Author Topic: Little and large - building 2 vertical steam engines.  (Read 12237 times)

Offline Ye-Ole Steam Dude

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Re: Little and large - building 2 vertical steam engines.
« Reply #210 on: November 03, 2018, 08:31:47 PM »
Hello Peter,

Looking real good at this point. I was not able to view your video?

Have a great day,
Thomas

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #211 on: November 03, 2018, 08:34:47 PM »
Thanks Thomas  :)

For some reason the video doesn't appear to have uploaded properly so I'm re doing it. It is only a 3min video explaining what I intend to do next etc but should be re posted shortly.

Edit - It should have uploaded now.
« Last Edit: November 03, 2018, 09:51:31 PM by Gas_mantle »

Offline gary.a.ayres

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Re: Little and large - building 2 vertical steam engines.
« Reply #212 on: November 06, 2018, 01:01:27 PM »
Great progress Peter. Looking good...

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #213 on: November 06, 2018, 02:26:07 PM »
Thanks Gary, I now have the valve chest partly made so hopefully I'll have it running in a week or 2  :)

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #214 on: November 08, 2018, 07:43:11 PM »
I'd really like to get the small engine up to the same build stage as the 'biggun' but as I'm getting close to being able to test run the no4 I've decided to continue with it first. Although the valve chest isn't quite finished it's well on the way so here is an update of where I'm now up to.

The valve chest casting doesn't have a raised boss to drill for a valve rod guide and I guess it isn't really essential but I'd like the finished engine to have one so I've decided to make my own. I was under the impression that no4 and no9 cylinder / valve chest castings were the same but as my casting has the 'S' orientated for a horizontal (no9) engine this may explain the absence of the valve rod guide boss.

Anyway enough of that, first thing to do is to square of the chest casting in the mill.



With the cover similarly squared off it's time to drill the 4BA fixing holes on both parts together. I kinda think an engine of this size could possibly benefit from more fastenings (maybe 10?) but the drawings show 6. so 6 it is. I'll mill out the 'S' later.



I hope this method will line up ok to drill into the cylinder casting  :facepalm:



Well with them drilled I may as well tap them



Drilling for the inlet flange I made earlier.



The valve rod needs to enter the chest at 3/8ths from the port face which isn't quite central to the casting boss but the intention is to machine the brass flange and the casting as a single unit so the finished result should be central. It is drilled and reamed at 5mm with an 8mm dia milled hole 7mm deep to accept the packing gland.



It wasn't practical with the tooling I have to drill right through the casting for the valve guide on the top face, so I drilled from above with a vice stop to hopefully pick up the same axis. It is then tapped at 1BA.



So with the 5mm valve rod in place I'm up to here.



It lines up ok but is a bit tight although I think it should be fine. The top (free end) of the valve rod needs turning down to a smaller dia (prob 3mm) and it will then locate in a drilled guide. I'd like oil to be able to get past the valve rod in its guide so assuming the rod is 3mm dia I'll drill the guide at 3.1mm and this hopefully will ease the present tightness.



It seems to be taking shape.



With a bit of luck I'll get the valve rod gland fitted and profiled, followed by the top guide and slide valve in the next day or 2. That should allow me to test how it responds to the valve before making the eccentric  :)

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #215 on: November 10, 2018, 09:14:48 PM »
I'm pleased to say I now have the valve and valve rod in place and things seem to be coming along.

The valve rod is 5mm steel turn at one end to 3mm where it will enter the guide (I didn't photograph making the guide but it is a simple turning and drilling job on a piece of hex brass), another  short portion is turned down to 4.7mm to thread at 2BA for the valve nut. I did wonder I'd need a steady whilst tuning but the deepest cuts are near the tailstock centre and the turning for the thread only involves 0.3 mm off the diameter so with very fine cuts things went well.



I'd already done the preliminary work on the valve rod gland to it was now just a case of bolting it in place then using the boring head in the mill to profile it along with the casting boss. There were a few hollows in the casting and to fully machine them out would have meant making the part thinner than I wanted so I chose to stop here then finish with a file and emery.



The valve block is the usual slide valve and is machined from a piece of brass, it needs a 1/2" x 9/16" pocket on the underside so once machined to the overall size the pocket is marked out. (the small hole is just a remanant of a previous operation in the in the piece of scrap and is of no significance)



The smallest slot drill I have is 3/32" and that coped nicely at machining the pocket.





