Monday, November 26, 2007

LHS Lay Down

With the RHS now edged and awaiting it's mate, it was time to lay down the LHS, or Left Hand Side of the gun. I photographed a few different steps of the process for this half, just to show more of the techniques I use.

Before laying in anything, I need to powder up the mold. My plan here is to do a combination of resin and 1630. When I did the other half of the rifle, I found that 1630 isn't always at its best when it comes to tiny nooks and crannies, because of its viscosity. My plan for this half is to lay down resin into the more complicated parts of the mold, let it cure, then lay down 1630 on top of it. The primary motivator here is the large detail piece in the center of the mold. This detail was cast separately on the other half. If I attempt to do this detail piece in 1630, I would expect pretty poor results.

Anyhow, here's the mold.

Next up, it's time to powder the mold. Why??? By putting baby powder or corn starch into a mold prior to pouring resin, you're doing yourself a huge favor. When you have a thin coat of powder in your mold, you'll be able to take advantage of a little thing known as "Capilary Action". Basically, the powder will physically draw the resin into hard to reach places, oddball corners, and tight spaces. If you ever get a resin piece with "blow outs" (the technical term for bubbles in the resin), this was probably caused by a person who didn't know to powder his molds. Folks, if you're pouring resin without powdering, you're just wasting your time. Or the time of whichever sucker is buying your resin parts. Rant over.

Just to be clear, lets walk through powdering a mold. The goal is to get a thin coating of powder over the entire mold, and in every corner. You do NOT want clumps of powder sitting in recesses. Clumps = bad.

I tend to put the powder on pretty liberally. You don't have to, but I want to make sure everything is covered.

I then use a brush to push the powder around, and make sure it's in all the recesses. Don't worry about clumps yet.

I don't have a photo, but the next thing to do is blow out the excess. I use a can of compressed air, but mainly because this mold is so huge. For a smaller mold, you can just turn it upside down and tap it a few times until there's no clumps.

And then you're ready to lay down some resin.

Recall that the first thing I'm going to do is pour in some resin, into the tough to get to places. I mixed up a little cup, and poured it into place.

I then used a chip brush to push the resin up against the walls, into the details that I want good exposure on. The purpose here is only to get a thin coating. I'm not going to wrestle with this stuff as it cures and try to force it to stay on the walls. Just a thin coat is all I need. I do this in all of the areas I want covered this way.

Because I have already walked through the process of laying down 1630 in an earlier post, I'll skip it for this one. I did things a little bit differently on this side, mainly because I realized I didn't need to be as tidy. Last time, I was really paying attention to getting crisp edges, not realizing that I'd end up sanding down all that flash with the cheese grater. That cost me time, which meant the 1630 had less work time.

Here's the left side all finished.

I forgot to post about a really cool thing I found at Home Depot. They now make these really neat tops for gallon paint cans. It adds a pour spout to any can. This is REALLY helpful, as it saves you all the time of cleaning up the lid after each pour. Without them, you also tend to get a bunch of stuff running down the side of the can after each pour, which gets really messy really quickly.

I gave it about an hour and a half to fully cure after my final lay down of fiber, and then demolded. Just like the last one, it came out beautifully. Only a TINY TINY bit of damage to the mold. I was a bit concerned about that circular detail piece, and what it might do to the mold upon exit. Recall that the free standing side detail mold died after just a couple of pulls. But no worries, it all turned out fine.

It took about another hour of work with the cheese grater and dremel to get all the flashing off and the edges up to snuff, but it turned out really nice.

There was only ONE tiny problem with the pull. One of the detail pieces, which is specifically poured in resin to avoid any problems, had a couple of blow outs in it.

Turns out, I didn't completely blow out all of the powder from the mold before pouring the resin in. There were clumps! This is what clumps look like when you don't get rid of them.

The good news is that it was a simple matter to just pour some resin into the mold to make some replacement parts.

Naturally, the piece came out great. Because I had some extra resin, I poured up copies of the other detail pieces, in case I ever need them, or something goes wrong with the mold.

Similarly, I poured up a duplicate of the center detail piece from THIS side, as I figure this will be the first thing to go on the mold when the time comes.

That's it for tonight. I spent WAY too much time on this tonight. I should be sleeping in prep for a busy day at work tomorrow, but the long weekend threw off my sleep schedule pretty thoroughly. Tomorrow, I'll take a look at mating up those two halves.

As always, thanks for reading.

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