Hello fellow makers, For this instructable I am going to show you how to make a crossbow pistol. I made this project partly for my own interests, but mostly I did it for the awesome people who visit and publish here on instructables.
I realized when researching this project that there was almost no plans for building something like this on the internet, and I wanted to provide a more detailed documentation to serve as inspiration to all of you makers out there. This is an advanced project and I do not suggest that it be undertaken by anyone who is not thoroughly familiar with the basic principles of wood and metal work.
I got a lot of inspiration from This Instructable for my project, but it is too bad the author did not choose to finish it.
I've added diagrams to make this instructable as easy to understand as possible. Forgive me in advance for the low quality pictures used throughout this instructable(Insert lame excuse here). Here it is and I hope you like it.
Note: Every picture in this instructable contains an attached text box, telling what things are and what is going on.
Step 1: Tools/Materials
Note: Pictured above are the main tools and materials you will need, but others will probably be required.
- hardwood block 5''X 1.5''X 15''(grain running lengthwise)
- aluminum hobby sheet 1/8'' thick
- 5 steel 1 1/4'' washers with 1/4 inch center hole
- 5/32 brass rod
- vent hose clamp
- 3/16 steel rod
- 1/4''X 1.5'' steel Chicago bolt with corresponding male end screw
- metal 50 lb pistol crossbow prod found here
- 1/4''X 1.5" steel flat-strap
- 1/2'' wood dowel
- small rubber mat 1/8'' thick
- 1/2''X 1/6'' brass flat-strap
- 1/8 steel compression spring(at least an inch long)
- 2 brass colored countersunk wood screws 1/2'' long
- 4 small Flathead wood screws
- wood stain
- clear coat, polyurethane
- Table saw(optional)
- Electric drill
- Various metal and wood files
- Drill press(not necessary but nice)
- Sandpaper 220 grit
- Set of wood chisels(optional)
- Soft jawed Vise
- Drill bits from 1/16-1/4
- And various other tools you might find in your workshop including screwdrivers, pliers, hammers and saws.
- Large 1 1/4'' forstner drill bit
- Vegetable tanned leather
- Thick cotton string
Step 2: The Stock
First plan it out. After you find or make a design you like, draw it out on paper to 1/1 scale. Using copy paper or your printer's scanner, copy your drawing onto another piece of paper and cut out a template using the outer edge of the design as a guide. Next transfer your drawing onto the hardwood block by tracing the template along its edge. When you are happy with the shape, cut out your design with a bandsaw.
Next, using a tablesaw or dremel, cut a 1/4'' wide groove on the top of the crossbow for the arrow track.
Drill a hole at an angle up the handle using a 3/16 bit. Then pin it with a 3/16 steel rod cut to a length of about 3'', This step is important to retain the structural integrity of the handle.
Place the crossbow stock blank in a wood or soft jaw vise and start shaping the stock using rough wood files(I suggest round, flat and half round files to get in all the nooks).The shaping you will be required to do by eye. Use your drawings as a reference. Start wherever is comfortable for you. Make sure to leave the trigger housing large enough for the trigger slot and, enough material in the handle so that it is not too thin.
Try not to make the forend too thin like I did, this is where your prod will go and the point that will be under the most stress.The shaping of the stock is the most flexible step and any design can be used(within reason) to make this weapon unique.
Step 3: The Stock. Part 2
When you are done shaping the stock you can start working on the roller nut hole. Drill it half the width of the stock deep(In my case 3/4'' because my stock is 1.5'' wide) plus 1/8'', to allow for the roller nut's width,(The idea is to have the roller nut lined up with the arrow track on the stock) and position the bit so that it cuts away a little bit on the top of the trigger housing(see picture).
Next cut a shallow ramp into the top of the trigger housing and a small cutout behind that using a bandsaw(see picture). After doing this finish cutting the arrow groove back until you reach the small ramp that you just made.
If you are using the same prod that I did draw the shape of the prod cavity seven inches forwards from the center of your roller nut hole and at a slight upward angle(so that the prod sweeps up toward the arrow rail when fitted). If you are not using the same prod find the draw length of the prod you have and use that as your measurement instead. Drill out the prod cavity with a 1/4'' bit and shape it with small round or flat file.
Optional step: Put a 3/16'' steel pin through the stock, long enough to stick out about 1/4'' on either side and positioned 1/2'' to 3/4'' behind the prod cavity(This is just for looks in a later step and completely optional)
Step 4: Roller Nut
Mark your release notch on one of the 1 1/4'' washers a little swept back (so the bow string can't 'creep' upwards). Also draw out the rotation control slot. Carefully cut them out using a dremel with a cutoff wheel attached. Make all of the notches a little smaller than you planned. Using the first washer as a template, mark and grind the subsequent 4 washers the same.
