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19/10/2007

I took Helen to Whitwick yesterday for a test run. We started off very well with Helen pulling very well and very crisp exhaust beats so I'm hoping the new valves will be an improvement over the old ones. However, 3/4 of the way around the track disaster struck! Some-one had been working on the track earlier and had left a square of 1/4" steel lying on top of the track which I didn't see until the last minute. I couldn't stop in time to avoid hitting it so we came a right cropper and Helen finished up well and truly derailed. A quick inspection showed that fortunately the only damage seemed to be to the middle cylinder cover at the front of the frames which flew off and got mangled when the driving truck went over it. Also one of the dummy tank fillers flew off somewhere and couldn't be found.

I suppose I was partly to blame for not inspecting the track before running ( you are supposed to) but some-one else's carelessness could have caused a great deal of damage.

During all the excitement of the 'accident' the fire had gone out so I had to push Helen back to the steaming bays and I noticed that the front bogie kept coming off the rails. This had taken the brunt of the collision so I assumed something had got bent. A close inspection did not reveal anything amiss so I relit the fire and did a very cautious second lap. The motion etc seemed free so nothing was bent there but the front bogie still kept derailing so I called it a day. I'm going to the running day on Sunday so that will give me time to check Helen over at home.

Last night I took the front bogie off and immediately spotted the problem. Both spring pins on the left hand equaliser beam were bent quite badly and this was obviously stopping the beam moving freely. The pins were quickly replaced with new ones and the bogie refitted so hopefully everything will now be ok. The only other damage to the bogie was a small nick in the flange of one wheel but I don't think this will matter. An inspection of the underneath of the loco revealed no damage at all which surprised me considering the force of the collision. We both got away lightly!

Whilst the loco was on it's side I checked the lubricator drive again and it still seemed to be slipping occasionally. I had noticed on the second lap at Whitwick that very little oil appeared on the rim of the chimney. I removed the drive arm with the roller clutch and tried it on a piece of 1/8" silver steel and it seemed to work fine although there seemed a lot of play on the shaft. I went on the internet and looked up the data on the roller clutches and I think the housing for the clutch is too thin allowing the outer casing of the clutch to expand under load and hence slip on the shaft. The data recommends a steel housing with a minimum thickness of 0.11". I had used brass with a wall thickness of only 0.05" so this may well be the problem. The clutches rely on the housing to control the outside diameter of the outer race. I'll make a new driving arm with a thicker boss and try that. If the lubricator still gives problems I'm fitting Hydrostatic!!

I've turned up a new boss for the lubricator drive arm and silver soldered it on after drilling out the old one. I turned up a little plug gauge to bore out the boss to the correct diameter for the roller clutch which was then pressed in. The clutch does seem a better fit on the lubricator shaft with less play than before. Let's hope that solves the slipping problem! The notes on the roller clutches do suggest that additional bearings should be fitted to properly align the clutch with the shaft but I've never seen that specified on any of the loco lubricators that I've seen. It is possible to get the clutches with integral bearings but they would be too large for Helen's lubricator. Probably ok for a 7 ¼" loco!

I've also turned up a new tank filler cap to replace the one that went awol although I'll have another look for it on Sunday. I'm bound to find it now I've made another one! Rather than make a new cover for the middle cylinder I've straightened out the old one but it does look a bit worse for wear. I'll probably replace it later when I'm in the mood.

When I was running Helen on Thursday I used some anthracite that Steve Eaton from Chesterfield had kindly given me and this burns really well and gets very hot. The safety valves were blowing off furiously all the time during the run and wasting a lot of water (apart from the fact that I couldn't see a thing through all the steam!) As an experiment I've turned up another sleeve for the blast pipe with a slightly larger hole which should soften the blast slightly and reduce the draught through the fire. It may even be possible to remove the sleeve altogether. Hopefully I'll get chance to try this on Sunday. I've also made a baffle to block off the front of the ashpan to see what effect this will have on the fire. This was made from a bit of thin brass held on with a couple of screws so it can be easily removed again if it proves to be detrimental to the steaming. One bonus of having the baffle is that it will stop some of the ash and grit getting onto the pump eccentrics which are right in front of the ashpan.

