Edward Adams's 2½" Gauge 'Monstrous'

Page 2


I can't believe that it's over two years ago that I last wrote anything here! I've been tied up with other projects though and also have been somewhat incapacitated over the last twelve months due to my leg problem. That is much improved now and things are slowly getting back to normal.

I decided to spend a few hours in the workshop and make a start on the new wheel rims for the trailing wheels to replace the Vee shaped ones. As mentioned on the previous page, I had been given a couple of steel blanks to make the new rims so it was just a matter of maching them to size and fitting them to the wheel centres.

The blanks were much thicker than I needed and it took quite a time to machine off the excess. I used the Denham lathe to rough machine the blanks to thickness and then rough bore them to take the wheel centres. It's nice using the Denham as it has the power feeds on both the saddle and the cross slide but I was a bit disappointed with the performance of the lathe as it proved impossible to take a decent cut without a lot of chatter. This had been apparent when I had machined some wheels for a 7.25" B1 and I suspected that the main spindle bearings on the lathe were not adjusted properly. Setting up a dial indicator on the chuck and using a length of wood as a lever against the bed to try and lift the chuck showed that there was indeed a lot of play in the two main bearings at the chuck end of the spindle. I took the top off the headstock and tightened up the adjusting nuts as much as I dare without making the spindle stiff to rotate. This did improve matters considerably but it's still not right and needs further investigation. I hope the bearings are not shot as it will be virtually impossible to find suitable replacements. Even if I could find some, the cost would probably be more than the lathe is worth!

Anyway, I got the blanks rough turned and then used the ML7 to finish them to size. I intended to shrink fit the new rims and so bored them smaller than the diameter of the centres. I used the rule of thumb of 0.001" per inch of diameter plus 0.001" smaller than the centres. The centres are near enough 3 inches in diameter so I made the bore of the rims 0.004" less than that.

To fit the rims, I cut three bolts to fit between the two wheel centres, fitted them with nuts and tightened them gently to hold them in place between the edges of the centres. This gave me three 'stops' for the new rims to drop onto and align the backs of the rims with the backs of the wheel centres.


The 'stops' to aligh the rims. One has already been fitted


The rims were simply heated up on the gas stove and then dropped onto the wheel centres. I heated them to a very dull red but I don't think they needed to be that hot as there was quite a gap between the wheel and the rim until they cooled down.



Both rims fitted

Hopefully I have got the fits right and it just now remains to machine the treads which I'll do between centres. Nothing should move as the wheels are pinned to the axles and the quartering will not be affected.


I seem to be getting back into the workshop again now after having a long absence due to the leg problems so I decided to drag Monstrous out of hibernation and get back on it.

I've decided to go over the complete chassis and at least get it running on air before attempting any repairs on the boiler. The motion was very stiff and I think this was mainly due to a lack of lubrication to the cylinders. I suspect that the lubricator was not working very well, if at all. Granted the loco has not run in a long time but there was no sign of any oil in the valve chests.

The chassis was very dirty and rusty in places so I thought it best to strip everything off it and give it all a good clean. It all came apart quite easily as most of the bolts and screws were loose and in fact there are quite a lot missing altogether! It looks as though someone has had it to bits and not put it back together very well. The only difficult part was getting the connecting rods off the crankpins. The big ends use ball races and they were an extremely tight fit on the crankpins. I had to make an improvised puller to get them off and even with that it was a struggle. Once they were removed I could remove the coupling rods and the rest of the wheel assemblies.


Crank Axle

Pump Eccentric and Strap

The cylinders came off quite easily but you have to remove all three valve chests together as the steam pipes that connect the outside steam chests to the inside one are threaded at both ends so that you can't remove the steam chests individually. I had already looked in the inside steam chest which was very dry and the outside ones were also very dry with no sign of oil. Fortunately, the port faces seem in quite good condition with very little wear but I haven't looked at the cylinder bores yet.



The inside cylinder is held by five screws on each side, two of which were behind the outside clinders. I expected there to be some hidden behind the outside cylinders so I removed those first and it was quite fiddly to get to the bolts holding those as the front ones were very close to the inside cylinder block. The oval holes on the bolting faces of the inside cylinder block are the exhaust ports. These go through holes in the frames and connect up with the exhaust ports from the outside cylinders.




Inside Cylinder Block


The photo below shows the very bad galling on the slide bar. I think both the crosshead and the slidebar are plain mild steel which is not the best combination of bearing surfaces. I suspect that a lack of lubrication in the past hasn't helped.




As mentioned, the outside cylinders had to be removed first and these are held with a lot more bolts, some of which are fiddly to get at.




The oval slots in the bolting faces are to connect the exhaust from the inside cylinder to the exhaust pipes between the frames. Quite a neat idea but it gives a rather tortuous path for the exhaust from the inside cylinder.


