Pressure Cast Bases

[amphoterik]

Howdy everyone. Finally got my pressure pot system to stabilize without leaks (gobs and gobs of of "cast-a-gasket") and am going about making resin bases. The bases I have made have overhanging rock and tile, which make a large amount of air bubbles. In the past when I cast these, even if I used a stick or something else to clear the bubbles out, there were still a ton. I have cast the bases under pressure a few times now and they have come out perfect. The big downside, however, is getting the bottom of the bases even. So far, they have either sunken in because there wasn't enough resin, or ballooned out due to too much resin. This weekend, I am going to be doing some measured experiments to gauge the perfect amount of resin to use to cast flat bases. I will be taking pictures and posted them here.

In the meantime, does anyone have any advice or experience to give me?

[mangozac]

I've not done bases before, but I've heard of some people filling the bases with resin and then using plastic to wipe the excess resin away. I'm sure Bec will have some more to add, since she's doing some mass base casting at the moment.

[blind pig]

I have indeed been casting up several hundred bases in the last month.

It is just a matter of knowing just how much to pour in and not over pour, or worse, too little resin (which is more of a problem). I generally get it right, but if I do pour in a bit too much, I use my Ryobi bench sander to make sure I have a flat bottom on my bases.

If you don't have a bench sander, using 40 or 80 grit sandpaper stuck on a *flat* piece of board (like 12mm MDF) is perfect for ensuring flat bases when they have been over poured slightly.

Wear a suitable dust mask when sanding resin.

Post pics of finished resulty.

[amphoterik]

Sanding is what I have been doing so far. I am basically going to experiment to find that perfect curve of resin so that it cures flat.

[blind pig]

[silent35]

Been casting bases also myself and agree, the best you can do is get them a little concave or overflowing. I overfill the molds a little and then drag a spatula across the top of the mold to get rid of excess resin. This results in a slight concave bottom, but not noticeable.

I find the bases come out better with a slight concave then overflow. You have to sand a lot more with the overflow.

I was not pleased with Back2base-ix's products. They don't try to smooth out their bases and there is a lot of overflow. Also the resin they use is quite soft.

[mangozac]

I don't see why a slight concave is a problem anyway. It's the bottom of the base and won't be seen. Normal plastic bases are hollow!

[Munkey Joe]

Ok Im going to necro-post a bit bit I will put my input in.

When Im casting in plaster (merlins magic mostly ) I use a putty knife to smooth the bottom.

Resin I don my mask and get the venerable belt sander out, IF my casts are wonky. mostly they are pretty good. I have used the old Glass technique () for resin but honestly I see little need for it with bases.

[paulson games]

I do the bike bases for my wolves in a two part mold that way there's no issues with the bases not being level or being concave etc. All I have to do is clip them from the sprue material and no sanding needed.

Here's a pic of how I set up the bases for casting, this would be as viewed from the bottom of the bases, the grey pieces are the sprue that's made with pieces of strip styrene that's about 1/8 of an inch thick. I pour on one side and the sprue lets the resin flow into the other bases and the air flows out through the vents in the top into the reservoir.




As the sprue is attached only to the bottoms of the bases all you need to do is clip the sprue flush with the base and you won't need any sanding to have everything level.