Introduction: Blood-Spraying Evil Dead Chainsaw Arm!

About: depotdevoid is short for The Depot Devoid of Thought, the place where you go when you lose…

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Ah, Halloween is upon us again!  I am not as consistently awesome at costumery as my brother, but I have been known to build a thing or two or three, and generally overdo it this time of year.

My friend Felicia volunteers at a small theater in Bend, Oregon.  She acted in their production of Richard III, and mentioned to the director of their upcoming production of Evil Dead:  The Musical that she might just know someone who could build them a new chainsaw arm to replace the one Bruce Campbell signed the last time they ran the play.

For the uninitiated, Evil Dead:  The Musical is based on the movie Evil Dead 2:  Dead by Dawn, which was written and directed by Sam Raimi (of Spider-Man fame), and starring Bruce Campbell (of Army of Darkness, Bubba Hotep, and Brisco County Junior fame).  The movie is a masterpiece of the comedic horror subgenre, both hilarious and disturbing at times.  Crucially to this instructable, there is a scene where the main character, Ash, has to cut off his own hand with a chainsaw.  He later replaces his removed hand with that same chainsaw, wielding that and a sawed off shotgun to do battle with the demons he has unwittingly summoned up.

When Felicia asked if I'd be interested in building them a chainsaw arm prop, I leaped at the chance!  I'd put that Dalek I've been struggling with on indefinite hold and focus my energies on making the best darn chainsaw arm I could . . . and when they asked if I could, you know, maybe make it spray blood everywhere . . . well, let's just say I stopped chanting "Exterminate!  Exterminate!" and started chanting, "Swallow your soul!  Swallow your soul!"  After that, they even asked me to make them a Necronomicon . . . and how could I not!?

Here's a video of me acting poorly and cutting off my hand:

Read on to learn all about how I built this thing from scratch, or jump ahead to read more about the play itself!

Step 1: Gather Materials

Here's a hopefully complete list of the stuff I had to buy:
  • Large juice container
  • 2 small plastic bottles
  • Roll of sheet metal
  • Tape measure
  • Nylon cord
  • A bunch of 5/16" nuts and bolts
  • 1/8"x1" thick aluminum bar
  • Wood trim about as wide as the aluminum
  • 4" rubber plumbing coupling
  • 1/4" clear plastic tubing
  • Small hose clamps
  • Reel of #41 roller chain (if you're not plumbing yours for blood, bicycle chain will work just as well)
  • A couple of small plastic bowls
With a lot of the things I make, I try and repurpose stuff I already have on hand.  These are all things I happened to have lying around, some of it (particularly the CO2 system) might be a bit tricky to source:
  • CO2 charging system (from a homebrew mini-kegging system)
  • 1" wooden dowel
  • 1/4" plywood
  • E6000 epoxy
  • Hot glue
  • Spray paint in a variety of colors
  • Silicone caulk
  • Cardstock
  • Laminate film
  • 7" cedar 2x2
  • 3/8", 7" long carriage bolt
  • 1/4" thick piece of rubber or flexible plastic
Tools used in the manufacture:
  • Jigsaw
  • Hot glue gun
  • Screwdrivers
  • Box knife
  • Dremel
  • Bench vise
  • Rasp
  • Drill
  • Pliers
  • Awl
  • Printer
  • Shears
  • Steel wool
  • Heat gun
Finally, I did a lot of research for this, and I would be remiss if I didn't mention that I based the design on images pulled from Google image search of the Homelite XL chainsaw used in the film, and also that I drew heavily on this instructable, and this one, for inspiration and ideas.

Step 2: Label / Stencil

My original idea was to actually buy an old, non-working Homelite XL chainsaw, as that was the make/model used in the movie.  Unfortunately, everyone on craigslist who was selling an old, non-working Homelite XL chainsaw (a surprisingly large number, by the way) was a total flake and couldn't seem to coordinate letting me give them cash money for their garbage.

