How to Make Fiberglass Molds from your 3D Prints | Carbon Fiber Sword Part 1

in this video I’ll be creating a
fiberglass mold from a 3d printed sword, and this will later be used to create a
carbon fiber version of the sword. so the parts that I’m using are a kit from CP
3d printing. this is the sword of Perseus. now I have two options for the handle
and crossbar. I’m going to be using the version without the decorations because
that’s going to lend itself better to being cast in carbon fiber later on.
the blade is in three parts. so these do need to be attached together. first I’m
removing some material from the seam lines so the gap will be easier to
fill later. on I’m also taking down that gloss on those flat surfaces so the glue
will adhere better. there’s a channel running the length of all of the pieces
so that a dowel can be inserted. so this I’m going to glue in place using Gorilla
Glue which will expand to help fill in any gaps, and I’m not going to add on the
handle and cross piece to this because I’m going to create three separate molds
for the sword. it’s going to be much easier to cast in the carbon fiber later
on with the parts separate. and I did make sure that the glue was
spread onto the flat surfaces also so that it would stick together the parts to
each other in addition to adhering them to the dowel. this is going to give us
the best level of stability I’m adding a couple of clamps to hold these pieces
level with each other and in place while the glue cures. there are some print
lines that need to be filled in and then I’m also going to fill in the detailing
that’s left on the cross piece and at the base of the pommel there because
those aren’t going to transfer well into the molding and casting process. so I’m
just going to fill all of those in with some wood filler. this is very quick
drawing so you do you have to work fairly fast and then just do small
sections. allow it to dry fully, and then you can just add on more layers if it
wasn’t built up quite enough. of course this is also the time to fill in that seam line between each of the sword blade parts. this particular filler is rather strong
so you want to use it with good ventilation. but it does dry quickly
which is a plus for adding multiple layers quickly and not having to wait a
whole day for it to dry. pretty much by the time you finish one piece and come
back around to it after finishing the other pieces, you can go ahead and add
the second coat right away because it only takes about 15 minutes for that to
be cured enough to add another layer. and I am over building the seams because you need something to sand down to reach that level. it’s still going to be a process of multiple layers, but it’s a good head start if you do over build those areas a little bit. now I’ve sanded this flat. I’m using a sanding block on
all of these areas because that’s the only way it’s really going to get flatted out.
the wood filler and the plastic sand at different rates so it’s especially
important to ensure you’re using a flat surface to sand, not just free-handing it.
another plus of using the wood filler is that it is very easy to sand.
I also reinforced the tip of the sword to make sure that I get a good clean
line on that. once I had done a couple of layers of the wood filler I added a coat
of filler primer. this will, for one, help to fill in additional gaps, but it also
helps to reveal what areas need additional filling. of course removing
the dust between coats so that your primer is going to adhere well to the
plastic. I did several coats of the wood filler,
primer, different colors of the primer and then just standing with the flat
surface. and that primer does tend to gum up the sandpaper quite a bit, so if you
just brush it away you can extend the life of your sandpaper somewhat. and it
is helpful to use a couple of different colors of the primer just so you can see
how deep you’re sanding each time. those coats of primer do help to make it more obvious anywhere that needs some serious filling with the wood filler. and then it
also will, over the course of several layers, smooth out the print lines on the
rest of the sword. it’s quite a process. it takes quite a few layers, so you just
have to keep going back and forth between the filler and the various
colors of primer until it is flatted out and your print lines are gone and that
seam isn’t coming back through. after all of the sanding and filling
I’ve added a coat of black paint and some gloss sealer. and then of course
that does need to cure for a couple of days to ensure that it’s not going to
have any sort of bonding issues when we go to create the fiberglass mold from
that. but there’s a rough assembly of the parts and it’s not absolutely perfect
but it is close enough that we’re going to be able to polish down the finished
mold to get it to that perfect finish once we go to cast the parts. we’re gonna
keep those separate and create a flange for each of the individual parts. so I’m
using a mix of foam and corrugated plastic. this model does have a blunted
blade which I want to go ahead and make that a sharp blade. so I’m using clay in
addition to recessing the part deep into the flange. so I’m just gonna build that
up and create a sharpened edge and ensure that the resin isn’t going to
seep under and that the mould will release. the clay gets a little bit messy
so you just have to clean up and re-polish your part after the border is
all in place around all of the edges. I followed the same process for each of
the parts, cutting a piece out of foam and then adding a coroplast piece on top.
just going to make it easier to release the parts. once I have the parts trimmed to shape
then I’m using some packing tape to secure them to each other so they’re
easier to work with and trimming out any excess material as necessary to ensure
that the parts fit down into the flange. I’m using more clay to build that up so
that I have just half of the part showing above. that’s going to be my cut
line once I cast apart from these molds. so it does need to be as level and
smooth as possible. it’s going to make it easier down the road with the clay in place and everything
cleaned up it’s time to add some release wax. so this takes quite a few coats
ended up doing probably around 10 coats just to make sure that these are going
to release properly and also just to help fill in any possible imperfections
on each of these parts. just spread it on and let it set up and then polish down.
give it about half an hour between coats. I also did a coat of PVA, again just to
ensure that I get a good release. with all the prep work done I’m adding the
black surface coat. this is a thickened epoxy, so it’s going to capture the detail
and create a glossy surface that will be good for casting parts later on. I’ve applied two coats of the surfacing
epoxy. now it cured a little faster than expected, so it was no longer tacky when
I went to add the fiberglass. so I did key the surface with some coarse
sandpaper before moving on to the additional layers of fiberglass. I’m
starting out with lighter weight fiberglass and trimming relief cuts as
needed to fit it to the shape. each layer gets wetted out before moving on to the next layer. I’m using a variety of weights for the fiberglass and gradually building this out so that it’s going to end up being a rigid mold. the fiberglass layers are progressively
heavier to bulk out the mold and ensure that it’s going to be rigid and not
deform when it the parts are under vacuum when we’re casting them later on.
depending on the type of fiberglass, various levels of relief cuts are needed.
some conform better than others. also the more complex shapes require a bit of
finagling to ensure that the fiberglass covers all of the parts and all of the
recessed areas are properly reinforced. one of the layers is a heavyweight
chopped strand mat so this should hopefully ensure that the mold is thick
enough and built out enough that it’s not going to have too much torque to it or
deform once it’s in a vacuum bag when we’re trying to cast it in carbon fiber
later on. it does take a bit of effort to get this sweated out because it is so
thick. these parts are fairly complex into some portions though so you really
can’t conform that particular type to the shape, so I just used some strips
around the flange area and over top to add some rigidity there. originally I
wasn’t intending to cure this under vacuum, but this chopped strand ended up being so thick that it didn’t want to press down. it
kept wanting to pop up, and I didn’t want to have voids there. so I did end up
placing these items into a vacuum bag for a while just to compress that a bit
and ensure that there weren’t voids under the edges of the chopped strand. I added a final layer of a
lighter-weight fiberglass over top of the chopped strand to press down those fibers that were kind of sticking out everywhere and just
smooth that out so we get a bit of a nicer surface that’s not going to be as
prone to giving you splinters. the molds should be all cured now. I’m removing that release film that I had added when I placed it into the vacuum
bag. so let’s go ahead and see if these can be removed properly and see what’s
the surface we have underneath. the next step is to get the mold parts
cleaned up, remove all of the rough edges on the flange and fix any imperfections
that may be on the mold because we don’t want those to transfer to the cast parts.
so once the cleanup is done it’s going to be time to cast the sword in carbon
fiber and see how we can fit all of these parts together. so that’s going to
be part two for this series.

Dereck Turner

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