Watash, over in the HO forum you wrote: <BLOCKQUOTE>quote:</font><HR>another thing you might do. Wrap a small piece of modeling clay in suran wrap. and gently press it into the boiler over the front drivers then gently press the boiler down onto the frame. When removed, that shape can be covered with plaster with a malt straw as a sprue (for a mold). When the plaster has set for a couple of days, or until hard and dry. Yse a fine thin coping saw to split the casting mold. Remove the clay and wet just the edges of both parts of your mold. While wet, apply a thing layer of new plaster along the surfaces, and press together wrapping with rubber bands to hold in place. When dry, remove the rubber bands and apply an old "C" clamp gently just to hold the two halves together (just in case). Heat the plaster very slowly untill it gets 375 to 400 degrees F. Pour molten lead into the sprue until the sprue is full, and let cool. Remove the plaster. The lead weight will fit in the area better than you would expect. With a little practise and common sense, you will find other things to make this way too. <HR></BLOCKQUOTE> Do you like this method better than taking # 9 lead shot and glueing it over the boiler weight, or covering the motor with saran wrap and opening the smokebox and pouring the shot in mixed with some glue??? I've also wrapped solder around pilot and trailing truck axels to keep them on the rails, this helps with the trucks but not so much with the loco weight, something about 'sprung' vs. 'unsprung' weight. Thankx as usual
Pouring a solid (molded) slug of plumber's lead is the greatest concentration of weight, short of pouring the entire boiler. To keep the plastic boiler for looks, the idea is to gain the greatest body weight over the drive wheels. We nearly messed up the first try. We pressed suran wrap all around inside the boiler and taped the outer edges together on top of the boiler. Then we wraped the motor and frame in suran wrap and taped it under the wheels and cylinders. We added a couple of layers of 3/4" masking tape all around the motor,and over the worm gear. We slipped soda straws over the wire leads and taped them to the rear frame then we inserted the frame into the boiler. The boiler/frame was mounted up side down on our work bench. We poured bird shot (more weight in same space as one buck shot ball), until it came up to surface at bottom of boiler. Then we mixed polyurethane and slowly poured over the bird shot at one side until it came up on other side. (Liquid seeks it's own level). Polyurethene also shrinks slightly when curing. That afternoon we went out to check it out. We discovered that polyurethane also generates heat during the cure, and thinned out and flowed farther down out of sight. When lifting out of the boiler, we found that we should have wrapped the motor in such a way as to create a draft angle. The motor was too tight to get out of our new casting. We finally pried the frame out by removing the motor mounting screws. The motor finally came out because the masking tape gave way allowing some slippage. The bad thing was that the masking tape had vulcanized to the suran wrap, and the polyurethane had a death grip on the suran wrap. It took more time to clean up than it did to prepare. The casting survived almost intact, and we didn't break any plastic parts. The decision was made to use molder's wax, or modeling clay from then on. Casting the solid slug was much easier and heavier, but you will lose the plaster of paris mold each time and the wax pattern.
Hello My dad is a beekeeper, and when it comes to mold making he swears by beeswax. This stuff easily melts easily in a can set in a pan of boiling water and can then be poured into the boiler(sarnwrap Sounds like a very good idea), and then used to make the casting. Because it gets liquid, and it easily cleans off of anything(well, almost), it can be used to make just about any casting. Anybody ever try it?
Benny,thats one of the waxes we use for really fine detail lost wax castings. We put the cast of the wax in the frige so it gets hard, then carve any additional detail, and slick off any flash. we always make at least 4 waxes, attach sprues, then attach them to the tree and cool again. Bee's wax is one of the easiest to use because it dusts very well without having to spray with hair spray to get it dusted the first time around. It doesn't have to remain cold while dipping either. You can clean up your tools with hot water and a little isopropyl alcohol.
