Author Topic: Reinventing the Real.  (Read 2198 times)

Offline Jasonb

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Reinventing the Real.
« on: May 21, 2022, 07:05:41 PM »
While making the Stuart Victoria last year I started to feel like I would also like to make the Real to go with it. So I bought Andrew Smith's book (cheapest source of drawings) on building the Real and started to look a pictures of them on the net, the more I looked the more I saw that I did not like and that included what Stuarts are asking for the kit. So over a few winter evenings I developed a different version that has gone by the working tile "Unreal" which addresses some of these issues and also more closely follows the etching from Andrew's book that was his inspiration.



Although I could have made the flywheel and cylinder from scratch I decided to use just these two Stuart castings as I felt that others who may want to follow suit would find these the most difficult parts to make from scratch. I also went for a metric design based on nominal sizes rather than direct conversion of the old imperial sizes again with many beginners now of an age where they were taught metric at school that make sense and if using handwheels on modern metric machine sit is easier to keep track of whole metric numbers rather than working to several significant figure after the decimal point. This results in a model with 25mm bore and 50mm stroke

I'll go into more detail during the build about the various modifications but a summary is as follows

Base - This is a very expensive casting at 45 for what is little more than a rectangle with tapered sides and rounded corners So something with a bit more shape and detail
Columns - Again something with more shape and detail than the plain tapered ones
Entablature - This is shaped the wrong way for any form of classic architecture being larger at the bottom than the top all for the sake of easy removal from the sand so that needs to be corrected and some additional detail added at the same time
Pulley - change for one closer to the one shown in Andrew's book not the standard Stuart one used on all their 2 x 1 models
Flywheel - remove the "lumps" they now cast on the rim, add some counterbalance weight and fit with a gib head key
Valve/eccentric - modify layout to do away with the dog legged valve rod and make an eccentric correctly shaped for vertical use
Cylinder - move exhaust position as it gets a bit tight between column and exhaust position
Crosshead and guides - change to rod guides which was another feature of the engraving in Andrews Book.
Conrod - change from the tuning fork design to one similar to the other 2 x 1 Stuarts and Andrew's etchings

On the cost front this model work out at about 200 which is half of what Stuarts are currently asking. This is based on buying most materials by the 300mm length so you will have some over for the next engine. Larger diameters by the 25mm length where available. The cost also includes enough for fixings etc as well as the price of the two castings.

A few more bits of tooling and cutters may be needed but those will last a long time and if used over several more models will not amount to much. I did make use of my CNC for some of the parts but just about all could be done with manual machines and only one part would need a bit more of a redesign to make it a bit easier to cut from solid.

Next time I'll start on the construction of the base. And don't worry as unlike the Wall engine this one is finished and runs very well so there will be a happy ending to the build.
« Last Edit: May 21, 2022, 07:09:29 PM by Jasonb »

Offline crueby

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Re: Reinventing the Real.
« Reply #1 on: May 21, 2022, 07:40:16 PM »
Nice proportions on that! Looking forward to seeing this one develop...

Offline Jo

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Re: Reinventing the Real.
« Reply #2 on: May 21, 2022, 09:30:47 PM »
The Real engine is rather nice  :embarassed:



Jo
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Offline samc88

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Re: Reinventing the Real.
« Reply #3 on: May 21, 2022, 09:43:31 PM »
Thus sounds great, I shall be keenly following along

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Offline 10KPete

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Re: Reinventing the Real.
« Reply #4 on: May 21, 2022, 11:47:59 PM »
That's quite the impressive engine, Jo! What was it powering?
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Offline Jo

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Re: Reinventing the Real.
« Reply #5 on: May 22, 2022, 06:34:40 AM »
It used to run a Mill and Mash drive  :DrinkPint:

Originally built in 1829 by H & W Davis of Landport and she worked in Fareham Brewery until 1952. She is now at the "Stretham Old Engine" museum in Cambridgeshire  ;)

Jo
« Last Edit: May 22, 2022, 06:51:13 AM by Jo »
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Offline Jasonb

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Re: Reinventing the Real.
« Reply #6 on: May 22, 2022, 07:06:15 AM »
Though not "the Real" engine that Andrew Smith used as his inspiration it is just one of many true (crank at the top) engines and like the engraving he used has (had) one end of the crankshaft supported in the building's wall.

I did not go as far as making it two columns and a wall as there are a couple of other engines on my to do list that will be made that way, this Thomas Rose being top of the list. I also wanted to keep the general feel and simplicity of the Stuart Real in this instant rather than make a scale model of a specific engine.

In the last image you can see the engraving he used as well as his own engine that had the larger dia pully.

« Last Edit: May 22, 2022, 07:14:51 AM by Jasonb »

Offline Jo

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Re: Reinventing the Real.
« Reply #7 on: May 22, 2022, 07:49:28 AM »
The guys in SIMEC like Andrew did some interesting things back in the 1970s with their "reuse of Stuart Turner Castings". I haven't read the book but the Stuart Turner website points at the Fareham Overcrank Engine as its claim for the original and it is rather nice  :embarassed:

The Stuart model Real design is a pretty little thing, especially when it is in motion  :)

Jo

P.S. Surus has just shown me he has some Overcrank Engine Castings  :pinkelephant:
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Reinventing the Real.
« Reply #8 on: May 22, 2022, 10:13:44 AM »
They just use that image as an example of a "real" or "true" vertical http://stuartturnersteam.com/6Pack/Real/Real.html

It would be resonably easy to replicate, the crank and piston rod guide are very similar to the Benson as it the governor. Columns just smaller versions of the Otto Langen so just milling and dividing and the entablature with it's pediment can be milled from 2 or 3 bits of bar, look forward to seeing your rendition Jo. :stickpoke:

Offline RReid

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Re: Reinventing the Real.
« Reply #9 on: May 22, 2022, 02:51:36 PM »
I can definitely see the appeal. There is an elegant simplicity to those over-crank engines. Watching with interest!
Regards,
Ron

Offline Michael S.

