Tower Models O Gauge Class 20 by Jinty 52

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Now for something completely different. Well for me any way.

As I have nothing of my own in the pipeline and my brother only had the Tower Class 20 sitting in his kit drawer, I offered to build it for him. I have still got the Seven Duke on the go but that is now at the painting stage, and I need something to actually build. He bought it from Tower Models some years ago and since then it has been gathering dust while other project took priority.

Of the thirty plus O gauge kits I have built, this is only the second diesel loco, after the MMP Class 08, that has crossed my workbench, (kitchen table) and it is mostly cast white metal not etched brass. Not my favourite medium but needs must. Also there is the advantage of a much reduced number of parts to assemble resulting in a quicker build. I don't know much about this class or diesels in general but my brother has provided quite a bit of reference work to help me out. Also if any of the diesel freaks out there spot any errors as I go along, I'd appreciate the heads up. So what's in the box?


Nice sturdy box that will hold the completed model when lined with some foam packing.



Several pages of A4 instructions with some prototype info, hints on kit building by Tony Wright, parts list and diagram of the etched parts. The instructions are a mix of exploded diagrams and text and look more than adequate.

This is a "complete kit" and comes with motors, gears and wheels.


The small castings are sealed in polythene as usual with DJH/Tower.


And the big lumps of metal.






And the etched parts.


A closer view of the bogie etches.


And the roof fan grills. Nice!


There are lots of molding tabs and flash on the large castings so I decided to start there. These are some of the large tabs on the footplate edge - 10 of the s*ds!


And here they are after filing and cleaning up.



A close up of the nose cowl.


And the cab.


And the cab rear. I still need to drill out the "flash" and clean up the small windows on the rear of the cab. The end with the big windows is the front. A least that was the direction they tended to drive them. Usually two loco with the nose cowl ends together. Further work is needed on the other windows but this is all I had time for so far.


Not bad for 2 nights work. I wonder how many etched pieces it would need to replace these three castings?????
One final point. The weight of the damn thing. It's nearly 6 pound including the box, so won't lack adhesion!

Edited February 17, 2018 by PAD

[3 link]

Very nice PAD,

 

The castings do not look to bad at all, what did you use to remove those white metal tabs? I usually sacrifice a couple of cutting discs for any thick white metal myself, and also what did you use to buff that body up like you have ?

 

Sorry for all the questions, I cannot help being a nosey s*d.

 

ATB,

 

Martyn.

[pwr]

Given the necessary thickness of the castings flush glazing the cab won't be that easy. Have you given that any thoughts

 

Paul R

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Hello Martyn,

Yes the castings have fettled up quite nicely.

 

My first thoughts were a cutting disc followed by filing. However, I tried my side cutters on one of the tabs and found the metal was soft enough to snip the bulk of it off. Did the rest the same way then tidied up the remaining stubs with a 1 inch file. Had to keep stopping periodically to clean the white metal out of the grooves in the file. Did that with and old Swan Morton blade and brass brush.

 

To buff up the castings I used a mix of course and fine Garriflex blocks, and dare I say it, a scratch brush in the tight corners.

 

Paul,

I'm not sure but I think the glazing is applied to the outside of the apertures with the etched frames on the outside of the glazing. If that's the case then I may get away with just matt blacking the thick edges to disguise. May also consider thinning the metal around the apertures but that will be a real pain. I'll think about that for later.

Cheers,

Peter

[JeffP]

Decent build with interesting extras here: http://www.7mmlocomotives.co.uk/gallery2/main.php?g2_itemId=300

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Thanks Jeff, But I've already saved the photos to my reference file for Class 20s on my PC.

[CloggyDog]

Based on the photos, you have a standard production batch disc-headcode 20 (fluted equalising beams, round oleos, small 'English' cabside window), so suitable numbers as built are D8020-27/35-69 (later 20020-7/035-49/051-69/128) though some of the Pilot Scheme batch (D8000-19, later 20001-19/50) were later given bogie and buffer swaps to make them visually very, very similar (but, as always, work from photos of a particular loco!)

 

I notice the etch also gives the larger 'Scottish' cabside windows, if you fancy deepening the openings - that gives you D8028-34/70-127, later 20028-34/69-127, though for a green 'un, you'd also need to cut the tablet catcher recess below the window (the last of these were plated up circa 1981, but the bigger windows remained, apart from on 20115 which had an 'English' style disc cab fitted after an accident in 1972).

