Saturday, January 31, 2015

DBR1: one step forward, three steps back

So the body work to date has involved the following steps:
  1. Sunday: wash major body components in warm water and lots of dish soap;
  2. Apply Tamiya primer;
  3. Wet sand with 1000 and 2000 grit Tamiya paper to get rid of the lumpy stuff in the middle of the hood and elsewhere;
  4. Repeat steps 2 and 3 (twice);
  5. Monday: get fed up with ongoing lumpy stuff bubbling up under the primer;
  6. Tuesday: drive to hardware store and pick up paint thinner;
  7. Wearing hospital nitrile gloves, soak body in paint thinner, scrubbing with a nail brush;
  8. Replace hospital nitrile gloves regularly in the course of Step 7 as they don't seem to stand up to paint thinner for very long;
  9. Wash repeatedly in warm water and lots of dish soap;
  10. Although Step 9 yielded plenty of brown goobers (a.k.a. suspected mold release agents) in the residual thinner, I decided to rinse and scrub in alcohol anyway, leading directly to Step 11, which is:
  11. Wednesday: drive to pharmacy and pick up more isopropyl alcohol and acetone (what the hey, I was in the shop anyway). Also pick up a couple of toothbrushes.
  12. Thursday: out of town on business so no progress;
  13. Friday: Final cleanup with paint thinner, scrubbing with a toothbrush;
  14. Soak in soapy water, then alcohol, scrubbing with a toothbrush;
  15. Hospital nitrile gloves don't seem to mind immersion in rubbing alcohol, which is probably a good thing if you think about it;
  16. Wash repeatedly in warm water and lots of dish soap;
  17. Saturday: drive to national auto parts chain store and buy a can of Dupli-Color Sandable Primer; this seemed the least aggressive of the three available choices, the others being Primer Sealer and Filler Primer;
  18. Apply Dupli-Color primer to one of the Jimmy Flintstone bodies in case it tends to turn expensive resin bodies into a formless glob - it worked fine except where I didn't remove all the mold release agent :-) 
  19. Apply primer to DBR1 body components;
  20. Breathe, it all seems to be working. Go back to wet sanding.
Is it better? Yes, definitely. Is it perfect? No, there are still a couple of bubbles. This just reinforces how important it is to deal with mold release agents.

To be fair, the quality of the mold, now that it has a decent coat of primer on it, is much better than the various Jimmy Flintstone bodies, perhaps not surprising given the price differential. And perhaps the Jimmy Flintstone bodies need the Filler Primer which apparently fills in large nicks and scratches.



Monday, January 26, 2015

DBR1: the importance of removing mold release agents

After having problems getting primer to stick to the body, I decided that my dish soap cleaning may not have been aggressive enough to remove all the mold release agents, so I followed instructions online here, an excellent link if you can put up with the fact that the text IS ALL IN CAPS. (I've inserted the relevant text below, converted to lowercase, for the CAPS-impaired).

So I put the remaining resin bits in my strainer and soaked them in isopropyl alcohol (rubbing alcohol) for a few minutes. I followed that with a scrubbing with a toothbrush, then a careful washing in warm water with dish soap and more scrubbing. As predicted online, my strainer came up with big strings of brown goop, so something was happening.


Some tips:
  • Wear nylon (hospital-style) gloves when mucking about in the alcohol.
  • Use a fine mesh strainer sitting inside a larger pie tin. Make sure the pie tin doesn't have a pin hole in the bottom by testing with water before putting in a load of alcohol. Don't ask me how I know this, let's just say it's the voice of experience.
  • Put the plug in the sink, you don't want to lose some critical little bit down the drain hole. Do the bits in small batches so you can quickly spot a missing bit, especially the smaller stuff (i.e. do all four disk brakes together, etc.), and immediately rummage around in the sink to find anything missing.
Next: I'll have to strip the failed primer off the body parts (body, hood, doors, trunk lid) so I can give them the alcohol treatment. First, though, I'll need to get more alcohol, and more paint thinner to strip off the primer first. I'm low on acetone, too, so a trip to the pharmacy and the car parts store is in order. It's all a bit of a mess to be frank, but the optimists will be calling it a 'learning experience'. Whoopee.

