Member postings for martin ranson 2

To anyone building the IDRIS loco ... I have happily spent most of this summer running the loco round the small track in our back garden ... managed to keep SWMBO happy by mowing the grass with one eye on the loco ... I have discovered several things that may be useful ... the Roundhouse safety valve slowly dropped its blow-off pressure as the O-ring got squashed ... instead of 40 PSI it was lifting at 30 PSI ... this had to be reset. Needed a tiny bit of brute force !

I found the best way to run the boiler was NOT to allow the safety valve to lift ... pity, it looked good ... I tried to run it at a maximum of 35 PSI ... the steam valve ended up at about 1/4 turn open ... I used the gas valve to set the boiler pressure with the engine continously running.

The water pump drawings further in the series show a ram of 3/16 diameter ... now I have got everything running better I have swapped the ram for a smaller size of 5/32 diameter ... this also takes less power from the engine ... possibly even 9/64 would do the job ... when using the water pump I started with the boiler water gauge half way up the glass ... not filled to the top.

My small track has lots of tight radius curves ... the engine ran much, much happier when I made the wheels on the wagons loose on their axles ... with 2 wheels fixed on each axle the engine slowed right down ... so much so that I ended up always pulling a bogie wagon (from SWIFT SIXTEEN) with a large steel bar as a ballast load ... without any load to pull the engine was likely to fall off sideways on the first bend.

hope this is useful ... martin

Hello Andy ... nice to hear from you ... Jason has answered the question perfectly ... the thread gets squeezed outwards in diameter.

martin

To Mr. STEAMBUFF please ... looking at Neil Wyatt`s post just above, it seems you are Dave ?????? . thank you for your prompt reply ... that answers some of my questions ... possibly the tank has not been tested to 490 PSI ... maybe it has only been tested to 375 PSI, this is still very high, but yes, it does give a wide safety margin allowing for mis-use ... my concern has always been that we could be over-testing some designs of tank.

The other thing I have never managed to get an answer to, is the test temperature for all the sets of figures quoted on the MPBA information kindly supplied by Neil Wyatt on 22nd of August ... these appear to be the same readings I was aware of many years ago ... I tried to find the ambient temperature for those sets of figures ... I even went to an Annual general meeting of the MPBA armed with a small gas tank fitted with a pressure gauge ... after lots of phone calls and letters, I could never find anyone willing to answer the question of gas temperature for those figures.

Do you know anone who would know what the temperature was please ?? ... my guess would be 60 - 80 degrees ... to me, the figures do not mean much without a quoted temperature, because the pressure goes up and down like a yoyo with change in temperature.

Regards, martin

To STEAMBUFF please ... your reply on the 22nd. concerning gas tank pressures ... you seem to be suggesting that ROUNDHOUSE use a working pressure of 245 PSI in their tanks... I do not understand such a high figure ... to me that is not a working pressure, it is a worst-case scenario ... I do not know how they would use 245 PSI and feed it through a single -stage pressure reducer ( i. e. the gas valve ) to get about 10 or 20 PSI into the burner ... many years ago I conducted several experiments on a small gas tank 2/3 full of gas to see what happened if the temperature was raised or lowered ... I have just repeated that test and achieved virtually the same results.

All the tests were done outdoors using pre-heated water from an electric kettle ... definitely no flames involved !!

My figures are typical because nowadays the gas bottles I buy no longer state the ratio of butane and propane ... they just say it is a "mix"

The pressure in the tank is about 40 PSI at 22 degrees C. ... to achieve approx. 245 PSI needs the tank to be at a temperature of 100 degrees i. e. boiling water.

Are you saying that ROUNDHOUSE allow their tanks to run at that temperature ... mine tend to run at about 30 -50 PSI so the temperature is "hand-warm" ... once upon a time I was told never to heat canisters above 55 degrees C.

martin

Hi Alex ... the question of test pressures always produces different values depending on who you ask ... if you are having it tested at Chelmsford and planning to run it on their track I would be guided by them ... possibly even find the local Chelmsford boat club as they may have a lot more people who use butane/propane gas ... some people have figures which have an enormous safety factor built in ... ask at Chelmsford.

martin

Morning Alex ... wow, that is a squeeze for the 3 valves !! can I ask if you have arranged for it to be pressure tested at the Chelmsford club?? same idea as a boiler test, but a bit higher pressure.

I may be a bit of a "thickie" but I still have not worked out how the tank fits under the burner at the rear of the boiler. Any chance of a sketch or a photo please ??

martin.

