Monday, October 15, 2018

Batmobile Side Mech Progress

These side mechs are painstaking work. And honestly, it's no wonder this car has taken me so long to get it to where it is today. And by that, I mean "in the shop of someone who is a competent builder that is also not me."

It's a weird combination of me just being slow, a perfectionist, and also just having a hard time finding time to work on the thing. Cuz you know I have all those other pressing priorities like winning arguments on facebook and updating my blog. Wah wah. Sad_trombone.gif.

With that in mind, I have made a lot more progress in the past week on the side mechs. For those who are following along, you will recall that this type of work is literally my least favorite type of all maker work. The process of putty, sand, primer, repeat is pure madness. But let's get to it.

I spent a couple weeks working out of the model shop at Fonco Creative Services, as it was close to my place, but had to bug out as they suddenly got a big piece of work in. A simple relocation to my workshop and setting up of a spare table got me back up and running in no time.

The bat signal is always watching over me, of course. I mean, come on.

I refer to this piece as "the coffee can" and there are two of them, one for each side and they are mirrors of each other. After looking at the way the whole thing assembles together, I realized a good time saving maneuver is to plug up the open end with a disk of styrene. That will save me some time cleaning out the existing recess, and will also make the mold less complicated. It will also give a nice surface to which I can glue or bolt other parts of the side mechs.

This little gasket-looking connector piece was not originally a stand alone part. There is a piece of the side mechs that is basically like a 90 degree curved and tapered tube. You can see it in a photo below. The white part. Much like the coffee can, there is one for each side, but the ONLY difference between the two pieces is the orientation of this gasket on the tip of it. So I made the strategic and money saving decision to only mold one in it's entirety, but then mold this piece as a separate piece, thus allowing me to create the mirror version of that tube without having to make a separate mold for the entire thing.

What you're seeing here is the early phases of my clean up process. I cut a styrene disk to fit into it, glued it in with super glue gel, then laid down a coat of spot filler putty.

And here is the final product, with a little bit of love and spray primer later.

Let's jump ahead and take a look at this assembly:

See the big white part? And the tip over on the left? That's where I cut off the gasket you see me working on above. Now check out the other end. See the grey, bigger gasket sitting on the table? As originally modelled, that too was a part of the white angle tube. It was all connected. In order to make it easier to mold and cast, and to further my goal of only making one large mold for the tube, that gasket was separated and will be cast as a separate part. This gasked needed treatment similar to the smaller one shown above.

So I cut a styrene disk, glued it in.

Then started cleaning up the seam. A little putty, a little sanding, and it's all but invisible. This will make attaching the gasket to castings of the tube super easy. Previously, all it would have is a micro thin lip to attach glue to, making the bond fairly week. Now I can just bore drywall screws through it if I wanted to.

This piece is proving to be difficult to work with just because the quality of the print wasn't super good. Lots of clean up around the edges and lips.

I did two passes at it today and made a lot of progress. This is also another example of a piece that has a drivers side and passenger side version, both mirrors of each other. Much like with the tube above, I chopped off the little flange that makes the pieces unique, and will cast everything separately. So instead of two large, complex and unweildy molds, I will have one medium complexity mold that can be optimized to use the minimal amount of rubber, and then a tiny mold for the flange that can easily be flipped and attached to create the mirror versions.

This next little piece is proving to be one of the most difficult to clean up. Just lots of tiny corners to get into and perfectly cylindrical parts are always hard to get right. I had the idea of just rebuilding most of it using tube stock and my lathe, but thought better of it. It's coming along. Probably another 2 or 3 sessions with it and it will be ready for molding.

At the end of the days work, here are three parts that are ready for molding. The two gaskets, and also the little flange that I spoke about earlier.

I decided to make my mold boxes out of corrugated cardboard this time, instead of foam core, which saved me the trouble of cutting all those little slits in a strip as I had done before so that I can get a rounded shape out of it. It worked great.