Text from http://www.resinparts.com/workingwithresin.html follows, to save you all dealing with the caps; note comments on primer at the end:

"How to remove mold release from your parts:  
Assemble materials needed:
  • You will need a bath towel, cotton balls, a bottle of isopropyl rubbing alcohol, dish soap, a roll of bounty paper towels, and a toothbrush.
  • The first step is to group all parts on the bath towel next to your kitchen sink and arrange your materials so they are easy to get to.
Now fill your kitchen sink with warm water and a generous amount of dish soap (do not use extremely hot water or you could warp your parts!)
  • Use one cotton ball per resin part and wet it with the rubbing alcohol
  • Using the cotton ball now soaked with rubbing alcohol to wipe down the resin part in a circular motion to break loose any mold release
  • Mold release is silicon based and needs the alcohol to break it loose from the part
  • Failure to complete this step will not remove all traces of mold release from the part
  • Do each part one at a time and use a new cotton ball for each part
  • While the part is still wet with rubbing alcohol, place it into the sink and proceed to wash it like you would your dinner dishes using the toothbrush.
  • I recommend getting it soapy from the bubbles on top of the water surface and brushing all areas of the part before placing it into the sink to soak before you rinse
  • The rubbing alcohol breaks the mold release loose from the part and the dish soap washes it away from the part
You must complete both steps to successfully remove all traces of it from your parts.
  • Once finished soaking the part, remove it from the sink and dry with a new paper towel
Your part is now ready to work with. Use a new cotton ball and paper towel for each part you are cleaning as traces of removed mold release may be cross contaminated from part to part.
 
A note about using primer on resin parts: When it comes to the choice of primers used on resin parts, I strongly recommend that you use a sandable automotive primer. I personally use Rustoleum sandable automotive primer on all my castings and it has great results. I discourage the use of "plastic primers" on cast resin parts as I have personally had less than desirable results. In general, hobby primers lack the desired solvent strength to stick well to resin parts. Another benefit to using the sandable primer is that it goes on thicker than regular primer helping to fill any pinholes or scratches."

Sunday, January 25, 2015

DBR1: initial cleanup of the body

Lots of new things to learn here. The Profil 24 kits look a lot like the Porsche 908 kit from MFH that I have been struggling with for something like a year and a half now; you get the larger resin bits in a bag and smaller stuff in a series of little sealed baggies. Unlike a styrene kit, parts are not numbered on trees, and often include fairly large pieces of sprue or remnants of ports for resin delivery or air evacuation as the mold is filled. Figuring out what is the part and what is the sprue can be challenging. Also surface detail will be rougher than a good styrene kit, so count on lots of wet sanding. That being said, some of the larger mechanical components (engine, gearbox) can be molded as a single item where a styrene kit might devote 20 or 30 pieces to this.

So let's get to it.


I started on the exterior body panels: body, doors, hood, rear hatch and gas filler cap cover. The goal was to clean them up enough that everything fits with minimal gaps. There is lots of scarf and bigger stuff to clear away, for instance in the fender vents in the picture above.

The first thing I discovered is that resin is a lot softer than styrene, and you will want to be careful with the Number 11 blade. The panel scribe and a set of nail files from the beauty section of the local drug store are your best bet. Test fit regularly to avoid taking off too much material.


The left side door has a bit of a gap but I think that will be OK at this point. The rest of it all fits reasonably well.


The Tamiya primer went on with some flaws, not visible in the picture above. A wet sanding with 1000 grit and a second coat of primer may not have improved things, and I am not sure that 1500 or 2000 grit is the answer. Pictures below show some strange behavior at the leading edge of the hood, and on the nose of the body.





Online, it seems that removing mold release agents requires scrubbing with isopropanol alcohol, followed by soaking in water and dish soap; my soaking in dish soap may not have been enough and may be the cause of the blotchy primer. A stronger primer, such as Rustoleum auto primers from the auto parts store, also seems to be necessary according to a range of online resources.

A parallel step was an initial cleanup of various chassis bits. Figuring out how this all fits is a challenge as there are few doweled joints. A lot of test fitting, both joining of chassis bits to each other and to the body, give an idea of where everything needs to go. Clamping everything properly while glue sets will be critical.

So anyway I'll let it all sit for a week while I go back to the office and see what it looks like next weekend.

Resin kits: overview

Resin has a whole different value proposition (to use a current management expression) from styrene.