28/10/2007

I took Helen to Whitwick last Sunday for a run and managed a few laps before the big boys came out to play! It was a public running day so I came off when passengers arrived so as not to hold up the proceedings.

Helen did not seem to steam as well as before so I put the old blast nozzle sleeve back but this did not help much. I think the baffle I fitted to the front of the ashpan may be the problem so I'll either cut it down or remove it completely next time and see if the steaming returns to normal. Helen also seemed to struggle a bit round some of the curves and didn't seem as powerful as usual. I did notice that when running in reverse there seemed to be a tight spot in the motion which was not there when running forward. I'll have to investigate this further as it only seems to happen under steam. I am wondering if the valve timing is out. I've had the valves in and out so many times recently and it is possible the timing has altered, perhaps just on one cylinder. One of the 5 inch locos also seemed to struggle on some of the curves and it seemed as though the gauge was too tight although it has not been altered so far as I know.

In the meantime I've been finishing the injector test rig and trying out various injectors (see injector section) and hope to have at least one working and fitted for the next outing.

01/11/2007

I've checked the valve timing now and it was miles out! No wonder Helen was struggling a bit. I've reset all three valves so she should run a lot better next time out. This was probably causing the 'tight' spot when running in reverse - one of the cylinders was probably opening to steam too early at one end of the stroke.

I'm going ahead with fitting the injectors as all of them seem to work reasonably well on the test rig and I want to see if they will work on the loco as well.

I've made two new check valves for the injector feeds with O ring seats for the valves. This time though I've designed the body so that the O ring is trapped between the body of the valve and the bottom fitting so that it cannot rise up the body with the ball as happened with the original hand pump clack. I've tested both check valves with the test boiler (another use for it - checking fittings) and they seem to seal ok.

New check valves with O ring seat retained by a separate bottom fitting

05/11/07

I've fitted the 4oz and one of the 8oz injectors to Helen and given them a steam test. They both seem to work fairly well although one of the steam valves is leaking slightly and needs to be looked at. The new O ring check valves work fine with no leaks.

The pipework for the injectors was a bit tricky (a real plumbers nightmare!) with quite a few bends to get around various bits and bobs. The worst ones were the steam pipes which are quite long and took a long time to get right.

Left hand injector and pipework

We went for a run at Whitwick yesterday and had a very good day. Now that the valve timing has been reset Helen runs very sweetly and pulls away easily and smoothly. My brother and I did about 15 laps before calling it a day. I need to check the speedo on the driving trolley again as the calibration still appears to be wrong. One lap of the track should be 0.24 miles but the speedo is reading 0.44 !

The 8oz injector was a bit temperimnetal and worked when it felt like it! The 4oz worked nearly all the time but would sometimes not pick up at full boiler pressure. It seemed to be happiest at about 75psi when it picked up every time and pumped with only a slight drip from the overflow. I did try running with it on all the time so as not to use the axle pumps but it actually tended to overfill the boiler and dropped the steam pressure eventually. Still, we are getting there! As mentioned in the injector pages, more work needs to be done on the injectors until they work as required. I also need to fit some very fine filters on the water supplies to prevent any debris reaching the injectors.

Before this run I had also increased the spring tension on the front bogie (by stretching the old springs a bit!) and the front bogie seemed to behave itself and stayed on the track with no problems. It was interesting to note that another chap was there with a 5" Maisie which was also experiencing bogie problems.

16/02/2008

I can't believe it's over 3 months since I last updated these pages! How time flies. Poor old Helen must be feeling very neglected!

Not much to report really, construction wise anyway. I took Helen to the New Years Day steam up at Whitwick and a good time was had by all. My brother and I ran Helen for maybe 3 hours non stop but were struggling to keep steam up towards the end. When I got home and cleaned her up I found a couple of fire tubes completely blocked and several others partly blocked which explains the reluctance to steam. The firebox tubeplate was nearly solid with ash!