The motion brackets were removed as a complete assembly with the expansion links etc.



The axle pump assembly is held with just three screws so came off easily. It's a neat design with two rams being operated by the one eccentric via a rocking arm and a connecting link.



The last thing to come off was the lubricator assembly. As mentioned earlier, this is driven directly by the two to one lever for the conjugated drive to the inside valve. The pivot shaft for the lever fits in a bearing housing on top of the lubricator and extends down inside the lubricator to operate a pawl and ratchet drive to the pump ram. The shaft has a tight spot when it rotates and I suspect that the shaft may be bent slightly.




Once the frames were stripped I set to with a wire brush to clean all the rust off them. The side frames are just bare steel and had never been painted but they had a fair bit of oily gunge on them which had probably kept any serious rust at bay. The steel trailing frame is a brazed up fabrication which had been painted black at some time but most of the paint had come off and the frame was badly rusted.




The horns are massive and are probably castings for a 3½" gauge loco. They need to be wide though to take the ball bearing axle boxes. I guess that the wheel castings are also from a 3½" design as the treads are far wider than on a 2½" gauge wheel.

The trailing frame seems a bit flimsy considering that the loco will be a powerful beast with such large cylinders and I'm sure it would bend if you tried to pull a really heavy load. It's also just brazed together with butt joints and no reinforcement. I think I would have fitted angles in the corners to make the assembly a lot stronger!

There were a few broken bolts in the frames that needed drilling out and retapping so I did this job next by clamping the frames to the table of the small mill. There are two blocks at the rear of the side frames that take a pivot for the steam brake actuating lever and two of the securing bolts had been sheared off. I managed to shear off the remaining two when I tried to remove the blocks so all four of these had to be drilled out.



There was also a broken bolt in the bottom of one of the horns that secures the hornstay so that was given similar treatment.



I noticed several more of the holes in the bottom of the horns looked as though they had had broken bolts in them at some time that had been drilled out. They may need further attention when the time comes to fit the hornstays again. A lot of the problem is due to some of the bolts being 3/32" Whitworth which was a common size when this loco was built. Unfortunately, they are not very strong due to the coarse thread and are easily broken if overtightened or rusted in place.


Having cleaned up the rear frame I gave it a coat of rust treatment to kill any remaining rust. It says to leave this for 24 hours before painting so I decided to have a go at machining the new rims on the trailing wheels.

The best way seemed to be to mount the axle between centres as the axle had already been centred at each end. I chucked a homemade cente which I had made for a previous job in the three jaw chuck and as luck would have it, the crankpin of the wheel nearest the chuck rested nicely on one of the chuck jaws which acted as the driving dog. The other end of the axle was held with a centre in the tailstock.



The first job was to machine the rims to the finished diameter of the flanges and machine the front and rear faces. The rims had a little bit of wobble on them which the machining eliminated fortunately. Next, on to machining the treads.

I managed to find a HSS lathe tool with a Vee shape and a suitable radius on the end that matched the root radius of the existing wheel treads and used that to machine the new treads. The topslide was set over to an angle of 2° to put the coning on the tread and the straight part of the Vee of the tool was set to match the angle of the flange which is about 10°. That way, you can machine the whole tread just using the topslide and the tool automatically machines the radius at the root of the flange and also puts the correct angle on the flange at the same time. It does get a bit hairy when you get part way through machining though as the tool has a large area cutting on the edge when you get to the flange and it's difficult to eliminate chatter. I struggled with chatter all the way and had to take very shallow cuts at a very slow spindle speed otherwise the chatter and noise was horrendous!



I don't know what the steel was that I used for the new treads but it certainly wasn't free maching mild steel. It eventually blunted the HSS tool but fortunately I found a carbide tipped tool that was the right shape to finish the job and that worked ok although there was still a big problem with chatter. I don't think it helped having to machine the whole wheelset between centres instead of machining just one wheel bolted to a faceplate. It wasn't really rigid enough for this sort of machining.

To get the diameter of the treads to match the existing ones I initially mounted one of the existing wheelsets between the centres and set the tool up so the edge matched the existing angle of the flange. I then made a note of the crosslide dial reading when the tool touched the tread and the topslide dial reading when the edge of the tool touched the flange. Then, so long as I machined the new treads to the same settings on the dials, the new tread should, in theory, match the existing treads. During machining, the saddle was locked to the bed to maintain the position of the crosslide.

Once the treads were machined I put a 45° chamfer of the edge of the tread and a 45° chamfer on each side of the flange. The flange was then rounded off by hand with a file.

I hadn't been looking forward to this job but it went ok apart from all the chatter and the treads seem to have come out fine.