To accommodate the valve nut and rod it's now just a matter of milling 5mm channels on the outer face



That then takes me to this point, it's a bit boxy compared to the one in the Stuart plans but it will never be seen and I'm happy with the critical dimensions



It fits ok an slides nicely so I think it will do the job. If need be I can always trim a bit off the outer profile to improve steam flow in the chest if it is too big to the point of choking the engine.



Digressing slightly and thinking forward I thought as I intend this engine to run on steam it would probably be a good idea to fit drain cocks, forum member Florian saw me mention them and kindly offered to sell me a pair of his homemade drain cocks at a good price. I bought them and I'm well impressed with the quality, they ought to give a nice finishing touch to the engine once fitted  :)






Not long now until steaming up  :)

Offline crueby

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Re: Little and large - building 2 vertical steam engines.
« Reply #216 on: November 10, 2018, 09:20:40 PM »
Thats quite a delicate bit of turning!
 :popcorn: :popcorn: :popcorn:

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #217 on: November 10, 2018, 09:30:28 PM »
Thanks Chris, I found that with a newly sharpened HSS parting blade it worked quite well, I managed to get the open end to 3mm dia to fit in the brass guide drilled to 3.1mm that seems to give a bit of allowance to stop the rod binding in the guide and allow oil into blind end.

Offline gary.a.ayres

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Re: Little and large - building 2 vertical steam engines.
« Reply #218 on: November 11, 2018, 04:10:39 PM »
Great progress Peter. Looking good!

Florian's drain cocks are little gems too.

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #219 on: November 26, 2018, 12:05:05 PM »
Thanks Gary, with a bit of luck it will be chuffing away shortly  :)

My main computer finally packed up after about 6 years of hard labour so I did have a few days with only my tablet which isn't great for taking images, but now armed with my new sooper dooper Windows whateveritis computer I have now been able to upload a few images from my camera showing the progress so far.

Firstly I decided to fit the new drain cocks, the intention is to run this engine on the hot stuff so it made sense to fit drain cocks. With M5 fine threads I found that tapping into cast iron wasn't a great success so I opted for fitting threaded brass sleeves first.



With the cylinder threaded they add a nice little touch and I'm pleased with the look. They may need a bit of shimming to get them both upright and parallel but I'll deal with that at the cladding stage.



Making the eccentric seemed to be the obvious next step so it's time to turn down a piece of steel that will form the sheave. I did wonder about making this from brass and making a steel eccentric strap but settled on the opposite, so steel it is...



Another area I pondered over was how to 'captivate' the strap on the eccentric, I thought it may be easier to cut a groove in the sheave and turn the strap with a raised internal diameter to match but having looked at other engines it seems it is more usual to have the groove in the strap and the raised 'ridge' in the sheave so I thought I'd give it a try.

Here I'm starting to turn the sheave diameter but leaving the 'ridge'. The plans call for this to be 1 /32" high which doesn't seem a lot to me but I'll stick with that.



With the outer diameter successfully turned I need to now work on the 5/32" throw so the crossslide is set at the required radius allowing the tool to scribe a line, a centre punch marks the spot  :)



With the part now sitting on parallels in the 4 jaw its a simple job to line the punch mark up with a tailstock centre to obtain the required offset.



Drilling and reaming to 12mm for the crankshaft.



I hadn't noticed until now but it looks suspiciously like I may have left a parallel in the chuck while turning the boss  :facepalm:  Anyway I got away with that one  ;)



Kinda looks like and eccentric sheave, so time to part it off.



Parting off with an offset workpiece probably isn't a good idea but with a sharp tool it works fine.



So far so good...



With the sheave tapped at 3mm for a grub screw it time to look at the eccentric strap. A disc of  scrap brass about 9mm thick looks just about big enough for what I need, I'm not too worried about the outer profile being exactly as the Stuart drawing suggests as long as the finished item looks appropriate in scale, shape etc. Here it has been hacksawed in half then silver soldered back together for machining. A small flat on each side was milled to help holding in the 4 jaw and aid profiling later.



Before mounting the strap in the chuck for boring I thought it worthwhile making a tool to cut the internal groove and testing how it performed. Broken centre drills are a readily available item for most beginners and they make useful blanks when it comes to making one off tools.

