Friday, August 21, 2020

Yet More Details

As at least one person spotted the sandboxes in the previous post are designed to fit on a Simplex locomotive. My original test print was designed mostly to check the shape and to see if the hinge would work. The next step was to finish the lids with the details seen on the real thing.

There appears to be two common types of lid, one showing the Simplex logo and one giving the company name, although I've yet to work out if there was any pattern to which was fitted or if it was pot luck. Looking at photos some have one of each (you can usually only see the front ones as the rear ones are often in shadow inside the cab) and some have two of the Motor Rail Ltd version. I think, now I've done the design work for both, that I'll go with one of each.

I received a few other comments about sandboxes, mostly people saying that they often contain anything but sand. Apparently they are a good place to store spare coupling pins or the starting handle. Also it's not unheard of to open one only to find a mouse nest.

Okay, so I'm insane, but the idea of a mouse inside one of them was too much to resist. Fortunately I didn't have to do much to achieve this as I found a nice model of a mouse on Thingiverse which I scaled down and printed. Because it was so small I printed it sat on a fake floor that would just slot into one of the printed sandboxes.

And with that I think the sandboxes are now complete.

Thursday, August 20, 2020

Too Many Details?

I've heard people suggest that the larger modelling scales are easier as the pieces are larger and easier to see. I really don't think this is true. In my experience, and I've talked about this before, what tends to happen is that as the scale goes up you end up modelling smaller details that wouldn't be visible or possible in the smaller scales. I'm fairly certain that there should be a limit to this though, for my sanity if nothing else, but I'm still not sure where the line should be drawn.

Whilst I may not know where the line between sensible and ridiculous should be drawn, I think I've got quite close with the latest bit of detail work. I'm slowly gathering parts together to complement a 16mm scale kit I'm going to build and one of the kit parts I wanted to replace was the sandboxes. They aren't a particularly complex shape and I have prototype drawings so it was easy enough to produce some using my 3D printer.

So far so sane.... except....

Yes, I designed them so that the hinge would work, the lids would open, and they could actually hold sand. Now my problem is that I need to find some finer sand, but have I finally gone insane or is this a perfectly acceptable level of detail?

Tuesday, August 18, 2020

10HP Baguley: Back a Few Steps

I finished the previous post on the 10HP Baguley by saying

In theory the next step should be adding a little filler and cleaning up all the joints before painting. Oh if life were only that simple!
which was because I already knew what happened next...

It turns out that when I originally soldered the cab back on, I'd not done it very well. Having trial fitted the chassis into the model I noticed that the back wall was no longer vertical. While trying to correct this it fell off and for some reason the floor came loose too. I took the photo after cleaning up all the parts ready ro reassemble everything.

Rather than trying, and probably failing, to solder the rear wall on again I instead opted to use some two part expoxy. I started by using the epoxy to fix the floor into the right place as this gave a much bigger contact patch to then make sure the rear wall was fully attached. I also decided to change the approach to couplings and so cut off the Greenwich couplings while the model was in pieces.

Once everything was back together it was time to start applying some filler and that brings us up to date. It's been about a month since I added the filler and I've still not got around to sanding it back as I've been distracted by other things. Hopefully I'll get back to it soon and then I can move on to painting it.

Sunday, August 2, 2020

Spot The Difference

Alongside building the tiny OO9 model of the 10hp Baguley I've been looking through the parts for a much larger 16mm scale kit I'm going to build shortly. I'm not intending to give any hints as to what the kit builds into as yet, but instead I want to talk about bolt detail.

The kit is mostly laser cur MDF parts and the bolt detail (which is quite prominent) on the prototype is represented by circles etched into the surface of the part. Clearly this doesn't give any relief meaning that the details will mostly disappear under a layer of paint. Now there are obviously many ways you could add more detail. Some people use dots of glue, others use brass rivets, and you can of course buy plastic nuts and bolts that can be glued in place. All of those are probably easier than what I choose to do, but then I own a 3D printer.

