Help for Stuart 10H please

[klank]

As a rank beginner my first engine build - a Stuart 10H - birthday present from wife.

Before cutting anything I have bought the little book on building the 10V and read and re-read anything I can find about building this type of engine.
I have a Chester DB7VS lathe and Seig mini mill - both of which I have been "practicing on" - making simple tools/accessories etc. to gain confidence.
This will be my first essay into real model building and have to confess am a bit nervous.
I have just fettled the castings a bit and sprayed them with grey primer (might help with marking out?)

My question is regarding the cylindrical "cross head" part of the main soleplate casting.
Forgive me if this sounds dumb, but is it supposed to be bored out (plans show 5/8" dia.) and the gun metal crosshead machined down to fit?
How does one do the boring?
I am trying to visualise some way of setting up the casting(s) to do the necessary machining.
The booklet gives some advice and a picture - but the 10V casting is a bit different - and I may be a bit slow on the uptake.

Has anyone done this - and is there a preferred method?

Any help/encouragement would be much appreciated.

[lancelot]

Hello Klank,
the answer to this is ''yes'' in both cases, the Soleplate needs boring out for the Crosshead and the Crosshead would have to be turned down to fit.
Setting up the Soleplate would be similar to how I set up the ''Score'', I used as large a face plate my lathe could manage and with an accurate right angle located to the faceplate I clamped the Soleplate to the angle, centering for boring can be done in a number of ways, I decided to use the bolting flange of the Soleplate (where the Cylinder would attach to) and set my boring center to follow the pitch circle of the fixing studs for Cylinder to Soleplate. Remember to fix a balance weight to the faceplate to offset the weight of the ''Job''.
Use a standard boring bar ,and do not forget to allow for ''Spring'' in the bar when heading for final cut, Like Wot I Did Once ;D
All the best for now,
John.

[dickdastardly40]

Klank,

As a general rule I always fit the hole to the shaft, i.e turn the shaft to size then bore or drill the hole to just undersize and take small cuts with a boring bar until the shaft just slips in.

The advantage of this is that is's easier to measure the shaft including the tolerance along it's length than the hole which with the best will in the world may pick up a light taper due to bar spring. As you slip the shaft in feel for tight spots, you can use marking blue to highlight them. I bore right to left, then reverse the feed with the same cut, which I find tends to negate the spring to a certain extent.

When you set the boring bar have minimum overhang possible, take light cuts to avoid chatter.

I'm afraid I can't comment on the setup as I haven't seen the actual casting concerned.

Good luck, let us know how you get on.

Al

[klank]

Lancelot, Dick
Thank you so much for the info. and tips - I get the idea now - much to learn - never considered the effect of "spring" when boring.
I intend to use a Glanze boring (tipped) bar in a pretty chunky holder in the tool post.

I may well ask some more beginners' questions - "crie de coeur" before this is finished.

It seems difficult (for me) to understand the drilling operations necessary to the cyl. block - the booklet and supplied plans show a pair of drain cocks (?extras?) and inlet/exhaust (I think) tappings but these are not referred to very well - I feel a bit of a fool saying this but for a beginner, the supplied 10H plan/ instructions/7V booklet are a little confusing.

Anyway, I shall slowly proceed and see what happens.

I do appreciate your kind help.

With best wishes

Peter

[jgb7573]

Hi Peter,

Firstly congratrulations to your wife on buying you the kit of parts! I've not built a 10H but like the look of them.
Drain cocks on these engines are usually optional extras. They are there to allow condensate to escape while the cylinder is warming up at the start of a run. You need to get the water out of the cylinder because otherwise it could fill up. And as water does not compress, you could end up damaging the engine. They're not strictly necessary on a slide valve engine though as the water will get pushed back up the steam ports, lift the slide valve off the port face and escape through the exhaust. However, they'd almost certainly be present on a full size engine (along with more complex lubrication arrangements, governors, water pumps and so on) and they look nice. So it's up to you.
The inlet and exhaust tappings on these engines are also left up to the builder to decide on. They depend largely on what arrangements need to be made for a particular installation in terms of piping up. The locations of each of these are shown on the drawing so that you know where steam has to go in, and where the exhaust has to come out, but that's all. So, it's up to you.
Have fun building your engine. There's a lot involved in even a simple engine and learning is a lot of fun.

[klank]

Hi jgb,
My thanks to you for further useful nuggets of info.
You have confirmed what I thought drain cocks were for, but I did not realise that the positions for mounting them and steam in/out tappings could be "flexible".

When I get to the cylinder stage of the build, I may ask for some more help - can't do much at present - right hand doesn't work too well - recovering from carpal tunnel surgery.

Best wishes
Peter

[lancelot]

Hello Klank,
I put a photo up of the Score... yours doubled up...will give you some idea of the stud and drain cock positions,
keep it going...
All the best for now,
John.

P.S. sent you a P/M with photos , hope you get it ok.

[klank]

Hi Lancelot - I have replied (pm) to your pm - cannot see the photos unfortunately (white box with red cross in it - do not know what to do).
None the less, I appreciate the trouble you have taken to reply - many thanks - most kind of you.

Peter