Stuart Triple new build

[Charles Lamont]

The main wear on steam engines is the valve steam pressure keeps the valve against the valve port no need for springs

Under load, no. But if you get close to a (full size) compound traction engine on slow tick-over you will probably hear a regular clonk as the low pressure valve alternately lifts off the portface an slaps back on. I think those tiny springs in the valve nuts are a clever idea.

 

[Alec Ryals]

"he did a simple mod of putting a pair of very light springs on the valve nuts to keep the valves pressed against port" --> No need to change the steam engine..

To running test for each cylinder: Remove the two connecting rod to other cylinder who is not in use (due less load caused by friction), the cylinder who is under test/adjusting timing must have connecting rod to run the steam engine. Also you are adjusting/running the triple steam engine as if it were "one cylinder steam engine".

After each cylinder has correct timing and running test for each cylinder is done, mount all connecting rod and the two manifolds on place and the triple steam engine is ready to run.

Here are a ton of good tips in this link.. Stuart Triple Expansion Engine

Here is my triple expansion steam engine running at airpressure.

Nice engine i built one also Tricky timing lol

 

[Emers]

My Crankshaft
It has been an interesting journey.
I started by purchasing some 1144 steel from the USA. It was recommended by several people on this site. My approach was to put centres in the ends and turn between centres. This did not work out very well. I turned it oversize on all the journal's but i had problems with it not running true. I feel it was internal stresses being released. I could not get it to a point where I could get the journals to clean up to be usable so I decide to build a Crank by the build up process.

 

[Emers]

My 2nd attempt at building a crank was to use some 3/8 dia silver steel it is ground bar. I measured several lengths at my supplier and found some which measured .3748". When producing the webs for the crank I used a 9.5 mm ( .374" ) reamer which gave me an interference fit of about .0003" after a light polish of the silver steel rod . This worked out well. I made a little fixture to press the pins together and keep them aligned. Next I will machine and fit the counterweights for the crank.

 

[Emers]

Hi Again
I have progressed slightly. I machined the counterweights and fitted them to the crank. when assembling things I realised 2 of the main bearings had a bit too much clearance about .0035" so I closed them up .005" and reamed them to the correct size. this resulted in having to use .002" shims top and bottom of the bearings to keep them all in alignment, this has worked great. The drawing calls for 7BA studs riveted through the counterweights to fasten them together I did not like that idea so I drilled and tapped the crank 2mm as I had some SHCS in stainless so they can be removed and painted later.
I also machined the disc wheel today a straight forward machining job, to get a good fit to the crank which now measures .374" I bore about .002" undersize and using an adjustable reamer held in the lathe running at 150 RPM and slowly bring the hole to size using some kerosene as a lubricant this works great, just make very small adjustments and I have gauge pins to check as I increase the hole to size.

 

[Richard Hed]

Hi Again
I have progressed slightly. I machined the counterweights and fitted them to the crank. when assembling things I realised 2 of the main bearings had a bit too much clearance about .0035" so I closed them up .005" and reamed them to the correct size. this resulted in having to use .002" shims top and bottom of the bearings to keep them all in alignment, this has worked great. The drawing calls for 7BA studs riveted through the counterweights to fasten them together I did not like that idea so I drilled and tapped the crank 2mm as I had some SHCS in stainless so they can be removed and painted later.
I also machined the disc wheel today a straight forward machining job, to get a good fit to the crank which now measures .374" I bore about .002" undersize and using an adjustable reamer held in the lathe running at 150 RPM and slowly bring the hole to size using some kerosene as a lubricant this works great, just make very small adjustments and I have gauge pins to check as I increase the hole to size.View attachment 133844View attachment 133845

It never ceases to amaze me how beautiful great work is.

 

[Emers]

Thanks for the complement. I try to do things correctly as per the drawings

 

[Richard Hed]

Thanks for the complement. I try to do things correctly as per the drawings

I try too, but not always successful.

 

[Emers]

Continuing my build.
I have made the eccentrics they posed some concern on how to tackle I started by holding by the extra material on the casting and put a 3/8 hole first and turned the .500 x 3/16 shoulder Then I made 2 fixtures to mill and turn the offset part.

The fixtures were made so they could be used in the mill (The flat to get aligned ) and the lathe. the holes are positioned so when the part is clamped the offsets are in the correct position, It is fixed through the bore of casting. It was a bit tricky but they came out great.
The centre eccentric which is split in half to attach to the crank was made by getting some cast iron from my supplier and machined into two rectangles (easier to hold in the mill) centre hole machined then drilled and tapped to clamp together then put on a mandrel in the lathe to turn .500 x 3/16 boss. Then I could use the fixture to mill the offset sections

This completed these pieces the onto the eccentric straps.
My description here is not great but I hope people get an idea of how I am making these parts.

 

[Emers]

Now for the eccentric straps. More fixtures.

Used the fixture for the eccentrics to bring to thickness then split them and drilled & tapped to hold together.

Fixture to turn

This is an alignment piece it allows me to get the parting line and the part centred

One half positioned

Then clamped

Alignment piece removed

2nd half screwed to the piece clamped

Clamped

In lathe and machined

Finished turning. I have several short videos but they say they are too large a file so will have to work on that.

 

[sniffipn]

to minimise editing time, could the videos be posted on youtube - and a link posted in this thread?

 

[Emers]

Yes just checked this idea out I will post the videos on YouTube and post the link.
Thanks

 

[sniffipn]

as a hobby machinist, inspiring and helpful to see the use of fixtures. the more so with a triple where several of same part to be machined. thanks

 

[Emers]

Have uploaded 2 short videos machining the eccentric straps

 

[Alec Ryals]

Have uploaded 2 short videos machining the eccentric straps

nice setup i used a 4 jaw

 

[Emers]

Hi Alex
My 3 jaw is adjustable a Pratt Bernard Grip True my fixture is machined concentric with the OD running true so when I put any work in the 3 jaw I check the OD is true and I know the piece to be bored is perfectly running true. Great for setting jobbing work running perfect I mean within a couple of .0001"have used them for over 25 years. Very rarely use 4 jaw except where job requires to be held very tight

 

[Emers]

Hi Everyone
I have progressed since my last post. I have made several extra pieces the eccentric straps were completed and fitted to the crankshaft.

Next made the eccentric rods and the expansion links and the columns. Assembled to base.

More to follow

 

[Charles Lamont]

The main wear on steam engines is the valve steam pressure keeps the valve against the valve port no need for springs

No. On a compound or triple, running at low pressure on air or steam, it does not.

 

[Emers]

Back Again
Have made the next part the Reverse Shraft Bracket. Once again simple fixture to hold the casting after machining thickness and drilling some holes then into the fixture to machine the outside profile I have uploaded a 30 sec video to you tube to give an idea of the process I used.
The link 20220324 Reverse Shaft Bracket
And a photo of the up to date progress

 

[Emers]

Hi Again
Next parts the drag links 6 off required pretty straight forward to make I used key steel and some simple fixture.