Mercian 7mm Midland 1F Kit

[Fastdax]

Ah OK. It's not too clear from the photos exactly where the holes are.

 

I think you are right to leave off the square spacers and make your own. A bit of rail or an "L" shaped bit of brass sheet of the right width would do the trick. You could make a couple but leave them loose until you know where the motor/gearbox will sit.

 

I did something similar to my Deeley Dock Tank build, but I repurposed a motor mounting spacer as a frame stretcher to take the compensation pivot:

 

http://www.rmweb.co.uk/community/index.php?/topic/109283-duncans-7mm-workbench-ian-kirk-coaches-and-ixion-fowler/page-3&do=findComment&comment=2344910

[Ray H]

 

Here's the fairly modest method used for adding a bit of springing to the front two axles. The bearing holes have been lengthened slightly and small handrail knobs fitted to the inside frame part of the bearings and then some 0.45mm nickel silver wire used between the two bearings and soldered to the piece of copper clad that can be seen.

[Ray H]

I did have the chassis running over a week ago but it was doing so very erratically. I first thought it was the pick-ups because they could frequently be seen sparking where they touched the rear of the wheels. Consequently I tried different phosphor bronze to that supplied with the kit because it didn't seem to be springy enough with the consequence that contact between it and the backs of the wheels kept getting lost as the phosphor straightened out under what seemed like the slightest pressure from the wheels.

 

The replacement wasn't much better so I tried 0.7mm nickel silver wire. That was far too stiff and was enough for the friction it was causing to stop the wheels from rotating. Next came 0.45mm nickel silver wire and that took me back to the lack of springing with still no reliable running.

 

It was around this time that I thought there must be something else wrong! It also dawned on me that one possible (and maybe probable) reason for the way the contacts were losing their springiness was the continued picking up of the chassis and resting it in my hands whilst I looked at one side or the other. It also dawned on me that the contacts that I was fitting were fairly short.

 

I'd been using PCB sleeper strip glued horizontally to the side of the frames and all but filling the gap between the two wheels. As a result the contacts were vary short and any shaping to get them to rub on the backs of the wheels was too near the edge of the tyres. This meant that the fulcrum was at the end of the PCB strip.

 

But that was getting to be the least of my worries so I exchanged a couple of mails with my colleague and he advised stripping everything down and basically starting again.

 

 

[Ray H]

I stripped the chassis down, removed the (middle) driven axle and then fitted the axle with the worm attached into the gear box. The motor and worm appeared to be meshing correctly.

 

Next came trying the chassis, wheels & axles, with no pick-ups, no coupling rods and no worm/gear wheel. The chassis rolled really well. It didn't rock when stood on a flat surface either.

 

I then refitted the (basic) springing on the ends of the axle bearings. Here again I'd previously used PCB sleeper strip glue horizontally on the inside of the frames with short lengths of 0.45mm nickel silver wire soldered to the PCB and passed through the eye of a handrail knob that had been affixed to the horizontal (shaft) of the bearings. However, this time I re-positioned the PCB centrally between the two axles to be "sprung" and used much longer pieces of wire. The result is shown in my post 27.

 

I then refitted the coupling rods and again had no problems with the chassis rolling back and forth along my two yards of test track.

 

The motor, worm & gear wheel were next, wired direct to the controller. Geronimo! The motor turned but the worm and gear wheel very quickly stopped meshing, leaving the motor/worm to spin round, make a strange noise and leave the chassis stationary. The motor & worm were moving sideways whilst the gear wheel wasn't.

 

These two images show the relationship between motor, worm & gear wheel.

 

 

 

 

[N15class]

Looking at your photos you need to pack out each side of the brass wheel. To hold it in the correct position. The crank pin bushes can also be shortened.

[Ray H]

By chance I happened to pick up the wrapper for the gearbox, worm & gear - which I thought I'd thrown away - and re-read the assembly instructions a little more slowly.

 

I had misunderstood those assembly instructions. They clearly stated that the flanges of the two bearings that come with the gearbox etc. should be positioned next to the gear wheel. I'd taken this to mean that the bearing flanges should be soldered to the inside face of the gearbox (as can be seen in the previous two images) rather than to the outside of the gearbox. I was slightly puzzled over the need to trim said bearing's lengths to stop them pushing the frame bearings outwards.