The lubricator was working really well (too well in fact) and was supplying far too much oil so that needs adjusting.

The front bogie still derails every now and again so I'm going to have to get it sorted once and for all. I've thought of fitting a thicker washer inbetween the loco stretcher and the bogie stretcher which will lower the bogie frames and raise the axleboxes in the horns. This should allow the bogie wheels to drop more before they leave the rails and will increase the weight on the bogie as well. Strange that the problem is only with the front bogie - the rear one has never derailed yet!

I'm not happy with the axle pumps as they don't seem to be able to keep up with the demand. I did a few calculations and designed a spreadsheet to calculate the pump output versus the water consumption and even at 100% cut off the pumps should be able to supply far more water than needed. I think I may have found the reason today. I was designing a twin ram water pump for Simplex this morning and had a look at the drawings for Helen's to remind myself how I'd done hers. I suddenly realised that owing to the way I had made the bottom fittings for the pumps, water could leak past the threads of the fittings back into the inlet pipes when the ram was on the pumping stroke. This wouldn't have been noticeable when I tested the pumps before fitting them but will be a major problem when pumping against boiler pressure. I reckon this leakage is causing the low output from the pumps. What I will have to do is seal the threads on the fittings so that this cannot happen. Fortunately the fittings are easy to get at and I can do the job without dismantling anything apart from unscrewing the fittings!

I've still got to do a bit of finishing work on Helen such as dummy steam pipes and handrails etc but nothing major. I've purchased some handrail stanchions from the Association (didn't fancy making them!) but they look a bit 'chunky' to me so I might turn the bases down if I can. There's also a couple of improvements I want to carry out whilst the loco is stripped for painting.

I've been looking at various colour schemes trying to decide what colour to paint Helen and I've more or less decided on a green of sorts. I came across some photos on Station Road Steam of a King Arthur class loco painted in dark olive green and that colour rather takes my fancy. I think with black and white lining it would look rather smart. I've been 'painting' an outline drawing using CAD and it looks ok. Still, there's time to change my mind yet!

I'll probably give Helen another run or two and then get down to the painting - can't put it off much longer! The first 'local' 2½" gauge run of the season is at Whitwick in early May and then the National rally at Rugby is on June 8th so I want her finished before then.

21/02/2008

Yesterday I took out the bottom fittings of the axle pumps and carefully resealed the threads all the way along with the liquid PTFE to try and prevent any leakage. This was quite a tricky operation and care was needed to avoid getting the sealant where it wasn't wanted!

After leaving it overnight to set I decided today to give Helen a run on the rolling road to see if there was any improvement in the boiler feed. There was a problem straight away as the inlet valve on the hand pump had stuck solid and I couldn't free it. This had happened before but it had freed itself after a bit of vigorous pumping of the handle. Not so this time! I remembered reading somewhere that a cure for sticking balls (sounds painful!) was hot water so I poured some boiling water into the rear bunker and lo and behold the ball freed immediately and I could fill the boiler.

I lit the fire and as soon as pressure built up the whistle valve started to leak badly and I could not stop it. I thought 'it's going to be one of those days!' I hoped that if I could build up sufficient steam pressure the whistle valve would seal itself but no chance. The only thing to do was drop the fire, let things cool down and then dismantle the valve. Fortunately this is a fairly easy job. It just meant removing the cab roof, disconnecting the pipe to the whistle, and unscrewing the valve.

Inspection of the valve showed that the spring which presses the ball onto the O ring seat was badly rusted and had seized solid in the housing. I think I had made the spring from an old stainless guitar string but it obviously wasn't very stainless! The ball also looked rusty and proved to be magnetic when tested with a magnet. Obviously it was an ordinary steel ball and not a stainless one. I must have picked up the wrong sort when assembling the valve or else some of the stainless balls I've got aren't! I'll check them with a magnet in future before fitting them.