This little fella is a bit rough and ready but ought to manage a small groove in a piece of brass.





With a simple holder made it seems to cut external grooves ok at the correct size for the eccentric.



The strap is drilled then bored to be a close fit on the main body of the sheave.



This photo isn't great but here I am ready to plunge in on the far side and (hopefully) end up with a neat groove. I chose to cut away from the camera with the lathe in reverse largely because it was easier to see what was happening but I guess it's not really important either way.



It seems to have done the job  :) There is a hint of chatter on the bottom surface of the groove but it is small and that area shouldn't be a contact / running area.



Quite happy with that...





I'm not yet sure how well the strap will fit until I've profiled it then split it to assemble over the sheave but I'm cautiously optimistic.

The next stage after finishing the eccentric assembly will be to make the rod leading to the valve rod, I could do with a bit of advice here if anyone can help. The eccentric sheave will sit outside the line of the valve rod, it's only small (perhaps 3mm) but does mean I'll have to incorporate a 'dogleg' in the eccentric rod  :(

I had initially planned on the rod being a tapered flat bar but now that I need to add an offset I'm thinking a round rod about 5mm dia may be a better option. Anyone got any advice how to create accurate 'dog legs'? Will heating the steel help? I'd be grateful for any advice  :)

With a bit of luck I'll have it running in a few days  :pinkelephant:

« Last Edit: November 26, 2018, 12:20:12 PM by Gas_mantle »

Offline Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #220 on: November 26, 2018, 12:28:15 PM »
Looking good

Don't right off a flat rod just yet as they are easy to offset where they fix to the strap so you can keep a straight rod, just position the fork as needed



If you do want to put a jog in the rod then a simple way is to stand two bits of 3mm flat vertically in your vice with a gap between equal to the length over which you want to form the jog. Then take your 5mm rod and put it horizontally in the vice with one bit of the flat steel in front and the other behind. Now tighten the vice to bend the metal. Next up from that is to make a jig, this was for a double bend but same sort of principal



« Last Edit: November 26, 2018, 12:32:56 PM by Jasonb »

Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #221 on: November 26, 2018, 01:29:00 PM »
Thanks Jason,

A flat bar with a taper does look neater and a bit more like the real thing so I'll take a few measurements tomorrow and assess what is achievable. I sort of wanted to keep open the option to add a Stephensons reversing gear later depending on how well the engine looks and performs. Having made all of the moving parts from barstock if I do add reversing gear I'd want to do likewise if I can.

The eccentric offset is a bit annoying but not the end of the world, when I made the soleplate and bearings I kinda made them up as I was going along so a bit of a cosmetic error has crept in. Ultimately it stems from making the crankshaft larger than the plans and then the same with the 'Lego' bearings.I've made some roughed out bearing caps here to get things secured down but they are still work in progress  :headscratch: A bit of rounding off and some brass oil cups ought to soften things a bit.

This the lie of the land at the moment with the sheave against the bearings :-





Cheers  :)




Offline Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #222 on: November 26, 2018, 01:49:55 PM »
You could easily half the thickness of the flange on that bearing which will pull things back a bit.

Flat also works for reversing gear, here most of the offset is done with the forked ends, the pump rod is jogged. Both use the same simple lap joint to fix rod to strap



Or you can get a bit more adventurous and bolt the rod to the end of the strap, one rod is bent and the forks differ




Offline Gas_mantle

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Re: Little and large - building 2 vertical steam engines.
« Reply #223 on: November 26, 2018, 02:15:05 PM »
Thanks  :)

Now you have mentioned it and I've had a proper look, I agree the bearing flanges can be reduced significantly and with a bit of luck if I machine a flat rod properly I ought to be able to accommodate the offset (watch this space  ;) ).

In the top photo of reply 220, is that a split strap running on a sheave over its entire width with side walls instead of a guide groove?


Offline Jasonb

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Re: Little and large - building 2 vertical steam engines.
« Reply #224 on: November 26, 2018, 02:47:21 PM »
On the Minnie which is the top engine all the eccentrics have a 1/32" flange either side so the strap just has a plain bore right through.

The lower photo has them done like yours with the raised rib in the middle of the eccentric.

In both cases the strap was bored after splitting.