Pages

Thursday, December 18, 2014

Build a Quick and Simple Montagnard Style Crossbow



Montagnard is a French term referring to several hill tribes in Southeast Asia.  Many Montagnard tribesmen, with the help of U.S. Special Forces, joined in the fight against the Viet Cong during the Vietnam War. Historically, the Montagnard people used crossbows for hunting and self defense.  These crossbows are simple and no-frills, but they are very effective and can be very powerful. 


I have recently become interested in crossbows, and for my first project I decided to build a copy of a Hmong crossbow.  Although there are tribal and individual variations in these crossbows, they all work pretty much the same.  The major difference that I found in these bows is the trigger system.  Some of the bows used a “T” shaped wooden trigger that drops down through a slot in the tiller (stock).  Other bows use a little lever on the side of the tiller that lifts the string when you push down on it with your thumb.  I used the “T” trigger on the first bow that I built, but I couldn’t get it to work reliably enough to suit me.  I ditched the “T” trigger and tried out the lever system.  This worked very reliably, but because the lever is mounted on the right side of the bow it tended to lift the right side of the string first and thus caused the bow to shoot to the left.  I corrected this short-coming by putting a lever on both sides of the tiller with a dowell connecting the two levers.  This lifts both sides of the string at the same time, and although it is probably not strictly traditional, it makes the bolt (arrow) fly much straighter.

Here is a quick tutorial on how I built my Hmong style crossbow.  The tiller is built of scrap ¾” shelving lumber, and the 30” prod (bow) is made of hickory.  I won’t go into making the prod in this post as there are already several posts on this blog about how to make a bow and bowstring.  I will say that I have made one similar crossbow using 3/4” schedule 40 PVC pipe for the prod, and it worked very well.  If you are leery of trying to make a wooden bow, you may want to go the PVC route.

First I drew out the outline of the tiller on a ¾” pine board.

Then I used my band-saw to cut out the tiller.  You could do this with a jig-saw or even a hand saw, but it’s quicker and easier if you have access to a band-saw.  I used a wood rasp and sandpaper to round off the edges and clean the stock up.

You need a shallow groove in the top for the bolt (arrow) to rest in.  I made this by drawing a line down the center of the top then using my knife point to scratch a shallow groove along the line.  With the groove to act as a guide, I rubbed back and forth with a round file to create a rounded groove about 1/8” deep.  That’s as deep as you really need.

Now it’s time to mount the prod in the tiller.  I found the center of the prod and took a few measurements which I transferred to the side of the tiller.  I drilled several holes through the tiller and then used a rattail file to complete the slot.  I took my time on this with a lot of pauses to check the fit of the prod.  It needs to be a snug fit.  Don’t worry if you get the slot a little too large.  You can use a small wedge or two to hold the prod in tightly.  I have seen these wedges on several Montagnard crossbows.

The trigger assembly consists of three parts; two levers and a short piece of ¼”dowel rod.  I cut the levers out of some ½” scrap.  I cut them in a little bit of a fancy shape, but this is not at all necessary.  They could be simple rectangles.  

 I drilled a hole in each lever, making sure that the holes lined up perfectly.  The holes in the levers are a little smaller than the dowel so that the dowel can be trimmed down and wedged tightly into the levers. 

I positioned one of the levers where it will need to be on the tiller and marked the tiller where I could drill a hole through it for the dowel.  I drilled this hole a little larger than the dowel so that the dowel will turn easily in it.

I put a little wood glue on the dowel and inserted it into the right lever, then I stuck the dowel through the hole in the tiller.  I held the other lever up to the dowel and marked the dowel so that I could cut it to the correct length.  I removed the dowel from the tiller and trimmed down the other end until it would fit in the left hand lever, but I did not glue it.  Repeat, DON’T GLUE ON THE SECOND LEVER YET.

Now I paused in construction to give everything a nice coat of stain and took a break to make some arrows while it dried.   

Montagnard arrows are made of straight, round shoots or bamboo splits.  They are split on one end, and a folded bamboo leaf is inserted for a fletching.  The split in the shaft is then glued back together and wrapped with thread to reinforce it.  

 I made a traditional arrow, but it didn’t perform very well and the bamboo leaf tore up after about three shots.  I guess I need a Montagnard to show me how this should be done, because I obviously did something wrong.  As an alternative I cut some 5/16” dowels about 14 inches long and fletched them with duct tape.  They performed much better.

When the stain had dried I inserted the trigger assembly and very carefully glued the other lever on.  You want to make sure that you don’t get any glue on the inside of the lever or you may end up with it permanently, and immovable, glued to the side of the tiller.  Also make sure that the two levers are dead even so they will both lift the string at the same time.  Now I have to set it all aside until tomorrow so the glue can dry.

OK, the glue is dry and it’s time for a little test firing.   

Using a pointed dowel and duct tape arrow I shot at a dense foam target from 30 feet.  The arrow still shot a little to the left, but the penetration was about five inches.  Not bad.   

I shot it for distance, and boy was I surprised.  The arrow flew 82 yards which was about twice what I was expecting.  The crazy thing is that the arrow hit a treated post in front of my shop at the end of its flight and the sharpened wooden point stuck 1/2 “ into the post. 

This is definitely not a toy.  I believe that with a little practice you could easily hunt small game with this crossbow.

5 comments:

bigdog632 said...

Would you be able to use regular crossbow bolts with this?

Sensible Survival said...

Haven't tried them. Cock feather would have to go up, naturally. The downward slope of the other two fletchings might lift the shaft up out of the groove in which case the string would pass beneath the shaft, catch the back of the fletchings and flip the bolt up. Could be dangerous. Exercise extreme caution if you decide to try this.
Hank

Quentin Jones said...

Hank,

Wonderful blog; love this particular article. So much in fact I have taken to building my own simple-crossbow, albeit I did find some interesting additions/changes.

Using this as a guide I will be replacing the wooden-prod you have here with a steel-prod;
http:// shop.slobowscrossbows.com/SloBow-Steel-Crossbow-Prod-SB-104-SB-104.htm, and was wondering if the same design you have would work with this sort of material?

If so, or if not, what changes would need to be made in the design besides binding or using iron locks to mount the steel-prod? My main concern is in the lever system for the trigger, and the reinforcement of that area using metal to brace where the string will rest.

Please let me know what you think about this,
Lonnie

Sensible Survival said...

Lonnie,
Sounds like a fun project. I have actually been working on a crossbow that has a different kind of trigger mechanism. It has a rotating wheel called a nut that holds the string. The nut is in turn held in place by the trigger. When you pull the trigger it lets the nut rotate forward and releases the string. I'm sure that if you do a search you will come up with this design. It is much stronger than the lever system. For my prod I'm using 3/4" PVC. It is attached in a similar manner to the Montagnard bow but is a little stronger with a separate nose piece that clamps down over the bow and is held in place with four long wood screws. Good luck with your project, and thanks for reading.
Hank

Olivia Alexander said...

These are truly amongst the wonderful informative blogs.

pimpmybow.com