Member postings for David Machin

Once again, many thanks to you all. I have found the revised design.

First, I must apologize to you, Julian, for asking you to look out the relevant ME. I have an ME index book, and could do it myself, which I've just done!

I have found the copy of the relevant ME, and the revised design, which has, significantly, 4 x 1/4 inch balls, and I can now see that it will work. If anyone wants to know, it is an article by Martin Evans on Page 273, Vol 146, March 7, 1980. There are numerous follow up letters the same year in postbag about this.

My very grateful thanks to you all, since in the end, you led me to the improved design, which I didn't know existed. Shows how more thoroughly you read - and remember - the articles than me! My excuse is that I was working then - but then, I would expect, so were you!

Dave.

Many thanks to you all.

I would very much appreciate you finding, Julian, the relevant copy of ME in which the revised design appears. I will also try to get hold of the drawing sheet from ME, Michael, if Julian cannot find the ME, or runs out of precious time!

Dave.

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Thanks for your posting, Henry.

This is the first confirmation that the pump does work! Is the clearance of less than 1/8" between piston and end covers at each end of the stroke important? Pumps normally have little clearance here, but to get water to the single ball end on its suction stroke, (as I say in my first posting), this may be essential.

Dave.

Many thanks for all your postings.

I would be grateful for any source of a redesign drawing, Michael, but presumably your pump works!! Also, I don’t know what you mean, Stew, when you say, ‘PM sent‘.

Dave.

Julian,

I have looked at Super Simplex and also the Fairlie articles, and cannot see a redesign which suggests it would be any different.

In fact, the late Martin Evans is saying that he has done a redesign partly to reduce its water output! The other part of the redesign was to turn it round end for end, thus changing the drive end, i.e., from the sheave and eccentric. (This was to allow more room for other parts of the loco.)

So can you tell me where to look please?

Dave

Many thanks for such a prompt response. I will look at the ME index to see if I can find the issue which will provide further enlightenment!

Dave.

Has anyone made a Simplex double acting water pump exactly to drawing which works OK?

I ask this because I want to make a double acting water pump, and have examined the pump drawings for the Simplex Locomotive, designed by the late Martin Evans, and have difficulty in understanding how it works, particularly at one end of its stroke.

At the double ball end I can see its workings easily. But at the single ball end, after water has been delivered, there is no apparent passage for water to fill the enveloping volume as the piston moves towards the other end, when both balls will be closed to suction, as the delivery stroke at that end has started. As far as I can see, this will create a vacuum, perhaps only relieved when the piston arrives at the double ball end, when pressure of delivery falls there, and the balls will drop to allow a momentary flow to the vacuum at the single ball end. This would seem to require very rapid transfer of water at that point, and an inefficient system.

I would appreciate some help on this before I go mad, either making the pump in blind faith, or redesigning a better system!

Dave.

Success at last!

I have sleeved the water gauge feed 'tubes' to the boiler down to match the glass bore, which I know is contrary to what you said, Julian, but it has done the job.

I had a steam up this morning, which was completely successful, the level being controllable throughout, with no problems at all.

So my thanks to you all for your kindly contributions, particularly about cleaning the boiler with the drain cleaner (sodium hydroxide) from Wilco.

Happy steaming,

Dave.

Thanks Julian.

When I have some suitable weather, I will have do as you suggest. That may be some time if recent forecasts atre to be believed......

Thanks again,

Dave

I have twice tried to add another post , without success.

Here goes again: First, thanks for your latest posts. I will try out your suggestions ASAP, but I expect this will now be after Christmas, and when some dry weather occurs! Julian, do you think I need to have more Sodium Hydroxide boiler cleaning attempts?

Part 2

Steaming was good, until the end of the test, when just as I decided to finish, the boiler pressure dropped to nothing. Lacking steam pressure, I could not properly blow down the boiler. (I should say that the reason I have been leaving the boiler to cool, is to be able to see the true level of water in the gauge. Since LBSC said leave any residual water in the boiler until the next steaming, this is what I have always done. I must change this.)

I then let the boiler cool down. When cooled to room temperature, I found that the water gauge level now reached the top nut. Since with cooling, the water contracts, it is likely that the level, when hot, had completely filled the boiler, which probably explains the drop in pressure. This is probably just as dangerous as too low a water level. And this is what water gauges are supposed to show!!

It occurred to me afterwards, with much too high a water level, as detailed above, that during the run I had, as usual kept the axle-pump by-pass closed, but had done some experiments with ‘notching up, thus saving steam (and water). Also, I had used the hand pump to try to raise the level back to ½ a glass. (It didn’t affect the water gauge reading, but these two actions explains, perhaps, the rise in water level).

So what to do? I wonder if the cleaning needs repeating, but how many times? If so, this is surprising since the boiler has been steamed many times this year - January to December.

However, I was totally ignorant of any need to remove remaining flux deposits in a new boiler.( I also have a new boiler waiting for the 3 ½” gauge LNER A3 Pacific I’ve been building, so the ’education’ on this is very timely. All thanks to you, Julian.)

