Standard 4MT build - Scale 7

[TomatoStains]

Adrian

 

Do MOK say which particular ABC unit is recommended?

 

I will be following this thread with much interest, although mine, when I get it, will be a 'narrow gauge' version

 

When I was looking at the 4MT this time in 2010 this is what Dave Sharp said re motor... "What you need is an ABC Mini with a Maxon motor... You need to tell him that its for an MOK kit so that

its fitted with minimum chamfered main brgs not with the large chamfs he sometimes fits."

 

Hope that helps.

 

Dave

[peejay]

When I was looking at the 4MT this time in 2010 this is what Dave Sharp said re motor... "What you need is an ABC Mini with a Maxon motor... You need to tell him that its for an MOK kit so that

its fitted with minimum chamfered main brgs not with the large chamfs he sometimes fits."

 

Hope that helps.

 

Dave

 

Yes that helps muchly, many thanks Dave.

[jazz]

Hi Adrian, just caught up with the thread. Oh, how I am drooling. I wish I could run one on my layout.

 

That looks one beautiful kit. I guess it will keep you busy for a week or so?

[Adrian]

Do MOK say which particular ABC unit is recommended?

As mentioned the instructions say the mini gearbox with a 22mm diameter motor. I think the reference about the chamfered bearings is because in the kit there is an etched cradle to fit around gearbox for the rear axle rocking system. The main chassis suspension is a compensating beam between the front and centre axles, the rear axle is driven and is a rocking unit. The motor cradle has a sliding system to allow the motor to rock from side to side but it does need this etched cradle around the gearbox. However I'm going for a sprung suspension so I don't think the chamfered bearings are necessary.

[Adrian]

Having got back into the swing of things I turned back to getting the frames sorted and the suspension fitted. So using the dimensions checked courtesy of Miss Prism, I started to layout the positioning for the suspension fulcrum points. The frame spacer is included here because after drilling a small hole in the appropriate postion that is going to be the rear most fulcrum point for the wire. Getting the spacing sorted was a simple marking out job, but I had to sort out the vertical positioning which will set the ride height. I really ought to sort out an adjustable system but I couldn't think of anything simple so the fulcrum points are just soldered in at the minute. If I need to change the heigh later I'll just have to adjust the brackets on the hornblocks instead. I used the rocking arm supplied in the kit to determine the planned ride height for the hornblocks, for the weight of the kit the initial calcs suggest a spring deflection of just under 1mm so the fulcrum points were moved down by this amount.

 

Once this was done I got out the rest of the various spacers for the frames - a total of 14 separate pieces.

 

Most will only fit one way so you can't really go wrong, the only couple that needed care was the large X frame with the etched writing on, I wasn't sure how much of this would be visible under the boiler so I made sure this faced downwards and the the other one was the bolster attachment frame for the front pony truck. The slot and tabs allows it to mounted either way round, the attachment holes should be towards the rear and this matches up with the side frames.

 

This also shows the slot I had to cut in the top of the ashpan etching at the side, this was to allow clearance for the CSB fulcrum and wire to pass through.

 

Before soldering together everything was check for being straight and square which it was. The vertical cradle in the middle being the cradle for the motor and gearbox.

 

Once soldered up the majority of tabs all have to filed off, half a dozen need to be left to mount the etched rivet overlays later so I circled these with a marker pen so that I wouldn't get carried away and file them all off.

[ozzyo]

Who's axleboxes/horn-blocks are you using? As some of them run loose on the axels.

 

OzzyO.

[Adrian]

Who's axleboxes/horn-blocks are you using? As some of them run loose on the axels.

I'm just using what is supplied in the kit, the hornguides are etched units with tabs to slot into the frames, the axleboxes are just brass turnings supplied in the kit. All I've done is bore out the axleboxes to fit small roller bearings.

 

 

 

[ozzyo]

Adrian,

it's just some of the roller bearing that you get now are for 4.8mm and not 3/16". Not a lot in it. but you want the bearing to turn and not the axle to turn in the bearing. If it is a 4.8mm inside bearing you could use a spot of Loctite to stop the axle moving.

 

OzzyO.

[Adrian]

Adrian,

it's just some of the roller bearing that you get now are for 4.8mm and not 3/16". Not a lot in it. but you want the bearing to turn and not the axle to turn in the bearing. If it is a 4.8mm inside bearing you could use a spot of Loctite to stop the axle moving.

Sorry for being slow on the uptake, I see what you're getting at now. The roller bearings were advertised as imperial sizes and they are a very snug fit on the axles.

[Adrian]

Managed to grab a bit more time to solder up the frames, once that was done a lot of tabs had to be filed flat so that I could fit the etched overlays. These were fitted and some splashers over the rear driving wheels, followed by more tab filing and cleaning up

 

 

 

 

Once the frame was soldered up it was imperative to have a trial fit of the wheels just to see what it would look like you understand. The wires for the suspension haven't been cut to length yet hence sticking out of the front for the minute. However it was comforting that they fitted.

