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Member postings for Tony Martyr

Here is a list of all the postings Tony Martyr has made in our forums. Click on a thread name to jump to the thread.

Thread: triple expansion engine piston rings
17/09/2020 09:55:40

The engine has indeed got gunmetal cylinders and two part gunmetal pistons. The hard brass rings of the design have a scarfed joint (gap) and an excentric bore giving a 3/32 thickness opposite the gap which is at a 1/16 thickness.

I have made one for the HP cylinder which will have steam at about 80psi inlet. Since i'm going to the effort of a complete rebuild I think I will get some material and follow the design for the IP and use graphite in the LP which exhausts into the condensor. It is not an easy engine to work on once assembled and has required more modified spanners and nut runners than any other project I have undertaken.

Thanks for the suggestions


16/09/2020 15:08:01

On stripping the Bolton/Bertinat triple expansion engine that I had machined and assembled in the 1990s (never run because I hadn't by then built a boiler of sufficient size), I find that there are no piston rings in the IP and LP cylinders.

The design calls for hard brass rings of varied cross section and since the LP is 1.5" diameter I now remember that the material was not to hand - still isn't.

Smaller engines seem to run OK when fitted with graphite string packing in leu of rings but I'm concerned about its fixing in the larger grooves (already machined)

Any suggestions of suitable materials to go in 1/4 x 1/8" deep gunmetal piston grooves which will run on steam?


Thread: Recovery of oversized sheaves
09/09/2020 16:03:33

Since the working loadlines in the top and bottom halves must be 50 odd degrees centred on the vertical centre-line I don't think the crescent shaped gap around the halving joint is going to be of concern, indeed it may aid lubrication. As Jason says it all depends on the amount the originals are oversized. I will do some careful measurement and report back.


09/09/2020 13:54:57

Hi Brian, Your reply has triggered a memory of my apprenticeship days and metalling of big gearbox bearings - this led me to the answer! I will mill a small amount of each of the halving joints, thus pinching the bore below size on the vertical axis and then machine out to the correct size, there is sufficient metal in the casting to allow this - I don't have to add metal!!

cheers - Tony

09/09/2020 10:00:44

I have finally got round to stripping and rebuilding a model triple expansion engine that I built from Reeves casting some years ago. I am very impressed by some of the work (!?) except that all the excentric sheaves seem to be too loose - can't be wear from the few hours run so I must of not appreciated the clearances needed when I built the engine. The thought of machining a completely new set of 6 sheaves or excentrics fills me with dread so I wondered about 'remetaling' the sheave bores with silver solder and reboring. This is probably more difficult than making new excentrics but seems more interesting.

Has anyone done such remedial work succesfully?


Thread: Silicone oven liner material
30/08/2020 16:44:17

Hi Dave

The lakeland sheet is 0.005" thick so I intend to try it out on the cylinder faces where the use of paper has proved very difficult to execute


30/08/2020 16:01:13

I'm sure I have seen mention here on the possible use of the 'Lakeland' oven liner sheet as a gasket material - but I can't find the posting.

It would appear to be a good material with which to cut intricate gasket shapes and use with a 'mere smear' of sealant

Has anyone experience of using it for steam engine gaskets?


Thread: cylinder oiling drillings and Tangye mods
25/08/2020 08:43:45

Thanks Jason - I do like the photos. I would like to know how the cross-head slides within the main frame were set up for machining, perhaps on a horizontal borer but its a horribly 'bouncy' intermittant cut demanding a very ridgid set-up..

As for the hole in the excentric sheave as the answer to the adjustment of the valve timing - of course!
Why of earth didn't I see that as the answer - I'm trying to think of an excuse other than senility.

Thanks for your help

Rik: I don't know how far you've got but to get the 4 bearing alignment sorted out in the horizontal plane I machined the two inner bearing pedestals and then made a plain shaft jig to check the height of the two frames having already machined the bearing seatings - it meant having to take the castings out of the milling machine a couple of times but resetting with a precision level worked OK.


24/08/2020 12:29:53

I have just finished my first build and run on air and steam of a Double Tangye engine.

I have now stripped it in order to make some modifications and cure some leaks.

The drawing shows a undimensioned tapping on the top centre-line of each cylinder labled "tap for oiler".

What sort of 'oiler' would function against full steam pressure? Would that be an oil cup with a screw-cap for use before and after running?

The two modifications will be to improve the function, probably at the expense of form and style.
1. The valve excentrics can only be adjusted by removing the sheaves which is more than a little inconvenient - redesign required.
2. The governors looks pretty but doesn't work well so both the inlet valve and the governors drive need replacing to include ball bearings.

Rather amazed that a design would put 4 close coupled bearings in line on a rigid shaft - my apprentice test piece was scraping 3 in line and that was bad enough - these are worse because the caps of two of them are at 45 degrees making disassembly unnecessarily difficult. A bit of a challenge!

Thread: Govenor drive belts
01/07/2020 09:17:21

Thanks to all - I have now found what I needed from Mamod spares

Thread: ISO Container for Workshop
30/06/2020 09:24:56

Look for a second hand Site Cabin which are based on ISO containers. They already have the door, windows a power-cable inlet and security shutters fitted.