The spring was replaced with a small stainless one (I hope!) that I had salvaged from an empty inhaler and the valve re-assembled and fitted back onto the loco. I'll try another steam test tomorrow all being well.

I've also had a look at the front bogie again and whilst playing about noticed that when the springs are fully compressed the equaliser beams foul the front and rear corners of the chassis stretcher and prevent the bogie turning. I took the bogie off and the beams had quite bad marks at the points were they could touch the chassis indicating that they had been doing so whilst the loco was running. This may well be the cause of the bogie derailing now and again. If the springs are compressed too much when the loco enters a curve and the beams foul and prevent the bogie turning then the front wheels will be forced off the track.

As a temporary measure I've filed a chamfer on each corner of the frame stretcher to give the bogie more freedom to turn. I'll see what happens at the next run but I think the bogie may still need stronger springs fitting to put a bit more weight on the wheels.

28/02/2008

Another steam test went ok and the whistle valve behaved itself this time! The axle pumps seemed to perform a lot better and actually put water into the boiler at full steam pressure. Unfortunately, the O rings on the rams now seem to leak due to the higher pressure so water drips out of both pumps all the time! A minor problem though that can wait till stripdown time.

Today I took Helen for a final run at Whitwick. I've decided that it's now or never and tomorrow I'll start dismantling ready for painting.

The pumps now more than keep up with the demand from the boiler and a couple of times I overfilled the boiler and got a shower due to priming! It's very difficult to set the bypass valve to keep the level constant and a finer thread on the valve would be useful. However, you can tell that the pumps are putting quite a load on the loco and she slows down quite a bit when the bypass is closed fully.

The lubricator is still delivering far too much oil despite the drive rod being set at the very bottom of the lubricator arm so that's another thing to be sorted out. I think a single ram pump would be quite capable of supplying all the oil needed so I may make a new one.

Despite the modification to the frames the front bogie is still derailing and I am pretty sure now that the springs are too weak so I'll fit stronger ones on the rebuild.

The next part of the project is going to be fun I think! I've got plenty of plastic containers to put all the bits in that are taken off and the actual strip down won't take long at all. It's the painting and rebuilding that will be the difficult bit. It would be interesting to count all the individual parts that have gone into the loco!

Cleaning everything up will be a right job as everything is now covered in oil which will have to be removed completely before painting. I've also got a lot of filling and sanding etc. to do to get the surfaces in a suitable state for painting. I'm not particularly interested in getting an 'exhibition' finish as I don't think that's really practical for a 'working' loco but I do want her to look reasonably smart!

My thoughts at the moment are to strip the frames completely down to the components parts, clean up, give all the bits a very thin coat of primer and then bolt the frames and stretchers back together before putting on the finishing coats. That way there will be a coat of paint between all the metal to metal surfaces but not thick enough to increase the inbetween frames distance by any significant amount. Before I do anything though, I'll give Chris Vine's excellent book on painting a very thorough read!

01/03/2008

 

Well, poor old Helen is now just a pile of bits! It didn't take long to dismantle her but it was a messy job with everything covered in sticky steam oil. Disconnecting the steam pipe and blower inside the smokebox was a filthy job! It would have been better to have washed her down with paraffin or petrol first I suppose but I didn't have any to hand.

A quick inspection showed that all the bearings, valve gear pivots, etc. seem to be in good condition but the cylinder steam pipes were a very loose fit in the steam manifold and have probably been leaking badly again which probably accounts for the steam oil all over the tops of the cylinders. The silicon O rings have gone very soft again and actually have bits missing. The Peek seals also look in a bit of a state and probably weren't doing a great deal. I am either going to have to bite the bullet and pay £10 each for some Kalrez O rings or, better still, redesign the manifold to use screw connections with copper seals. I rather favour the latter!