 

Class 20s were wired such that 'forwards' was bonnet first (so the end with the big windows is technically the back!) and I notice the small cab front  windows need opening out.

 

The castings certainly capture the look of the best diesel class BR bought

 

What era is it for??

[John Tomlinson]

This looks superb, and you've got a lovely finish to the castings.

 

Another detail to look for is in the large side grilles, which have a horizontal cross bar roughly in the middle. The size of the bar seems to differ by batch, so the RSH locos look a bit different to Vulcan ones - something to be vaguely aware of as you look to choose the final identity of your model.

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Thanks for the info CloddyDog.

It will be in BR Green with grey roof (no yellow warning panels), so early doors after they were introduced. I think my brother said he wanted it in the D8020-27/35-69 series but need to do some research before deciding.

[PAD]

This looks superb, and you've got a lovely finish to the castings.

 

Another detail to look for is in the large side grilles, which have a horizontal cross bar roughly in the middle. The size of the bar seems to differ by batch, so the RSH locos look a bit different to Vulcan ones - something to be vaguely aware of as you look to choose the final identity of your model.

Thanks for that John. As I am not really into diesels this is the kind of thing that will slip by me . Cheers, Peter.

[cheesysmith]

The forward or A end of single engine diesel loco's was towards the free end of the engine. On one end of the engine you would have a generator hanging off it, being a EE product, the other end powered the radiator fan drive and other equipment like compressors. So the radiator is the A end, or forward, even thought the cab was at the B end, or back.

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Hello All,

It's been a  long  time since this  thread  was updated due  to the  fact  that I got  p*s*ed off dealing with the chobham armour that the thing is made from, and another steam loco kit came into my possession so the enthusiasm for the Class 20 waned.

 

However, as I have  been slow restart the build, my brother Mick(having nothing better to do and it is his kit anyway) has taken up the challenge. As the kit is now available again, we thought the build  might be of interest to anybody contemplating making a purchase, and a comparison with the JLTRT can be made (See Sandy Harper's excellent  build). Plus, I'm away from home with nothing to build and I'm getting withdrawal symptoms!  This is my methadone fix.

 

From where I left  off, he has spent a long time fettling the  main body cowl and  cab to improve the fit onto the underframe. A lot of effort has been devoted to getting a good alignment between the  cab and the cowl, and also to disguise as much as possible, the  error with the side sheet.  The cab (although not square in profile - it tapers from front  to rear) is not square, if  that makes sense. I can't  remember the exact nature of the error so if there are  any  questions Mick will answer.  I think the  bottom edge needed packing to raise it and  also extra fixing points have  been added to the  cowl to get the  underframe to fit better. Anyway enough blah, blah, here are some  photos.

 

The  bogie mounts screwed to the underframe.

 

The underside with some of the underframe detail added.

 

The cab details fixed to a plastikard base plate to make  them removable  to aid painting.

 

The cab innards placed on the underframe and  the  buffers held in place  with blue  tack.

 

And from t'other end.

 

Some  shots with the  cowl and  cab in place.

 

Here are the buffers prepped  up. Mick had to ream out four 14ba brass washers to insert into the  buffers to stop the springs going through the buffer castings. He also  had to drill into the castings to enable the buffer heads to have sufficient travel.

 

Mick,

If you  want  to continue the  write up feel free.  If  you  are not  sure  how  to do it  I'll show  you  on Thursday when I'm back up north. If you  want  me to update the  thread in the  meantime just mail me  the  photos, and  of  course feel free to add any comment to the  above.

 

Cheers,

Peter

[Jinty 52]

Thanks Peter,

 

The pictures don't look too bad!

 

The cab correctly slopes inwards at the rear, but the casting is not symmetrical. In addition I had to pack it up with 40 thou plastic card to ensure the top of the cab was flush with the top of the engine compartment. I also had to use plastic card shims between cab and the engine cover to ensure a reasonable fit. A bit time consuming but I got there in the end! The work done since then has been straightforward.