 

By this time I'd hacked at the original (gearbox) bearings and the strange noises from the gear wheel/worm indicated damage to one or both. The gearwheel at least had managed to deposit brass filings on the inside of the gearbox.

 

A quick phone call to Markits and replacement gearbox, bearing, worm and gear wheel were winging their way to me (and the postman came up trumps delivering said parcel within 24 hours of the items being ordered).

 

The new gearbox was folded to shape, the worm fitted to the motor shaft and the middle (driven) axle gradually re-inserted into the frames passing through the new gearbox bearings and worm wheel.

 

 

 

The final job (for today) was to then fit new pick-ups.

 

This time I returned to the phosphor strip but with the PCB strip cut in half and mounted vertically on the outside face of the frames approximately half way between each pair of wheels. The phosphor strip stayed in one piece. This effectively moved the fulcrum much further away from the wheels with the result that the springiness has remained.

 

Test runs along my two yards of straight track have not thrown up any problems. I plan to take the chassis to the club tomorrow evening to try it around some curves. This may involve temporarily fitting a DCC decoder as the DC part of the club layout only has a small amount of curved track and can't provide a continuous run.

 

[N15class]

Ray you may need to shorten one of the bushes to allow the gear wheel to sit centrally under the worm. Pack the other side to allow it to rotate freely but move side to side. The instructions tend not to say anything about this.

Edited November 21, 2018 by N15class

[Ray H]

Thanks

 

At this moment in time the gear and worm are slightly offset as per the way that I read the assembly instructions: " . . Gear & Worm OFFSET for SINGLE boss . . " (their capitals, not mine).

 

I did try and align them the first time around and I'm minded to think that this may have been what has caused parts of the teeth on the gear wheel to become specks of brass on the inside of the gear box. I did compare the old and new gear wheels yesterday and the teeth on the old one are (now) noticeably shorter than on the new one.

 

I'm hoping that tonight's run on the club layout might show up any problems that might exist with the current (offset) alignment, in which case I'll take another look at it but for the moment as it seems to be working OK I'm tempted to leave things be after all the time I've spent getting this far.

[Ray H]

The chassis had a further short running session on the home test track yesterday afternoon with the result that the gearbox and gear wheel had to be moved sideways slightly when the mesh between the two went awry again. They are now almost vertically aligned but without the grinding sounds it was making when the initial worm and gearwheel were in use.

 

It then went round part of the club layout in each direction last evening and at one stage when it was hidden from view it did sound as though the gear and worm weren't meshing. However, when I went to look I found it was trying to push a stationary loco and several coaches that it had run into, backwards. That'll teach me to check that the route is clear before moving motive power!

 

It backed off with no trouble. I then got involved with something else and didn't get a chance to test it further. Hopefully it will get a bit more of a test at the club this afternoon when there are fewer of us around.

[w124bob]

Did I read somewhere that a tiny amount of cheap toothpaste can be used as a sort of bedding in paste ? Or have I just made that up!

[Ray H]

What I didn't mention earlier was that a manufacturing glitch necessitated the replacement of the "new" worm. As a consequence yesterday's tests were with the original one. As far as I was aware the chassis was running OK when I removed it from the club layout last evening.

 

The replacement worm arrived today and was fitted without delay. Imagine my concern when I put the chassis on the track with said new worm only to find that most of the time the worm and gear wheel were not meshing (yet again)!

 

Luckily and for some unknown reason I checked the motor fixing screws were tight. They weren't, so I re-tightened them and the chassis ran happily on (DCC) speed step one on my test track at home and ran similarly on the club layout this afternoon, although on speed step 3 simply so that it went round the layout a bit quicker without stopping other people from using the layout.

[Ray H]

It has taken a bit of to-ing and fro-ing in between other un-associated tasks but I have at last got the chassis to creep along the whole two yard length of my test track. I fitted a temporary decoder, set it to 128 speed steps and the chassis ran the full length in both directions on speed step 1 and only had to be encouraged to keep moving once  - and that was on track that hadn’t seen a track rubber for a while.

 

And so to the next step:

 

The instructions say to “Mount the brake shoes on the 0.9mm wire pegs (please note that the sockets on the brake shoe castings may need to be filed down slightly for fine scale chassis, check position of shoe against wheel).” (My highlighting of “on the 0.9mm wire pegs” which is the bit I’m struggling with).

 

A previous (assembly) instruction had said: “From the 0.9mm wire provided, cut three lengths 27mm long and solder these in place through the holes provided for the brake supports. These provide extra rigidity and anchorage for the brake castings.”

