Martial Makers

(Originally posted on Back in the Gi)

Similar commercial equipment: Body Opponent Bag (BOB), Century Wavemaster 2XL Pro

One of my favourite pieces of equipment is “BOB”, the Body Opponent Bag manufactured by Century. If you don’t know BOB, you should. It’s a free-standing striking dummy made of foam that has a distinct torso and head and allows for much more realistic striking practice, both in terms of power (vs. a training partner) and accuracy (vs. a heavy bag). The only downsides to BOB are that it can’t be struck from the back or below the torso (or, if you have the XL model, below the shorts) and the fact that it is quite expensive. If you want to have a 360-degree free-standing striking target with a separate head for accuracy and/or you are on a budget, the options are pretty limited.

I already have a BOB and a hanging heavy bag in my hojo, so technically I don’t need any more striking equipment. However, for practising against multiple opponents and for the purposes of developing something inexpensive that might be useful for my fellow martial artists, I decided to see what I could make. All in all, I am quite pleased with the results.

Here is what the finished striking dummy looks like:

Below, I provide some details on how I built this striking dummy.

Here is what you will need:

Supplies list

* Car tires (2). These can be obtained for free from an automotive repair shop.
* Concrete mix (4 x 30kg bags). These cost about $5.00 each.
* 2″ x 4″ x 8′ boards (3). These cost about $2.50 each.
* Large G.I.-style top-loading duffle bag (42″ x 24″). This can be obtained for $20 or less from an army surplus store. The strap should be cut off.
* Duct tape (2 x 45-yard rolls). These cost about $5 each.
* An old futon mattress. These can easily be found in classified ads for no more than $25, and sometimes they may even be free. Note that one mattress can make two striking dummies.
* Miscellaneous supplies: wood glue, screws, large nails, extra foam, pillow case, strong spring, small piece of plywood.

The total cost varies according to whether a duffle bag shell is used (you could get by using only duct tape) and what one has to pay for a futon mattress. The deluxe model would cost about $70 in materials, whereas a cheaper version (no duffle bag) might be $50 or less. Much lower than even the cheapest free-standing punching bags I have seen. With the size, weight, and separate head on this one, it’s much closer in functionality to higher-end models costing a few hundred dollars.

The first thing to do is make the centre post and base. For this, I glued and screwed three 2″x4″ boards together (two together and perpendicular to the third).

To help keep the post in place during and after the base is made, I glued and screwed a small piece of plywood to the bottom of the post. In addition, I drove some large nails through the post so that they stuck out in different directions. The plywood and nails are there to anchor the post permanently in the concrete. The post was then left overnight so that the wood glue could set.

I then placed the post inside two old tires and filled them with concrete. The concrete needs to be pushed into the empty spaces of the tires, and it’s important to wear gloves for this as concrete can cause nasty chemical burns due to its alkalinity. Once the tires were full and the level of the post was double checked, the concrete was allowed to set (about 48 hours).

With four bags worth of concrete inside the tires, the base is now very heavy. It would take a pretty serious kick to knock this thing over. However, it is still portable if it is moved by tilting it low and rolling it along on the tires.

To make the striking surface, I used half an old futon mattress, which is basically just a canvas cover containing various types of foam and padding. I rolled this around the post and attached it with duct tape. Then the entire thing was covered in duct tape to keep it in place and to compress the mattress material to make it firm for striking.

If one were not offended by the site of duct tape, one could stop here and have a perfectly serviceable free-standing bag. However, I wanted something that looked a little more professional and I also wanted to have a separate head on the dummy.

In order to add a head, I trimmed the post down and attached a block of 4″x4″ wood to it using a spring/garden hose connector that I had available. I simply drilled a hole into both the post and the block of wood, set the spring inside, and fixed it using some screws through the wood and the hose.

I then filled in the top of the futon, taped it over, and then added a foam collar under the block of wood. This helps to keep the head from wobbling too much. This was taped in place as well.

I then placed the duffle bag upside down over the taped futon. A small slit had to be cut in the bottom of the bag in order to get it over the block of wood. I worked the duffle bag down as far as it would go, then cut off the metal rings that would normally be used to tie the bag, and I attached it with black duct tape at the bottom.

To make the head itself, I used a piece of 2″x6″ and glued and screwed another piece onto it as shown in the picture below.

I covered the wood with foam padding using a staple gun in order to prevent any injury from hitting wood, and attached it to the wood block. I then build up the head using foam and padding, sealed it with duct tape, and put a pillow case over it. I also placed foam around the bottom part of the block of wood to make a neck. Then the pillow case was attached using duct tape around the neck area.

As finishing touches, I spray-painted the visible parts of the concrete with black paint and I attached a foam mat to the bottom of the tire to make it quieter when the tire lifts off the ground slightly as the dummy is struck.