Thursday, August 9, 2018

Is It Just Me?

I'm beginning to wonder if either I'm drawn to kits with design issues, or if I'm just not very good at building kits accurately.

Having finally battled all that was weird and wonderful with the Canopus kit I thought the kit for Ivor the Engine looked quite a bit easier. Okay I made life more complex for myself by deciding to make my own wheels, but in itself that shouldn't affect the design of the kit. Having built up the chassis (fairly easily I may add) I've now made a start on the body, which in turn has led me to discover a couple of, potentially, catastrophic issues.

So far I've formed the splashers and attached them to the footplate, which also includes the front buffer beam. What you can see, in the photo above, is the chassis slotted into the footplate containing one of my wheels on the test axle I turned.

The first problem was that the chassis wouldn't fit into the footplate as it was slightly two long. After a lot of careful filing I've made it fit and the fixing holes appear to line up pretty well. The second problem though is that the chassis wouldn't fit with the wheels attached. In the photos you can see that I've bent the front of the splashers that are inside the model to get the wheel to fit, and it still feels like it's catching when I turn the wheel. I think the solution to this will be to cut away the extra metal, as it can't be seen once the model is assembled, and isn't needed to keep the chassis central once the screws are in place. Before doing that though I wanted to figure out why the wheels didn't fit.

Looking again at the instructions, which are just a sequence of photos with no textual description, I think all the photos show the 7mm version of the kit and not the 4mm version. It's difficult to be sure as most of the photos don't include anything to give a sense of scale, but they all seem to have previously appeared in this RMWeb thread discussing the build of the 7mm kit. The one page that is clearly for 4mm gives the size of the finished model and is the place where it suggests to use Ultrscale OR Markits 5'3" 16 spoke wheels with 8 spokes removed. As I was making my own wheels I took the 5'3" as a starting point and produced 21mm wheels (5.25*4). As I made the wheels to RP25-110 the flange depth is 0.025" or 0.635 giving a total wheel diameter of 22.27mm. The instruction page also states that the wheelbase is 22.50mm which as far as I'm concerned is just a bit too close to 22.27mm for comfort. In fact placing two wheels against the chassis I'm not sure they will fit without the flanges touching!

Reading through the thread on RMWeb I did notice that the suggested wheels in 7mm scale are actually 5'2" diameter not 5'3". I know that would only change their diameter by a small amount (they would be 21.94mm over the flanges) but that extra clearance would probably be great for both the splashers and between the wheels.

I can't be sure that the flanges will touch until I turn up a second axle (I've just the test axle so far) but if they do then I guess I'm going to have to try and reduce them in size slightly which is a real pain, although it might mean I can remove the slight flats on the flange from removing the wheels from the sprue. Mind you that isn't really the point; if I'm following the instructions for a kit am I just picking kits with issues, or am I just not assembling them accurately enough?

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