 

I should add that the chassis measures 25mm between the outer faces of the frame sides thus leaving approximately 1mm of the aforementioned 0.9mm wire protruding from the outer face of each external frame side.

The first two images show the 27mm lengths of the 0.9mm wire soldered where I believe the instructions are telling me. The 1mm protrusions can also be seen

 

 

 

The third image shows the cast brake shoes, several of which required a lot of re-shaping and filing to clean up.

 

If I had to guess I would say that the protrusion marked A on the leftmost  brake shoe casting possibly has to be removed and, equally possible, the casting then needs a 0.9mm hole drilling to a depth of around 1mm so that the casting can be soldered in place over the protruding 0.9mm wire "peg". I have checked the overall thickness of the casting with said protrusion being removed and the shoes appear to line up with the wheel tread.

My concern with fixing the shoes is that it could no longer be possible to remove the wheels from their axles.

 

Would anyone care to suggest how I should attach the brakes shoes?

[Fastdax]

You could remove the 27mm wires and open out their 0.9mm holes until the "A" pegs fit in without slop.

 

Then fix in and solder the stretcher rods at the bottom of the brake arms and tie the whole lot together with pull-rods, soldered on..

 

The whole assembly should then be removable by springing the tops of the brake arms apart and taking the "A" pegs out of the chassis holes.

 

This assumes the pegs are a consistent diameter.

 

If removing the 27mm rods leaves the chassis too floppy, reinstate L-shaped stretchers made of scrap etch.

[Ray H]

That sounds like a plan, thanks.

 

The next instruction says "Cut four lengths of 0.9mm wire, 47mm long. Pass three lengths through the lower holes of each pair of brake shoe castings and one length through the brake control bracket on the chassis."

 

Presumably these will need to be soldered centrally to hold them in position.

 

The instruction continues "Laminate together the two halves of the brake pull rods and solder in place. Take care to ensure that these clear the coupling rods when the wheels are revolved."

 

I've just checked what I believe are the pull rods and they don't have any holes but they do have dimples which appear to line up with where the lower holes in the brake shoes would be. Presumably the ends of the 0.9mm wires are soldered into these dimples otherwise the dimples would actually be holes.

 

The instruction concludes with "Take the brake cranks and solder in place either side of each pull rod. Fix in place the etched brake cross pieces between each pair of brake shoes."

 

I've no idea what either the brake cranks or the brake cross pieces look like but I think I know a man who might at the club so I'll ask him later in the week.

[Fastdax]

The brake cranks are probably these:

 

 

They sit just behind the rear wheels. When the vacuum or hand-brake is applied, the cross-shaft between these cranks rotates and the cranks pull on the bake pull-rods.

 

If you make the brake arms/shoes/cross-rods/pull-rods detachable as a unit, you will need to make the joint between pull-rods and cranks not fixed, so that the pull-rods can be removed, leaving the cranks attached to the chassis.

 

No idea what the "etched brake cross pieces" are. There are some elongated diamond shapes on your etch with an etched groove along their length, as if they could overlay the rods joining the bottom of the brake arms. But (on 41708 at least) the bottom of the brake shoe arms are connected with plain rod, like this:

 

 

BTW, I'd drill the dimples in the pull rods 0.9mm and solder the rods right through, then file back to resemble nuts. It will be a lot stronger like this.

[Fastdax]

A correction - there is no vacuum brake that operates on the loco brakes - just a manual hand brake applied by cranking the handle on the front of the coal bunker. 41708 may have been built with steam loco brakes, but these have now been removed.

 

The vacuum bags front and rear are for train brakes and were probably added after 41708 was first built, when it was required to shunt vacuum-braked stock. The train brake has its own control in the cab. The ejector on the RHS of the smokebox creates the vacuum for these brakes.

 

41708 now also sports steam-heating connections to heat coaches, probably dating from its life in preservation. I can't tell from my photos whether the loco actually generates heating steam or is just through-piped. Maybe the former as the steam pipe does seem to run through the firebox.

[Marshall5]

 

 

41708 now also sports steam-heating connections to heat coaches, probably dating from its life in preservation. I can't tell from my photos whether the loco actually generates heating steam or is just through-piped. Maybe the former as the steam pipe does seem to run through the firebox.