So I tried to get the shape of the chainsaw as close as I could, and also made a label and a stencil for added realism.  I made the label in, printed it, laminated it, and glued it over the pull start assembly.  

The stencil took a bit more work, I had to print it on two pieces of card stock, tape them together, and cut out the stencil.  The result looked great!

The images above are the original files I printed out to make the label and the stencil, feel free to use them as needed.

Step 3: Pull Start Mechanism

The very first thing I actually built was the pull start.  I wanted to make sure that it would be usable, just like on a real chainsaw.  This idea popped pretty much fully formed into my head.

the concept is very simple:  a dollar store tape measure is cut down, rope is epoxied to the end of it (along with a nut for guidance) and a piece of dowel is tied to the end of the rope.  This gives both the look and the feel of the pull start used in the movies.

Step 4: Pull Start Housing

The pull start housing is simple.  I picked up a package of small, flexible plastic bowls from the dollar store.  I cut the rim off the first one and painted it silver.  I cut a bunch of slits into a second, and painted it red.  

I glued one inside the other, cut a hole (which I reinforced with a washer), and fed the string from the pull start mechanism through.  

Finally,  I glued the mechanism in place inside the housing, and it was done!

Step 5: Chainsaw Body Base

I searched the grocery store for a jug that best matched the shape of the Homelite XL.  What I came up with was a gallon of Arizona iced tea . . . which it turns out I don't like very much.  After giving most of it away and cleaning the bottle, I carefully sawed it in half and cleaned up the edges.  

I knew I'd be painting the jug, so I took this time to scuff up the inside and outside with steel wool, to (hopefully) get the paint to grip better.  I've had pretty bad luck in the past with spraypaint on plastic!

I finished this step by cutting the neck off both sides.  I obviously didn't need that part, and it kind of spoiled the overall shape.

Step 6: Widening the Body With Sheet Metal

The jug would of course be too narrow to really look like a chainsaw, much less to fit all the stuff I needed inside.  I picked up a roll of 7" wide sheet metal at the hardware store.  I started by folding over the end, so it wouldn't be too sharp.

Next, I drilled a hole in each side of the sheet metal near the end, about 3/4" in from the edge, and a corresponding hole in one side of the jug.  Holding the sheet metal in place on one half of the jug with a nut and bolt, I wrapped it around and used a sharpie to mark spots I thought looked good for bolts.  

I removed the one bolt I'd installed and cut the sheet metal off a couple of inches past the full wrap around point, then folded over that end to protect from sharp edges.  Using a straight edge, I marked a corresponding drill spot on the opposite side of the sheet metal, then lay it flat on a piece of scrap wood and started drilling holes.

From there, I put the sheet metal back on the half jug with a nut and bolt.  Starting at the next hole in the sheet metal, I drilled through the jug beneath and installed a nut and bolt to hold the sheet metal in place, and then continued doing this all the way around.  

Once I'd gone all the way around, the couple of inches of overlap in the sheet metal came into play.  I removed that very first nut and bolt and drilled a hole through the overlap, so that the first bolt would go through the sheet metal twice.

When that was finished, I removed all the nuts and bolts, and repeated the process on the other side of the sheet metal and on the other half of the jug.

Step 7: Adding the Wrist Cuff

In the movie version of Evil Dead 2, Ash cuts his hand off and uses a clamp to hold the chainsaw to his stump.  I couldn't find something that looked exactly right, but this guy used a plumbing fixture that does the job nicely!  

I marked out a spot that looked good on the sheet metal, poked a hole in it and started bending it away.  Use gloves!  

Once the hole was the right size, I trimmed back the jagged edges of sheet metal to about half an inch long.  I loosened the clamp on one side and slid the fitting into the hole.  The clamp was slid back on, over the loose edges of sheet metal, and tightened up.  This provided a remarkably sturdy cuff!

