I'm planning on making a multipurpose woodworking workbench-desk combo in the near-future. to keep the cost of that workbench low, I have decided to make everything of plywood and mdf. This will include legs made from 5 layers of plywood etc. In order to do this I need a lot of clamps, preferably large so they can span an entire table. Since I now only have 2 small clamps I decided to start building bar clamps out of wood.

These are easy to make clamps which can be as large as the longest piece of wood you can get your hands on. Since my clamps turned out looking mostly look like one I found on the internet, I didn't include a SketchUp file, you can find that online(see options step for the link).

Step 1: Materials

Materials, per clamp:

Lumber. I used a standard size 50x75mm (which is actually 44x69mm due to planing). Length depending on size clamp. I started with approximately 150cm and ended up with a maximum clamping width of 100cm.
Plywood. 2 pieces of 70x175mm, 2 pieces of 25x175mm, 2 pieces of 90x175mm and 2 pieces of 69x(44+2*plywood thickness)mm.
Screws. 38 pieces of size 4x30.
Threaded rod. M10, length 30 cm.
Nuts. 5 pieces M10.
T-nut. 1 piece M10.
Lag bolt. 1 piece M10.

Tools:

Workspace. (Something like my small balcony is just enough.)
Miter saw. Electric is faster, but not necessary.
Drill.
Wrench.
Screwdriver.
Jigsaw.
Hacksaw.

Step 2: Prototyping

Do this, it's fun:

So, I wanted to build some bar clamps. Let's see what materials I have and make a simple prototype, that's prototype 1.

Don't do this, it's a waste of your time and money:

I bought all the materials for 6 bar clamps. Don't measure, just start with a hand saw and a drill and see how it turns out. Prototype 2 looks okay but everything is skewed so it doesn't really work great. Eventually it will end up in my wood pile.

Step 3: Options

I first looked at normal clamps an how they worked before searching the internet. They all had a fixed end and a non-fixed part which fixed itself by friction when something was clamped. The threaded rod was positioned in the non-fixed part of the clamp. However most larger clamps have the threaded rod on the fixed part. So many choices to be made.

Fixed end:

I decided I would add the threaded part to the fixed end like all other large bar clamps. For a little while I thought about making the fixed end non-fixed, but eventually I didn't do that.

Non-fixed end:

The non-fixed end has only one main option, how to make it hold position while clamping. Many option can be found on the internet and I added a couple of them here.

Let's start with the option I used. This option is used by a woodworker called John Heisz. Large holes are drilled in the bar. The non-fixed end has a lag bolt embedded which will fix itself in the hole. After I finished my clamps, it turned out my clamps almost looked the same as the ones of John Heisz even though I thought I only used his method with the lag bolt. He has free plans available on his website: www.ibuildit.ca/ So check out his website for a some very nice projects and sketchup-files, including this Instructable.

Option 2 is the option I first considered. I wanted to drill holes through the side of the bar. The non-fixed end would be fixed by putting a bolt through the end and the bar. I started searching for other options to fix the non-fixed end because I didn't like the idea of having a loose part to lock it in place. This however, could be solved by mounting the loose bolt with a string to the non-fixed end. An advantage of this method would be that it is easier to apply to a steel version which can achieve higher clamping power.

Another solution for fixating the non-fixed end is by letting it grip on the bottom side instead of on top like the lag bolt. Using two small metal bars, a rod is position on the bottom of the bar where it fits inside a groove. When pressure is put on the block, the rod fixes itself in the groove. A couple of disadvantages are that the grooves can be hard to make. If you want to drill them you need to do that before cutting a part of the beam of, therefore you almost certainly need a table saw which many people don't have. On average these ends are positioned more loose on the bar. So when you want to store them they tend to fall of the bar more easily.

The last option I found interesting was the use of threaded rod for friction. Instead of using a lag bolt like in the design of John Heisz, you can mount a piece of threaded rod on its side to create friction without adjusting the bar itself. This would allow you to use all beams of the same size with different lengths. I can't find where I found this option anymore, when I do I will post a link.

Moving bar:

Depending on how you make the ends you need to shape your moving bar. All designs I showed above stick out under the bar. So there you have the option to guide the moving bar over the bar by adding support beneath the bar. However many designs can be found online which are not supported beneath the bar and are only attached to the threaded rod. When you choose such a design there is the option the threaded rod will bent upwards and/or sideways when the threaded rod sticks out a lot. Normal clamps do not have this problem because the threaded rods used there are hardened much more than the threaded rod used in this project.

Step 4: Cut All Materials

Again, do this once for all bar clamps.

Using the miter saw, cut the lumber to 1 piece of 9cm, 3 pieces of 7cm and 2 pieces of 2.5cm. The rest of the beam will serve as the bar of the clamp. Sand all the pieces. I will explain the angled cuts in the next step.