 

The buffers are in fact the DJH castings supplied with the kit. However, white metal (or rather pewter) buffer heads are supplied which I was not keen on. I therefore purchased a set of turned steel buffers and castings from NMRS Models. The buffer heads were fine but the castings were inferior to the DJH produced ones! The modifications I made were so that the heads could be used with the DJH castings.

 

I'm still amazed that I managed to "con" you into fettling the three main castings in 2014 and was not surprised when you lost interest!

 

As I've had this kit for about 12 years I'm determined it will be finished this year. I'll take more photos as I progress and you can post them on this site.

 

Mick

[Rob Pulham]

Hi Gents,

 

After reading this I suddenly don't feel quite so bad about my 06 (8F) build stopping and starting.

[Jinty 52]

The Radiator Grills

 

I had hoped to show below a pictures of the two etches required to make a radiator grill. Unfortunately I've some how managed to delete one of them just before commencing this post!!!

 

A copy of the relevant instruction drawing and a photo of one of the etches will have to suffice.

 

 

 

The two etches are in fact identical. However, you will note that there is a space at the right hand side of the etch E40 where marked with an asterisk. The space would have appeared on the left hand side of the missing photo of E41! I angled each blade upwards at about 45 degrees using a steel ruler to get them started and then a Stanley blade to increase the angle, making sure that the blades on both etches match. E40 is then placed over E41 and soldered together. The result is as follows:

 

 

It should read E41 and E40 !!!

 

The grill was then soldered to the inside of the body and the process repeated for the other side.

 

 

The radiator is then positioned over the etch on the inside of the body casting. However, as I don't want this to receive a coating of body colour I intend to epoxy this in after painting. The horizontal "bar" that goes on the outside of the grill appears to be too short to attach to the body, so I made my own. (This appears to be a pivot point for the blades on the real thing and should be between the blades). You will see from the following pictures how this is fitted and will be fitted at the same time as the radiator.

 

 

 

 

Well that's all for now. The next task is the cooling fan and the mesh cover. I've already done most of this work but will leave that for my next post.

[PAD]

Nice work Mick.

Get your finger out. You need to finish it before Rob Pulham finishes his 06(8F)!

Cheers,

Peter

[Jinty 52]

I'm on it!!!

 

Here are the steps and ladders. I've added a couple of pins to the ladder to secure it to the body side.

 

 

I'm determined to finish it by the end of April so I can get started on either:

 

The Easy-Build Class 108 two car set, or,

 

The Engineer's inspection saloon or the Driving Brake Third from Side Lines.

 

I've had them for a few years too.

 

Better get moving on that 8F Rob!

 

Mick

[Jinty 52]

Cooling Fan assembly

 

As can be seen below, the fan assembly consists of three parts.

 

 

Each blade should be angled downwards as shown in the exploded diagram in the assembly instructions. As there is very little verbal guidance, close attention to the diagram is important.

I bent mine in accordance with a picture of the fan assembly on a 5 inch gauge model I located on the internet. As I write this I am looking at the assembly diagram, I see that it shows the blades to be bent the opposite way - arghh!!!!! Too late to go back now!!!

 

The blades are assembled one on top of the other but offset to create a 12 blade fan. I have seen models where the blades have been assembled in parallel to create a 6 blade fan.

 

 

The etch centre cover can then be attached

 

 

I used 179 degree solder to assemble the fan and added a 10BA screw underneath using a 145 degree solder. This is to make it easier to handle when painting it up. When final assembly takes place the screw will be shortened considerably. This is entirely optional. you can paint it just as well with it stuck to a piece of blue tack before finally attaching it to the fan housing!

 

 

Cooling Fan Cover

 

This comes as three etches. Unfortunately I made a mess of photographing them but the diagram below makes it clear what they look like before assembly. E31 and E32 are elliptical but the difference is only 2mm. E31 has 14 half etch holes around its circumference to represent the retaining bolts. No mention of this is made on the instruction diagram. I didn't fancy punching them out on such a fine etch and I decided to assemble it with the holes facing upwards and drill them out to take brass rivets available from Eileen's Emporium (Domehead Brass Rivet M0.5mm x 7mm).

 

 

 

 

The next picture was taken to illustrate the ellipse. The following one shows the three etches assembled. A little bit of remedial work was required to re-align E33.

 

 

 

The holes for the rivets had not yet been drilled out (0.5mm) at this stage. The whole assembly was then put through the rolling bars.