See that little black sharpie mark on the inside of the box? That's my fill line. Before building out the boxes, I measure the height of the piece I am going to mold, then I add about a 1/4" to it, and I use that measurement to mark the fill line. I have never been good with eyeballing how much rubber to pour into a box, and always end up using WAY more rubber than needed, so I developed this method as a helper for my own personal shortcomings. Of which I have many, of course.

Lastly, here's all the piece super glued down to the surface. I try to give about a half inch of border around each piece. Maybe a little less. I defintely don't need more, and maybe less would be ok. I really define the height of the fill and the thickness of the borders based on the shape I am molding, and how well the mold will hold it's own shape when it is empty. It varies a lot based on the complexity of the part. Something you just get with experience, I suppose.

Ok that's all I have to show off for now. Thank you for taking the time to read it, I greatly appreciate all the good folks who are keeping up with my blog, are asking questions, and maybe are even learning a thing or two from my ramblings. Until the next time!!!

Monday, October 8, 2018

Time To Make The Donuts

When it comes to building a replica of the Keaton era Batmobile, the place that many builders stumble is on a component that is often referred to as the "Side Mechanics" or "side mechs" for short. These have proven to be the most difficult pieces to find originals of. To my knowledge, nobody has ever discovered the origin of most of the pieces that were no doubt cobbled together from discarded industrial junk. There is a piece that has been identified as a part from a hot air balloon, but that's about all I know.

It has been my goal to put together a top notch replica of the side mechs for my car. Regular readers of the blog will know that my pal Tim Neill in canada modelled the side mechs based on extensive research and reference, and they are absolutely amazing. Tim offers them for free to download on his Batberry blog. Here's a link directly to the files, should you be so inclined.

A friend printed these files for me, and I set about the task of cleaning them up. My goal is to produce them in resin and/or fiberglass. I have kicked around the idea of getting them plated, but honestly I think painting them will be good enough.

For reference, here's what they look like on a screen used Returns car:

The process of getting this right has been incredibly time consuming. Cleaning up the 3d printed parts is super labor intensive, and also intersects poorly with my anal-retentiveness when it comes to perfection. I have invested easily a couple hundred hours in puttying, sanding, primering... repeating until these things are at a point of quality that I am happy with. Cleaning 3d parts is not only an art, but it's also a tremendous hassle. The filament sands differently than putty and primer. It's very resilient. A real pain.

I finished cleaning up the part that is often referred to as "The donut" almost a year ago, and finally just got around to molding it. In this post, I will walk you through the process I used to mold. This will be a fairly technical discussion, so if you don't really care about materials and techniques, you can skip this. I found a great video by my pal Bill Doran that showed his technique for doing a brush on, jacketed mold, and this proved to be very valuable to my process. Here's a link if you'd like to check it out.

Prop: Shop - Molding & Casting 101: Brush on Molds for Helmets & Masks

I started by bulding a box for the donut, with about 1/2" of space around it. I used 1/4" foam core, which you can get at Michaels or any art supply store worth its salt. I cut slits into a strip of foam core at about every 1/4" so that I could shape it into a circle. Building a square or rectangular box for this project would have wasted a lot of rubber. I used Smooth-On's Rebound 25 for this mold, which is an expensive platinum cure silicone that is resilient and really takes the shape nicely. It's billed as a product that sticks to vertical surfaces. While true, it's not quite... accurate. More on that in a moment. I brushed on two coats of the stuff using a 1/2" chip brush from home depot. Oh, the base is made out of a scrap piece of MDF. I glued the donut to the MDF using super glue gel. No accelerant needed. Here's a pic of the donut with the first two coats of Rebound 25 on it.

The real takeaway from this photo is that the stuff isn't thickening up in all the right places. The horizontal surfaces are acquiring a nice, even and thick coat, but the vertical surfaces are not. Though thick, the rubber still tends to succumb to gravity, and only leaves behind the thinnest of layers on vertical surfaces.