I haven't stripped the cylinders yet to look at the O rings on the pistons but they seem to move ok with a slight resistance so hopefully they will be ok. The O rings on the axle pump rams do seem fairly loose in the bores which is no doubt why they were leaking slightly. I am not sure how good water is as a lubricant for silicon O rings. Perhaps it's not very good? Then again, the bores of the pumps were only reamed so perhaps the finish is not quite good enough for the O rings. It might be worth giving them a polish before re-assembling them.

The next job is to clean everything down thoroughly and I think I'll get some paraffin and use that to get the worst off. I've got some POR 'Marine Clean' which is a very potent degreaser and I'll use that to finish off with. I've used it before and it's very good. The problem is that anything steel rusts immediately after you've used it! I've then got some POR 'Metal Ready' which is an anti rust treatment that dissolves any surface rust and etches the steel surface leaving it with a zinc phosphate coating ideal for painting.

02/04/08

Over a month since the last update! I don't seem to have achieved much in the workshop lately due to working in the garden and having a good clear out and reorganisation of the house. Poor old Helen has been really neglected. I really must get on with the painting though as it's now only about 6 weeks to the first official run of the year and I've done very little in that direction yet!

Over the last week I have started looking at paint and have been trying out a few types to see if they will be suitable.

The first job is to find a suitable etch primer for priming the brass parts of the loco before the top coat is applied. Brass is a very difficult metal (along with the other copper alloys, aluminium and galvanising) to get paint to stick to as it rapidly oxidises when exposed to the air and most paints will not stick to this oxide layer. A primer must be used that contains an acid. This acid eats through the oxide layer and forms a good bond to the metal. Etch primer comes in two forms - a single pack which can just be painted on as it is, and a two pack which has to be mixed together before it is applied. I am not sure of the difference between the one pack and the two pack but I decided to give a one pack variety a try as it seems easier to use. Note that a lot of these etch primers must be used with the special thinners supplied for them as ordinary thinners such as cellulose or white spirit will not work with them.

There are many manufacturers of these etch primers but I decided to try U-Pol Acid #8 which is readily available in a 450ml aerosol from Halfords and car paint dealers. The idea of being able to use an aerosol appealed due to not having to clean out the air brush or spray gun every time it is used. This primer is also one recommended in Chris's excellent book.

As suggested in the book, I tried painting a few test pieces first and sprayed a piece of brass sheet with the primer which went on easily and dried to a nice flat grey finish. As Chris mentions in the book though, it does go on quite thickly compared to using a spray gun and would tend to fill in any fine detail if you were not careful. The idea is to get as thin a layer on as possible whilst still looking wet. If the paint surface looks dry when you spray it, there's a good chance that the acid will not etch the surface and the primer will not stick. You also want to try and avoid having to sand the primer afterwards as there is a danger of rubbing it off any high spots leaving bare metal again.

The instructions suggest that the primer dries in about 10 - 20 minutes but I left it for a couple of hours to be on the safe side. I then tried scratching it off the brass and I could only do this with a knife showing that it seemed to have adhered properly. I then tested it's temperature tolerance and 'cooked' it in the oven at 200°C for about an hour. It did go slightly brown in colour but seemed to be tougher than before and took even more effort to scrape it off. The only surfaces that are liable to get to that sort of temperature are the smokebox and the cylinders so I think this primer should be up to the job. Incidentally, the primer can also be used for all the steel surfaces as well which saves having to buy two different ones. The only concern I have about using the aerosol is that I think it will be pretty wasteful on small parts. However, it is also available in 1 litre cans for brushing or spraying on, but does not seem to be as readily available in this form. Fortunately I found someone on Ebay who sells it in tins at reasonable prices so I've ordered one from them. Hopefully I'll be able to use it in the airbush which will be better for the small bits and for getting into awkward corners on the frames etc. I've actually got two air brushes - a good quality one (Badger 175) and a cheapo one which I reckon is also made by Badger as the illustrations in both sets of instructions are the same! I can maybe use the cheapo one for the primer and the good one for the top coat.

 

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