Monday, December 11, 2017

1966 Cadillac Coupe de Ville

My house is being renovated and I have moved to rented accommodations where I suspect paint fumes would be most unwelcome. (The photo shows my house as of Friday, not the rented accommodation...)

It will likely be February before I get back in, and probably March before my workspace is set up again. So no building for a while. However the mailman, for some reason, keeps bringing me boxes, so I am daydreaming. For example, this very nice vintage Jo-Han kit of the 1966 Coupe de Ville turned up today.

It's a long, low, barge from the post-fin era; it will sit nicely next to the Lincoln Continental and Chrysler 300. The obvious thing to do with something like this is to get it into the weeds as with the 300, also from Jo-Han, that I built a while back. There are lots of pictures of tail-dragging baggers on line, but only a few with chopped tops. In fact I could only find one after a brief online search (click here). Which makes a chop an interesting option.

The picture at the top is the model as it came out of the box. Next are a couple of options for a chop of about 3" at scale. The middle picture shows tilting the C-pillar forward and extending the rear deck; in the bottom picture the C-pillar has not only been tilted but also moved forward to the point where there won't be a rear seat and it becomes a Club Coupe de Ville. A third option, not shown, is to tilt the C-pillar but keep the rear deck intact, which would require extending the roof. (The online version would appear to follow this method).

What do you think? Comments welcome!

Wednesday, November 29, 2017


My home has been taken over by a wrecking crew, which will hopefully be replaced by a construction crew in the not too distant future ... so no modeling for the foreseeable future if only because of the dust.

Meanwhile I am vicariously modeling by means of a number of FaceBook groups which provide lots of interesting tips. The New Modelers Club is run by a great admin named Randall 'Krazee Wheelz' Wheeler; the Model Car How-To's and Model Car Aftermarket are run by an equally great admin named John Papp. And for fans of airplane models, there is a Finnish group called Oldie & Goldie Scale Models. Posts are sometimes in Finnish, and FB's translation app is horrible, but the membership appears to be worldwide. All highly recommended.

Thursday, November 16, 2017

3D printed LS3 V12 motor Part 3

Here are two more pictures comparing the roughness of two 3D printed parts, 10 years apart. The blue wrench looks like 0.5 mm between passes with the printer head (two furrows per millimetre) while the valve cover from Shapeways is more like 0.12 to 0.20 mm between passes (5 to 8 furrows per millimetre).

Painting with Testor's enamels and a brush leaves a relatively thick paint layer that obscures the ridges, especially when a light sanding has taken off the high points as identified by a coat of primer.

I completed the engine with starter motor, oil filter and a water pump from the parts bin. One important point: drilling out a hole, even carefully with a pin vise, will be challenging because the material is quite brittle and will split and crack if you are not careful. In the photos you can see where I was trying to hog out the hole for the crank in order to fit a pulley and belt assembly from the parts bin.

I filled in the hole around the crank pulley once it was all glued up, but the rigid, brittle nature of the material is worth keeping in mind. Of course it is possible to select different materials in the ordering process; I picked the Frosted Ultra Detail option, but the White Nylon option may be more forgiving as well as cheaper.

Overall, a mean looking engine. Now I just need a mid-engine chassis suitable for a 9-litre V12 ...

(PS it has been pointed out to me that the Chevy logo on the valve cover is backwards ... I have flagged this for the people making the parts, and presumably this is a minor software edit. I hadn't actually noticed, given that most of my past work is on imports ...)

So are we there yet? Not for bodies, unfortunately, until the resolution can be improved significantly beyond the current level of about 0.15 mm (about 0.006"). That being said, the possible level of detail is also 0.006", or about an eighth of an inch at 1:24 or 1:25 scale. This is minuscule -- bolt heads on a water pump are going to be 3/8" or 9/16", for example. Just be careful what material you select because this can have an impact on what you can do with it. To summarise:
Selection of subjects
Mainly high-volume, high demand markets
Mainly specialised markets for low-demand niche products
Potentially very extensive once the necessary computer files exist
Excellent, smooth surface
Poor today, visible ridges due to tracking of printer head
Depends on molds
Potentially very high level of detail at the scale of the printer head resolution
Variable, can be brittle
Depends on material selected – can be brittle
Prep needed
Dish soap, dry, primer
Alcohol or acetone to remove mold release agents. Putty for pinholes and bubbles. Heavier filler-primer needed for more porous castings. 
Dish soap, dry, primer

Wednesday, November 15, 2017

3D printed LS3 V12 motor Part 2

I wrote about this back in early October (click here). I have since received the correct intake manifold, so it is time to move forward. 