And that's where a product named "Thi-Vex" comes in. It's what's known as a thixotropic agent, which basically means it thickens the stuff up while retaining all of the rubbers original properties. Ie, it doesn't effect the cure time, the pot live, the shelf life, etc. I mixed up another batch of rebound 25 and eyeballed an amount of ThiVex and went to town. You basically just add it in a little bit at a time until you get it to a consistency that you are happy with. I was going for a cake frosting level of thickness. I then applied it to the donut using a "senior" tongue depressor. Those are the big ones, mind you. Not like typical Popsicle sticks. So complicated!!! I tried to make it as smooth as possible, though I was definitely going for function over form. Here's a pic of the donut after one attack of thickened rebound.

I ended up doing another pass with thickened rebound, then a final pass of non thickened rebound. I then pulled off the box walls. I used a piece of copper tubing to bore holes in the outer lip of the mold. These will serve as keys for the rigid jacket, and hold the flexible part in place.

I brushed a ton of wax paste on to the MDF base, as it is very pourous and anything I put on top of it will probably attach to it pretty firmly. Now it's time to make the jacket. I chose Smooth-On's Plasti-Paste, which is also what Bill uses in his video. It's super easy to work with, fairly non-messy, and is really quite rigid even at thinner applications. I mixed up a batch and as with the rubber applied it with a tongue depressor. I did two coats, which was probably not necessary.

I left that to cure, and in a few hours I pulled it off the MDF base using a spatula and all was good in the world. Here's a pic of the underside of the piece.

At this point it occurred to me that a mistake had been made. In order to save time, I decided to forego making a seam down the middle, which would have allowed for easy removal of the jacket. The donut proved impossible to remove, so I ended up cutting a seam line down the middle of the jacket using a dremel tool and a big cutoff wheel. No damage to the mold or donut, but it added some complexity to the final steps, as I now have to manually align the two halves of the jacket and keep them stable while casting up a donut. Not a big deal, but if I had it all to do over again, I would have done the jacket as two separate parts.

Success was still within my grasp, and as a test I used Smooth-On's 65D to rotocast a donut in two pours. It came out EXCELLENT and with a little clean up it will be ready.

The other side mech pieces are also coming along. Here is the first pull out of the mold of one of the attachment pieces. I don't even know what the name of this piece is but who cares it looks great.

That's it for now. Thanks for reading. I'm really happy to be making progress on this build again. Maybe some day I will actually finish it.

The Ugly Work of Fiberglass

Fiberglassing is messy work, and frankly I do not like it. Fortunately for me, my man Paul on the east coast is doing a lot of this work for me on the Mattmobile. A few progress pictures to show off.

These are replacement bumperettes. Not certain I spelled that right. These are the things that go right under the front headlights, and make it impossible to drive on any road that isn't entirely flat. Great design!! There's also a mold for the front wheel hub in there, if I recall correctly. From what I am told, most modern replica cars use the same wheel hub for the front and rear, though they are in fact different sizes on the screen used cars. So now mine will have both sizes. Yay for small victories.

Paul was also kind enough to remake my dash pad for me. I didn't even know that was a real term until recently. That's the thing that you put your french fries on when you're driving home from Burger King. The part that sits horizontal. This is a pic of the newly laid up piece.

Lastly, here is the dash board being joined to the dash pad. These originally shipped as two pieces, but having them joined and all the gaps filled in will give it a lot of structural strength and will of course be entirely pretty.

In other news, there's been a lot of work on the side mechs lately, and I have started doing some pulls from the molds. Results are absolutely outstanding and I could not be more thrilled. Still a few pieces to finish cleaning up the masters of, and a lot of molds to make. I purchased another 2 gallons of RTV from SilPak, and I am hopeful that this will be enough to see the project through to completion.

If you are just discovering this blog, please be sure to visit my facebook page for this build, as I tend to update that more frequently and you can also ask questions and follow discussions on different pieces and photos.