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I'm looking for a way to cast a rod out of clear epoxy resin. (I want to make a fake lightsaber.)

The most obvious way would be to use a hollow cylinder-shaped mold, but I'm wondering if I have options.

I can imagine there might be some process involving a spinning object that currently eludes me, that would result in a rod with a perfectly smooth surface—smoother than could be achieved by using a mold, due to centrifugal forces and or gravity and such. ("The Force" exempted.) Submerging in some sort of liquid, maybe? Out-of-the-box-thinking.

As for molds, suggestions for good molds are welcome too! I was thinking about PVC plumbing pipe, but have no idea how to retrieve the rod (intact) after the epoxy has set. Maybe I could grease the pipe with baking spray prior?

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    Have you looked at buying suitable acrylic rod (arbitrary example website, they also do tube -- lighter and cheaper) instead of casting yourself? – Chris H Mar 3 '17 at 9:41
  • What size are you looking for then? Approximately a life-size lightsaber? – user24 Mar 4 '17 at 1:30
  • @Creation E: Initially a small keychain-sized test, but if that works out well, yes, a big one. – Protector one Mar 4 '17 at 19:49
  • @Chris: I have, but I want to try making something myself. For fun. :) – Protector one Mar 4 '17 at 19:50
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    A way to make it seamless is using some pipe as a mold, and destroying it in the process of extracting the final piece. – SF. 2 days ago
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So assuming you want it solid and not hollow. I really think the comment Chris H made about the pre-cast acrylic rod would be a much better option financially and structurally.

If you do want to go down the route of casting however, the pipe option is one you could do with. If you ensure there's mold release all down the inside of the pipe, giving it a push at the end providing it doesn't decide to fuse with the pipe - lots of people de-mold with air guns too. However, you have to allow for the fact that when resin is curing, it heats up. So even if you make sure you buy the straightest pipe imaginable, you can still run the risk of it warping and trying to fuse with the pipe.

Heat and general casting also create the other issue - air bubbles. If this is a life size model, then you probably wont find a vaccum chamber to remove the bubbles. You Might get away with it if you have a lot of time to let the air bubbles out - like a resin that cures over a few hours, but if any remain, they will catch any light you throw up though the saber and will stick out like a sore thumb.

I cast a huge chimney before for a giant replica of the Battersea Power Station. To do this, the blank was made - originally turned by one of the woodworkers on the team, and then detailed ribbing was added. This blank was then cast in silicone rubber using a large pipe it could sit into. This also involved a plug being made too, as the top half was hollow on the inside to reduce weight. Once the silicone jacket was made, before removing the chimney, we removed it from the pipe and created a 3 part (two sides and a bottom) fiber glass jacket which could be bolted together to make sure it kept it's shape. Something that large will not stay straight on it's own. This is the kind of method I think you'd need to use if you want a smooth rod that will be straight and usable.

The other thing you need to consider is the structural integrity of the rod. A lot of clear resins would not be very shock absorbing if they're cast that long and thin. One bad smack could cause it to break at the hilt - which if you make the mold wouldn't be too bad. An Acrylic Rod would be able to stand up to a bit of abuse, and you can chose to frost it if you want to catch the light better. You can also shape the top so it has a nice dome finish like lightsabers would have.

Lastly, if it's something that's going to take a lot of abuse, no just for display etc. I would recommend getting a Ludosport saber, or at least looking into what kind of polycarbon their lightsabers are made of, as they can withstand a lot and still look rigid.

I'm sorry I know it sounds fairly negative, and I don't mean to put you off casting if that's what you want to try. I'm just trying to highlight what you're trying to cast is not normally something that would be done when there are other cheaper less time consuming options available. If you want me to go into more detail of how you could use a silicone jacket to make it I can do.

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  • Thanks for all your pointers and anecdotes; I appreciate it! The reason I going to try casting myself, is because I want to experiment with adding particles to the resin to get a uniformly lit rod using a single light source, a opposed to one that has multiple LEDs or those that are diffusely lit from the source. I also don't intend to hit stuff with it, but I agree that other options would probably be wiser for sake of durability. – Protector one Mar 6 '17 at 10:45
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There are lots of products out there specifically designed for ensuring that items produced in a mold release properly. They are called (wait for it...) mold release products.

Google that and a bunch of different options should pop up for you (I actually googled "mold release for casting" but it might be interesting to see what type of results you get if you leave off the "for casting" part. Newspaper headline tomorrow: Giant mold is released by unknown person, takes over the world!)

Now granted, I have never worked with resin, so this is all guesswork on my part. But this is how I would tackle such a project. Saw your piece of PVC pipe in half lengthwise--use the thinnest saw blade possible, and then sand or file the cut edges smooth, so that the two halves come back together snuggly.

Then line your pipe with something like cling wrap, wax paper, or parchment paper (I would look for an industrial equivalent, so that it won't require so many overlapping individual pieces), making sure to cover the seams between the two pipe halves, so that the liquid will not leak out when you pour. I think you could probably use something like a glue stick to temporarily adhere the lining to the pipe interior during this process to make it easier to keep the lining in place.

Spray the inside of the lining material with the mold release, and then use clamps to reform the pipe into a cylinder. Pour your resin, and once it has set, you should be able to release the clamps, pull the top half of the pipe off, and remove the liner.

I think that this should work pretty well to eliminate needing to file/smooth the edges where resin could otherwise leak out between the two pipe halves.

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  • Great tips! Top drawer. – Protector one Mar 2 '17 at 20:59
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    If you could cut two slots nearly all the way through, down opposite sides of the tube, you should be able to split it open with a screwdriver after casting. A dremel with a cut-off wheel and a home-made depth stop might do the trick. – Chris H Mar 3 '17 at 9:36
  • @Chris H: That sounds good! – Protector one Mar 3 '17 at 10:33

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