Are you suggesting that steam for train heating is generated by passing the steam pipe "through the firebox" or am I misunderstanding your post?  Steam for train heating is taken from the boiler (usually via the steam manifold) and passed through a reducing valve to reduce it from boiler pressure to around 50psi suitable for carriage heating.

Ray.

[Fastdax]

I guess I was suggesting that but your description sounds very much more correct.

 

My photos of the underside of 41708 show the steam heat pipe apparently exiting the back of the firebox, but that may just be a convenient pipe run rather than a means of generating steam.

 

Apologies if I assumed incorrectly.

[Ray H]

I managed to find some more time to progress the model onward today although as you'll discover shortly, it may not get much further forward for a few days.

 

 

I did as suggested and enlarged the holes in the frames to accept the mounting for the brake shoe casting. I also removed the 0.9mm rods that the instructions indicated should be added and replaced the two in the centre of the frames with some scrap etch as suggested above.

 

I have lightly soldered everything in place and once again run the chassis up and down the test track to check that it still moves unimpeded. I even cleaned the track beforehand.

 

 

The second image shows the status as it is now but again opens up a mystery. The brake rods are 47mm long - as directed by the instructions - but this underside image clearly shows that they are too long. I'll leave them be for a while but think they'll need to be trimmed in due course.

 

I haven't tried "popping" the shoe locating pins out of the frame as yet but even if I can the left hand most of the four locating rods passes through the frames so I won't be able to fully remove the brake gear from the frames.

 

There won't be any work on the model for at least a couple of days because my Antex soldering iron seems to have taken a dislike to mains electricity (or something similar). I don't know what the standard Antex warranty period is but I doubt it is more than two years - and the iron is now 24½ months old so a replacement looks on the cards. New elements are around £44 (+ p&p?) from Antex - if indeed it is the element that has gone; the display has disappeared - whilst a new iron is just over £60 (+ p&p?). Perhaps I'll treat myself to an early Christmas present.

[N15class]

If you don't solder the small brake cams to the cross shaft,only to the pull rods it can all be sprung off.

Yes trim the lower cross pulls back. Just leave 0.5mm sticking out.

[Ray H]

If you don't solder the small brake cams to the cross shaft,only to the pull rods it can all be sprung off.

Yes trim the lower cross pulls back. Just leave 0.5mm sticking out.

 

Thanks for that idea. I'll have a look at that when I next have the model nearby.

 

I enquired of Antex whether the iron was economically worth repairing yesterday. I had a mail response from them this morning and they have said they'll mail me a replacement - iron? - free of charge. Thank you Antex.

 

Let's hope the mail service isn't too slow.

[Ray H]

Work on the chassis has been on going. It would appear that there is just one remaining item to attach thereto but first a couple of pictures . . . . 

 

 

Look closely at the above image and compare it to the one below!

 

 

Can you spot the difference?

 

The final task on the chassis as far as I can see from the instructions (other than fitting the pipes to the sandboxes) is to fit the said sandboxes. I did this out of turn because I'm also supposed to:

 

Laminate the two parts of the chassis toolbox front and fit between the chassis frames. Cut in half the toolbox wrapper & solder in place, ensuring access is left for the mounting bolt.

 

I've no idea what these parts look like but it's club this evening so hopefully someone will guide me. In the meantime, back to the sandboxes.

 

The sandboxes are white metal castings with the inevitable oddments of flash that need removing. I set about this working on the assumption that the long side of the castings was soldered to the frames. Consequently and probably without thinking deep enough about why I was finding what I did, I removed the approx. 5mm diameter by about 2mm deep protrusion from said long side thinking it had something to do with the casting process.

 

It wasn't until I had done all four and had then looked at one of the lose-up pictures of 41708 that I realised that the long side of the sandbox should be horizontal (and that the sandbox should be affixed to the frames by the smaller flat side). The protrusion that I'd so glee-fully removed was in fact the filler/cap.

 

Fortunately, having looked at the picture of 41708 again I could see that the filler cap and fixing were shaped. I turned this to my advantage and cut three different size discs from 0.010" plasticard which I then stuck together and fixed to the casting.

 

The instructions also state that the sandboxes should be fixed "in front of the guard irons". I must admit that this could have been an easier place to fix them although the sand pipes would need to have been significantly longer. However, looking again at the picture of 41708, as far as I can tell the sandboxes appear to be positioned between the guard irons and the wheels/brake shoes so that's where I've put them. I shall make fitting the pipes one of the last jobs, possibly after painting.

