Stuart Major Beam Engine

[Steamhead]

Hello Andy.  They are two separate cased models.  Making a mirror pair is an interesting idea....you've got me thinking now!.  I see you machined the rebate on the top of the steam chest....nice touch.   Alan

[Chipmaster]

"Making a mirror pair" - I have this part built Twin Grasshopper that was passed on to me to complete in 2013 by a friend who had owned it for many years. He saw it advertised in Reeves shop when they were in Marston Green Birmingham and bought it.  I wonder whether anybody else tried a twin Grasshopper?
 
Work has progressed beyond the stage featured in these photographs (these were taken nearly 3 years ago) but my Stuart Major, Economy, Chuk and Retlas arrived and jumped the queue. Perhaps I'll do a short item about this model, which I think originated in Model Engineer in the 50's and was updated in 1965. I have a copy of the 1965 article by Sydney Owen and the complete plans.
These castings are brass and gunmetal - one engine is all brass the other all bronze. However, there are some issues with the model as it came to me,

- The bore is 1.5" with iron piston rings which don't seem ideal for running in the brass and bronze cylinders. I think I'll re-bore the scored cylinders and substitute silicone O rings.

 -The fabricated crankshaft is in one piece with the cranks set at 180 degrees and is quite straight but I think it would be better to separate the two engines and have a coupling between them perhaps with the cranks at 90 degrees for self starting.

- It's a very heavy model, perhaps it would be a better bet to make two separate engines.

- As a twin the engine will need a fair amount of steam.

Food for thought Alan.

Andy

[Steamhead]

Andy, The grasshopper is a solid looking bit of kit.  I think it would be really something as a twin.  Gunmetal bores: I've never seen cast iron rings in them but that's not to say it isn't done.
I have seen good old fashioned graphite rope in a gunmetal piston in gunmetal bore....they always seem to be very smooth with virtually no drag.....just a thought.
I agree crankshaft would be better done at 90deg.  And yes, you will need hell of a boiler to run it. Alan

[Steamhead]

Hello Andy...For when you come to do the pump.   When at it's highest point I found the piston rod (84) was out of its guide in the main pump body, so effectively there would be no packing gland.  To fix, I made sure that the bottom plug (89) was no more than the 0.125"  spec.,  then made the piston 3" rather than the 2 29/32" spec.  The top stuffing gland is 1/2" spec.depth into the body, best to reduce this to 0.4375".(and also the gland by 1/16").  If the piston bottoms out then you might need take take a smidgeon of the bottom of it.    (If,  like me, you did the assembly with the stuffing gland in situ , then put the piston in,you would not notice there was anything wrong).   I hope you are keeping busy in the workshop  Alan

[b.lindsey]

Still following quietly here Andy. Nice progress on the Stuart Major, but I like the twin grasshopper too

Bill

[Chipmaster]

Just over three years since I did any work on my Stuart Major, a house move and several projects on the new home plus other / easier model engine projects kept the Stuart Major in the background. I had wondered how I would form the small slots (5/64" and 3/32") that feature in several parts of the engine. These slots accommodate tapered cotters or wedges used to lock parts together. Fortunately Dave 'Chipswitheverything' told me how he had formed the slots on his own Stuart Major so I started work on the cast iron connecting rod copying Dave's method.

Off to a good start with the con rod turned between centres taking light cuts.
WP_20190416_15_53_36_Pro (2) by Andy, on Flickr

Machining various sections.
WP_20190416_16_51_30_Pro (2) by Andy, on Flickr

Using a form tool.
WP_20190416_17_27_34_Pro (2) by Andy, on Flickr

For the fish bellied central section I varied the angle of the topslide.
WP_20190423_17_27_07_Pro by Andy, on Flickr

The slot in the big end was cut with a slitting saw then closed with a piece of steel glued and pinned.
WP_20190428_16_49_53_Pro by Andy, on Flickr

Cutting the slots in the fork ends.
WP_20190427_17_36_37_Pro by Andy, on Flickr

Everything was going well.....

Andy

[Ye-Ole Steam Dude]

Hello Andy,

Glad to see the work continues, I will be following.

Have a great day,
Thomas

[Chipmaster]

Thanks Thomas.

I made the retaining strap by drilling though a piece of flat steel bar then held the bar in the lathe toolpost, two cuts with a slitting saw formed the legs of the strap.
WP_20190505_15_07_04_Rich by Andy, on Flickr

The  3/32" slots in the strap were milled with a slot drill and finished with needle files.
 WP_20190505_18_38_15_Pro by Andy, on Flickr
WP_20190506_16_35_22_Pro by Andy, on Flickr

Milling the step in each leg of the straps.
WP_20190509_12_11_34_Pro by Andy, on Flickr

The finished connecting rod and straps, then I started fettling temporary cotters or wedges.
WP_20190509_17_42_52_Pro by Andy, on Flickr

Unfortunately a cotter jammed and I broke the casting trying to get it out. This picture shows how the thin casting broke. I was being heavy handed.
P1080900 (2) by Andy, on Flickr

To be continued..........

Andy




 

[b.lindsey]

Time flies doesn't it. Good to see you back on the build but sorry about the mishap with the casting.

Bill

[cnr6400]

Hi Andy, are you going to attempt a bronze weld or silver solder repair of the break-out? Should work fine if you V out the break a bit to get the filler metal well in. Clean Clean Clean, flux well and get it to a good red heat then flash some bronze or silver solder in. good luck!

[jeff l]

good to see you back on this build , sorry for the mishap though.

[Jasonb]

Andy, I see you were fitting plain wedges when a wedge and matching cotter is the usual means to retain these straps, not only do they pull the strap tight around the bearing but the cotter prevents the strap from spreading. A single wedge also needs a matching sloping face on the components if it is to work and not get stuck, this is more commonly used on say a piston rod to cross head joint..

[Chipmaster]

Hi Jason, I decided to have a go at more work on  the Major assuming it would take longer for you to complete the Allman engine for which I also have the castings and intend to complete using your plans. However, just as I started you posted the video of your Allman running.
I agree with what you said about paired wedges and cotters. The plain wedges In my pictures were supposed to be a loose fit, just a temporary means of holding things together. I’ll make up the correct cotters and wedges when the connecting rod and it’s straps are finished. A replacement connecting rod casting would cost about £70 delivered and I could have the same problem again.
How did you form the slots shown in your pictures, particularly the deep slots?

Hi cnr6400, too delicate for me to attempt that sort of repair so I decided to amputate and replace the forked end of the connecting rod. I wasn’t happy with my work on that end of the con rod anyway so it had to go.
Andy

[Jo]

Pleased to see you back on the Major Andy, shame about the fork failure.

... I decided to amputate and replace the forked end of the connecting rod.

That's a good way to go forward 

Jo

[Jasonb]

Cutting from solid what a good idea

The slots in the pictures are 1/16" wide, first I drilled each end and then a couple more holes between right through. Changed to a 1/16" 3-flute cutter and did a series of plunge cuts at something like 10thou intervals but could only go about 1/2 depth so had to come at it from both sides.

Finished the slots with modified needle files that I ground the teeth of the faces so they only cut on the edges. ARC now sell special files for just this sort of job which I have bought and am waiting to use them on the current build.

https://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Tome-Feteira-Files/Swiss-Pattern-Needle-Files/Joint-Square-Edge-Needle-Files

J

PS Allman now painted and back together. More drawings have been done