Step 8: Roughing Out the Chainsaw Bar

My mental design for the chainsaw bar involved an inner core of plywood that reached inside the chainsaw body, to be used as the main support for the handle.  The first step in building this would be to cut out plywood in the correct size and shape.

I have a real chainsaw, so I took a close look at the actual shape of the bar.  It kind of tapers slightly at each end, though more dramatically at the base, so I sketched out what I wanted on a piece of 1/4" plywood.  On the end of this, I sketched out a shape based on the inside of the jug, designed to sit flat up against on side.  

Using a jigsaw, I carefully cut out the shape I had drawn.  It wasn't a perfect cutting job on my part, but that was all right--this is completely covered up in a later step.  I cut a hole in the jug for the bar and test fit it.  Everything looked great, but I realized much later I should have made the slit larger.  It fit just the plywood core fine, but after I'd added everything else, it needed to be expanded greatly!

Step 9: Blood Spray Mechanism

For this step, I used a couple of CO2 mini keg taps I had lying around--I really only needed one, but one was partially broken, and the working one didn't have the right fixtures.  I took what I needed from both, and came up with this contraption!

I removed some of the unnecessary fixtures and bent the input shaft about 90 degrees using a heat gun.  There's only a limited amount of space inside the chainsaw for this, the handle, your hand, etc., so it's important to scrunch this down as small as possible.  

Next I removed the pour handle, as I wouldn't be using it for it's intended purpose.  I needed it to be always on, so I bent a nail into an appropriate shape and jammed it into the spot the pour handle was.  I used a small length of cord to tie the nail down, making sure the mechanism would stay on.

Finally, I cut off the pour spout and replaced it with the pour spout from the other CO2 system.  This was a better fit for the chainsaw as the the pour spout at the end of the flexible tube has a trigger in easy reach.  Once I'd finished up the rest of the internals of the chainsaw, I'd be able to place the trigger nearby or directly on the internal handle.

Step 10: Blood Tanks

The real Homelite XL chainsaw has a gas tank and an oil tank situated right next to each other, I figured that would be the perfect place to keep the fake blood!

I used a pair of vitamin water bottles for this.  After testing them in the chainsaw body, I realized they were a bit too tall.  I heated the bottom of each with my heat gun and squished them down, and once they cooled off they maintained their new, slightly shorter shape.

Next I cut a small hole near the base of each bottle.  I inserted a couple of inches of plastic tubing inside the holes and epoxied the bottles together.  I cut a third hole near the top of one of the bottles, and inserted the modified CO2 system input tube there.

I knew this tank would have to handle some pressure.  I didn't want to take any more chances then I had to, so I put five or six coats of epoxy all over the joins between the tanks and the input tube, on the inside of the tanks as well using a paintbrush.  Finally, I slathered them with several coats of silicone caulk and then pressure tested it . . . no leaks!

The last thing I did (no pictures, sorry!) was to cut a couple of slots in one side of the chainsaw body and the corresponding section of sheet metal, allowing the tanks to slot in place.

Step 11: Painting the Body and Blood Tanks

I used Krylon Fusion spraypaint for this.  I've had trouble before getting paint to adhere to plastic, so when I went to pick up an appropriate shade of red, I did some poking around until I found this stuff.  It's specifically designed for painting on plastics, and it seemed to work out pretty well!

I painted both the inside and the outside of the chainsaw body, I figured that way if there was any chipping of the paint on the outside, it would still show red through the translucent plastic.

I also painted the tops of the blood tanks (as they would be exposed).  After taking another look at pictures of the Homelite XL, I ended up painting one of the caps black.

Step 12: Adding Detail to the Chainsaw Bar

Using the plywood bar as a template, I cut out two pieces of sheet metal, each just slightly larger than the bar itself.  I epoxied one to each side of the bar, stacked some wood on it, and let it cure over overnight.