 

 

 

 

 

Here you can see how the spring wire for the suspension threads through the slot cut in the ashpan.

 

[3 link]

Hi Adrian,

 

One of my pet hates is sweating on overlays, could you please explain how you do yours as they seem remarkably clean and tidy.

 

Regards, Martyn.

[Adrian]

One of my pet hates is sweating on overlays, could you please explain how you do yours as they seem remarkably clean and tidy.

Thanks for that, I must admit I was a bit apprehensive as it's the first kit I've built with overlays and it seemed to be an awful lot of soldering.

 

I assembled it using the tab and slots to hold the overlays in place. I mainly use the Carrs solder cream so I put down a bead of solder along the edge for a short length (2" to 3"), added a little flux (courtesy of http://www.7mmlocomotives.co.uk). I then used an 80W iron running it along the inside edge of the frame, the solder will go where the heat is so it does get sucked into the joint. Don't get me wrong there is still plenty of cleaning up to do, the cleanliness was just an attempt to reach the high standard set by Christian. The final finishing was draw filing along the edge with a needle file.

[Christian]

Don't get me wrong there is still plenty of cleaning up to do, the cleanliness was just an attempt to reach the high standard set by Christian.

 

So blushing right now, thank you :-)

[Adrian]

Whilst cleaning up the multitude of castings for the springs, hangers etc. I thought I'd make a little progress on the bodywork so I'd get the feeling of getting somewhere. The bodywork initially is making up a few sub assemblies, the first one being the boiler and smokebox.

The first bit being a former to join the smokebox and boiler sheets together. The flat strip is folded into a square and then sandwiched between the two circular formers.

 

 

The boiler is supplied as flat etches so will need to be rolled. The smokebox is in two pieces, an inner piece and a half etched overlay.

 

 

This shows the rolling of the smokebox. The rolling bars can leave a small flat on one end so it is swopped around a couple of times to try an minimise this. When rolling the half etched sheet I use either a sheet of plastikard or card to protect the rivet detail. The boiler is tapered but rather than being concentric the bottom seam should be parallel with the smokebox, ie all one straight line. So when I start rolling the boiler the bottom edge is square to the bars, and slowly wind in the rear bar until the seam lines up with each other.

 

 

Once rolled up the formers are inserted and I use some jewellery wire to hold it all together.

 

 

Before it's soldered up the instructions mention fitting the clack pockets. These are small brass castings to be sweated to the inside of the boiler.

 

This was one of those awkward jobs that need a couple of pairs of hands. Trying to hold the boiler, casting, soldering iron was entertaining especially as the casting was inside the boiler. In the end I tapped the hole in the clack pocket 6BA so that I could fit a cheesehead bolt allowing me to hold it externally with a pair of tweezers allowing me to get the soldering iron onto the casting inside rather then the boiler wrapper. Hopefully the photo shows it better than my explanation.

 

 

Note the castings are handed as they have a slight taper on to match the boiler

 

 

Once fitted the boiler was soldered up and the inner smokebox wrapper attached. A steel rule was used to ensure the bottom edge was aligned.

 

 

Finally the outer wrapper for the smokebox was fitted and cleaned up.

 

 

That's it for the boiler at the moment. It can be put to one side as the next bit of the bodywork is the front footplate.

[Scale7JB]

Looking great.. It's going to be mega, I'm sure !!

 

JB.

[Adrian]

Trying to keep up with weekly updates to keep the momentum going but it seems to have been a bit of a slow week.

 

The next bit on the chassis was fitting the driving wheel springs and hangers. The instructions mention a couple of ways of fitting then, one is to solder them all in place, the alternative was tapping the hangers and bolting it together with 12BA bolts. So that I could drop the wheels as a unit I decided on the drilling and tapping route.

 

So 12 hangers were drilled and tapped 12BA

 

 

Soldering all the hangers onto the frame was fun, the casting was a good heat sink so getting the soldering iron in was entertaining, it might have been easier to do this before putting the frames together but I got it done.

 

 

The bottom block was soldered to the hanger on one side, the spring can be fed into the slot, the block on the other side is then used to clamp the spring in place. This can be seen on the frame in this picture, the hangers on the left have the bottom block soldered to them. This also shows the castings for the brake rod, note this can go 2 ways and it's not that clear in the instruction - I just hope I've got it right.

 

 

So finally the brake lever is fitted and one spring. The bits that need soldering have been done, it's quite fiddly fitting with all the 12BA bolts and the heads on the bolts are a little too big for my nut spinner which makes it awkward to bolt up and the close up photo emphasises the large head. I think I'll make up a nut on a threaded bar instead so that I can use the nut spinner and it'll look the right size then. That's a job for later after a bit more detailing on the frame.