When I was looking at the other wheels I suddenly noticed that one of them had a big chip broken out of the flange which I'm sure I hadn't spotted before. It's obviously been done for some time as the surface of the wheel where the chip broke off was tarnished. Unfortunately, the damage is worse than that as there is a crack all the way through the tread where the chip is and also one of the spokes is cracked all the way through.




The wheel must have had a right bang to do that much damage and I'm not sure what to do about it. It might be alright if I just leave it or should I have a go at repairing it somehow. I don't fancy trying to silver solder it which would be possible. Another way would be to machine part of the back of the wheel either side of the crack and fit a piece of steel to rebuild the tread and support the tread either side of the crack. One of the Kingette wheels had had a chip in the flange repaired like this and it seemed quite successful although in that case the wheel wasn't actually cracked.

In the meantime I've primed the rear frame and given it a coat of satin black paint so when that is dry I can start to put things back together.


I haven't made my mind up yet what to do about the damaged wheel. To do a proper repair really means taking the wheel off the axle and as the wheel is not pinned that would mean having to quarter the wheels again when the wheel is refitted which would be a pain. I could drill and fit a pin before I took the wheel off I suppose. I did look on the Reeves 2000 website today and they do do a wheel casting which pretty much matches the wheels on Monstrous. It doesn't say what they are intended for and they don't match any of the current 3½" gauge designs that they advertise. They could be for a design that they don't sell any more.

For the time being I gave all the wheel assemblies a good wash in paraffin and then blew them dry with the airgun. Some of the bearings feel a bit rough but I'll see what they are like when I've oiled them. I don't want to have to change any of them if at all possible.

By way of a change I had a look at the inside cylinder. I removed the rear cover so that I could inspect the piston and the bore and both were pretty dirty with a lot of black gunge inside. I think it was probably bits of the graphite packing used on the piston rather than dirt and grit. I gave the cylinder and piston a good clean with paraffin and they didn't look too bad afterwards. The bore is a bit scored but should be ok as the scoring is not very deep. I think it is all down to lack of oil again. The piston is still a good fit.

As mentioned before, the slidebar is quite badly galled but should clean up with some emery cloth. I'm not going to replace it. However, I did notice that it was bent which wouldn't have helped matters!



I managed to straighten it with some judicious thumps from a plastic hammer on a steel block and then rubbed it smooth on a surface plate and carborundum paper. It's not perfect but it will do.

Next I turned my attention to the crosshead which is a built up affair bolted together. The bottom piece mounts on the piston rod and the top surface bears on the underside of the slidebar. There are two spacers that go on top of this and bear on the sides of the slidebar and finally the top plate that bears on the top of the slidebar. The top plate is fitted with an oil cup for lubrication but I don't think it had seen much use! It's all held together with three bolts on each side. It was all a pretty poor fit and needed a lot of fettling to get it to run nicely on the slidebar with no play.



The top surface of the bottom part was badly scored and it wasn't actually parallel to the piston rod and only touched the slidebar at one end. I set it up in the mill with the piston rod resting on a parallel in the mill vice and skimmed the top surface with a fly cutter to get it flat and true again.



It was nice to be able to accurately measure the depth of cut with the new digital readout on the quill!

Next I did a similar thing with the top plate which had a deep groove in the underneath where it ran on the slidebar. I'm not sure if the groove was caused by wear or if it had been filed like that to get it to run on the bent slidebar! Anyway, it needed 10 thou skimmimg off it to get it flat again.



I then assembled the cylinder and slidebar to check the fit of the crosshead pieces. As I had skimmed the top surface of the bottom piece, there was now a gap between the running surface and the slidebar. That's not a problem as I'm going to fit a phosphor bronze shim to take up the gap. I've ordered a piece today as I don't have any to hand. I'm also going to fit a similar shim to the top plate. This will mean that the main bearing surfaces on the crosshead will be bronze rather than mild steel and that should be much better than before. For the time being I've made a shim out of some nickle silver sheet that I've got that happens to be the right thickness. With the shim in place the bottom part of the crosshead slides nicely from one end of the slidebar to the other so everything must be parallel.

The two side blocks had to have the bolt holes through them enlarged so that they could be adjusted to give a nice fit on the sides of the slidebar. With the holes as they were originally, the fit was very poor.

I then fitted the top plate and the crosshead seems to fit quite well now. It is a little tight when it gets to the cylinder end of the slidebar but I can adjust that when the bronze shim stock arrives and the crosshead is fitted permanently.

I next reasembled the inside cylinder and fitted it back in the frames to see how the slidebar aligned with the stretcher that the end of the slidebar bolts to.



Of course, the mounting holes in the stretcher don't line up any more now that I've straightened the slidebar! The two holes that take the screws that go into the end of the slidebar aren't too far out and I could 'adjust' those to make them line up. However, the mounting holes for the screws that hold the stretcher to the frames are miles out as the stretcher is a lot higher than it was before. I could machine some off the bolting face on the end of the slidebar which would mean the stretcher would sit lower down. The top surface of the bolting face is not perfectly flat so it could do with remachining anyway. It might be best to just make a new stretcher as it is only a piece of flat bar with some holes drilled and tapped in it.