Pros: Lots of opportunities to build obscure stuff you'll never find elsewhere. For example my collection of unbuilt resin includes the following:
  1. Le Mans and other long-distance road racers (all from Profil 24):
    • Maserati 450 S, car #19 as run at Sebring in 1957
    • Aston Martin DBR1, car #4, #5 or #6 as run at Le Mans in 1959
    • Alfa Romeo Giulietta SZ, car #35 as run at Le Mans in 1963
  2. Monte Carlo and other rally cars (all from Profil 24):
    • Porsche 550 Panamericana as run in the Panamericana in 1953
    • Audi S1 Group B, car #2 or #6 as run in the 1981 Monte Carlo
    • Toyota Celica Twincam Turbo Group B, as run in the East African Safari Rally in 1984 through 1986
  3. Custom transkits (all from Jimmy Flintstone, but requiring an AMT, Revell or similar kit to complete):
    • '61 Ford Starliner 2-door wagon
    • '59 Cadillac Cadalicious
    • '51 Chevy Leadstone
Cons: You really need to test fit every piece before beginning to even think about putting on primer or paint. There will be lots of time spent adjusting the fit, filling holes and gaps, sanding rough spots, etc. For example the Starliner wagon is a lousy fit on the AMT Starliner chassis, partly due to the resin interior shell being a poor fit in the resin body. Also the hood (from the AMT kit) doesn't quite line up with the resin body. So there is lots to do here, even with a quality styrene platform.



One exception to this rule appears to be the two Model Hiro Factory kits on my shelf (Porsche 908 and 917), where the resin parts are of excellent quality; however I suppose this is to be expected given the prices they charge: up to $400 (Canadian) for a full kit, versus under $20 US for the Jimmy Flintstone bodies. The Profil 24 kits are expensive, but cheaper than MFH kits, so it is reasonable that there is more cleanup needed. Photos of the Alfa and Porsche follow.



Going over the stack of un-started stuff, I decided on the DBR1 as my first resin attempt, mainly because the amount of cleanup appears to be less than some of the other kits. The Audi S1, for instance, has a lot of gaps to fill, see below; filing off excess is one thing, but building up to fill gaps is another.



The objective is to build up the #5 car driven to first place by Carroll Shelby and Roy Salvadori in 1959. Maurice Trintignant and Paul Frère were second in another DBR1; this was the last win of the late-50's domination of Le Mans by British makes. Salvadori passed away a few years ago at the age of 90; Trintignant went on to operate a vineyard and eventually became mayor of the local village; Frère had an interesting career, winning Le Mans in 1960 (in a Ferrari Testa Rossa, with Olivier Gendebien), then went on to work as a journalist (for Road & Track among others) and as test driver for Porsche. He combined these skills in producing a couple of very detailed books on the Porsche racing cars up to about the 917, including gems like shaving down the nut holding in the ignition switch for a documented weight savings of something like 15 grams on the 904. Typical German thoroughness... as for Shelby, I suspect you all know where he wound up.

The kit includes resin and spun-cast white metal parts, as well as a couple of photo-etched sheets, vacuum-formed clear parts, machined aluminum rims and rubber tires.


First step: washing all the bits in acetone (spun cast metal) and dish soap (resin) to remove mold release agents. Second step: cleanup of body parts for primer and paint, according to my new philosophy of getting the bodywork out of the way. Details to follow in subsequent posts. As this is my first resin build, I'll document it more thoroughly than I might with a styrene kit. You have been warned.





Saturday, January 24, 2015

Tidying up the display cabinet II: Past kitbashes

In trying to make room for new stuff, such as the recently completed 1972 Skyline 2000 GT-R, I've been looking through the cabinet and I've cleared out a bunch of junk, some of it dating back 30 years. However, while most of it is clearly at the rat rod end of the spectrum in terms of quality of execution, I came across some interesting engineering studies in the vault, and I thought it might be nice to get pictures and text out there, in case it provides some ideas for others. So over the last few months I've spent some time assembling this post, and a second one to come, as I've sorted through the collection and moved the real junk to the parts bins for reuse. So if you like something here and wind up building something better-looking on a similar theme, please let me know. So let's get to it!


First is a design study showing what a Honda version of a Toyota MR-S might look like. The engine is a 1.8 four with carbs taken from a Japanese kit of the Prelude, with the entire drivetrain transplanted to the rear. (The Prelude came to a bad end as a result of trying to shoe-horn a GMC Jimmy V6 into the back seat. I'll spare you the gory details; suffice it to say that it doesn't fit).


