Author Topic: Double Tangye Steam Engine  (Read 109334 times)

Online Jo

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Double Tangye Steam Engine
« on: October 19, 2013, 07:26:40 PM »
The Edgar Westbury Double Tangye “Type” Mill Engine builds upon an earlier design by William Ballantyne published in Model Engineer in 1933. The original engine was a single cylinder design and casting sets for it have been know to appear on Fleabay. Edgar Westbury chose to double up the engine to make a “double”, that is two equal diameter cylinders rather than a compound which has different diameter cylinders in which the steam being first used in the smaller diameter “High Pressure” Cylinder and subsequently further expanded in the “Low Pressure” Cylinder.

The original type of engines upon which it was based was produced by Tangye around the turn of the century, although it should be noted that Westbury was unable to get any information from Tangye to support his redesign. His design was for a double engine which consisted of two complete engines sharing a common crankshaft. Both engines arranged right/left handed were mirrors of each other with independent valve gear, governor and throttle. The idea being that it represented a type of engine that you could make the engine up as either a left hand or right hand engine as single handed engines. But with a double engine with readily accessible working parts it could have been possible to disconnected one of the crankhead bearings and eccentric strap and run the remaining engine as a single providing better economy on light loads.

But as mention Edgar Westbury did not actually get any evidence from Tangye’s that they ever built such engines or that if they did anyone actually disconnected the second engine. The Westbury design published in 1953 originally showed a single Watts governor on one of the engines. If a single engine was always the one that was disconnected then this is adequate but subsequently in the series of articles for some strange reason the idea of putting on two governors came about. Hence many of the models you will see today have two watts governors fitted:



Technically Tangye’s about this time were always fitted with Pickering governors and records show that even on double engines a single  :ThumbsUp: Pickering Governor was used to control both engines.

When Westbury designed this engine he took the opportunity of reusing an existing model engine flywheel that was readily available. To date I have been unable to find any Tangyes that have a flywheel similar to the one he chose, their engines had a much simpler flywheel design.

So this build is going to take a standard design seek to make a model that is more like the original engines made by the Tangye factory and as for the colour.. :shrug:.. most are black.

Jo
« Last Edit: December 15, 2019, 01:23:28 PM by Jo »
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Online Jasonb

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Re: Double Tangye Engine
« Reply #1 on: October 19, 2013, 08:13:44 PM »
So you are not tempted to make it a compound rather than Double high?  :mischief:

J

Online Jo

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Re: Double Tangye Engine
« Reply #2 on: October 19, 2013, 08:26:46 PM »
No twins have their advantages as well ;) I have seen the compound that was published in ME a few years back and it is not for me. Most of these engines went out to the colonies and for their use smoothness of running was desirable but an increase in pressure was not. Operating your boiler on what ever sugar cane remains was kicking around was never going to generate the same amount of heat as best Welsh steam coal which was too expensive to ship out. So most of these engines made do operating on lower pressures, so I question if whilst they were built as compounds if they really operated as compounds. I have seen engravings of Tangye doubles  ;)

My starting point for this engine is a set of castings that have been partially started by a "toolmaker" and his mate as for who did what: lets say there are some opportunities for correcting what has been done  :lolb: . I have been having a think:



Jo
« Last Edit: December 15, 2019, 01:25:02 PM by Jo »
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Offline b.lindsey

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Re: Double Tangye Engine
« Reply #3 on: October 19, 2013, 10:04:24 PM »
Very nice engine Jo. Looks like they left you plenty to do too :)

Bill

Offline steamer

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Re: Double Tangye Engine
« Reply #4 on: October 19, 2013, 10:44:05 PM »
Nice looking engine Jo!   Looking forward to it!

Dave
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Online Jo

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Re: Double Tangye Engine
« Reply #5 on: October 20, 2013, 08:00:48 AM »
To be honest not a lot has actually been done with this set of castings. The cylinder has been started. Someone has bored both of them and drilled the steam ways:



You can see that they have used three holes as the steam ports. Yes I know they are not evenly spaced but that does not matter. You can also see in the photo that there is a slight flat been filed on the edge of the cylinder bore, this is only a small flat to enable the ports to be drilled they are going to need taking out deeper to clear the rear cylinder cover and enable the steam to enter that end of the cylinder.

They have also milled the steam ports, ok the ends are not 100% in line but they are equally spaced…



What is annoying is that the steam chests have had their two faces machined and drilled but the drilling is not square to the outside of the steam chest and does not match the drawings. So the steam chests are going to have to be used as drilling guides for the cylinder and the covers.

