Thursday, June 30, 2022

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!

Tuesday, June 28, 2022

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

Saturday, June 25, 2022


Having got the chassis for Ivor to the stage where it rolls along the track, I wasn't entirely sure what to tackle next. This is complicated slightly because the step by step instructions (well series of photographs) don't include some elements of the build. Specifically they make no mention of motorising the model. This is because the kit doesn't contain a gearbox. The schematic view in the instructions suggests fitting a "Mashima 1015 or equivalent motor" vertically between the axles driving the front axle via a simple gearbox containing a single worm/gear arrangement. Unfortunately it doesn't make any suggestions as to where you might source such a gearbox.

After designing my own wheels I didn't fancy trying to design a gearbox myself (although I think I could probably have done so) so went hunting for an easy option I could buy. In the end found a gearbox from High Level Kits which seemed to be a good fit: specifically the HiFlier.
The photo shows the parts laid out ready for construction. As you might be able to spot this is a sligtly more complex gearbox than the one I described being shown in the instructions, and will place the motor horizontally inside the boiler instead of vertically. Given the good diagrams and measurements provided by High Level Kits for their gearboxes I'm fairly certain it should all fit, but it seemed sensible to make it up first so that if I do need to modify the body in anyway I can do that while I build it rather than afterwards.

So far all I've done is gently open out the holes in the etch to take the bearings and shafts, and gently reamed the bearings and final gear to fit the 1/8" axle I'm using -- the parts are designed for 1/8" axles but also point out that the parts are all designed as "finish-to-fit" so they all need opening out slightly to give a nice fit rather than being sloppy. So far so good, next step will be assembly and testing with the Mashima motor I bought (can't remember the size I went for but will measure it for a follow up post).

Friday, June 17, 2022

It Rolls!

So after the apparent success of turning one working axle I had a go at making a second. Amazingly all went to plan, and more importantly they fit next to each other in the chassis.
As you can see even with the smaller wheels than the instructions suggested there isn't a huge amount of clearance between the two axles.
More importantly they also fit properly, albeit only just, within the splashers and it rolls!

Thursday, June 16, 2022

Two Wheels, One Axle

Having messed up the first attempt at axle making I spent some actual time thinking through the process a bit and came up with a plan. This essentially involved keeping a long piece of 1/8" axle steel nice and straight on the lathe using a fixed steady (a recent purcahse and this is the first time I've tried it) and then lightly makring the sections for an axle on the rod using the cutting tool. I could then cut the axle from the rod and face and turn with just the end protruding from the collet chuck. Unfortunately I forgot to take any photos while marking up the axles, but here you can see the end result (after I roughly cut the two sections from the rod).
So if you look at those you can see I roughly cut them from the rod, so from each end I need to face off at the first line, and then turn down the rod between the first and second line. This will give me a stepped axle which should enforce the correct back-to-back measurement; although each end needs turning down differently to match the insulated and uninsulated wheels.

So far I've only managed to do one axle but......
And just to prove that they both fit on track and roll

And you have no idea just how happy I am with that!

Monday, June 13, 2022

Actual Progress

Whilst it looked as if the new wheels would indeed fit inside Ivor there was only one way to find out.... turn some axles and try fitting them.

I ended up messing up the axles, both sorting the back-to-back measurement and reducing the diameter slightly too far but....
To my eye that looks pretty good but.....
there is still very little clearance when viewed from beneath. I'd already bent the hidden part of the splashers when trying to fit the original wheels and I would have still hadto do the same for these wheels which just shows how little space there is and still brings into question how anyone is meant to build the kit given the instructions.

So next step is to re-think how to turn the stepped axles to get them the right size, but this small step feels like real progress, so I'm happy.

Friday, June 10, 2022

Standing Still

So, almost four years since everything went wrong (the first time) with the build of Ivor I'm basically back to where I was before.
After a little more work today I now have four wheels with crank pins, two of which have been fitted with insulating bushes. In otherwords exactly where I was before I found that the original wheels didn't fit the chassis.

I took the same approach as last time, i.e. the simple approach, and "borrowed" the insulating bushes from a set of Hornby disc wheels. The crank pins are 14BA bolts, which will be trimmed to length later. In fact they are just loosly fitted at the moment as I decided the next step (turning axles) would be easier if I can check them against the wheels without the crank pins in the way.

No idea when I'll get to try turning the axles but this does at least seem like progress even if I'm no closer to a completed model than I was back in 2018.

Thursday, June 9, 2022

0.2mm from Success

I am never ever ever ever making wheels again. As you can probably guess the next step in the long running saga of building Ivor didn't go entirely as planned.

Having remembered from last time that it was hard work profiling the wheels I set everything up carefully and then turned the first wheel. Just as last time it was a slow process. I'm not sure if that's because the tool isn't as sharp as it might be, or if the brass Shapeways uses isn't ideal for turning, or if the Unimat 3 is a little underpowered for the job, but you have to take very very light cuts and I stopped frequently things cool slightly (otherwise the cutting tool gets so hot the oil smokes). Anway slow and steady got me to a nicely profiled 20mm wheel.

After the success of the first wheel, I made a coffee, and then profiled the second wheel. Then I made another coffee and profiled the third wheel. Then I made another coffee and started on the fourth and final wheel.

I took the final wheel nice and slowly and was just 0.2mm away from a completed wheel (i.e. I needed to advance the cross slide by just 0.1mm) when the threaded rod of the wheel holding tool sheared off and the knurled knob when flying across the room; fortunately away from me. So that's the second time I've had that tool fail now and I've no idea if it's just a bad design or something I'm doing wrong. Either way I was now just 0.2mm shy of four completed wheels which was rather frustrating.
The rod had snapped very close to the wheel so there wasn't enough left to try and screw anything on to the remaining stub. In the end I used the live centre to push the fixing against the wheel. It wasn't pretty and the wheel did slip a couple of times but it stayed straight and allowed me to reduce the diameter by the final 0.2mm.
Fortunately I think none of the remaining work to use the wheels would need the wheel holding tool (they just need holding in the step chucks) so hopefully I can continue on with the build of Ivor, but I don't think I'll ever try making my own wheels again.

Wednesday, June 8, 2022

Signs of Life

Given how sporadic, or none existant, posts have been over the last year or so I've no idea if anyone is still reading this blog, but believe it or not there are signs of some modelling happening!

Some of you may remember that for Christmas all the way back in 2016 I was bought a kit for building an OO guage model of Ivor the Engine. This was a nice present and the first from my then newly born son, Toby. Well Toby, is now five and a half, and I now have a second son, Thomas, who is 14 months old. What I don't have though is a completed model of Ivor the Engine.

The last time I blogged about the kit was almost four years ago in August of 2018 when everything had gone horribly wrong: I'd broken the wheel holding tool for my lathe and the wheels I had made, although correct to the instructions, didn't fit in the model. At that point I put the kit away in a box, never expecting it to be four years before it would appear again.

So where are we know? Well, fohrmann-WERKZEUGE were very helpful and sold me replacement parts for the wheel holding tool which saved me quite a bit of money over buying a complete replacement. Of course any money saved was then spent on having new set of wheels produced. These are essentially they same as last time (lost wax brass castings using 3D printed waxes all done through Shapeways) albeit slightly smaller to solve the main issue that arose with the originals.
So far all I've done is separate the wheels and drill out the axle hole to 2mm, but as you can see roughly placing them against the chassis suggests that they will fit this time, especially given they will be fractionally smaller once I've turned them on the lathe to properly profile the edge and add the flange.

I've no idea when I'll get to do more work on the wheels but hopefully it won't take four years before there is more to report.