Guy Helmet part 3
I see a pattern here, procrastination and lack of progress has not helped me stay on top of this blog. As I write this entry, I only hope I get this out quicker than the other posts. I was dissatisfied with the last mold and its lack of cooperation, so I decided to do another, slightly different, offering me a wider range of molding. I will still work with the fiberglass resins but also going to try the slush casting. I’ll explain this over in a bit. First, I have to express my gratitude for shear luck and happiness with my most recent purchase for this project.
At the end of the last entry, I was on the fence about forking out a bunch of cash to get all the new materials for molding. Luckily, I am a ‘member’ of Blick art supplies and they send me junk mail, like everyone else. On the upside to this, the day I decided to go and buy additional material I dropped by the mailbox (which I never check anyway) and found a 40% off coupon for any one item in the store. So I thought this would help some, it didn’t – it helped A LOT. Instead of having to buy everything seperately and spending about 130$ for everything, I found Smooth-ons starter pack that included everything I needed for 70$ retail. It had: rebound 25, plasti-paste II, smooth cast 300 (slush cast), THIVEX!!, step by step poster, dvd, and sonite wax. But with said coupon, I dropped to 45$! I like deals especially when they stack.
I was super excited about the Thivex and after using it, was absolutely amazed at how far I could spread the rebound. I worked with about 6 ounces at a time. By increasing its viscosity I was able to use a smaller amount and get a better coverage around the helmet. I can’t emphasize how useful this stuff was and how much I encourage you to get this for ANY project using moldable silicone. Even with using a 1/4 of the stated amount makes the mold more viscous which makes it much more manageable and controllable. I used a total of 4 pints (2 of each halves since you mix them) on this mold to avoid any issues with thickness. I am even considering purchasing one more just for good measure, but then again I remember its expensive and promptly change my mind until I got another coupon in the mail and went for another combo pack. This was good since I decided to double the plasti-paste as well.
Whats Covered – When last left off I was at a major snag with the mold and casting, building a second mold, which will be completed and covered. This update will also include a quick casted prototype. I want to get a feel for the different types of casting I can pull off. I have also taken a different route for this than seen by Volpin here, which is retarded good and I probably wont be able to match it, but the goal is to try, right. Although I will be building the bases for the LED’s it won’t be covering any wiring or LED’s for some time, that is total unchartered territory for me. I had intended to get more stuff up per installments but I realized I would rather get stuff on the site quicker, so I have decided to just blog as I go.
Since my last mold was too thin. I decided to take the opportunity to make this second one thicker, more durable and with a more sturdy base for variable molding. The hole drilling and pull tabs work well, but still a pain in the butt. And since I am making a second mold it doesn’t matter. unless I need a backup mold. This was a major step backwards, but I feel necessary.
I went to Lowe’s hardware store to get a board strong enough to not flex while casting. I found a 3/4 piece of melamine plywood scrap (picture is of shelving, but I was able to get plywood). After talking to one of the reps, they marked it free and just gave it to me. Money saved is, well, money simply not spent. Aside from having a particle board interior, this board is perfect. The plastic offers a perfect surface to work on without issues of wood debris, dust or particles getting in the way.
I placed my bust in the middle of the board and started applying coats of Rebound 25.
I applied 3-4 coats working in sections covering the helmet as best I could starting with the ear area. I decided this was going to cause the biggest problems later on with undercuts. So I tried to fill it in with as much mold material would fit to avoid this.
Once the the helmet was covered completely, I decided to try a couple layers applied using Thivex. This was a great decision. I was able to make the mold work more efficiently.
I was able to use less at a time but spread it over more area allowing me to have more control in application. Because of this I was able to apply a number of coats with less and still get a thicker shell without wasting hardly any mold.
Mother mold – same as before, so an abridged version. I used 2 containers since I needed excess for the base, body and extra for bolting together.Instead of parting the material straight down the centerline, I went ear to ear, over the top at an angle adjacent with the top ribbing. I also applied a coat of fiberglass to the excess mold (as seen in part 2) for extra support and stability.
Sorry, its upside down here, only shot it took at the time with cast inside. Again drilling directly through the molds for the bolts for both the mold and the new base now.
Release agent is your friend, becomes buddy buddy with it. I used a good amount on the mold before applying the mother mold and still had some serious issues getting it off. I had to have serious help prying it off without breaking it entirely. And by that, I mean I actually cracked the front of the mother mold pulling it off. Luckily, I was able to fuse it back together with some fiberglass resin, which, in the sun during lunch and a trip to the hardware store to get bolts, cured perfectly.
Now that I have the everything pulled free of the bust. I took a circular drill bit and cut out a 2.5 inch circle in the center of my base.
This allows room for the casting resin. After a bit of cleaning the hole up from random particle board bits, I bolted the mold down to the board. Ready for casting resin!
Smooth Cast 300 calls for a mix ratio of 1:1 of 2 separate parts, 3 minutes pot life, and 10 minutes cure time. I write this down since It holds true and you have to physically keep moving your project around in mid air, allowing the resin to cover the entire interior surface area. It mixes clear and is very low in viscosity, so it pours like water.
I forgot here that I didn’t have a huge rubber stopper, like Smooth-on shows in the tutorials, so I had to improvise and use what ever was available at the time. I went with one of the plastic cups I use for mixing.
To keep it from collapsing in on itself, I stuffed it with a tennis ball. Although, not very attractive or professional looking, it seemed to work just fine for me. Followed with about 7 minutes of nonstop moving around to get maximum coverage. Although you can kind of feel and hear the liquid sloshing around inside, once it starts to set you can get a way with less movement.
Here is a of shots after we pulled the base off to see how it worked out.
The coverage was fairly good but thinner in certain areas, as you can see. Here is the helmets first pull as a cast from the smooth cast 300.
For the first prototype, it looked great. With the exception of the thinned areas, I was extremely happy with the turn out, and have been planning better methods for better coverage over the tough rises near the ears.
Another reason to be super happy about the results is the mold held up! the entire cast was practically flawless, with a few exceptions. Out of excitement, I grabbed a random visor close by and quickly cut out the excess unneeded parts of the helmet and placed it in to see how it would come out.
Please take into consideration this is a super first draft prototype and I plan to do more higher quality, which you will see posted later. Otherwise, sofar so good. Now time to clean up and do a couple of casts for real!
After thoughts – Something I noticed after pulling the first cast was air bubbles that didn’t release which caused thicker bubbling in the resin in the ear piece. I went through the mold yesterday and filled them in and should have fixed the issue, as well as a couple of other minute flaws. Either way I will have to go through and sand a few placed down and clean up but I am still very happy with the turn out.
Next up – make some more casts! This is way too much fun. Also more visors to vacuum form based off a cast. I am also going to get some tint suggested by Voplin here and start to work on the back head piece.
More to come, thanks for checking in. Please leave feedback and let me know what you think!