[ozzyo]

Hello Adrian,

 

have you got Items Mail Order catalog? He some times has BA size bolts with the next size down head on them. So a 12BA bolt would have a 13BA size head. I get just about all my nuts bolts etc. from him, order on a Tus normally arrive on a Wed. No connection just a very happy user.

 

OzzyO.

[Adrian]

have you got Items Mail Order catalog? He some times has BA size bolts with the next size down head on them.

I don't - do you have a contact address/email for them? I've just been getting them from various model engineering suppliers as I've been buying other stuff at the time.

 

 

 

[peejay]

I don't - do you have a contact address/email for them? I've just been getting them from various model engineering suppliers as I've been buying other stuff at the time.

 

Items Mail Order Ltd, 46 St. Martins Road, North Leverton, Retford, DN22 0AU. Email: items@btinternet.com

 

HTH

[ozzyo]

Items Mail Order Ltd, 46 St. Martins Road, North Leverton, Retford, DN22 0AU. Email: items@btinternet.com

 

HTH

 

 

The address that I have for him is as follows;

Mayfield,

Marsh Lane,

Saundby,

Nr. Retford,

Nottinghamshire.

DN22 9ES

 

Phone 01427 848880

 

He advertises in the Modeler most months.

 

OzzyO.

 

PS, just checked in the catalog (Jan 2010) he has no nut with the smaller head in 12BA, but he may have now!

[Adrian]

The next bit on the frames required a few small taps and dies which I didn't have, so whilst I'm waiting for those I thought I'd start on showing the progress on some of the body work. As mentioned before it does build up in a number of sub assemblies before fitting it all together, so the next bit I'm looking at now is the front footplate.

 

The first task was finding and cutting out all the main components.

 

 

 

The saddle is then folded up and the cross members that will support the footplate are soldered in. This was all straight forward and went together well.

 

 

 

The next bit needed a little care and the boiler which I'd prepared earlier. The smoke box saddle has a rectangular frame (item marked A in the first photo) which needs rolling to the shape of the smoke box. I started it with the rolling bars but with it being a thin frame and quite small it would roll the centre bit but then just put a crease in near the edges. I wanted the edge of the saddle to fit close to the boiler I used a polished hammer and gently knocked the saddle into a curve at the edges.

 

The other bit to note about this frame is again there are two ways it can fit. It has etched slots in it for tabs on the footplate to go through and locate the boiler, So these need to line up with those on the boiler and there is a wide end (the one with the A on in the photo) and a narrow end. How this fits on the boiler means that with the wide side to the rear then the saddle fits flush with the back of the smoke box. Judging as best I can from the photo's this is the way it should be. If it's the wide end to the front then there is a step between the saddle and the smoke box, so in the first photo I laid it out the wrong way, the wide end should be to the rear.

 

 

 

Another point to note is that to get the saddle to fit flush I had to remove some of the etched rivets on the rear of the smoke box.

 

 

 

Once that was sorted it was all soldered up including the side frames and half etched overlays.

 

 

p.s. Thanks for the address for "Items" - I'll get a catalogue sorted.

[Adrian]

A small update on the footplate progress. The top footplate sheet is a thinnish bit of half etched nickel. The instructions recommend leaving it on the etch whilst folding various edges.

 

 

 

So once the various sides have been folded it's then removed from the etch and the main drop folded to fit. The footplate unit has the bufferbeam and the lower footplate sheet fitted.

 

 

 

The underside of the footplate has small half etched slots so that the cross members from the saddle provide a positive location for the footplate. This is then all soldered up.

 

 

 

One thing to be aware of is fitting the front buffer beam. In the instructions the first photograph showing the buffer beam shows the long drop tab to the right of the slot for the coupling hook. I believe this is wrong, it should be on the lefthand side, as per this photograph, and in fact the next page in the instructions show it on the lefthand side.

 

 

 

So the main front footplate is soldered in and cleaned up.

 

[Horsetan]

I wonder if those beautiful etches could be shot down to 4mm scale.......

[45609]

I wonder if those beautiful etches could be shot down to 4mm scale.......

 

Just had an identical thought......

[Jol Wilkinson]

I wonder if those beautiful etches could be shot down to 4mm scale.......

 

Ivan,

 

having done it the other way round (4mm to 7mm), it's quite straightforward if the artwork has been produced using CAD. The real benefit is that it isn't then too difficult to alter fold lines, slot and hole sizes, etc. correctly to suit 4mm scale material thickness, bearings, etc.

 

Just reducing the artwork in toto doesn't always produce good results, which is why it isn't done too often. It would be shame to take what is clearly a very fine kit in 7mm and produce something that is a bit indifferent in 4mm.

 

Jol