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| Xiaou2:
Heya, Just wanted to pass on some notes about aluminite. It may appear hard - but at any less than 1/2" and its pretty brittle. Drop it to the floor and it will break in many places. This means that any fine details are very much in danger of cracking off at the slightest pressure. The stuff isnt too expensive - but - the rubber needed to make the molds is! And since you need a lot of it... it adds up fast, especially if you make mistakes... or have to make several molds. The plastic itself has to be just the right tempature as well as pre-heating the mold to ensure it will develop correctly. Sometimes my parts would come out sticky because of this - and wouldnt cure properly. Thinking about this now... the water meltable plastic is actually much harder and durable than alluminite. The only drawback is that its kinda tricky to work with... as well as the fear of it changing form in a 'heated' situation. I suppose if you coat alluminte creations in some sorta hard epoxy... you might have better durrability. Id recomend other stronger and more professional plastics. Btw - if you want to experience aluminite without buying it - its sorta the same as 'JB Weld'. Ohh - and about your mold there... you might try making a 2part mold next time. Took me a little bit to get the hang of it... by submerging only half the object into the rubber, and half into clay. When the rubber cures... then you remove the clay, clean it up, and wipe it with release agent... then fill the rest of the mold to completely cover the part. When that is cured... you should be able to pry the 2 halves appart. Dig a 'fill' channel to the main empty body. You can use rubber bands to keep the parts together when you fill it. If done this way.. there is very little problems with having to sand and clean up the parts. However... if you have too many odd caverns and details... air bubbles will get caught when you try to cast the plastic. Supposedly, if you have a Vaccume chamber, you can illiminate this problem... but, they are major expensive. |
| ErikRuud:
Alumilite, Smooth-on and many others are polyurethane resin. JB Weld is an epoxy, not really the same. Sticky castings are usually caused by inaccurate measuring of the two parts. Part A in poarticular canabsorb moisture from the air. This added moisture can also cause the stickiness. Polyurethane resins come in moany varieties. If the standard resins are not strong enough use some of the others. Smooth-On's "Task" series of resins are designed for high strength. I use the smooth-on resins to create HO Scale slot car bodies. I have had bodies come out brittle. I have also had them come out with the consistency of a fruit roll. You HAVE to get the mixture just right. You can recycle some of the silicone mold material from your old molds and mistakes by cutting them in small chunks and using them as filler in ne molds. Just keep the filler chunks away object that you are molding. http://erikruud.freeservers.com/maelstrom/resin.htm http://erikruud.freeservers.com/maelstrom/Resin/index.html http://erikruud.freeservers.com/maelstrom/Resin/pictures.html |
| darkcape:
ERIK genius idea useing old latex to fill in the voids. I would not have thought of that in a million years. glad I havn't trashed my old mold yet. and I have to agree JB weld and alumilite are extreamly different only similarities are that you mix 2 halfs to make a whole. will look into smooth-on but i'm very happy with alumilite. and i can pick it up at the store next to my house. does anyone have any idea where to get larger quanties of latex for the mold? for 10 - 20 pieces the 20 oz jar is going to take forever with a lot of wasted conatiners. back to the clay mines. never would have thought I had lost so much technique from high school art class.but i guess if you don't use it you lose it. ;D |
| ErikRuud:
Yes, it is nice to pick it up at the hobbyshop, but they tend to just carry the basic varieties. If you need something else(high strength, clear, etc), you will have to order it from somewhere. Most of the resin suppliers have silicone (not latex) in larger (Gallon) sizes. You could use latex, but it has a tendency to shrink. I cannot take credit for the recycling idea, it has been around for a while. I like to use Legos for making mold boxes on smaller items. |
| Xiaou2:
Guess I should have been a bit more specific. I meant that in terms of brittle-ness...jb weld is simular. When its dry - jb weld has a simular texture, feel, strength, and cracking property. While it is a paste - its still a plastic like substance made from a 2 part mixture. darkcape, if you use sculpy - you can bake your model hard... and that will give you the ability to do the 2 part molds - (using clay to temp. cover one side). Aluminite carries the gallon jugs of the rubber. Its like 100$ a gallon i think. Which is how things add up quickly : ( I dropped like 500$ easily trying to make tron spinners.. but failed cause the encoder wheel spokes were too brittle, missing, bubbled...ect. |
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