Gearbox Testing

Having sorted out how to keep the gearbox in position the next step was to finish assembling it. This involved cutting two shafts for the intermediary gears and then simply slotting all the parts into place. With that done I had this...

The only downside is that one of the screws to affix the motor is not accessiable through the gear train. Fortunately it's possible to fit the screws to the motor then fit. As long as the bottom screw is as tight as possible while still fitting then everything is held nicely in place.

Of course the important question is does it actually work. Well...

We're Going To Need A Bigger Hole

As expected once I'd bolted the motor to the gearbox there was no way it would fit through the hole in the footplate, at least not when the gearbox was mounted on the axle as it was impossible to get the angle right, even with the gearbox free to rotate around the axle.

The solution was to use a jewllers piercing saw to lengthen the hole in the footplate by about 9mm at which point I could slide the parts together nicely. This was possible even with the gearbox held vertically with some masking tape; I still need to sort a more permanent way of holding it in place.

I know it's not the best of photos but hopefully you can see that the hole is longer now. You can also see that the motor shaft will certainly need shortening as currently it would protrude into the cab which would stop me fitting the body and chassis together. That means that as I expected a flywheel is probably out of the questions but we shall see exactly how much shorter it needs to be, once I've built the cab.

Just to prove that things do fit, here is a terrible video of me slotting the footplate over the motor and into place: it can't be that bad if I managed it one handed while holding the phone to film with the other hand!

You're Not Thinking Fourth Dimensionally

Having mentioned in a previous post that I'd carefully measured to ensure that the gerbox and motor would fit, I've now discovered a slight flaw in the plan.

That is the drawing I made which combines the plan of the loco from the instructions, the gearbox, and space for a nice chunky Mashima 1620 (16mm x 20mm) motor. As you can see it all fits nicely. Unfortunately not only was I not thinking in three dimensions, I wasn't fully thinking in four dimensions either.

There was nothing wrong with my planning and I could build the gearbox and the motor will fit inside the boiler just as shown. The problem is that I didn't consider how I would actually get from assembling the chassis with the gearbox and motor to the point where the body was fitted.

Yes, I'd checked that the gearbox would fit between the frames but the mounting lugs for the motor are wider than the gearbox. This means whilst I could assemble the chassis with the gearbox in place it would never fit through the hole in the footplate so I wouldn't be able to slot the body on. Fortunately the gearbox has two mounting points, so I could remove the lugs and it would fit through the chassis.

Except of course that the motor is also way too wide to fit through the chassis; in fact to make it fit I'd have had to cut off the rear of the splashers and left a much weaker chassis. Fortunately I have a Mashima 1215 motor in stock which will mount to the gear box and fit through the hole in the footplate... at least it will on an angle. I need to bolt it to the gearbox first and see if it will slide in or if I will still need to lengthen the hole slightly. It's a double shafted motor and while a flywheel would be nice I think I'll need to trim the extra shaft down to help fitting it in. We shall see.

Oh and I still need to work out how to keep the gearbox vertical as currently it will spin freely on the axle. Of course not being part of the kit there are no nice mounting brackets, but I think I have a plan to solve that problem