johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment. I read every comment and respond to most.

Tag: Painting model cannon

Assembly Modules

First, I have decided to NOT rivet the final joins of the chassis. Instead I am using dome head stainless steel bolts and nuts. The main reason is that the other end of the rivets are in impossibly small (for me) cavities and spaces, and I could predict that the final riveting result would be horrible. Even using threaded rivets would be incredibly difficult. This decision does cause me to reflect on the 1866 cannon builders who managed such perfect results with red hot rivets in confined spaces, and again, to be awed.

As you can see, the bolt heads are same shape and size as the 2mm copper rivets. My intention was to paint the rivets and the bolts (after filling the hex holes) and then they would be virtually indistinguishable. However, that plan was blown out of the water by SWMBO. (read on).
The copper rivets and stainless bolts. Not kosher. But interesting?

To divert, back to the painting.

Question. When painting a model, is it best to assemble the whole model then paint, or to completely disassemble every part, paint the parts then reassemble?

1. Disassemble and paint the parts then reassemble. This results in complete paint coverage of all parts. It results in clean separation of different coloured parts. Mistakes involve limited areas and are easier to correct. However, the thickness of the paint can alter carefully machined tolerances. And surfaces can be painted which were intended to be unpainted.

2. Assemble the entire model, then paint. This can make some recesses, corners and hidden areas difficult to access. But the appearance of the entire model can be assessed as the painting progresses, and major mistakes in colour choice can be corrected. The painting process does not alter dimensions or fitting together of components. But paint edges and joins can be difficult to keep neat and straight, particularly in my inexpert hands.

3. (Obviously what I chose to do). Partial assembly, into modules, then paint the modules separately. This has the advantages of both 1 and 2. The modules can be stacked together to periodically assess the results. The modules are smaller than the complete model, and easier to handle. Difficult decisions regarding colour, or whether to paint at all, can be deferred until the easier parts are painted, and some idea of appearance ascertained progressively.

So that is what I am doing. I have painted the bottom part of the chassis, and the carriage. Etch primer at this time, but already firming up ideas about final colour. And my colour and design expert advisor (SWMBO) has had some input into this decision.

These are the main modules, 4 of them. The barrel assembly is stainless steel and it will not be painted. At the rear are the carriage and bottom part of the chassis, which have been primed. The main chassis beams containing the movement gears are unpainted. The carriage looks naked without its bling.

At this stage, I asked for advice from SWMBO. She has suggested that the primed modules should be painted satin black, which should contrast nicely with the brass/bronze components. Avoiding gloss will minimise the finishing defects. Some filling of defects will be required in any case. The black colour will be tested on the carriage, and if it looks OK, the chassis subframe will receive the same colour.

SWMBO’s most interesting suggestion is to NOT paint the main chassis beams at all! Well, a clear lacquer will be required to prevent rust.

But. What about disguising the copper rivets/stainless bolts?

SWMBO: “they look interesting. Leave them.”

Me: “but, but, but, they do not look authentic.”

SWMBO: “This has to look like a work of art, otherwise it will be just a boring dust gatherer.”

She wins.

Painting Covers a Multitude of Sins

After my crap riveting of the carriage, I could have ripped them all out and started again. Or, I could slap on a coat of paint, and take another look.

Well, that’s what I did.

Well, actually, before that I telephoned my riveting expert about my rivet problems, and he gave me some further advice……

  1. Put a G cramp on the compressor hose to restrict the air flow
  2. Polish the ends of the snaps, and round the edges slightly
  3. Check that the shape of the snaps mirrors the shape of the rivet heads. It didn’t. I had thought that the dome rivets had hemispherical heads, but on closer inspection, they were flatter than a hemisphere. So I made some new snaps, and took great care to make sure that the rivet heads fitted more precisely into them.
  4. Be more careful to keep the snaps perpendicular to the surface.

I did replace the worst rivets, and I was much happier with the results.

Then some paint. But first I gave the carriage a thorough wash in detergent to remove any trace of machining oil.

Then, using a pressurised can of etch primer, used my spray booth (a cardboard carton open at one side) to give it a coat.

I quite like that colour. The blue splog is some marking paint. The etch primer refused to stick to the marking paint. Next time I will give the parts a wipe with acetone before painting.

And, with a bit of paint, the carriage doesn’t look half bad?

Even the crappy rivets do not stand out too badly.

Of course, some areas showed up as needing some filler…..

Some time and effort required in some areas to fill defects and divots before the next coat of paint.

I quite like that colour. Maybe with just a touch more blue in it.

And note: NO RUNS, NO BRUSH HAIRS.