Hi, this is Wayne again with a topic “Building up to Maker Faire: Part 5”.
Hi my name’s Sean Thorson. I make props and costumes for all sorts of different applications and this year to get ready for the Maker Faire, I’m building the giant bad guy robot from the original Robocop movies called ed 209. It’S going to be everything I can do to get it done just in time for the event, and here we go welcome back we’re looking at 26 days, left to finish this project. It’S been about two weeks since the last update. So let’s go ahead and look at the parts that are in progress right now, so the last time you were here, I just about gotten the toes to the point where they’re finished up and ready for molding. And now, if you take a look, we’ve got all six toes nice lightweight pulled in fiberglass. They still need a little bit of body shop, work and then primer and paint, but otherwise they’re ready to go. I also have one of the thighs here. It’S coming together. Still need to make the hydraulic rams that will run up and down in between the rockers and the top of the thigh, but otherwise it’s a finished part moving on I’ve made pulls of the shoulder flap. So this part, I just had a couple of pieces of wood. Last time you were here now, I’ve got the pair of them all pulled and ready to go. These will fit nicely into the main body here: prototype for the main body. I’M gon na go ahead and call it about 90 % done still have a little bit of smoothing and filling it needs to be done before I can start glossing it up and getting it polished and ready for molding fitting into the side. Here went ahead and pulled out CNC machine and cranked out parts of the gimbal for the armpit here. So this is the outer portion there’s also an inner portion and with a little bit more sanding and filling these parts are gon na, be ready for vacuum.
Forming the next part that was nearing completion in the last update was the waist and pelvis section here needs a little bit more wet, sanding and cleanup, but otherwise it should be ready to be molded here pretty soon recent pieces out of the molds. These are the little flaps that go just above the lower leg, because they’re actually locking flaps that go on either side of the heel block. When the robot activates these will move, then I’ve got a few small parts that were just about ready to mold here.
So these are going to be the hinge pieces. That’Ll go on the end of our ankle flaps. This is one of the small details. It goes in a gun pod and then these little guys here I’ve been calling the oil filters, but they’re, probably a smoke launcher arrangement that’ll end up fitting into these recesses over here. So if you’ve been following the flicker feet at all, by now you’ve seen pictures of the prototype that I put together for the elbow it was all cut out on the CNC machine and it’s a big heavy wooden piece. It’S really not going to be especially sturdy, especially since it’s made out of MDF if it gets any kind of moisture to it. It’S gon na fall apart and start to deteriorate pretty rapidly, so I’m gon na end up duplicating it again in resin, like a lot of the things that I’ve put together so far now, unlike the solid resin cast pieces that we’ve done before like this, this was Made with a block mold, it’s a solid piece: it’s got a little bit of weight to it. There’S really no reason to do that with the elbow parts, because they’re rather large, it’s going to end up weighing quite a lot and cost quite a lot of money worth of resin. So, in the end, what I’m gon na want to make is a lightweight hollow copy of the prototype made out of resin. The process that I’m going to be using is the same process that I typically use to make helmets right. This piece is rotocast in order to make a nice lightweight hollow piece. Basically, what I do is I make a mold, and then I put just enough resin inside to coat the surface roll it around until I’ve got a good coating all the way over and then once it cures, you end up with a hollow shell, that’s fairly sturdy And lightweight so that’s an overview of the process. In this case, I’ve got two parts of the elbow. One of them is ready to start a mother mold, so this mold was made in a different manner than the block molds that we made earlier on this one called a glove mold or a jacket mold.
Basically, I’ve taken the rubber here get a print coat to pick up all the details on the surface and then after that cures I add thixotropic agent, which basically is it’s going to increase the viscosity and it’ll, make the rubber itself actually thicker. So it will cling to vertical surfaces without just flowing all over the table, making a huge mess and wasting a lot of material after that cures, once I’ve got it built up thick enough. The next step is to actually build a fiberglass mother mold. Now the clay that you see on here is going to become the parting walls for the fiberglass mother, mold, and the mother.
Mold itself is basically made in the exact same way. The fiberglass molds that I use to make parts earlier on in the series. Now.
The other half of the elbow joint I’ve already made rubber jacket mold and I’ve already made the fiberglass mother mold. So this one was the two-part mother mold just to get the two halves lined up, and the purpose of the mother mold is to keep the silicone rubber from collapsing or twisting under its own weight. The rubber itself is still flexible so without something to hold it straight. It’S gon na end up, caving in on itself and we’ll end up with a part, that’s warped or twisted in some way. So I’ve got two halves of the mother mold. Once the fiberglass is cured.