Whilst many of the parts are too complex to replicate in their entirety and will need individual bolts adding as details, there are four pieces that fit at the corners of the chassis. These are just 18mm by 10mm and have five bolts on each. These seemed like a sensible starting point to check things like the size of the bolt head etc.

It didn't take long to draw these up and print out some test pieces. The first print I made is on the left. I printed this at the normal settings I use, which means each layer of the print is 0.05mm thick. Unfortunately as you can see (especially if you click on the image for a full size version) the layering is very pronounced on each of the bolts and it is very clear that they are made from multiple layers. To the naked eye the layering is less obvious but I fear it would be highlighted by painting and weathering.

So the next print I did is the one on the right, which was printed using layers just 0.02mm thick. The layering is still just about visible in the photos but I can't see it with just my eyes. The problem of course is that printing at 0.02mm instead of 0.05mm takes a lot longer. On a piece this small, just 2.175mm thick, the print time is increaed from roughly 12 minutes to around 27 minutes. While that's not a huge problem, if I was printing a much bigger model the difference would get quite significant.

I was especially annoyed with the longer print time in this case as the 0.05mm layers are perfectly acceptable for the main rectangular piece which takes up most of the depth. When printed at 0.05mm there are 43 layers in total with 32 of them being for the slab and 11 for the bolt heads. When we print the same piece with 0.02mm layers then there are 109 layers with 80 for the slab and 29 for the bolts.

Some of you may remember that back in April of last year, I discovered that the layer height specified in the files the printer uses is actually ignored and each layer is instead given it's absolute position above the bottom of the resin vat. On that occassion I used this to essentially double expose a single layer of the print in order to improve the result. Having moved on to using a different resin (specifically the Elegoo water washable black resin) I've not needed to continue using this trick, but I decided that the use of absolute positioning rather than layer thickness meant I might be able to speed up printing parts like these.

So I took the two files I'd produced and merged them. This resulted in a file with 61 layers where the first 32 layers had a thickness of 0.05mm and the final 29 layers had a thickness of 0.02mm. It took roughly 16 minutes for this file to print and the result is in the middle. Even under a magnifying glass this print is indestinguishable from the one on the right where all the layers were printed at 0.02mm but took ten minutes less time to print. I'm calling this a success.

The same trick should make it quicker to print some other pieces in the future where I only care about the layer thickness in certain areas of the model. For instance, any model printed with supports doesn't need the supports printing at thinner layer thickness, so the print time could be reduced by using 0.05mm for the supports and 0.02mm for the first layer of model upwards.

Sunday, July 26, 2020

10HP Baguley: Step 7 (and Inadvertently Step 8)

So in theory we are now getting very close to the end of the instructions. As you can tell though given the gap since the last post in this sequence, not only have I been very busy with work, but things didn't entirely go to plan. Anyway here is the text of step 7 from the instruction sheet.

Fix the bonnet into place – in order for the front of the bonnet to sit flush with the front buffer beam, some material may have to be removed from the back of the tank where it fixes against the cab and the locating ‘pips’ into the running plate at the front of the bonnet may also need adjustment. Once the adhesive has cured/solder cooled, file back the locating pegs flush. Fix the sandboxes into place.
The bonnet is a whitemetal casting and usually I find these really annoying as by the time I've bought a kit the moulds are old and the parts need a lot of cleaning up. Of course with this being a new kit this isn't the case and the quality of the castings is superb. Just look at the detail and how square and clean the edges are... and yes this is before I did anything to the casting.

I didn't have to do much to the casting at all. The only thing I found was that the locating pins were a little big for the holes in the etched parts, but this was easily solved by opening up the holes ever so slightly and then the bonnet just dropped in and fitted perfectly.

As with the whitemetal casting used as part of the cab floor I choose to superglue it into place rahter than risk damaging it by trying to solder it. As you can see I couldn't resist fitting the chassis to check how the whole model was looking.

The next step was to fir the sandboxes which are also nice whitemetal castings. As with the bonnet I just had to open up the holes in the etch ever so slightly for them to just drop right into place.

