Chris Craft 19ft 1940 Barrel Back – Dumas 1:8 (Part 6)

It’s past time for another post about the Chris Craft build. This activity was always intended as one to learn the new techniques required for marine models on. Because of that, it is effectively  pacing the Miss Severn build, and only getting attention when I need to practise or prototype something for that primary project.

The most recent activity has been around the deck fittings. Dumas insist on having them plated before they have been polished, so even though they are chromed the surface is very granular whereas it should be highly polished. Those that come with the Miss Severn kit are the same. Having tried to resurrect a number of them, I’ve come to the conclusion that it actually easier to make my own from scratch.

I’ve alread written about casting the bow fairlead and light in an earlier post. The fairlead is still awaiting plating, but I have got around to plating the bow light casting and fitting the lenses. Unlike the Miss Severn bow light, this one one isn’t functional but the lenses were made in exactly the same way. CAD model – 3D print – RTV mould – cast clear resin.

No ‘Chris Craft’ flag yet. I’m undecided on whether to use the kit’s or not. It isn’t very convincing, but I’m not sure I can do better.

The lenses are OK, but not quite as sharp as I’d like. There’s something about the clear resin I’m using I think. It’s not curing as it says it should. The surface is remaining tacky for days and only hardening when removed from the mould. I’m not sure what I’m doing wrong yet.
The eyelets come with the kit, but I have made some rings to attach the flag. I’ve tried to make the top of the flagstaff look a bit interesting. The wood has been stained with Liberon’s Georgian Mahogany spirit wood dye, airbrushed on.

The rear flagstaff and mounting base have also been completed in the same way. As well as recasting the mounting base, I also drilled out the reaward facing holes, as I think this functions as an engine bay vent too.

Both flagstaffs are removable and are secured with stainless steel pins while on the model.
Another bit of interest added at the top of the pole. The ‘light’ is self-adhesive aluminium foil wrapped around the pole prior to the plastic bead being slipped over it. The bead was given a good polish before fitting,
The newly cast and plated base with the vent holes drilled out. It looks alarmingly like a bird skull.

The rear flagstaff base is fitted to the engine cover by a 1mm brass peg glued into the base.

Other items to come in for attention recently are the lifting eyes. These have been made, polished, but not yet plated. As mentioned before I did try modifying the kit’s items but gave it best in the end, not least because I found they were subtly the wrong shape. The photo below shows the various stages from wooden mould, through rough casting, to finished and polished fitting awaiting plating. The half improved kit item is behind for reference.

Note the lower edge of the kit item’s tail. The pictures I’ve seen of real boats indicate it should be horizontal.
Making the lifting eye mould. One of the joys of making the masters in wood is that it neatly floats in the uncured RTV, so that achieving a half and half mould is relatively easy. 3D printed parts sink too far in so other arrangements are required.
More no expense spared casting technology.
Hot, <Robin Williams voice> Damn Hot! </Robin Williams voice> from the mould.
The same exercise was carried out for the engine bay handles and chocks.
I’ve made enough for 2 boats so that I have spares in the event of cock-ups.
I’m reasonably pleased with the finish considering these haven’t been plated yet. They are bare polished tin alloy in the picture.

The next item on the list is the horn. This is more complex and beyond both my carving capabilities and that of my 3D printer.

The kit’s horn is shown above.  Some real examples are shown below.

Antique Boat Sales (www.antiqueboatsales.com)

My CAD model of the horn. The trumpet is based on a simple 1/X curve for those interested. The 1:8 model is about 30mm (1 1/4″) long in real life.

As my printer isn’t good enough to handle an object like this so I exported the design as an .STL file and sent it off to some professional guys to get it printed for me. I did two versions, not being sure which would be the best method to adopt for casting. One is a complete assembly and one in three parts.

3D printed items.

The separate items are being used to make moulds as I type. The assembled model is awaiting a second print as the first had a flaw in the rim of the dome. You can see the problem below.

Dome with printing flaw on the left. How it should look on the right.

Hence, I’m awaiting new parts to continue…

The process of getting 3D parts professionally printed is something I want to get sorted and understood well. I’m intending to use the same idea to produce a scratch built engine for the Miss Severn model, and a few others I have in mind for the future.

8 thoughts on “Chris Craft 19ft 1940 Barrel Back – Dumas 1:8 (Part 6)”

  1. Wow again. Have you posted your casting techniques yet? Metal, sources, heating, pouring? It’s really clean and impressive. Your postsd are a balm to us all these difficult days–Thanks!

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    1. Yeah, I have. Back in Chris Chris Craft No.4.

      https://mbiqmodels.com/2018/11/05/chris-craft-19ft-1940-barrel-back-dumas-18-part-4/

      I’ve learned a lot since then though. One of the key things being how important the dusting with French chalk is to ensure the metal flows everywhere you want. I’ve also increased the gas escape routes in my moulds.

      Most of my casting materials come from Tiranti.

      https://tiranti.co.uk/product-category/casting/white-metal-tin-alloys/

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      1. Ah Tiranti! What a great place. I have visited when in London from the US last summer, and in year’s past. Very fond of that place! Thanks.

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      2. You’re ahead of me then. I’m strictly mail order.

        On the subject of casting temps, all I can say is don’t go too hot. If the surface of the liquid is going yellow it’s more than you need.

        I tend to let it just melt, then give it a bit more for luck! I did invest in an infrared temp gun, but have learned that they don’t do well on mirrors…

        I also make sure that I scrape the surface clean on the melt before pouring to remove slag. In fact making sure the melt is clear of inclusions is important I think. Handily they seem to readily stick together if you sweep an aluminium spatula through the liquid.

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  2. Your skills are an inspiration! I’ve been building my own Chris Craft Barrel Back over the last year and it’s nearing completion. Must admit I’ve incorporated a number of your ideas into my build. Examples are the cockpit dashboard, seats and rear hatch assembly. With retirement boat building has become a major hobby for me. I enjoy your blog and am inspired by your creativity and problem solving skills. Thank you!

    Liked by 1 person

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