Saturday, March 16, 2013

Starting The Project

Let's get this loco started.

A good chassis is the base for a good model. Extra time and care spent now will repay you with years of trouble free operation, especially with a steam locomotive.

Here are the two bags of bits that we need to take pieces from to begin our chassis. By referring to the instructions identify all the required parts. For our 35 class, we need both chassis halves, 4 etches which will be soldered in between the two chassis halves and 2 solid spacers machined from square bar. Part numbers, 136, 142, 139, 140x2, 141 and 138x2. 4xM2 screws are also required.identify and collect the needed parts.

Carefully remove parts from the etch to avoid bending or damaging them. Many methods have been offered at different times. Some use a knife and a block of wood, say use a small chisel against the block of wood. I have used both these methods but actually prefer a small pair of metal shears. Sometimes I even use a Dremel with a small work wheel.

Tip number 1.... Get yourself a container to store parts which are not immediately used. 

I like to compare the two chassis halves to each other, to ensure that they are in fact the same. Put them back to back and see that all the holes and such line up together.

Some chassis use a bearing soldered in for the axles. This one uses a bearing which will be trapped by a cover plate. A much better arrangement I think, especially for future servicing or replacement of parts.Use care and work slowly with a file until they just fit.  

There will be some cleaning up to do. You can use jeweler's files to do this. Make sure there is no distortion around the check outs for the axle bearings from the manufacturing process. A gentle tap with a small hammer will fix that. Do not use heavy blows as this will do more damage than good. Carefully and slowly file just enough material so that the bearings fit just snugly

Take the solid spreaders and clean any burrs around the screw holes in the ends with a drill bigger than the hole. I generally use about a 1/8" drill mounted in a file handle. This will firstly allow the chassis to sit flush against the spreader and allow the screw to travel into the spreader properly. The base of the screw may not initially travel fully into the spreader. Using your 1/8" drill again, take a little more material from the screw hole until it does. Just a few turns will do.

By referring to the instructions, identify right and left sides, using the spreaders, (138), join the two halves to begin construction. If the screw holes in the etch are tight, open them with a small rat tail file or a cutting broach. The forward etch spreader, has a shallow bend. you can generally do this with no tools, but a pair of smooth jawed plyers may help. I use a Hold and Fold bender, available from Gwydir Valley Models, but it is not really necessary. It does however make the job easier and often much neater. Bend a little at a time until it sits in the rebates in the chassis. Back off one screw and fit it. Do the screw up again. fit the other three now the same way. The rear etch spreader has a small terminal attached. You can add a short length of wire before painting, or simply tin the tag and scrape the paint off later, when you fit the motor and gear box.

Page 6 of the instructions shows the motor and gearbox being fitted at this point, along with the wheels and axles. I do not do this. In fact the motor and gearbox are always fitted last by me, or at least after the chassis is rolling sweetly and is painted. The steel axles will not take kindly to being washed and a far better paint job can be achieved without them fitted.

What we will do though, is test fit the wheels and axles and see that everything is square. Once happy, we can solder this much together.

I use a Dick Smith T-2200 set to approximately 400C for this job, with LACO Regular Soldering Flux Cream, available at Reece Plumbing and Carr's 145 or 188 solder. 179 could also be used. You could use Carr's Green label Flux, Baker's or a number of others. I like Laco as it is a cream and easy to apply. It is also not toxic and non corrosive. Don't forget to clean up. I use Simple Green All Purpose Cleaner which I obtain at Bunnings.

If you have any questions, join Soldering Techniques Facebook page. Hopefully we can sort your query for you.
Til next time, keep the irons hot.....                                            Macca.