The next day, I took the now metallic bar outside and painted it white everywhere it would be exposed.  Using the stencil I made way back in step two, I painted my home made Homelite logo on each side of the bar.

I carved a handle out of an old chunk of 2x2 I had.  Using a long carriage bolt, I attached it to the internal part of the chainsaw bar.  

Finally, with a screwdriver and some steel wool, I scuffed up the fancy paint job I'd just finished.  This turned out really well, as the bar now looks both well used, and like it's actually solid metal!

Step 13: Plumbing and Chaining the Bar

The chainsaw bar is the part of the prop that actually needs to spray blood, so I had to plumb it for fluid delivery.  I used a small hose clamp to seal off the end of the 1/4" hose I had, then stuffed that all the way around the bar, between the thin sheet metal layers.

After that, I wrapped my #41 roller chain (which looks like chainsaw chain without the blades, or like overly wide bicycle chain) around the bar, covering up the tubing.  I secured the chain to the portion of the bar inside the body with a couple of screws, then epoxied it around the bar itself--I didn't want it slipping loose during the play!

To finish this section, I drilled holes through the bar and body and secured it in place with three bolts.

Step 14: Installing the Pull Start

This seemed simple in my head, but it turned out to be a lot more difficult than I thought!

Using hot glue, I tacked the pull start housing onto the outside of one half of the body.  The surface I glued it to wasn't perfectly flat, which where the trouble came from.  I had to kind of hold it to an unnatural shape, which it kept trying to flex out of.  

Once it was (I thought) securely tacked down, I slathered epoxy all over the joins and let it sit . . . overnight, some of it pulled apart.  Also, the epoxy and the spraypaint didn't interact well.  I ended up redoing the epoxy three or four times (which took a few days), before I got it right!

Step 15: Bringing It All Together, Part One

With nearly all of the components finished and (mostly) installed, it was time to start bringing the two halves of the body together.  

The left half had the sheet metal fully bolted in place by now, holding the blood tanks on their side.  The CO2 system was installed in the tanks as well.  The right half had the bar and handle, as well as the tube that was the target of the CO2 system.

I started by heating the chainsaw bar tube and stretching it over the nozzle of the pour spout.  It was harder than it looked, the tube didn't want to stretch that much!  When I finally got that in place, I secured it with a hose clamp.

Next, I epoxied the pour spout to the handle.  The "trigger" was in a position where the person holding the handle could hit it with their thumb.

Step 16: Bringing It All Together, Part Two

I now had to bolt the two halves together.  

I wrapped up the excess tubing (which I really should have trimmed down well before this step), and stuffed it in the right side of the saw.

I knew I'd have a hard time with some of the bolts, as the nuts they'd be installed on were almost totally inaccessible with the two halves coming together.  To try and stop this problem in advance, I hot glued all the nuts over their holes before getting to work.  This strategy met with mixed success, some just fell right off, others worked perfectly.  

It was frustrating at points, but with some patience I was able to bolt it together!

When it was all done and I was able to reach inside, grab the handle, and start waving the saw around, I had one of those moments you have when you're making something . . . having seen this creation in my head for so long, and then to see it really start to take shape on the workbench in front of me . . . well, I admit I did a bit of a happy dance.  I knew then that it was all going to work out!

Step 17: The CO2 Cartridge

Since the blood spray would be powered by CO2, I obviously needed to be able to change the cartridges.  This is a two hand job, one to hold the mechanism and one to, rather forcefully, turn the cartridge holder hard enough that the little spike punctures the cartridge.

With a dremel and a pair of pliers, I made a hole in the sheet metal over the CO2 intake.  I carefully cleaned up the edges so they wouldn't be too sharp.

Finally, I cut out a rubber washer from some 1/4" rubber and glued that over the kind of ragged, crappy looking hole.

Step 18: The Handle

In the movie, in order to fit the chainsaw over his stump, Ash has to remove the original handle.  He replaces it with a bent piece of metal and a wooden handle.