Thread: Govenor drive belts
30/06/2020 09:20:08

On a beam engine I built some years ago the watts govenor was driven through a coiled spring steel 'belt' that was bought as a length, cut to suit and jioned by screwing the tapered end into the cut end. I have no idea where I got this material from - can someone point me in the right direction?

I am a bit concerned that such a drive using vee-groved pulleys might not be able to drive the Double tangye arrangement I have made and have seen in photos that a flat belt has been used - scarf-jointed and glued?


Thread: The story behind my forum image
03/06/2020 11:15:42

The posting from Howl is particularly interesting because it reports a TGA from an observer's point of view.

One strange feature of the attacks is that one typically emerges out of the state with no sense of shock or distress.

One truly horrible part of my first case was that I was sent a video of my lecture which I found I could not watch - here was me apparently acting normally but not being conscious of the event at the time - a sort of robot which is the image in the photo that started this posting.

A set of common features of both events was that although I didn't feel nervious they were both big events and I had practiced the content and the timing of each presentation. A consultant said that was probably what enabled me to perform a complex task for so long and why the (unpracticed) question session at the end created the problem in my performance, yet I remained in a TGA state, in the case of the last case for 3 more hours.

I have corresponded with several people who have suffered similar cases and it is difficult to find a common cause but stress must come into it.

02/06/2020 17:14:00

Michael - it was worded perfectly because the whole concept and experience is bizarre.

I did not relate this but 4 years later I had a repeat event. I gave a talk to a local U3A group and remember only arriving at the venue. I gave the talk, cracked jokes, and once again started to behave strangely during questions. Luckily my sister was in the audience and got me out. 4 hours in Hereford hospital and I suddenly 'came out of it' as my wife was driving me home. I have absolutely no recall of anything inbetween and never will have. The Consultant said to me "if you decide to murder anyone and claim TGA as a defense please call me as your prime witness". So was I conscious ? not really but fully functional. I don't give lecture any more - except to my grandchildren.

02/06/2020 16:15:57

'TGA by proxy' is a mind-bending concept.

How about inventing a self-test one could run each morning to prove that you are, or are not, laying down memory (in TGA state) - in fact it is impossible.

02/06/2020 15:38:27

The photo used as my forum portrait was taken during the time I was giving a presentation to an engineering conference in Graz, Austria. The point of interest is that during the 6 hours preceding the lecture and for the one hour it took, I was in a state of Total Global Amnesia (TGA) which means that although apparently rational and giving a coherent talk I was laying down no memory. I remember going to bed the night before but the next memory was being aware of being asked in German to count a medic's fingers while we sat in an ambulance.

That morning I had dressed, had breakfast, talked to colleagues, taken a taxi, listened to lectures and had lunch before my lecture. A friend sitting in the front row realised something was wrong when I was asked the first question at the end of the talk - I started the talk over again!

A stroke was suspected, but TGA is benign, except that it is deeply unsettling, and cases of long duration and complex actions are quite rare. Graz is the site of the Sigmund Freud Institute where I was sent for 3 days having every test known to man before being passed out as fit but bewildered. I will never get my memories of the day back because I never saved them. I look at that photo a wonder what the hell is going on in there!


Thread: Chilled cast Iron - a small Rant
02/06/2020 15:19:50

I have consider the 'send them back' option and may do so but if the hole positions are clear of the chill (which is full depth on the edges) they will be usable. It is many years since learning about chemistry of cast iron, I seem to remember that I found it about as boring as the chemistry of boiler feed water in power stations

01/06/2020 16:59:06

The job of machining two small valve chamber covers should be a nice simple task - in fact the job was saved for a relaxing evening.
But the whole outer edges of both cast iron pieces are chilled and can't be milled. A tipped lathe tool makes an impression but tends to 'bounce' leaving high spots. I have reverted to rubbing the machined surface on a blued-up surface plate and carefully grinding the high spots with a Dremel. A surface grinder would be nice!


Thread: Another 'glue' question
21/05/2020 16:09:47

I need to temporally attach two thin Bronze flanges to a casting's face in order to drill through 10BA holes on a 15mm PCD all mounted on a dividing table. What loctite would you use? there will be little lateral force applied during drilling but it is essential for no movement to take place and de-mounting causes no distortion or surface damage.

In a previous life I used to glue thin brass sheets to a face-plate when turning the knife edges on windage baffles, then release them with a hot-air gun - but I can't remember what grade of loctite we used.


Thread: Adhesive for rubber sheet?
11/05/2020 09:38:40

I used an Evostick impact adhesive to glue the footwell lining in my Caterham some years ago. I had to lie on the ground with my head right under the dashboard and it took some time to get it done. Immediately upon completion my wife drove me to dinner with some friends - I had just got to their front door when I projectile vomited and passed out (quite an entrance). The doctor explained that breathing deeply in a confined space the trichlorethylene fumes was not a good idea.

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