Hi Alex ... yes you could soft solder them, but there is not much area of solder in the middle of the joint ... Silver solder is a lot stronger ... you could always make up a soft-soldered spare and test it to destruction with a spanner ... if it does not need much force to break loose then stick with silver solder ... I have used this type of assembly for many shapes of valve over many decades ... so far, none has ever broken ... maybe I am guilty of over-engineering ?? ( again ) ... let me know what you think after you have done an experiment.

martin

Morning Alex ... good for you ... the only way to learn anything is to experiment ... my scrapbox is always full of my mistakes ... usually the bits come in handy for something ... a quick skim on the lathe or a dab of silver solder and an old "whatsit" is useful to make a new "thingummy"

martin

Morning Alex ... if the gears you bought have 30 teeth then I am not sure what size they are ... 48 DP would be a bit small and 40 DP would be a bit larger then the ones you have. ( does anyone use 43 DP ?? )

If they are metric, then 0.5 mod would be a bit small and 0.6 mod would be a bit larger than yours ... maybe there is another system for small gears ?? I know there is a system for much larger gears called CP ( circular pitch )

On page 874 of the same issue I did put that 40 DP would be ok ... the important thing is the outside diameter, so everything will fit in the available space.

Can I ask whether your gas tank and fittings will fit under the burner assembly hung out of the rear of the boiler ?? Does your design alteration include altering the position of the gas tank relative to the burner ??

martin

In issue 4514 starting on page 252 there is a general description of a turbine locomotive ... what a wonderful machine ... Mr Jeggli criticises himself on the last page of the article ... I think he deserves total praise ... if anyone else looks carefully at the published photos they would realise he has incorporated a lot of very clever systems into the model ... all home-made I assume ... is there any way he could be persuaded to add some details of various parts of the loco ??

Shown in photos 20 to 23 is the burner module with all its parts ... the burner itself looks tiny as regards overall length measured from the 2 inlet pipes to the burning surface ... this seems to be gauze and not ceramic ... clever !! looking at photo 21 this shows the steam pressure diaphragm valve removed from its location ... it is tiny !! ... what may be the adjusting spring is only just over one turn ... the ones I have previously made have usually been at least 10 mm in length and equipped with 2 locknuts.

The water pump has its own built-in guide for the ram and the pump body looks as if it swings the 2 water pipes as it moves ... neat and space-saving !!

Please Mr Jeggli, any chance of publishing any details in the magazine ??

To John Rudd ... it has been a long time since I have talked about pressures inside gas tanks ... thank you for pointing it out ... I try to take the utmost care with tank construction ... if I look at a plastic tank inside a commercial gas lighter I am horrified ... it seems to be from a different world considering the armour plated heavy-weights I produce ... many decades ago I was totally unable to find out much information about actual tank pressures and types of available gas jets ... with only one exception no-one would tell me anything.

I got so fed up with the secrecy I collected everything together and published it in MODEL BOATS ... the June 2005 issue ... pages 40 - 45 ( ten years ago ) "gas tanks and burners for small steam boats"

One of the things I discovered was that the actual pressure in a tank 2/3 full of gas was a lot less than the figures I was quoted by the "experts" ... I did eventually discover that the figures I was given had been roughly doubled for a safety factor and then, for some reason, they were doubled again ... someone else added their own safety factor.

I was expecting hundreds of pounds pressure ... the only way I could arrive at approx. 100 P.S.I. was to heat the tank to 55 degrees C ... the pressure at 22 degrees C was about 40 P.S.I.

All my experiments were with the tanks 2/3 full of gas ... NEVER heat any vessel which is TOTALLY full of liquid.

If this is of use to anyone, all the details are in the MODEL BOATS article.

martin.

Alex ... I am not sure if you intend to mount the proposed tank vertically or horizontally ... if it is vertical and mounted under the frames in the same relative space as the original then the tank volume would probably be a whisker smaller than the existing one ... (approx. 40 cc versus 42 cc) ... assuming you kept the SAME rear buffer beam assembly then I think the extra length needed for the frames would be at least 14 mm.

If you fit the tank across the frames it would produce a very large tank ... approx. 94 cc maximum volume ... this would be very much an advantage ... however it probably need the top edge to be lifted by 21 mm ... this may be quite a squeeze to get everything into place !!!!

As regards using copper tubes for the stays, no problem at all ... I have done this for years ... just make sure you use tubing with thick walls ... not the thin stuff ... for a vertical tank use 2 or 3 with a diameter of 7/32 inch ... these can be then used to fix the tank in place with 2 long bolts.

If the tank is horizontal then use 1 long tube as a stay between the two end plates ... use 1 very long bolt to attach the tank through the engine frames ... something like 7 BA or 2. 5 mm.

If you have another idea in mind please let me know ... I struggled for hours trying to think of another place to put the tank ... I could have used the tender but I did not find a suitable type of flexible pipe ... ( anyone any ideas for buying a small quantity ?? )

If you do solve it can you send me a photo please ??

martin.

Alex ... could I echo the words above about using standard 32 mm track ... the gentleman called "steambuff" has mentioned a possible source of track at Colchester ... is there any way you could "beg, borrow or steal " enough track to make a small circle ? preferably in your own workshop ? ... having your own test track is infinitely easier than waiting for a fine day to use the Chelmsford track ... any final tweaking is done at your own speed with no-one watching when it goes wrong ... everything I have ever built has needed a bit of T. L. C. before I was happy with its operation ...e.g. gland packings to re-do ... valves that do not seal ... spindles that are too tight ... bearings that seize up as the engine gets hot ... realizing that I can not see the gauge in the place where I fitted it ... etc etc.