Pin the washers all together temporarily through the center with a tight fitting 1/4'' wood dowel and line up all the notches. Place this roller nut unit on your drill press and clamp it down. Drill two 3/16'' holes in the roller nut unit, one on either side of the center hole, making sure to keep the notches in alignment while doing so(If confused see pictures).
Note: If you do not own a drill press and only have a hand drill do the exact same step but drill through them one by one instead of all together using the first washer you drill as a template.
Pin the roller nut unit together with two 3/16 steel pins cut to the width of the roller nut, and secure them with liquid or gel superglue. file down if necessary.
After the glue dries take the wood dowel out of the center of the roller nut and trim the release notch and rotation control slot with a dremel. Also cut out the sear catch at this point. Fit the roller nut unit into the roller nut hole to make sure the positioning of the sear catch is right(see last picture), don't do anything more to the sear catch other than roughing it out, until you are ready to fit the trigger.
Step 5: Trigger Gaurd
To fashion the trigger guard, take your 1/8'' x 1/2'' brass flat strap and use pliers without aggressive teeth to carefully bend the flatstrap into whatever trigger guard shape you want, leave two tabs on either end of the trigger guard about an inch long to screw to, and be sure there is enough room for the trigger itself. I recommend drawing out the shape of the trigger guard you want onto a piece of paper in real size and using it as a reference while shaping your flatstrap.
Place the trigger guard where you want it to be on the pistol, making sure to have enough room for the trigger to pull(see first picture). Then trace out the shapes of the trigger guard tabs onto the pistol. With a wood chisel set or dremel tool inlet the trigger guard tabs into the stock where you made your marks.
With a bit the same diameter as your brass wood screws, drill a hole in both the trigger guard tabs. Then, using a bit the same size as your screw heads, counter sink the trigger guard tab holes so that the screw heads are flush with the brass when inserted.
Fit the trigger guard into the depressions in the stock and pre-drill the screw holes with a bit, slightly smaller than the diameter of the screw threads. Drive the screws using a screwdriver so that the wood does not split.
Step 6: Trigger Slot, Arrow Retention and Rotation Control
Use a 1/4'' bit to drill the trigger cavity. Start directly beneath the roller nut hole and make the slot about 1 3/8'' long, drilling as many holes in succession as needed, about 5/8'' deep.
Next take a steel hose clamp (I used a size 32) and cut a piece off of it about 4'' long to use for your arrow retention spring. Use a pair of pliers to give it the desired shape. Make sure to leave a tab on the back of the spring to secure to the stock (see 5th picture).
Slightly round the spring tab off with a dremel. Place the tab on the center of the stock just behind the roller nut hole and mark the outline with a pencil. With a dremel tool or wood chisels, inlet the retention spring tab in the stock, checking the fit after each cut. After the spring tab is inletted, fasten it to the stock with two small wood screws. Make sure to pre-drill all the holes.
To find where the rotation pin will go, place the roller nut in its hole in the 'cocked' position(see picture). Mark where the bottom of the rotation control slot is and remove the roller nut. Drill an 1/8'' diameter hole 1/2'' deep in the bottom of the roller nut hole where you're mark is. Then glue an 1/8'' steel pin that is 5/8'' long into the hole(The pin will stick out 1/8'' into the roller nut hole). When the roller nut is inserted the protruding end of the pin will sit inside the rotation control slot, keeping the roller nut from spinning more than it needs to.
Step 7: Finishing the Stock
To finish the stock sand the whole thing with 200 grit sandpaper and then fix the imperfections with wood filler. Next apply Red Mahogany wood stain very liberally to the stock with an old rag, then hang the stock outside to dry overnight.
After the wood stain dries apply two coats of glossy polyurethane clear coat, let the coats dry for two or three days each (It will take longer than two days to dry but most the tackiness is gone after that long).
Use a circular saw with a 1/4'' guide bit to drill out a thick disk of wood in the same type of wood as the stock. Then trim the disk so that it is flush with the outside of the stock when inserted in the roller nut hole with the roller nut. Next, cut the disk to match the cutout and ramp on the stock. Then sand it and finish it exactly the same as the stock.
(The hole drilled in the disk should line up with the 1/4'' hole in the roller nut and stock when fitted).
Step 8: Trigger
With a marker or chalk draw out the trigger design on 1/4'' steel flat bar. Then, take a 4'' angle grinder or dremel tool, and cut the shelf on the sear before you start drilling (See picture).
Using your design as a guide, drill around the perimeter of the trigger (Drill press is useful here) Using at least a 3/16 bit. Having drilled completely around the perimeter of your design slowly work the trigger back and forth with pliers to break the steel ribbons that are left holding it in place.
Clamp the unfinished trigger in a vise and shape it with a large aggressive file. Leave the extra material on the face of the sear so the sear can be adjusted when fitting the trigger. Drill the trigger rotation pin hole positioned straight back from the sear so the trigger won't slip when pressure is applied.
