Introduction: Epoxy Putty and PVC Shaping: Gun Stock Additions
What are we doing?
This is the process of using epoxy putty and PVC to create not only gun stock parts but simple 3D shapes that can be handled like 3D printed or wooden objects. These materials are very cheap to source and very easy to work with. My specific goal was to create stock additions for my Ruger 10/22, but this method can be applied to almost any shape you could think to make out of clay or wood. This whole project was kind of a proof of concept for this method of sculpting.
How will we do it?
In this guide we will go over:
- Two Ways of Shaping PVC
- Covering PVC frames with Epoxy Putty
- Two Methods of Attaching Epoxy Putty and PVC (EPP) objects
- Fit and Finish
What will you need?
- PVC of any diameter - I used 3/4 because it's what I had.
- 4-5 tubes of Epoxy Putty - Less is more.
- Silicone - Window sealer is fine
- 1 tube of epoxy
- Fiber Fix
- PVC Cement
- Various Screws and Nuts (#10 3" in this case)
- Wooden Skewers - The paddle ones work best.
- Sand Paper
- Dremel (woodcutter bit if you have it)
- Angle Grinder (flap disk and cut off wheel)
- Bench Sander/Grinder (optional)
- Exacto Knife
- Rubber Gloves
- Eye protection (duh)
- Heat Gun
Step 1: Step 1: Plan Your Design
As with any good project, the best thing to do is plan first, fret later. I knew that the factory stock for my gun didn't fit my hand well so I thought up and designed a grip that I liked better. For the first method of design I'm going to show you, you won't actually have something you can "handle" until you've finished shaping so it will be important to make a good design plan and follow it. If I had to name it, this method would be called the PVC Blank Design.
Once you have a rough outline of what you want, you'll need to measure a blank for your part. Now, the PVC I used was just about the right depth for what I wanted to do and the Epoxy Putty gives you a little leeway on that anyway. What the Epoxy Putty can't do is make up for the structural integrity of your PVC frame. It does NOT have to be perfect but it does need to be rigid and hold its shape under moderate pressure. What works best here is to keep your sections of PVC short and stocky where possible. As I mentioned before, less is really more here as you will be adding at least 1mm of Epoxy Putty later if not more to suit your needs.
I used PVC cement to make my rectangular blank fit together so that I could shape it without it falling apart. You can see I used painter's tape to prevent the cement from spilling off the sides. PVC cement kind of works like silicone when it's on the outside of the PVC like this so while it will hold together rather well, it certainly isn't invincible. Give it a good amount of time to dry before moving on to Step 2.
Step 2: Step 2: Shaping Your Blank
Here I cut out the piece from my outline to help me cut/grind my blank into shape. By the time I was done, I actually ground away one of the tubes entirely. Grinding PVC isn't much different from grinding plastic or softwoods. If you're not familiar with grinding, I highly recommend checking out some how-toos. There isn't much to it but like any other craft, you can either do it well or be pretty garbage at it. As far as what tools to use here, PVC is relatively soft so you can get away with using a bench grinder, a dremel, or an angle grinder. I used all three because I felt like I needed to but you could do this project with just one or two of them. It mostly comes down to what you're comfortable with. Also for those interested in grit counts, I used 120 for most of this. You could probably go lower but 80 might be too aggressive for this kind of application.
Because I was working on a gun stock, I had to go in with a rat tail file and sandpaper to recreate the curves of where I would attach this grip. In that aspect, it was the only place on this build where less wasn't more. Alternatively, you could also shape your stock to be a simpler shape so that you don't have to work so hard shaping the blank but that's up to you. In some ways, it depends on how much you want to damage your stock. That would probably put you past the point of no return.
On a safety note here, any time you're grinding anything while working with these materials (or really anything) you need to wear eye pro and a respirator. Gloves are always a good idea as well. Did I do all of these things the whole time? No. Did I instantly regret not using them? Absolutely. Condoms, seatbelts and eye pro folks - use em or loose em.
Step 3: Step 3: Affix and Fill
When I was happy with the general shape of the part, I attached it to my stock with some hot glue. Since the hot glue is really just to keep it in place before I wrap this part in fiber fix, that felt like a pretty safe gamble (it was). You could also use epoxy here. After it was in place, I filled the inside of the tubes with silicon to add some rigidity to the PVC. While I'm 90% sure the Epoxy Putty will take a beating, I wanted to make sure the PVC had all the support it needed. You'll notice in the other method that I do the same thing.
Step 4: Step 4: Wrap and Cover
At this point, you'll wrap the part in Fiber Fix to permanently affix it to your gun. Do yourself a favor, DO NOT put fiber fix anywhere you don't intend to cover in Epoxy Putty. If you have not worked with Fiber Fix before I highly recommend following the instructions. Novel right? The one thing the instructions doesn't quite get right though: use WARM water. Not room temp or lukewarm. A: Once the resin in the wrap cools down, it's game over and B: room temperature water isn't going to activate the resin. Now, the 10/22 is a relatively small rifle so I actually didn't need to use all of the Fiber Fix. I'd say three good wrap arounds and you're good. Cut it off in a conveniently sanded spot and go.