Not that I have done this !! but I have heard of people waiting until the house was empty during cold days in January ... temperature in the shed was 2 degrees above freezing and it was pouring down ... the kitchen floor looked to be a much better alternative ... a quick bit of circular track down on the floor and away you go ... just remember to clean up afterwards.

The boiler photo above looks like you finally have enough heat available.

martin.

Alex ... a question about your letter above ... does this mean you are using the rails for 2 1/2 and 3 1/2 inch tracks or does it mean you are using the rails for 3 1/2 and 5 inch tracks please ?? if you eventually get your own 32 mm track does it mean the bushes will need to be remade a different length ??

Does it mean you may need some new spacers to hold everything in place along the 2 axles ??

martin

Morning Alex ... like the look of the 4 wheels ... I do not know if this is any use to you ... the commercial wheels I bought had a thickness of approx. 0. 474 inches ( 12. 03 mm ? ) ... they were not all exactly the same ... I varied the size of the bearing bushes to match the individual wheels ... you may have to do something similar ... I positioned the wheels at the correct distance apart and worked backwards to get the width of the final drive gear ( fig 5 page 590, fig 17 and 18 page 873 

martin

Alex ... just a P.S. to my words above ... some of the commercial wheels I bought a few years ago only had a small flange ... I did not realise at the time ... the depth was less than 1. 5 mm ( actually 0. 055 inches ) ... the wagon with those wheels would occasionally leap skywards passing over a point ... problem ceased when I managed to re-cut the flange a bit deeper ...maybe 2 mm is a decent minimum depth ?

I have just been given a long list of jobs from SWMBO, so I will be busy for a few days ... have to turn the lathe off for a while !!! horror !!! back soon.

martin

Morning Alex ... welcome back ... wow ! a 2 mm cut in steel is very impressive, I am pretty sure my small lathe would be struggling ... how far away from the chuck were you cutting when doing the parting-off ?

As regards the angles on the wheels ... I am not the worlds best expert on railway practices ... what I have found out varies with who I ask ... the angle between the tread and the flange is a bit bigger than 90 degrees ... the tread is not parallel, it is slightly coned by about 3 - 6 degrees ... the flange is not vertical, it is tipped inwards towards the middle of the track by 6 - 14 degrees, typically 10 degrees ... where the tread meets the flange is sometimes a sharp corner and sometimes a very small radius, about 0. 5 to 1mm ... the flange depth for 32 mm seems to be about 2 - 3 mm.

If all else fails, try and measure the commercial wheels you have bought ... hope this is some use.

martin

IDRIS DRAWING ERROR ... in part 4 of the series, at the bottom of page 872 is figure 16 ... there are 3 references to 7 BA threads ... these should read 6 BA ... the text alongside the drawing correctly reads 6 BA ... cannot blame the gremlins for this one ... my fault.

martin

Thomas ... the only person who has seen your premises is your local electrician ... if he suggests lifting the floorboards then it is probably a good idea ... chipboard flooring is messier than floorboards `cos it makes a bigger hole ... if they are nailed down it is a bit daunting to find out what is underneath ... he will make a calculated guess as to where is safe to start hacking everything out ... hopefully he would avoid radiator pipes and wall sockets etc ... go with his idea but with one difference ... YOU lift the flooring ... find a clear space near a wall but clear of any nails ... gently hack a hole in the chipboard ... most flooring is somewhere around 3/4 inch or 18 mm thick ... do not go any deeper with a drill until you can check with a torch and a small mirror ... his cable ( s ) will either end up running along the joists or crossing all of them ( sod`s law )

Either lift a huge piece of chipboard or slice through the board with a circular saw set to exact depth ... if you are lucky and your cable runs along the joists then the edge of the joist can be reinforced with a piece of 50 x 25 timber well screwed to the side of the joist along its length ... I have been using that method for decades and so far no-one has fallen through the floor ... if you know anyone who is a joiner or a DIY person check with them if they agree with me or suggest a bigger piece of timber ??

Your electrician would probably nail the flooring back down, if YOU do it you can SCREW them down, then the flooring stops being a barrier and turns into an access panel ... next step would be to go and buy a sheet of flooring chipboard and a length of timber from the local builders merchant ... doing it yourself should also save a bit of money.

There is only one awkward problem, and that may be SWMBO ... she will not be happy ... I have been trying to solve this problem for 44 very pleasant years ... try flowers, chocs, mow the grass, wash the pots ... I can crawl with the best of them !! if the flooring crosses a bedroom possibly you would move the bed and wardrobes ... get the vacuum cleaner ready ... who knows what you may find !!!

This problem is far more important than the cable size !! if the electrician says a ring main extension or a single cable, maybe 10 or 16 mm, then do it ... life is too short !!

Keep the peace and keep it simple.

martin

Alex .. any chance of a photo please ? ... could you put a ruler adjacent to the wheels .. the overall diameter of the wheels should be 1. 5 inches or about 38 mm ... after that it needs a close check on actual dimensions of everything in the vicinity.

martin