[Ray H]

I hadn't really thought any further than working on the chassis so was a bit surprised at the relatively short time it has taken me to move forward with work on the body.

 

 

The valances took a few attempts to get them vertical, something that I did by eye because I reckoned (accurately or otherwise) that using an engineer's square would sap to much heat and make soldering difficult.

 

I also soldered the buffer beam in place both to the end of the valances and to the underside of the footplate. There isn't any indication in the instructions when this task should be carried out.

 

The footplate will only fit one way round - the wheels foul the footplate the other way round.

 

I also lightly soldered the two fixing nuts to the top of the footplate as indicated in the (exploded body) drawing that comes with the instructions. Again there's nothing in the instructions to say when this should be done either.

 

I should also add that a colleague lent me his rivet press last week so I've raised all of them whilst I had the press.

 

The next instruction says to "Take the cab front and solder in the position marked by the half-etched lines."  The cab front (at least where it is to be soldered to the footplate) is a piece of brass almost the full width of the footplate. The half-etched lines can be seen in the image below. The lines don't extend to the full width of the cab (front) and as can (just) be seen even if they did the base of the cab front would likely foul the flanges of the rear wheels. Not only that but the aforementioned cab front - being a piece of brass with no cut-outs or relief - can't fit where it is supposed to go because it fouls the shaft at the rear of the motor together with the raised area also on the rear of the motor through which the shaft protrudes.

 

 

I can probably remove the majority of the protruding shaft carefully with a cutting disc but that still leaves the raised area on the motor housing.

 

One way to make the cab front fit onto the footplate is to cut away the bottom of the cab front so that it no longer fouls the motor or flanges. My concern then would be that the body/footplate assembly will need to be manoeuvred into position rather than drop straight onto the chassis.

 

Another option seems to be to modify the angle at which the motor sits in the chassis. A disadvantage here is that I may start to find it difficult to fit a decoder and speaker if I raise the rear end of the motor.

 

Decisions, decisions, decisions!

[malcolmrhine]

Work on the chassis has been on going. It would appear that there is just one remaining item to attach thereto but first a couple of pictures . . . . 

 

261218_1.jpg

 

Look closely at the above image and compare it to the one below!

 

271218_1.jpg

 

Can you spot the difference?

 

The final task on the chassis as far as I can see from the instructions (other than fitting the pipes to the sandboxes) is to fit the said sandboxes. I did this out of turn because I'm also supposed to:

 

Laminate the two parts of the chassis toolbox front and fit between the chassis frames. Cut in half the toolbox wrapper & solder in place, ensuring access is left for the mounting bolt.

 

I've no idea what these parts look like but it's club this evening so hopefully someone will guide me. In the meantime, back to the sandboxes.

 

The sandboxes are white metal castings with the inevitable oddments of flash that need removing. I set about this working on the assumption that the long side of the castings was soldered to the frames. Consequently and probably without thinking deep enough about why I was finding what I did, I removed the approx. 5mm diameter by about 2mm deep protrusion from said long side thinking it had something to do with the casting process.

 

It wasn't until I had done all four and had then looked at one of the lose-up pictures of 41708 that I realised that the long side of the sandbox should be horizontal (and that the sandbox should be affixed to the frames by the smaller flat side). The protrusion that I'd so glee-fully removed was in fact the filler/cap.

 

Fortunately, having looked at the picture of 41708 again I could see that the filler cap and fixing were shaped. I turned this to my advantage and cut three different size discs from 0.010" plasticard which I then stuck together and fixed to the casting.

 

The instructions also state that the sandboxes should be fixed "in front of the guard irons". I must admit that this could have been an easier place to fix them although the sand pipes would need to have been significantly longer. However, looking again at the picture of 41708, as far as I can tell the sandboxes appear to be positioned between the guard irons and the wheels/brake shoes so that's where I've put them. I shall make fitting the pipes one of the last jobs, possibly after painting.

I built an Oldbury Models kit of this loco a few years ago which involved a lot of very enjoyable research including crawling all over 41708 and taking a lot of photo's. With reference to your query about the toolbox, the Midland era loco's were fitted with a toolbox between the frames at the rear (there is a good photo in Midland Locomotives volume 3, p 91 Wild Swan. The LMS/BR period locos had the toolbox relocated to the front nearside footplate, where they often seem to have received damage.

[Fastdax]