Drill a small hole on the back of the trigger for the trigger spring pin, and use superglue to secure the pin in place. (For the trigger spring pin I used a bit of a nail that happened to be the right size) Drill a corresponding 1/8'' hole on the inside of the trigger slot for the trigger spring to sit in.(If confused see last picture).
To fit the trigger, I put the roller nut in its hole, then placed the trigger on top of the stock, eyeballing where it should be positioned. Then I marked the stock through the center of the trigger rotation pin hole. Afterwhich I drilled the trigger rotation hole in the stock with a 5/32'' bit and secured the trigger into the slot with a brass rod.
NOTE: The second hole above the trigger rotation pin hole was for a safety mechanism that did not work out and is in no way needed to make this project.
Step 9: Prod Insertion
Fitting the prod to the bow was not easy the way I did it and I encourage you to try something else if you are inclined to do so.
First cut out a tiny rubber piece off of a 1/8'' rubber mat that is as wide as your stock and as tall as the prod cavity, 1.5'' x 5/8'' in my case. Then glue the rubber piece into the front of the prod cavity as in the first picture. Further secure the rubber with extremely small nails if you have them.
Next cut off a piece of 5/8 wood dowel 1 1/4' long, and cut it in half lengthwise, leaving one side of it flat. Place the prod in the cavity and using a nail punch and a hammer, drive the half round dowel between the prod and the rubber spacer to secure the prod in place. You may have to trim the half round dowel's flat side a little before you get a tight fit.
Optional step: Cut off a piece of steel rod long enough to protrude 1/4'' on either side of the stock. Make three shallow slots on both ends of the rod as in the picture, and insert this rod into the hole drilled behind the prod, as mentioned in step 4. Take some thick cotton string or cord and wrap it over the prod and the slots in the steel pin several times and tie it off.(see last picture)
Step 10: Sideplate
Draw the shape of the sideplate onto an 1/8'' thick aluminum hobby sheet and then cut out the sideplate with a dremel. Then, tailor the sideplate to fit the side of the trigger housing. The sideplate will be fitted on the side that the wood filler disk is on to hold the disk and the roller nut in. Drill two small holes in both ends of the sideplate, and use two small wood screws to attach it to the stock. Next, drill the rotation pin hole in the side plate with a 1/4'' drill bit, using the preexisting hole in the stock as a guide.
To put the trigger housing together, insert the roller nut and the filler disk, pin them together with the 1/4'' chicago bolt and screw the sideplate on. Then, tighten down the chicago bolt until snug(don't overtighten or the roller nut will not be able to rotate).(The last four pictures show these steps).
The crossbow pistol is now functional and can be fired. I have not yet found an effective way to cock the crossbow, other than placing the handle against my chest and pulling the string back. But I am looking for a more efficient way and will hopefully post another instructable or update on this subject soon.
Step 11: Disassembly/Assembly Video's
Some short video's showing the disassembly and assembly process. The sound is a bit sketchy because I had to doctor the videos to cut out some ''Copyrighted" music that was playing on the radio in the background.
Step 12: Bonus! Leather Prod Covers
The prod covers are optional but I believe they are an important safety feature if the prod breaks while the bow is cocked. These covers have to be tailored to each prod and this is only a rough guide.
You will need some simple tools such as scissors an awl, thick cotton thread, sewing needles and a little leather. Cut two pieces of leather about an 1 1/2'' wide and 6 1/2'' long and tapered them both on one side. Test fit the leather covers by wrapping them around the prod where they will be attached. Trim if necessary until you get a correct fit.
Using the awl, punch the same amount of holes on both sides of the leather covers, at 1/4'' intervals. Once you have done this start sewing the covers on to the prod with the cotton thread using a crisscross pattern, or a modified pattern of your own. After you get all the way to the end tie a knot and you're done.
The prod covers should slide off fairly easily at this point for easy installation of the prod. Just slip them back on after the prod is in place and before the bow is strung.
Step 13: Evaluation
Here are the spec's for the crossbow once finished.
Draw Weight: 50lb's
Bowstring: Generic 50lb bowstring available at sporting goods stores and Amazon
Overall Weight of crossbow:1.5-2lb's
Projectiles: Plastic pistol crossbow arrows.
Weight of trigger pull: 15 lb's (Quite heavy trigger pull, so it probably won't go off on accident)
Completion time estimate: 40 hours or so (Someone more experienced could probably do it in less time)
This is my first instructable and any constructive criticism will be welcomed. The building of this crossbow required a great deal of work and there is a good chance I left something out of my instructions.
Disclaimer- You are responsible for anydamage done while using or creating a replica or reproduction of this project. This is not a toy and can seriously injure or kill someone. Use with caution.