Once your Fiber Fix has cured, you're good to go with Epoxy Putty. Epoxy Putty works a lot like quick hardening clay. No need to add water, but I would wear rubber gloves while working with it. It also smells TERRIBLE. The real trick to working with this substance though is to use small bits at a time. That may be frustrating, but once you mix it together it hardens very quickly. You may only have two minutes or so until it becomes nonpliable. I found the best way to mix it is to cut off about a half inch from the roll, roll it into a snake, roll that back into a ball and repeat until it is an even grey color. Put it wherever you want to put it and then smoosh it into place. It's best to smooth out as many creases as possible as it will save you a lot of time later.
Epoxy Putty hardens in about an hour. I gave it a bit more time than that, but when it is hard all you have to do is smooth it with sandpaper. Be careful, if you sand over any of the Fiber Fix you will get fiberglass everywhere. Respirators, gloves and long sleeves folks. You may notice small inclusions and air pockets in the Epoxy Putty. They're pretty hard to avoid and very easy to fix. Mix up some normal liquid epoxy and fill the gap, scraping the surface to make it even. You'll have to go back and sand again but it's worth it to get an even surface. You can even cover the whole surface if you want, but I'm not a fan of wasting precious epoxy.
At this point you can go ahead and paint. Let's move on to the next method!
Step 5: Step 1 of the Heat Shape Method: Work That PVC
If you haven't worked with PVC before, there are a few things to know. First, if you heat up PVC you WILL let off Chlorine Gas. I know there are some of you who are experienced with the craft who disagree with me there, but especially for first timers I HIGHLY recommend a respirator when heating and shaping PVC if not eye pro. I speak from experience when I say Chlorine gas is not fun to breathe. Second, when you heat PVC... PVC gets hot. So maybe wear gloves?
You can see here that the piece I made here is less than beautiful. That's aye okay. All this is doing is acting as the skeleton of what will be an angle grip. All I did was cut a short piece of PVC for the brace and got some nice angled cuts for the grip. I heated the "flat" end of the angle and pressed it down with a piece of wood. Then, I heated both of the bottoms of the pipes and pressed them against my gun's stock to get a good fit. From there, I used PVC cement to temporarily hold the pieces together.
It was my intent to screw this piece in place onto my stock, so I made sure that I would have a place to put large amounts of Epoxy Putty wherever there would be holes. That meant leaving a nice flat surface on top and holes in the bottoms for Epoxy Putty plugs. Like before, less is more here. This method does take more Epoxy Putty since you're relying on it more for the shape of whatever you're making but it's arguably easier to shape and probably better fitted.
Step 6: Step 2: Apply Putty and Fill With Silicon
Much like before, you're going to cover the piece in Epoxy Putty. I did this piece over the period of a couple days. I made the top joint first so that the grip was sturdier and easier to work with and over time, I got the whole part covered. After that, it became more about shaping the grip to my hand and applying Epoxy Putty as needed. One of the beautiful things abount EPP objects and especially with this method is that it is super easy to correct mistakes. Put on too much putty? Sand it off later. Take off too much? Put on more putty.
You'll notice here I actually carved into the side of the angled PVC. That was more so I could get a more circular hole in the center. I made sure to get a good amount of Epoxy Putty inside that hole as well as just covering it up so that it became a part of the PVC's structure. That's a pretty good idea anytime you threaten the integrity of the PVC.
Step 7: Step 3: Shape and Attach
You will probably go back and forth between Step 2 and Step 3 of this method more than you would with the other, but you notice you get a much more defined shape this way. Because this was more cylindrical than the other piece, I found myself using long strips of 80 grit sandpaper and shimmying my way up and down the grip with it. Because I intended to use a textured paint, I didn't move up grits to smooth it out. While hard, the Epoxy Putty already has a pretty soft finish.
I added a pic rail to the bottom of the grip as well as sinking a hole near the top for a screw. The angled grip has two screws attaching it to the stock: one that goes through the angle support and the pic rail and one near the front. Because the angle isn't too dramatic, it was pretty easy to find long enough screws with small enough nuts. The pic rail was an easy 5 bucks on Amazon and even came with its own screws. I thought it added some real pizzaz and since it won't be easy to take off the grip in the future, it gave me the option to attach a bipod or other accessories.
Step 8: Step 4: Paint and Enjoy
That's really it. Once you have the holes drilled, the screws in, you're good to paint it and play with it. Epoxy Putty paints really well. Ultimately, while this isn't the prettiest gun I own or ever worked on, I am very happy with how it feels in the hand and how it shoots. It made my experience a whole lot better. Hope this helps you in whatever you do. Peace.