From the November 1983 edition of "Scale Trains" magazine (now "Model Trains International"). Reproduced by kind permission of the editor and copyright owner, Chris Ellis.
In the field of miniature motive power, the Class 33 diesel is undoubtedly one of Lima's outstanding successes, and certainly the longest running production model ... being first introduced in 1974 in 3.5mm scale, to be quickly followed by the 00 and 0 gauge versions. It is a loco which responds readily to upgrading....
Despite a good overall accuracy in basic dimensions, the width of the 3.5mm scale HO gauge version is unfortunately oversized by 2mm. Possibly, this error was created deliberately in order to provide sufficient internal clearance to the motor bogie so that sharp 'toy' curves could be negotiated. But, if one regards a track radius of about 3 feet as a minimum, then there is no reason why the body width should not be reduced to the correct dimension.
This piece of surgery is not as severe or as difficult as it sounds and should be well within the capabilities of any modeller who has had a certain amount of experience in upgrading proprietary items.
Dismantle the loco by prising off the body at the four retaining lugs, and then remove the motor bogie from the chassis by undoing the two screws holding the wheel keeper plate in position. The other bogie is released by sliding off the spade terminal from the centre spigot. The chassis moulding is then sawn down the middle and the cut edges filed smooth until a total of 2mm in width has been removed. During this procedure it is essential that both edges are kept perfectly straight and that continuous contact is made when the two halves are joined again. Before welding together with liquid cement, remove the buffers and finally strengthen the join in the headstocks with strips of Plastikard strategically positioned.
So far the work has been straightforward but more care is needed with the body itself. First of all, the large circular grille in the roof has to be removed intact. This is best undertaken by drilling a series of tiny holes around the periphery using a 0.4mm or 0.5mm (No 78 or No 75) drill, and then linking up the holes with a piercing saw fitted with the finest toothed blade. The object is to remove the grille with the minimum loss of body material.
With this accomplished, the body can now be cut into two - again using a piercing saw but fitted with coarser teeth. At each end of the roof the single cut divides into two - going along each side of the small end grilles and down through the middle of the frame uprights on either side of the central front cab window. These cuts and the resulting pieces are shown in the photos.
The re-assembly needs care and it is wise to make haste slowly. First, file the edges of the long straight cut to reduce the body width by the required 2mm making sure (as in the case of the chassis frame) that the edges are perfectly straight and making close contact all the way along. Check for any minute gaps by holding the two halves together against a bright light source.
Before attempting to deal with the small end pieces, it is necessary to weld the two body halves together - again using liquid cement. Some difficulty may be experienced at this stage, so shape up a rectangular block of wood (lumps of balsa from those cheap bargain packs are ideal) to the exact internal body width. This packing will act as a support - keeping the two halves square and at the correct separation at the bottom of the body sides. Leave for 24 hours for the weld to thoroughly dry out and harden.
Now comes the tricky bit ... fitting the end pieces. Use needle files for this, remembering that you have four surfaces on which to work. Go slowly and reshape by trial and error, endeavouring to obtain as perfect a fit as possible. The same advice applies to the replacing of the circular roof grille but don't worry unduly if you have to resort to the use of a body filler, such as Milliput.
With major surgery completed the remaining tasks are cosmetic improvements. One essential job is fitting the characteristic large-headed buffers and, for the HO model, brass round coach type from King's Cross Models are correct in diameter, even if fractionally too long in the shank. But, when the four corner steps above them are fitted, this small error is unnoticeable. However, the buffer beam needs modifying as it is too shallow in height by 1.5mm - so build this up with Plastikard. As I was fitting scale couplers there is room for quite a collection of vacuum and air pipes, ETH connections, etc., to be attached to the beam, but the amount of detail which can be included depends largely upon the type of couplings. For appearance, I prefer screw-type on locos and use the PC etched ones as they are scale in size and allow space for the fitting of all the buffer beam paraphernalia, if desired.