I found a length of sturdy but shapeable aluminum at Home Depot, and a bit of wood molding that was the right shape.  Using my bench vise and some elbow grease, I bent the aluminum into the proper shape and cut it down to size.  

The molding was first cut to the proper shape, then I drilled countersunk bolt holes into it.  It looked too new for something that was built in a crappy old cabin's tool shed, so I got it wet and rubbed it with ash from the barbecue.  Worked great, the wood definitely looked older and a bit sunbleached!

I then drilled 6 holes in the handle, two on the top for the wood, and four on the bottom for installation on the chainsaw.  I had to drill out some holes in the sheet metal and rubber at this point as well.  Installing it was a bit tricky, as the insides of the chainsaw had gotten pretty full, but it went relatively smoothly.

Step 19: Ageing the Saw

This is supposed to be an old chainsaw, and at this point it looked way too shiny and pristine.  My inclination was to cover it in blood smears as well, but the play's director assured me it would get PLENTY of that over the course of the musical!

The bar already looked beat up, but to age the body, I used two main tools:  a rasp and some black and brown spraypaint.

With the rasp, I would alternate between smacking, scraping, and gouging the body.  I put several dents in the metal, scraped the paint, and roughed up the wood nicely.

The spraypaint was trickier, I held it 2-3 feet from the prop and sprayed just a little out.  Immediately I rubbed the wet paint with a paper towel.  This made the finish look dirty, like it had been collecting oil and sawdust for a decade!

Step 20: Blood Holes!

The final step in preparing the chainsaw was to give it a way for the blood to spray out!

This was fairly straightforward, I simply used one of my smallest drill bits to punch a series of holes in the tubing.  


Step 21: Testing

Here's a video of me testing out the blood spray--it worked great!  In this video you can hear the hiss of the CO2 escaping, I was using the wrong size cartridge!  I fixed this later, and also widened some of the holes (you can see that only a few are really spraying blood at this point, most are just dripping). 

Step 22: The Play

What can I say about the play?  It was . . . simply amazing.  It was the most fun I've ever had in a theater, by a long shot.  By the end I was absolutely soaked in fake blood, and my cheeks hurt from smiling and laughing so much.  Everyone involved in the play, from the director and background staff, to the actors and the live band were just great.  It was a messy, ridiculous, bloody madhouse, and I loved it!  A local brewery even produced a limited run "Dead by Dawn Red" ale that was delicious!

I cannot recommend this musical enough!  Look around at Halloween time, there's a good chance someone in your area is putting this on!

Thomas Kuchulis, the actor who played Ash in the production, made a couple of necessary changes to my original design.  He removed the original handle and put a new one in there at 90 degrees, allowing a more natural hold.  It is simply bolted into the sheet metal, which I had considered, but I was worried it wouldn't be strong enough to do something like that.  They're seven or eight performances in and it's holding up fine!  If I built a new one, I would try to make a hybrid version of the handle that still is attached to the bar, but is rotated 90 degrees from my original design.

He also refined the bar, adding nozzles for the blood spray.  I wasn't able to get a picture of it, but it sprayed a lot farther and with more volume than before!

Here are a few snippets of video I was able to snatch when I wasn't hiding the camera from the gouts of blood spraying everywhere:

Step 23: Final Thoughts

This was one of the most purely fun projects I've done in a long time.  I loved the concept when it was suggested, I'm really excited about the use it's being put to, and I just had a great time taking it from concept in my mind to physical reality!

Seeing it put to such excellent use was really rewarding, I loved seeing something I made entertaining so many people!

Thanks for stopping by and reading about my project!  As usual, I'd really like to hear your thoughts, so take a moment to rate, subscribe, and comment!

If you should happen to build your own chainsaw arm prop (blood spraying or otherwise!), post some pictures or a link in the comments, and I'll send you a profile patch and a 3 month pro membership!

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