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Re: Reinventing the Real.
« Reply #10 on: May 22, 2022, 05:15:44 PM »
This is going to be a very nice model. I love those old designs where the crankshaft is on top of the cylinder. One of my first models was built in a similar way. Another one made of cast parts was added later.
But I always found the Stuart machine very interesting.
I have here two more views from a physics book from 1858. Also a nice construction.
I look forward to pictures of the making of the machine.

Michael

Offline 10KPete

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Re: Reinventing the Real.
« Reply #11 on: May 22, 2022, 06:35:39 PM »
Thanks, Jo. These older engine designs are very interesting and lovely to look at.

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline steam guy willy

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Re: Reinventing the Real.
« Reply #12 on: May 23, 2022, 02:41:35 AM »
Hi "J" , this looks like an interesting project and I will be following with interest.
"W"

Offline Jasonb

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Re: Reinventing the Real.
« Reply #13 on: May 23, 2022, 06:58:56 PM »
I decided to make a start with the flywheel while I was waiting for a delivery of materials that would have allowed my to start with the more logical base. You seem to read a lot that the current Stuart castings are not what they used to be but I have to say that both the flywheel and cylinder castings were very good - No holes, no hard spots, mould halves lined up with no step and very little flash. The only real downside is that Stuarts seem to only supply castings from the pattern used for the twin Victoria which have the ugly bosses cast in where two flywheels are bolted together.



I like to fettle my castings before machining so there is no risk of spoiling any finished surface if you slip with a file or grinder so that was the first thing to do. As the inner rim is not machined I like to set that to run true and was able to do so by holding in the 3-jaw. This allowed me to turn the outer surface, one side, clean up the hub and also bore the hole all at one setting. I like to bore the hole to finished size as a reamer is likely to follow a drill hole that may have wandered and I can also get a slightly closer fit than a typical reamer will give which reduces the chance of a wonky flywheel. Once I got close to size by measuring with the digital callipers I switched to using a piece of the crankshaft material as a plug gauge to get the final size.



I did the outside with the lathe running in reverse and used a boring bar mounted upside down which easily reached around the casting with minimal overhang



I then changed to the 4-jaw and set the machined surfaces to run true using one indicator on the OD and another against the side.



It was then a simple job to turn the other face and clean up the hub.



You can see where I have turned away the bosses that there are some flattish areas these were blended in with a Dremel using an oval shaped grinding point.

Stuart show a grub screw to retain the flywheel but I used a broach to cut a tapered keyway and machined up a suitable gib head key from gauge plate to fit.



Jumping ahead to when I test ran the engine it was quite noticeable when running slowly with no load that the engine rotated faster when the crank was moving downwards than up which is due to the added weight of the conrod, crosshead, piston and piston rod all pulling downwards and then the engine having to work harder to lift that weight back up again. So some strips of lead flashing were cut and bent to the curve of the inner flywheel and held in place with masking take to experiment with how much counterweight needed to be added. Once happy the two layers of Code 4 lead were bonded in place with JBWeld. Once hardened the excess JBW was cleaned up, a bit more U-Pol filler added to blend things in and you would think it was all part of the casting.





Offline Jasonb

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Re: Reinventing the Real.
« Reply #14 on: May 26, 2022, 07:18:18 PM »
As I had cut off a bit of 12mm PGMS to use as a plug gauge for the flywheel hole I thought I may as well work on the crankshaft next.

Starting with a piece of the 20mm square bar I had bought for the column bases it was machined down to an oversize rectangular section and then thinned further at the pin end followed by reaming the holes for the shaft and pin.



I could then use the hole to gauge the fit of the reduced diameter at the end of the crankshaft



The crank can then be shaped in a number of ways from simple buttons and filing, to using the rotary table or the CNC if you have one. I opted for the last and used a 4mm dia cutter with a 1mm convex corner radius so it left a nice fillet on the internal corners.



With that machining done the crank was Loctited (648) onto the shaft and set aside to cure. Hold the shaft to run as true as you can in a collet, 4-jaw or good 3-jaw and then skim the crank to finished thickness. This ensures the face that the crank pin will be tightened against is at right angles to the crankshaft's axis and therefore the pin should end up parallel to that when fitted.



I'll come back to the pin later once the conrod bush is turned and fitted so it can be used to gauge the fit.

While I had a bit of time to spare a small part was ticked off the list in the form of the valve rod clevis. I often mill my on small square, hex and rectangular components from round stock a sit's often not worth buying a 300mm length of a size you won't use much plus some small square stock is not that crisp and often comes with rounded corners. After milling the Slot was formed with a 1.5mm slitting saw then the part was cut off the parent bar. I used a square collet but the 4-jaw will do to hold while the end was turned, drilled and tapped, I'm using a 2mm radius tool which like the milling cutter mentioned above leaves a pleasing small internal fillet.