The cab steps already moulded on the bogie frames can, with advantage, be increased in depth by building up with scraps of Plastikard glued in position, while the small running board step can be added in a like manner. The lifting lugs are also missing in the original model and a representation of these can be included. Improvements to the body include separate handrails and lamp irons. For the former I prefer iron wire (which responds better to bending) but if the conventional nickel silver wire is used, then temper it slightly beforehand. After fitting, the contour can be (prototypically) flattened by filing and then polished. Lamp irons can be cut-down office staples, built up from wire or, better still, use the commercial etched products. Flush-glazing is really essential but time consuming as there are 26 windows! - and, for this, Perspex is preferable as it is not affected by styrene solvent. Windscreen wipers are from the Crownline range. Finally, the four openings on the body sides are filled in with small rectangles of thin Plastikard - but still allowing the fixing lugs to snap into position.
Naturally, all these modifications will have ruined the original paint finish so, after filling any slight imperfections with Milliput (or similar) and rubbing down to a perfect surface, the loco is given a respray ... in my case with Humbrol BR blue. The yellow end panels can be brush painted, and all underframe details given a bit of weathering with a mixture of Humbrol matt 66 (olive drab) and matt 29 (dark earth). Final touches are the double-arrow logos and number transfers from PC Models sheet 15, while the catenary warning flashes are hand painted in my case though several transfer sheets, such as those by Kemco, Kingprint, and SMS include them.
After removing the body by unclipping the four retaining lugs, dismantle the chassis. The motor bogie is removed
by undoing the two screws holding the wheel keeper plate. The unpowered bogie drops out after the spade terminal
is removed from the shank.
The surgery starts! Cut the chassis frame down the middle and file both surfaces straight and smooth - reducing
the overall width by 2mm then weld together. Remove buffers, strengthen buffer beam and increase vertical depth
by at least 1.5mm. Remove couplings from bogie frames.
First modifications to the body. Remove large circular grille by drilling small holes around the periphery and
join up with a fine-toothed piercing saw.
Body width is now reduced by 2mm by first slitting into two halves. Make a single cut along the roof centre but
divide the cut into two at each end ... each cut going down on either side of the small end grilles and on either
side of the centre cab window. Use a piercing saw for this piece of surgery.
Next, file both surfaces of the centre line cut until a total of 2mm has been removed, and a perfect fit obtained.
Weld together with liquid cement. An internal block of balsa wood cut to the correct internal width will hold both
parts of the body square and at the right separation until the join hardens. Then carefully smooth and shape the
edges of the end gap, and those of the centre window piece until a perfect fit is obtained. Cement into place.
Similar treatment is given to the circular grille and grille aperture until snug fit is achieved. A little body
filler may be necessary to cover up any slight imperfections. Again this same procedure is followed.
This 'before and after' photo shows how the roof join becomes inconspicuous with careful work and a respray. The
upper model is in its original condition; the lower model has had the body width reduced by the 2mm as described.
Cosmetic improvements can now begin. Here, the new buffers, brake, air and heating pipes and cables are attached
to the built-up buffer beam, and screw couplings installed. Guard irons are fitted to the bogies and the side steps
increased in depth. The lifting lugs unfortunately have to be attached to the outside of the solebars - due to
insufficient clearance between these and the bogie frames. Lamp irons and handrails already in position but windows
yet to be flush-glazed.
The completed model straight from the paint shops and ready for service. Using scale couplers instead of tension-locks
enables all the actual piping on the buffer beam to be duplicated in a realistic way. Note also improved effect
of the flush windows in the cab, though this is a difficult and riddling job, best omitted if you are not confident
of success.
Closer view of the end of the finished HO Lima model showing the improvements and additional detail given to the
basic Lima product. What was originally little more than a 'toy' has now become a presentable scale model.
....for anyone taken by the various articles on British HO, then the Lima Class 33 is a cheap beginning. It is long out of production but can be picked up usually at very low second-hand prices. As the pictures show, however, after the work is done the model is transformed to a realistic replica of the real thing. It is the perfect companion in period with Roco's '08' diesel shunter and Fleischmann's HO 'Warship' and if you want to try British HO for yourself the Lima Class 33 is a good start.