I trim the edges and go ahead and separate the shell, the mother mold, from the rubber jacket mold now, depending on the shape of your original part, you can get away sometimes with just taking your rubber jacket, mold and actually peeling it off just like a glove. Unfortunately, because of the fact that this has some fairly narrow parts to it, I’m not going to be able to get away with that. So I’m gon na end up having to split the mold. In this case, I’m gon na start on what will become the inside of the elbow. I’M just gon na take my knife here and I’m gon na start making this very clearly zig-zag pattern, as I cut along the rubber. The reason I’m not just going in a straight line is because I want to make sure that the cut will be easy to put back together when it comes time to actually make the rotocast copies. So the next step is going to be to start frying.
This thing apart and continuing with my zigzag pattern, so once we’ve got the prototype piece out of the mold you’ll notice, the mold itself isn’t really gon na hold up under much strain. If we pour a bunch of plastic into this as soon as you start rolling it around, it’s gon na warp and twist and collapse under its own weight. So this is the reason why we’ve built the fiberglass mother mold so just go ahead and take the rubber jacket.
Mold nest it inside with the fiberglass rip mother mold, give it a quick look on the outside and make sure that the seams are lined up and bolt it together. So once the part comes out of the mold, that’s just a question of nesting. The rubber jacket mold into the fiberglass mother mold, so that everything lines up properly and once you’ve got it all bolted together. The next step is going to be making sure that the seams are all lined up on the inside so that you don’t end up with a bunch of excess plastic leaking into that seam and creating mold flashing that’ll have to be cleaned off later so next step. I’M gon na go ahead and mix up a quick batch of casting resin stuff that I’m using now has a black pigment added into it.
So I don’t have to worry quite so much about paint scratching and showing through some bright white color, so this particular stuff mixes 1 to 1 by volume. I know we just need to stir it thoroughly to make sure that everything is blended evenly. You notice, I’m scraping the sides of the container, while I’m doing this just in case there’s any residue Part A or Part B that hasn’t been blended in yet, and the next step is just gon na be pouring it into the mold and once it’s been poured In we’re just gon na roll it around so that it coats the inside of the mold, want to make sure it gets coated evenly trick with a piece like this. With all the gear teeth on that sort of sprocket arrangement, it’s making sure that all the teeth get covered a lot of times.
When you see guys that are doing this, it don’t have a lot of experience. What you can do, instead of using the black resin like I’m using you, can take your regular white, resin and add pigment to it and since you’re going to want to do more than one layer, you use a different color for each layer. That way, you can kind of keep track if there’s a spot that you’ve missed in one of the second or subsequent layers. The challenge now is to just keep everything rolling around so that we don’t have a big puddle.
It’S probably a little tough to spot on camera, but you can see if we just let it pool it all kind of groups into one area and that’s gon na be a thick heavy spot. While everything else is paper-thin. I really don’t want that. So we’re just gon na keep rolling this around so that everything spread out evenly by the time it cures makes for a good workout.
You do five sets of five reps next thing. You know you’ve got a whole bunch of robot parts and much bigger arms. Now, in this case, I’m just trying to make a lightweight part, but if you were making say a costume piece of armor or a helmet, that sort of thing you want to be careful not to have little strings of resin that are gon na try and drip, And make all your stalactites and stalagmites and tiny little head stabbers inside that are gon na make it really uncomfortable.
So you end up having to go back in and grind pieces off before you have your part finished all right looks like nothing’s really moving anymore. So that’s the end of the first coat the next patch here, I’m gon na end up mixing pretty much the same ratio. I’M gon na stop a little bit shy, so it’ll be a slightly smaller batch of resin, but in order to make it a little bit more viscous, I’m gon na end up adding what’s called micro balloons or microspheres, it’s basically a filler.
It’S going to reduce the weight of the finished piece and basically these are tiny little glass bubbles hollow on the inside. So now, when I mix my resin, I’m just gon na go ahead and blend these in then we’ll just pour it in. In this case, you’ll notice, the resin ends up being a little bit lighter color because of the white powder. That’S mixed into it. All right coat number two coat number three, I’m just gon na go ahead and start laying up right now. Yeah dust mask is a good idea when you’re working with micro balloons, because otherwise tiny little bits of broken glass work their way into the air, while you’re breathing work their way into your lungs start, causing damage leaves scars all that chicks, dig scars.
But it’s hard to show them the ones on your lung tissue. So it’s a good idea to be wearing a mask, if only for that reason – and that’s pretty much it so we’re gon na – let that set up for a minute. So once the third coats dry rather cured and solid, we can go ahead and pull the mother mold apart and there’s a piece of giant robot elbow just a little bit of sanding and cleanup to get rid of some of the rough patches where the mold decided To tear and it’ll be good to go so once again, here’s the original that we started with and then here’s the rotocast copy a little bit of sanding and cleanup primer and paint, and it’s gon na be a pretty convincing piece of robot. So that’s the short version of roto casting make sure you read the accompanying article for even more details and pictures of the other half all finished.
I’Ve got 26 days left to finish the whole project. We’Re still making good progress, make sure you tune in next time. .