Unfortunately after gluing them to the footplate I spotted one small problem. They overhang the hole in the footplate which means that the chassis no longer fits. I can't see that I did anything wrong fitting these so I'm not quite sure how this happened.

Either way a little bit of careful filing and I'd reduced their depth enough for the chassis to fit back inside the body.

By making sure the chassis fits it turns out that I'd also inadvertently completed step 8 as well as that reads

Gently offer up the chassis into the body, there is limited clearance and this will be a touch fiddly making sure the motor leads do not get trapped by the running plate. It must be noted that the 'live' side frames will be in close proximity to the body which could potentially cause a short. However, painting the body to form a good insulation should eliminate the issue.
Given how tight a fit everything is I'm absolutely certain that the body will be shorting out the chassis at this point so I have not tried running it yet, and won't until it's painted to avoid doing any damage.

In theory the next step should be adding a little filler and cleaning up all the joints before painting. Oh if life were only that simple!

Wednesday, July 22, 2020

Mix and Match

As you may remember from a previous post, my son quite likes his Duplo and even uses it to build locomotives and carriages. What I don't think I've mentioned before is the large collection of wooden railway stuff he's also built up.

It all started when he was given this starter set as a present on his first birthday. There are quite a few different brands of wooden railway, most of which all use the same standards and so can be used together. That means the collection has expended rapidly with sets and pieces from Bigjigs, BRIO, John Lewis (although their range seems to have been discontinued), and a few of the wooden Thomas locomotives; after all we definitely needed a Toby the Tram engine!

As you can see with all these bits the layouts he can build (or he gets us to build) can get quite large and complex. One problem, that occurs more frequently that you might expect, is that you end up with an almost perfect layout but where you end up trying to join either two male or two female ends together. We do have some short pieces that do this, but because of the standard lengths of the track pieces often they won't fit. When you have two male ends to fit together there is no alternative to a piece of track with two female ends, but when you want to join two female ends there is another solution. You could just have a very short pin with two male ends without the need for it to actually have any track, and hence it will have no length when fitted but will hold the two track pieces together.

Given that it must be a fairly common problem for everyone rather than designing something myself I had a quick look on Thingiverse to see if anyone else had already done the hard work for me. It turned out they had so I just downloaded the model and printed a bunch out on my resin printer.

As you can see the connector pieces weren't the only thing I printed. While hunting for the connector I came across an even more interesting piece that allows you to use Duplo to lift up the track meaning we could build longer raised sections than before, which Toby thought was a brilliant idea.

Whilst I love being able to experiment with new models quickly on the resin printer it is exceptionally great for parts like this. I'm sure if they were available commercially they would cost a lot more than the cost of the resin I used. Plus rather than waiting for them to be delivered I'd printed all of those within about three hours of starting (I did two print runs as not all of that would fit in the printer in one go). They were all printed flat on the build plate as well so the only clean up was washing off the excess resin.

Monday, July 6, 2020

10HP Baguley: Step 6

Moving on to step 6 and we continue building up the cab area

Fix the cab floor to the white metal plinth making sure the planking detail is uppermost, carefully making sure the two parts are aligned properly as you may have issues getting into the cab a little later! Drill out the holes for the brake column and gearbox controls, the brake column is formed with a piece of 0.3mm wire and wheel, gearbox controls are formed from 2 lengths of 0.3mm. Now fix this sub assembly into place in the cab.
Gluing the two parts together was easy enough; there is no way I'm going to risk soldering white metal parts given the tools and skills I have. I then drilled out the holes (using a 0.4mm drill as I couldn't find my 0.3mm drill bits).

I did, however, solder the brake wheel to the 0.3mm diameter wire as I tend to find that soldering wheels to wire gives a much longer lasting join than using glue.

I trimmed the wire to length having test fitted the floor into the cab. I've deviated from the instructions (again) as I'm not permanently fitting the brake column or gearbox levers at this point as they'll by a nightmare to paint in situ.

Once I was happy that the floor fitted level inside the cab and that I could fit the brake column into the hole, I then glued the floor in place.

And with that done there are just two steps of the instructions left, excluding painting of course.