Jo
« Last Edit: December 15, 2019, 01:26:10 PM by Jo »
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Online Jo

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Re: Double Tangye Engine
« Reply #6 on: October 20, 2013, 08:11:04 AM »
The Base has had the top:


and bottom faced:



This is a very large thin casting and by looks of things the original machinist did not find any hard spots. The one concerning bit is the stands:



They have had their bases machined flat and the end faces machined but there is a  difference in height between the two cylinder faces  :rant:.

Jo
« Last Edit: December 15, 2019, 01:27:15 PM by Jo »
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Offline Stuart

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Re: Double Tangye Steam Engine
« Reply #7 on: October 20, 2013, 09:16:24 AM »
Jo
Looks like you have some repositioning machining to do,  can you not get a lump of CI its comes in square section and machine up a new correct steam chest ?

as you intimate in the first post it may have been made by committee


I have a comfy chair popcorn and a glass of water lined up ( no alc here due to meds , they no like each other )


looking forward to more instalments

Stuart
My aim is for a accurate part with a good finish

Online Jasonb

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Re: Double Tangye Steam Engine
« Reply #8 on: October 20, 2013, 09:59:07 AM »
I'd agree with Stuart, a new chest cut from solid would be the way I would do it. you could then incorporate a decent flange to mount the pickering governor and maybe even a gland for the valve tail rod that a lot of them seem to have. Will you be adding some "+" bracing to the valve chest cover which seems quite common on the Tangyes.

Back to the flywheel, most of the photos of existing engines are of singles so they would more likely have a lighter section flywheel than the doubles so don't go too skinny. A thick one will also help the engine run slower. You could also make it look like it was cast in two halves which seems quite common on the double & compound engines.

J
« Last Edit: October 20, 2013, 10:06:13 AM by Jasonb »

Offline tel

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Re: Double Tangye Steam Engine
« Reply #9 on: October 20, 2013, 10:09:46 AM »
Quote
What is annoying is that the steam chests have had their two faces machined and drilled but the drilling is not square to the outside of the steam chest and does not match the drawings. So the steam chests are going to have to be used as drilling guides for the cylinder and the covers.

....or plug all the holes and re-do 'em
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Online Jo

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Re: Double Tangye Steam Engine
« Reply #10 on: October 20, 2013, 10:32:57 AM »
Stuart, the good news is that the outside of the steam chest is still over size and need finishing.

Jason, I am thinking about a valve tail rod.. the bracing is quiet a feature on the steam chests :naughty:

I am limited on the flywheel diameter by the base. I also have not got any suitable bits of stuff that I could use so currently the existing flywheel is going to be volunteered for reshaping. The flywheel on this one is plain but nice:



So I am currently looking at the ones below. The existing flywheel is a five spoke one... I prefer 6 spokes  :shrug:

Jo
« Last Edit: December 15, 2019, 01:29:13 PM by Jo »
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Offline Steamer5

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Re: Double Tangye Steam Engine
« Reply #11 on: October 20, 2013, 10:40:16 AM »
Hi Jo,
 Dragging up a chair & waiting for more words of wisdom on the how's & why of machining those casting. The club I belong to has a Tangye mounted up in what is know as the "sauna", only a single & not that big, still a bit hard to fit under your arm though!

Cheers Kerrin
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Offline Stilldrillin

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Re: Double Tangye Steam Engine
« Reply #12 on: October 20, 2013, 11:00:30 AM »
Clocked in, overalls, barrier cream......  :)

You won't hear too much from me.  :ThumbsUp:

Bring it on, Jo!  :whoohoo:
David.
Still modifying bits of metal... Occasionally, making an improvement!
Still drilling holes... Sometimes, in the right place!

Online Jasonb

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Re: Double Tangye Steam Engine
« Reply #13 on: October 20, 2013, 01:25:28 PM »
Six spokes definately looks better and is more their norm. At only 5 1/2" its not that big to fabricate or cut from a billet of 6" CI, maybe even a chuck backplate could be used. Or if modeled on a two piece one you only need 1"x3" material

Online Jo

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Re: Double Tangye Steam Engine
« Reply #14 on: October 20, 2013, 01:56:08 PM »
 :thinking: I have just found a steel donut the same outside diameter as the Tangye flywheel casting and 1mm wider  :naughty:

This engine is a bit twee in full size for a two piece flywheel  ;).

Jo
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