Every once in a while I need to add weight to something be it an RC plane or a miniature that constantly topples over. In this project a plastic miniature base weighing about 0.5 grams gets increased by an order of magnitude. For this I have a simple system which can add weight to any object that can be hollowed out or has space.
For this project we need:
Step 1: Choose your weight
Find a coin or piece of metal the fits nicely in the space that exists or can be hollowed out. In small projects there is a limit as to how much weight can be added but with larger ones there will be more options. For miniature bases coins seem to work best.
Step 2: Preparing the part
In this example we are adding weight to a standard 28mm scale base.
This particular method of cutting out the support is for models that will be pinned (message me for more info on pinning or head over to some forums like WAMP). If the intent is to just use a figurine with the standard support bar simply cut the metal weight into small enough pieces to fit on either side of the gap and fix them in place with the method described in Step 4 and on.
A #1921 blade is preferred since it allows access into the tight space and the steep blade angle allows for easy down/inward cutting. Be careful not to twist the blade as that can cause plastic bits to fly off at great speeds. If it seems hard to cut the blade might be dull and in need of replacing. Also, making a rocking motion can help on thicker plastics.
Make sure to keep fingers out of the front area of the blade as it can slip and in close quarters this makes for a fast and sometimes deep cut. Slip joint adjustable pliers are a handy tool for holding onto small parts when cutting (get a cheap pair and spray/dip coat the teeth with a few layers of Plasti-dip).
For other parts and projects prepare them as needed to insert the desired metal weight.
Step 3: Sealing the gaps
JB weld starts off as a runny thoothpaste like subastance and then hardens enough to be drilled and tapped. So we don't want it just running all over the table.
There are many choices to seal any gaps: Hot glue, putty, clay, tape, instant mold, etc. Blue painter tape seems to work the best and doesn't get stuck in the adhesive. Instant-mold also does not stick to JB weld and I use it frequently to make objects and parts (want to know more, message me). It didn't seem right for this project because it would not be able to reliably seal the gap and keep adhesive from leaking.
Place enough tape over the top to cover any gaps and, for the base, some hanging over the edges. This excess will be used to secure the base to a surface, such as a cutting mat or cardboard, with more tape.
Step 4: JB Weld once
JB Weld is a two part one to one adhesive that hardens after it is mixed. I find it usually has a working time of about 2-4 minutes before becoming too tacky. It will then take the better part of a day to harden completely. Much like concrete once it has cured for a bit it can take impressions such as finger prints which can be fun or annoying depending on what and where.
My preference is to have the coin showing which is completely pointless and just a matter of taste. I also would normally do many bases at once and mix up a larger amount of JB Weld in a little dixie cup or the like (but not more than I could spoon into each base). If the coin is too thin to be flush (like the one I chose was) I first add only a little adhesive and let that cure.
Step 5: Weld again with a little complication
After curing a second small amount of JB Weld was mixed, spread and the coin placed in it. Trouble was the coin was now too high but a little pressure fixed that. Then when the pressure released the coin was pushed back up, the JB Weld that had been extruded out the sides was sucked back in. This is all a very interesting physics study but we're on a time limit so a quick fix was found to keep pressure on while the adhesive set.
Step 6: Stack em tall
Coins stacked on top and clamped down with a binder clip did the trick though it took a few tries to get the right number. If I had had one handy I would have simply used a c-clamp.
Step 7: Clean-up and file down
After curing overnight the base was removed from the clamp and tape. The extra adhesive made for an uneven edge but that is taken care of with a flat file. Flip it over and the once 0.5 gram base is now 5 grams and ready for use.
As I mentioned before I took extra care because I like to see the coins but one could just make a batch of JB Weld put some in the base, drop in the coin and add more JBW until the base was full. One step, no clamping but I thought a demonstration of the possibilities over simplicity would be better.
Thank you for reading.