MR2-FA: Photoshop Contest

I can't draw for crap.  This is a little sad for me as I used to draw comic books in High School.  The problem is that was 15 years ago and I've got exactly zero interesting in putting in the time to become good enough to do what I need for this project.  I'd rather be welding.

The photoshop contest that recently ended was specifically designed to help me find exactly what I ended up finding: a young-ish person that likes cars, has mad skill and some time to kill, and is still malleable enough that they won't try and ram their own ideas down my throat. 

And the winner is...the nice young man who drew these:

Welcome to the team laddie.  It's going to be fun. 

MR2-FA: The (Base) Model - Part 1

Before you go trying to build out a full scale version of a car it's typically a good idea to build out a scale model first.  You see this all the time if you watch car magazines.  There will be a lump of clay on a pedestal, then a couple shots later you see a finished clay shape.  Since I'm not building a car completely from scratch, but rather re-designing an already existing chassis, I've got a few more options that someone with just a lump of clay wouldn't have, namely that I can find a scale model the right size and start there.

I searched around and with a little help was able to find this:

It's a 10:1 RC car that's an exact scale model of the SW20 MR2.  10:1 is the perfect size for this if you don't have the ability to make something full size because any measurements on the base model or the car only need to be divided by or multiplied by 10 to get the corresponding line on whatever you're building.  Obviously I could just cut this up and run with it but I didn't because it would have been a wasted opportunity and I'd only get one shot at it.  If I cut up a line I later wanted back, I'd be screwed.  I could probably make it work, but it'd be a lot more painful than it needs to be. 

I decided instead to teach myself a new process - creating a resin reinforced latex mold.  I haven't done this before, but it's a pretty useful skill with a lot of potential applications so I was willing to spend the $80 in materials required to figure it out.  Latex as a material has some nice properties, and some tricky properties.  First off, the base latex and the hardener need to be measured precisely.  Luckily I've got scales for just such occasions - here we've got 300 grams of the base measured out.  When I'm working I almost always work in metric because way more precise than using U.S. measurements. 

Second - when you mix the stuff it introduces air pockets that you need to remove.  There's two ways to do this - 1) a vaccume pump 2)"Bombs Away".  I have a vacuume pump but it's not setup right for doing this and it'd take to long to get it there so I went with bombs away which is basicall just slowly pouring the mixed latex from one cup into another from three feet or higher away.  It's messy - but it worked. 

I didn't get this process right on this - my first - go but I learned what I needed to in order to be able to do the job right when I make the final mold of whatever the finished shape of my car is going to be.  In the interest of posterity I'll take you through that now. 

1. Secure the model to a base.  In this case I used a free (thanks Tap Plastics!) piece of acrylic sheet that they gave me when I got the molding supplies.

2. Mix up a precise amount of Latex according to the directions.  For this first pass - don't mix up very much. 

3. Do a thin layer over the model.  I applied this using the same process I use for wetting out chop mat which is called stippling.  You use the brush to jab the material into all the crevaces and make sure you pick up the surface detail.  Once I had the whole thing covered I brushed on a bit more.  I forgot to take a picture though.  Sorry. 

4. Wait until the first layer is tacky, meaning it's sticky to the touch but doesn't come off on your fingertip and then do a second, and thicker coating.  I did remember to take a picture of my second layer:

5. Keep going till you get the mold the thickness you need.  I was aiming for 1/4 inch, but I missed the mark in a few spots.  More on this later.

6. When you're absolutely certain you've got all the details picked up (for me this was after two layers) mix up another batch of silicon but this time add a thixotropic additive.  Thixhotropic is a fancy way to say thickening agent.  I found it makes the silicon more like a paste and you need to trowel it on rather than brush it.  Here we've got the third layer.  Looks kinda like a cake:

I could have and should have taken the time to get this smoother, but I had to go change a diaper on my daughter so I had to live with it. 

That's pretty much it for the latex part.  The next part is actually just adding fiberglass over the top of it so that the latex keeps its shape when you're popping out parts. For this I decided to use a couple of materials I mentioned in my post about materials. 

1. I did a layer of resin with Cab-o-Sil.  I like this stuff, but you better wear a dust mask.  I did, but just the small amount that got on my clothes proved to me that it's not a material to be taken lightly.  Eye protection is an abolute requirement when messing with this stuff.  You can see that it turns the resin into sort of a paste:

I then spread this over the model and the wooden trim I put together for it. 