The parts are semi-transparent as received; this will vary with the type of material you specify. 

Giving them a coat of Tamiya primer shows the detail available, which is otherwise hard to pick out on the translucent surface as received. 

The grainy texture of a cast block is reproduced nicely, but in the right light, you can see the regular step-wise grooves that arise when the printer head scans back and forth, as in the oil pan or valve cover. 

Fixing this could involve light sanding, or one could assume that paint will fill it. I'll try sanding parts where it will show (oil pain, valve covers), and simply apply paint where it won't (bell housing) in order to evaluate the importance of the roughness. 

The level of the roughness is noticeably less than in the adjustable wrench made using a $250,000 prototype machine in a university mechanical engineering lab about 10 years ago, but is still visible on close examination. 

I am guessing that a 3D printed body will not be as smooth as styrene or a good resin body. The advantage over resin is low porosity, high dimensional accuracy and no mold release agents. Styrene remains the best quality if you can get the specific parts you want. 

The area of improvement is now at the level of building ever finer printer jets, and stepper motor drives with smaller step sizes to bring tracks closer together. I suspect this will proceed rapidly; take a magnifying glass to output from a good inkjet printer on decent paper and compare to the late, unlamented 8-pin dot matrix printer. As well I am assuming Shapeways is using commercial-grade printers, i.e. better than the $1500 home hobby unit from Micro-Mark, but substantially cheaper than that $250,000 university prototype of 10 years ago.  

So we are getting closer.

I'll paint and build up the motor and keep you posted. 

Monday, November 13, 2017

Matra MS 640: just the glass missing now

Ooof. Wheels are on and the paint still looks OK even after a couple of coats of clear. (The clear that gave me fits was a dull clear, and is in the garbage).

For a curbside, an awful lot of effort.

There is also a tiny little wing, actually more of a flap that is meant to hang off the back of the rear cowling, that needs paint and assembly. It's a fiddly bit made up of a thin sliver of resin and two photo-etched brackets, and may get dropped. Some photos of the current car (the so-called 640B) show it installed, others not.

An oddball little car next to the cuddly and utilitarian Chevy, the muscular and brutal Audi and the lithe and svelte Jag. My last four builds were all resin kits, and all a challenge, but I am happy with the results. Subsequent builds will be better!

I will be moving out of my place in a week for a couple of months of renovations. As I'll be couch-surfing or renting AirBnB digs, I am guessing that spray paints will be frowned upon. So there might not be much to write about for the next while, unfortunately. Stay tuned.

Sunday, November 12, 2017

Matra MS 640: Finally got the paint to stick

I have never had a paint job fight me this much. Although to be fair, most of my painting problems in the past have been either,

  1. self-inflicted due to impatience or sloppiness, or
  2. resulting from the challenges of working with resin, or
  3. both of the above. 
This was probably a case of #3, and the picture below shows a monumental screw-up that arose after putting on the white and taping up for the blue, then shooting a quick coat of clear to seal the tape. The clear, a Tamiya clear, immediately attacked the Tamiya spray paint underneath. Ugh. Back into the alcohol bath for a second time. (The first time was documented recently.)

An extensive conversation on the Model Cars How-To forum on Facebook didn't come up with any clear reason for the problem, except possibly off-gassing from the resin. As there were several coats of primer and two of white on it at this point, I find that a bit of a stretch as I would have expected this to arise earlier. Anyway it looks good at this point and I will let it sit for a day or two before buffing the blue around the base of the fins and putting on the decals. 

There was no bleeding or seeping of the blue onto the white, which is a big relief, although the blue I decanted and brushed on is a bit darker for some reason. 

Will I dare to try clear again? Hard to say. But progress is being made and what is left on this curbside is pretty simple: decals and lights, then the chassis and glass go in. I've also got some photo-etched grilles to put adapt. 

Stay tuned!

Friday, November 10, 2017

Matra MS 640: Paint take 2

OK so I am starting this over, just as I had to start over with the Jaguar D-Type (click here). There is a pattern here ... I need to be more careful and patient, and I also need to be more careful around cleanup of the resin bodies.

So further cleaning up of the resin (maybe I wasn't aggressive enough the first time), followed by multiple coats of automotive primer-sealer to close up the porous resin body, followed by a couple of coats of light grey Tamiya primer, followed by 5 or 6 very light coats of Tamiya TS 26 white sprayed about 20 minutes apart, seems to have done the trick. (Only the fins will be white; the rest of it will be French blue). Now to let it harden before taping it up for the blue. 

Stay tuned!