The front suspension is the former Prelude's rear, and thus lacks steering; at 1:1 you would get a second front subframe and steering assembly from a scrapyard. The chassis is scratch-built, and the body, which was painted by brush (can you tell?), is a significantly carved-up Dodge Stealth (a.k.a. Mitsubishi 3000 VR4). I cut up several of these AMT Dodge kits and both bodies and engines from this kit (which doesn't appear to be available any more) will reappear later. This is, I think, entirely feasible at full-scale from an engineering perspective, although arguably there are plenty of GM FWD V6 chassis out there to pilfer from, providing plenty of torque for a sports car weighing a tonne or so. The body just requires some inventive fiberglass, much as the Brits were doing starting in the 1950's. The compact drivetrain allows for a very long hood which might fool you into thinking the engine is up front, and at 1:1 it may be that the cowl should be moved forward to improve the cockpit.




Next is one of the Dodge Stealth drivetrains, turned around and inserted into the back seat of a Japanese kit of the Suzuki Samurai. The Suzuki has had a horizontal body section, and the cockpit has been moved forward to make room for the twin-turbo V6 in the rear seat/parcel shelf area. The chassis retains the AWD system from the Dodge, except the front subframe is now in the rear and vice versa. It is assumed that there is a gearset somewhere that can be inverted, otherwise it will have one forward gear and 5 reverse gears ... a minor engineering detail to be worked out by the builder, and one that is easy in some cases, such as with old Beetle drivetrains converted for mid-engine use. This is a little harder to do properly at full-scale; given the small amount of space available in the back seat of the Samurai, it would work better with one of the longer-wheelbase variants.




With all those leftover Stealth bodies lying around, what better than to shove in a big block and some drag slicks. The Stealth was sold as a high-tech device, and this is the brute-force conversion: cubic inches and solid axles. The mechanical bits all came from the parts bin. The top chop involved tilting the roof forward on the C-pillar, which was not cut; the cut came from the A-pillar. Yes, yes, the engine is not straight in the chassis. Crude but effective. Probably not worth trying at full-scale.




In the same vein (big-block brute force inserted into a high-tech Japanese GT), the Acura NSX acquires a Ford 427 motor and blower, again from the parts bin. The transmission is modeled with a quick-change Halibrand diff from the parts bin; it should really have a proper transaxle in this location, but these are hard to come by in conventional kits. All the chassis bits are from the NSX which would probably be turned to pretzels by the torque of the blown motor, so don't try this at home! The purpose built scoops for radiators and air intake are particularly nice. Having to move the cockpit forward by about a foot at 1:1 means this would probably not work at full-scale, unless you were prepared to stretch the wheelbase, as normal people would not likely fit.




The Fiero below has a Blazer V6 drivetrain turned around and inserted in the back. (This is the same trick which failed with the Prelude). The transfer case intrudes into the passenger seat area, which probably means a pretty thin seat cushion on that side. This is probably not completely unrealistic at 1:1. (Apologies for the lurid colour scheme).





So that's a first pass at the topic; like I said, it tilts towards the rat rod end of the spectrum when it comes to fit and finish, but from an engineering perspective much of it makes sense. Stay tuned for more as I get around to posting, there's probably another half-dozen of these in the pipeline.

'72 Skyline: glass with Micro Krystal Klear

A number of bloggers and correspondents have recommended Micro Kristal Klear glue, from Microscale Industries, for clear parts, so I got brave, picked up a bottle at the local hobby shop and gave it a try on the front and rear windshields on the Skyline. (Unlike a lot of hardtop models, the glass is 4 separate pieces, not a single big molding).


The glue is white, sticky and high viscosity; it goes on thick, a bit like the white glue that we give to preschoolers to use with construction paper; it sticks to the brush and does not want to run into crevices which is both good (no messes) and bad (no contact between parts unless you push it in with a brush or other implement). It dries very slowly so you've got lots of time to move things around, and excess can be mopped up with a wet paper towel until it's dry. I left it for 30 minutes and tried to remove some fog on the inside of one window with a wet tissue, but the fog kept coming back and eventually the window fell out -- it turns out I was dissolving the glue around the rim of the glass and spreading it around, making new fog. I cleaned up the glass, put it back in with more glue, and let it sit overnight (upside down so as to avoid gravity loosening it).


That seemed to do the trick; as it is 4 separate pieces of glass, there is a possibility one or more could fall in once complete, and I would really like to avoid that scenario. (Being a bit paranoid, I added a drop of the old Testor's glue at each corner of the glass, just to be safe ...).