2. Once that started to tack up, I did a second layer but this time I added microspheres to help bulk out the resin so I didn't need to burn through as much.  I like this product too.  It bulks out the resin but doesn't change the viscosity so you could still pour it or wet out chop mat with it the same as if it was just resin.  As with the Cab-o-sil, this stuff works great but it's nasty so a respirator and goggles are a requirement.  Here we are after a layer of the new Cab-o-sil and microspheres resin mix:

3. I did one more layer with this mixture:

 

 I then did a single layer of chop mat over this with just regular resin with the surface curing agent:

So how did I do?  Honestly I only did OK.  I thought at first I could use the mold but on further reflection I'm better off just trying to make another one.  What did I do wrong and right?

Wrong:  I was trying to be a bit stingy with the silicon because I wanted to save a bunch for the finished MR2-FA model and didn't want to buy more.  Now I'm going to have to buy more anyway because I need to make another mold.  The key point is - make the silicon thick.  Like maybe 3/4 of an inch.  You want the mold to hold it's basic overall shape without the fiberglass.  The fiberglass is just to make absolutely sure nothing moves or shifts.

Right:  I got all the detail of the original piece and there were no air bubbles so my method of application worked, and worked well. 

Overall it was a fun process and I'm glad I took the time to try it.  All my mistakes are easy to fix and the experience was well worth it for when I make the second SW20 mold and the final mold of MR2-FA.  

Tip 4: Making Your Own Gauge Locations

Here's another question that comes up a lot so it's time for Tip 4.

Ok after seeing your center console with t gauges mounted above the cd player i almost died.I love it.I want it. I have to have it.  How do I do it?

Both my WRX and my MR2 came with dual din CD/Tape decks that take up twice the space of a new deck you'd buy.  Usually when you buy a deck the seller also tries to get you to buy an "install kit" which consists of a bracket and a pocket to take up the space that the original deck has just vacated.  The problem with these pockets is they're utterly useless as anything you put in there is going to come flying out the first time you hit the brakes with any meaningful force.

So rather than stick the pocket in like everybody else, I actually smoothed over the location and made a gauge mounting location.



The trick to this is a little bit of backyard engineering using unorthodox materials.  The problem with filling in a location like that is there's a 90 degree bend.  It's suprisingly hard to find plastic pieces that aren't part of something else you wouldn't want to ruin that also contain a 90 degree bend.  The solution comes from your local hardware store.  Walk in, and ask where to find these:

http://www.homedepot.com/h_d1/N-5yc1vZ1xh8/R-100318664/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

They're gass blocks you sometimes see in bathrooms.  Somewhere in that section of the store (I can't find a link to the actual product online for some reason) you'll find a piece of plastic that looks like this:



This is a bracket that you use to mount those glass blocks to the floor or wherever you're putting them. As you can see it's got a 90 degree bend.  It's also got a line down the middle that inexplicably is almost exactly the same size as the slot you need to fill in.  What you do from here is measure the location you want to fill, cut a piece to length, take down the edges, and glue it in place. 

As far as gluing it in place there's two things:

1. Reinforce the area. Well.  If you haven't pre-drilled your gauge holes, and I'd actually recommend that you not because drilling through it will tell you if you made it sturdy enough, you need something behind the piece you cut to actually connect it with the mounting surface.

What I do is get the piece that'll be on the front exactly the right size to fit the location I want to fill in first. 



Then I cut off a slightly larger piece for the back side and take off the 90 degree portion with a dremel and a cutoff wheel.



2. For glue I use a product category called "Plastic Weld".   I tried regular epoxy first because I have tons of it, but it didn't work.  I was walking through the auto parts store and found "Plastic Weld Epoxy" in the aisle that had RTV Silicon and such.  This worked much better.  It works better than epoxy on plastic because first off it's specifically designed for that job and it also has some flex to it just like the plastic pieces you're gluing together.   That way when the piece flexes (like when you're actually putting in your gauges) the thing won't crack. 

You will invariably need to fill in the gap between the piece you glued in and the location you're mounting it to.  You'll also want to fill in any minor scratches or imperfections on the plastic.  For that see Tip 1.  I just use the same bumper filler stuff I go over in detail in that post.