rust-preventing finish with "naval jelly", its got phosphoric acid in it and creates a phosphate coating that is grey and very durable, in fact its what is in primer paint to improve adhesion.

Thanks for the tips. My crosshead casting is bronze so that should be ok.
I made a little PM Research generator for my last steam plant, so I am definitely interested in your Edison plans!
Paint is a long way away right now but I think it will probably be a bit of a shelf queen so I will have to make up my mind on what colour eventually.

 

[jcreasey]

I have some castings that have been aging for a while too. Maybe not as long as yours, but you really have to let them age .
Doug

Unfortunately these things have a nasty habit of outliving their owners.
I'm determined to avoid that if I can!

 

[Steamchick]

I agree with the advice about using phosphoric acid based rust treatment or primer. A necessary rust prevention on all modern cars.... (with steel panels). It forms a resistive molecular thickness coating bonded to the steel, almost eliminating electrolytic corrosion .
But oiling and ķeeoping the models dry, and protected from rapid temperature changes - e.g. wrapped in Oily rags for thermal insulation - does a lot to prevent corrosion.
Nice model. Just make sure (by a single setting?) That the cylinder mounting face alignment is true and perpendicular to the crank bearing axis. As well as the cross-head slide surface.

Cheers!
K2