I spent most of today at the club at Whitwick helping with a charity event but I managed a couple of hours in the workshop tonight.

I took the slidebar off again and skimmed about 0.030" off the bolting face to square it up and also to lower the mounting stretcher. I then refitted it and made a new stretcher altogether. I adjusted the position of the two holes for the bolts that fastened the slidebar to the stretcher so that they were now in the correct place. I fitted the new stretcher to the slidebar and held it securely into the frames with a clamp so that I could spot through from the frames for the two screws each side that go into the ends of the stretcher.



The stretcher was then removed to drill and tap these holes. I think it took longer to tap the holes than to make the new stretcher as the steel was horrible stuff to tap and was very 'gummy'. I had to take it very slowly withdrawing the tap and cleaning it every turn or so as I was afraid of breaking the tap otherwise.

When refitted and the mounting screws installed the crosshead moved nice and freely so it all must line up properly now.



I decided to use hex head bolts to secure the slidebar rather than countersink head screws as used originally so that by making the holes in the stretcher a little oversize it is possible to move the end of the slidebar slightly to get perfect alignment.

One thing that I noticed earlier was that the slidebar is not central in the frames - it's to one side of the centre. I think that's probably due to an error when the slidebar was originally fitted to the cylinder end cover rather than it being done deliberately.


Only managed a quick hour in the workshop tonight but fitted the crank axle and the inside connecting rod.



I was worried that there might be further alignment problems following rebuilding of the slidebar and crosshead assembly but everything turns over freely. I'll refit the rest of th axle assemblies and then the coupling rods to see if there are any issues there. A lot of the original 3/32" hex head whitworth bolts that held the hornstays in place have been lost and replaced with countersink head screws. As it's next to imposible to get small diameter Whitworth bolts nowadays (and I'm not going to faff about making some at this point) I'm going to retap the horns 7BA, which is very close to 3/32" whitworth, and fit 7BA hex head bolts instead. The only problem is that I seem to have run out of 7BA bolts so have placed an order with EKP for another 100.

Re bolts - I tend to buy 1 inch bolts and cut them to the size that I want rather than keep numerous different lengths in stock. There is very little difference in the price between the longer bolts and the short ones. I might buy the short ones if I have a need for many of a certain size.

One of the chaps in the N25GA, Mike Boddy from Australia, has designed an excellent tool for cutting bolts to the required length and I've got a sample that he gave to the Association. I've used it quite a bit now and it really is very good and saves a lot of time.




It's like a pair of crimping pliers but with threaded holes through the top plate and corresponding holes through the bottom plate. You open the arms out, screw your bolt or screw through the relevant tapped hole as far as will give you the right length you require, and then just squeeze the handles together. This cuts the bolt and leaves a very clean end that needs little or no cleaning up. I tend to use it by resting one handle on the bench and hitting the top handle with the palm of my hand as I find that easier, especially for larger bolts or screws. The threaded holes cater for 12Ba to 2BA and 1.6mm to 5mm metric bolts. There are also plain holes to cater for 1/16" to 3/16" rivets. The plates are made from hardened steel and should be fine for mild steel and brass bolts/screws but I'm not sure if they would last long cutting hardened bolts.

I think that there is a similar tool available for cutting just rivets but not bolts as well.

The tool is not cheap (something like £65 plus postage from Australia) but would probably be worth getting one if you have a lot of use for one.


Not a lot done today as I've been working in the garden. With not being able to do much over the last 18 months because of the leg problem the garden has got badly overgrown again and needs a lot of tidying up. I've also been slowly taking down the apple tree that overhangs the workshop and shed. I don't like cutting down trees but this one has got completely out of hand and in the autumn when the apples are ripe, they keep falling onto the shed and workshop roofs and make a hell of a bang! The tree is also too close to the house and may damage the foundations if allowed to grow any more. I did cut it right down many years ago but let it grow again which was a big mistake.

The 7BA bolts arrived this morning so this evening I retapped the remaining holes for the hornstay bolts in the hornblocks and refitted all the wheel sets and the springs etc. Unfortunately, two of the holes were badly stripped and I had to enlarge them to 6BA. I noticed that the axlebox bearing for the damaged wheel is very rough and has a lot of play in it. Is this just coincidence or something to do with the damage? The other bearings are not too bad but some are a bit noisy. I'm wondering how much running this locomotive has actually had. Some of the running gear seems quite worn but the cylinder port faces show very little wear.

I've temporarily fitted the front bogie and the trailing truck back on the frames and I'm going to take the chassis to the club tomorrow and try it on the track to make sure it runs round ok.


To be continued


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