Sorry, this should have preceded Part1!

You may have seen my photo of the backhead, which was posted with this latest ‘saga‘. The photo worked, but the ‘saga’ didn’t. I think that there is too much verbiage. Stupidly, I hadn’t saved it, so I have typed up this new account, in Word first, saved it, and will hope to copy it into another post. It will have to be in smaller chunks.

Part 1

After the last run, the boiler was drained into a container for inspection. I found the water looked clean. On filtering, I Found there were only a few small bits of grit, and some fibres, but no oil. These ’foreign bodies’ may have been from the container used for the draining down. Thanks, Michael.

Next I completed all the points mentioned in the previous posts from you kind people. Viz:

1. Length of gauge glass. Stripped the top section, and found there was no extra length restricting the passage ways, either top or bottom. Thanks, Stick.

2. Boiler cleaning: I bought some Sodium Hydroxide from Wilko to clean the boiler. I made up a solution from the powder, using boiling water, and filled the boiler with it. I left this in for about 3 hours. On draining, I looked at the solution, and found it looked cloudy but otherwise clean. I am not sure if this is the appearance of the original mixed solution, because I did the mixing in a translucent container. The boiler was then rinsed through with clean water, a couple of times. Thanks, Julian, for the idea, and particularly for a supplier of sodium hydroxide. ( Wilko are selling it at £1.50 now, too.)

Taking advantage of good weather earlier this week, (Tuesday, 15.12.13) I had a steam up.

On reaching working pressure, the water gauge reading dropped to ¼ of a glass, and stayed there for the rest of the test, which, though better, was ominous, as one would expect SOME variation.

Many thanks to all you Forum posters. You all have been most generous with your time, and it is much appreciated. There is much there to look into.

Julian, I have made two attempts to send a photo of the backhead without success. Every time I upload the photos, this is carried out, but at the end of the upload, the page crashes, with the usual apology for the inconvenience, and that seems to lose the upload, because the album has the title, but no pics. I will ask someone who is more computer literate than I to help, and then have another go.

I will check/clean/etc and then get back to you when I have had another steam up. The problem will be finding a dry day!

Thanks again, and best wishes for Christmas if my next steam up is delayed.......

Dave.

I followed Julian's advice and reassembled the water gauge earlier this week. I tested it today (Saturday) on my short (80ft) track in the garden. Before steaming, I filled the boiler to half a glass. Annoyingly, at the beginning of the run, due to my glasses steaming up, I wasn't able to watch the gauge! When I managed to be able to see again, the level had fallen to the bottom nut, and stayed there as last time. I tried blowing down as Stick suggested, but it didn't help.

I continued running with the pump bypass valve closed all the time, and at least the level did not fall out of sight. I tried tilting the loco back during steaming, and the level did not change. As lunch was ready, I stopped the test after about 1/2 an hour, and let the loco cool down.

When the loco had cooled down , I tried tilting it back again, and the result was exactly the same as last time: the level rose to half a glass, and stayed there. To say I was disappointed is an understatement!

Has anyone any further ideas as to what I can try, please?

I have stripped the water gauge today, (having just completed a decorating marathon for 'er indoors), and did not find any grunge in the passage ways in either fitting. I tried a piece of tapping size rod in the bottom fitting, and found it went along the side of the water space in the boiler rather than strike the inner firebox, so no constriction there. Also I found no extra amount of bush beyond the the inner face of the backhead plate.

What I also noticed was that the 'feed bore' of both parts of the water fitting was at 5/32 dia. This is 1/32 bigger than the bore of the 3/16 O/D glass. I have been looking at as many drawings of gauge glass fittings as I could find, and in all cases the glass bore and the 'feed bores' were the same. Could it be that the glass itself is the obstruction? And reducing the 'feed bores ' to 1/8 dia would be the solution. Or does this matter?

I am getting desperate! Please help.

Dave

Many thanks to all you forum posters, particularly with reference to the bottom fitting. I was concentrating more on the top one. I will now investigate, as you all suggest, and hopefully, post success!.

Dave.

Thanks for the info. you are the only one who has replied! Do you think that a1/4 inch water gauge might help?

I have been rebuilding a 5 inch gauge Tich and fitted a new boiler. The loco has been steamed successfully numerous times, since January of this year (2013). The problem is that the water gauge always reads low, when there is, in fact, an adequate water level. The gauge glass itself has been increased proportionally in size for this 5 inch version to 3/16 inch O/D.

Recently, after a steaming, the water gauge showed level with the bottom nut of the gauge. I tilted the loco towards the rear, and on levelling again, the water level rose to just below the top nut and stayed there.

One thought was the top fitting of the gauge: this is a outside the wrappper, (as it is on Rob Roy). The hole from the boiler to this top fitting on LBSC's original drawing for the 3.5 inch version, is 5/32 dia. I have made the 5 inch version 7/32 dia. Is this hole big enough?

Any answers would be very welcome.

Dave.