Using the jigsaw, or table saw or anything else you prefer, cut the plywood to 2 pieces of 70x175mm, 2 pieces of 25x175mm, 2 pieces of 90x175mm and 2 pieces of 69x(44+2*plywood thickness)mm. Sand all the pieces.

Using the hacksaw, cut the threaded rod to 30 cm.

Step 5: Assemble the Non-fixed End

For the non-fixed end we first need to do an additional cut on the block of 9cm and 7cm. Saw a piece of both blocks at a 15 to 20 degree angle as you can see in the images. Some things you need to think of while cutting can be seen in the images.

Once the angles are cut you can drill the hole where the lag bolt should go and put the lag bolt in. Now you have two options, assemble the end before cutting the plywood to shape or vice versa. I first assembled the end and cut afterwards using a handsaw, but it probably is much easier to assemble the end after cutting the plywood with a jigsaw.

When you're finished with the assembly of the side to the block, the last piece can be attached. This is the piece of plywood which eventually will be clamping the object. For positioning and size see the images.

Step 6: Assemble the Bar Including the Fixed End

Before we mount the fixed end to the bar we're going to drill holes in the bar where the lag bolt can be fixed in. Make sure the holes are large enough to fit the head of the lag bolt. I spaced the holes 5cm apart, see images.

The upper block of the fixed end will house the threaded rod. So here needs to be drilled a hole as well. The hole should be large enough such that a t-nut can be insert at the side of the bar. Once the hole is drilled and the t-nut is inserted, screw the t-nut in place for extra support, see images.

Once the holes are drilled I mounted the fixed end. During assembly make sure the end is fixed at a 90 degree angle to ensure that the threaded rod is parallel to the bar.

Step 7: Assemble the Moving Bar

Before we assemble the bar, we need to drill a hole where the threaded rod and nut can go through. Do this at the same position of the block as you did for the fixed end. Also make sure the large part of the hole is wide en deep enough to house a nut.

When you drilled the hole you can assemble the bar. Because the lower part is small it is hard to put enough screws in to prevent it from twisting. I tried to prevent this by using wood glue. It can be smart to round the corners of the lower part such that they don't grip to the bar when clamping. Also, if the bar is to tight to the bar which prevents it from moving freely, you can remove some material from the pieces of plywood for better guidance.

Step 8: Assemble the Entire Clamp

We are almost finished with the clamp. The last thing we need is a handle to go over the threaded rod. I used a broomstick I had laying around. I drilled a hole in the center a little smaller than the threaded rod. This way the rod will stay in the stick just by friction.

The last thing we will do before the actual assembly is cut of the bottom ends of the two ends and the moving bar. Make sure all pieces are cut to the same length. Also make sure the screws you put in during assembly are far enough from the cut to prevent the sawblade from damaging.

Then we need to fix a nut to the end of the threaded rod. I did this by welding, other options are gluing or drilling a hole through the nut and rod and fix it with for example a nail. Put the rod through the moving bar. Like with the non-fixed end we now can attach the piece of plywood which will touch the clamp object, see image.

On the other side of the moving bar we tighten two nuts together. This way they can't come loose and fix the moving bar to the rod. Now we can put the bar-rod assembly on the bar and twist the rod through the t-nut. Twist the handle on the threaded rod and you're bar clamp is ready to use.

Optional:

Of course you can give your clamps a paint job if you like that. A good lacquer could be good for your clamps when you will use them in a moist environment.

Step 9: Do Some Pull-ups Using Your New Clamps

Although a wooden bar clamp won't provide as much clamping force as metal clamps, they still provide a very decent amount of clamping force. To show you the strength of my clamps I used them as brackets for pulling myself up. For the result of my once a year sport moment, look at the images.

If you liked my instructable, please vote for me in the tools contest.

Step 10: Future Improvements

I found some things I do not like about the clamps and how I made them. So here are some things I will do differently next time or will fix for these clamps.

Use rampa nuts instead off t-nuts. I first wanted to use normal nuts and press them into the wood and glue them in place, but then I found the t-nuts in the shop and used those. When I later searched the internet I found the rampa nuts which look like these are made for this task
The wood I used wasn't as straight and perfect to size as you want it to be. So when you have a tablesaw or something, re-saw your wood so everything fits together much better than mine.
I drilled the holes in the handles to small so one of them cracked. So drill them to a better size and glue them. Or drill a hole through the handle and threaded rod and fix them with a nail.
Mount a piece of metal plate between the hole in the moving bar and the two nuts. It's much better than just one ring to average the force on the wood.
Make the handles and the threaded rod shorter, mine are both way to long.
Add a hex bolt or something to the backside of the handle so you can operate the clamp with your drill if you need to cover a large distance.