I also used the Micro stuff on smaller glass bits, like headlamps and turn signals. For the first time, you can tell I didn't get the headlamp lenses in perfectly straight; normally they would have been all fogged up and it wouldn't have mattered.

Not knowing if it will adhere to paint or chrome, I scraped as I would have in the past, but maybe I'll try gluing without scraping on some scrap bits from the parts bin, just to see. The stuff seems too good to be true; not having to scrape would be mindboggling.


The rest of the finishing touches worked out well and the finished model is one of my better efforts if I do say so myself. All the little trim bits went on OK, the paint and glass survived the handling, and the engine looks good with the red wiring. The only real screw-up was the front license plate decal, which I fixed by the simple expedient of leaving it off. (Bet you hadn't noticed). So the approach of getting the bodywork out of the way early has paid off in that final assembly took an hour, not the usual frustrating full afternoon with the end in sight but all these annoying little details, like door handles, to get out of the way first. (Looking at the high-resolution under-hood shot, I noticed and fixed a chip in the heat paint on the exhaust manifold and some excess silver around the wingnut for the air filter. I also added a touch of silver to the three strut tower bolts on each inner fender. Time to quit futzing around.)


Next up: The matching '90 Skyline? Fresh from a success story, an alternative is to get to work on one of the six Profil 24 resin kits that have been sitting on the shelf for close to two years in some cases. Wiring up the 908 motor, with its 16 spark plugs and 8 injectors, is another option. Maybe I can even arrange an alternative throttle return spring mount, which has been the psychological holdup. Nothing builds confidence like success. Yippee!

Thursday, January 22, 2015

Auto show highlights (1:1 scale)

Here are some interesting highlights at 1:1 scale from the recent auto show here in town, perhaps of interest to kitbashers as a source of ideas. Get your saws out and read on.


First up, a Mini tow truck. The poster claimed it has the 1275 motor but my recollection was the 1275 motor had 2 carburetors, not one. Or maybe only the Cooper versions had 2 carbs. Anyway it is very cute, and probably built on the Countryman chassis which had about 6" more rear overhang than the Saloon.

So what do you tow with a Mini? Easy, a shortened Mini. 'Nuff said.


The chopped & channeled Beetle rat rod, with '30 Ford front suspension and wheels, was pretty neat, as was the associated channeled shopping cart (with 911 cylinder head and wheel). The aircooled motor with downdraft carbs is period correct but the absence of a cooling fan means it probably doesn't run for long, unless it's in winter weather, in which case the windshield will be frosting over. (I learned to drive in a 1966 VW bus and know all about VW 'defrosters'). 


 

There was also a channeled Radio Flyer kid's wagon and a channeled skateboard. There is some guy loose with a hacksaw and he needs to be stopped. Or not.



Following on the VW's suicide doors, there was a vintage Fiat Abarth 600. Very cute, a lot cuter than the current Fiat 500. The poster claims it is a 1960 original with a 1-litre motor, but we couldn't see in the engine compartment to verify.

At the other end of the spectrum, in every imaginable way, was the latest Rolls-Royce Silver Wraith which sports suicide doors as well as a very '60's roofline. The picture isn't very good, given limited sightlines, but I saw one of these on the street in Vancouver recently, with the same two-tone paint, and it looks really good. As well it should, given the half-million dollar price tag.


The roofline is, what, '66 Chevelle? Or maybe closer to the '68 Bonneville. The proportions are excellent, with the enormous size masked by the equally enormous rims. So this opens up all kinds of opportunities for '68 Bonneville rooflines. Anyway if I sell my house and cash in all my retirement funds, I might be able to afford it, but then the cats and I would have to live in it and share tins of cat food, and we couldn't drive it anywhere because of the insurance costs. Plus the cats would likely ruin the woodwork with their claws, just as they have ruined most of the furniture at home.

Finally Ford put together a Hot Wheels off-road buggy, dubbed the Rip Rod, to show off the 1-litre Ecoboost motor. The video of it pulling wicked powerslides in the desert somewhere was quite neat and can be found online. I suspect the sequential shift transaxle is not part of the new Ford lineup.



Oh, yeah, there were some regular cars too, you can read about those in the paper, or see them at your local dealer. Same old, same old, except that a BMW 3-series now comes with a 2-litre turbo-4. That lovely inline six used to be the best reason for picking a 328 over an Audi A4, but it's hard to see the difference anymore. Overall I saw no good reason to give up the Golf.