 

 

The final picture shows the cover with rivets added.

 

 

 

 

 

[Rob Pulham]

I'm on it!!!

 

 

Better get moving on that 8F Rob!

 

Mick

 

I'm on it too - I need to have it finished long before April because other parts arrived for the J6 today.

[PAD]

Hi,

Mick has pointed out  that I have spelt the word gauge wrong in the heading. Anybody know  if and how I can correct it?  

I don't want to look like the  dummy that I am!

 

Cheers,

Peter

[Rob Pulham]

Hi,

Mick has pointed out  that I have spelt the word gauge wrong in the heading. Anybody know  if and how I can correct it?  

I don't want to look like the  dummy that I am!

 

Cheers,

Peter

 

Hi Peter,

 

Go back to the first post and select edit and then use full editor and it will allow you to edit the title

Edited January 10, 2018 by Rob Pulham

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Perfect Rob.

 

Many thanks,

Peter

[Jinty 52]

Now that the cooling fan and cover are made up it's time to think about fixing them in place on the engine cover.

 

It quickly became apparent that a fair bit of fettling would be required on the inside of the engine cover and a little bit on the fan housing to get them to go together.

 

Out came the heavy duty files and the result is below.

 

 

The fan and fan housing are to be fitted permanently after the exterior has been painted. This is easily done by using superglue to hold the fan in place and epoxy resin to hold the fan housing in place. Epoxy resin allows time for the housing to be correctly aligned. (I personally wouldn't risk solder in case the heat damaged the paintwork).

 

However, I'd already decided that the fan would be bolted in and decided to bolt the fan housing on to the body. The following pictures show how I did it.

 

 

 

 

 

The fan housing was removed and drilled to take the 10 BA shaft on the fan, which was then bolted in place.

 

 

Finally the assembly was bolted back in place in the body.

 

 

Now to attach the grill to the body using the fan below as a guide for centring purposes. The leading and trailing edges of the aperture were tinned with low melt (70 degree) solder, and the grill was tinned with 145 degree solder, again at the leading and trailing edges. (the grill was constructed using 179 and 227 degree solder to ensure it wouldn't spring apart - unless I dwelled too long with the iron!

 

Once in place the grill was held down and heat applied with a 12 volt soldering iron, and here is the result;

 

 

Rob,

It looks like you will have the 8F finished before me, but I'll keep plugging away to encourage you. It's looking a very nice job by the way.

 

Mick

 

 

 

[Rob Pulham]

Cheers Mick,

 

I want to get it done because it's been haunting me for a few years but not at the expense of enjoying the journey this time.

 

I am most impressed at how clean and shiny you are keeping the whitemetal on this build. Although I am unlikely to build a diesel for my own use I have one in the pipeline for someone else.

[Jinty 52]

Thanks Rob,

 

I usually clean up after every little job and then move on. Peter does the same, but we certainly get through the glass fibre brushes! In this particular instance much of the soldering work has been done away from the main castings so far so cleaning up has been quick and easy.

 

A little more progress has been made today. I have been looking at the beading that surrounds the apertures for the radiator grills and was not too happy with the mouldings on my particular kit. Pictures of the real thing show what appears to be rivets on all four sides especially on the early versions. They seem to be absent completely from some later versions. My casting had a representation of most of the top ones and some of the lower ones, but nothing down the sides,  so using a picture of 20 210 shown in the Class 20 Profile in the January 1996 Modelling Railways Illustrated I decided to replicate them using Domehead  Brass Rivets - M0.4mm x 5mm available from Eileen's Emporium. This involved drilling out 20 x 0.4 mm holes on each side using an Archimedean pin vice. I managed this without breaking a single drill bit! I found that the best way to do this is to drill a little at a time, constantly withdrawing the drill, removing any clogging of the drill bit and adding a little oil into the hole before carrying on. The result is shown below:

 

 

The next job is to mount the door handles on the body sides. The castings supplied could be better. However, after a bit of light fettling I fitted them using superglue. I then burnished them with a three way nail buffer. For those that don't know, this is a glorified emery board with two abrasives on one side and a very fine abrasive on the other. I obtained mine from the local supermarket. Used in sequence they smooth the edges of the casting and polish it up. The results are shown below:

 

 

 

Well that's the progress for today.

 

Mick