Heavy Duty Corner Clamps

Hello makers, welcome to this page. In this Instructables, I am going to show you how I build heavy-duty welding clamps. This build is inspired by Jason from the Fireball Tools YouTube channel, and I am a huge fan of that guy and his wisdom. The only difference in my clamps is that I made them with angle iron and those he made are cast iron. Now, these welding clamps are absolutely easy to make and I call it a beginner welding project too because the wall thickness is quite thick enough that you are easily able to avoid blowholes. Since angles are hot rolled steel and because of that there is definitely you need to compensate in the accuracy but one thing which you are able to do is to keep the pieces in the square so that whenever you are going to take the reference from the sides you are easily able to make a square frame. To hold the job at its position I also decided to add tabs if I am working in mid-air. This build required very basic welding tools and the clamps themselves are extremely usable. So if you like this project and often do fabrication work then definitely give a shot to this project. If you have any suggestions to improve it then definitely feel free to post your feedback.

Tools used

1. Angle grinder

2. Drill machine

3. Drill bit

4. M8 thread tap

5. Grinding wheel

6. Flap wheel cutting wheel

7. Clamps to hold the job at its place

Material used

1. 50X50 mm angle iron

2. 50mm X 6mm strip

. 25mm X 12mm strip

4. M8 Allen head bolt

5. Primer

6. Paint

The first and foremost thing to do in this project is to cut down the material to the required length. Now my materials have been placed outside for more than a year that's why a rust removal process needs to be carried out. I use a grinder with a wire brush and remove the rust from the angle. Then made a mark around 10" and cut the angle piece it's absolutely necessary to mark both sides to get an accurate cut. Since I am going to build 4 of these clamps for 4 corners I need to cut 8 pieces of 10" in length.

Now for a right-angle triangle, we have two sides already and one thing left is the hypotenuse which we need to measure first before cutting. So what I did for accurate measuring was I place the angle piece onto the table and made them square or you can find it from the Pythagoras theorem.

√L²+B²= H

√10²+10²= 14.14" or 359 mm for accurate marking

From thereafter I measure the two opposite corners and to maintain higher accuracy I measured it into mm. Once that's is marked I cut down the piece into the required length.

Since the longer length of the angle needs to connect with two shorter pieces that's why the corner needs to be cut at 45°. For that, I made a mark with a combination square and transfer it onto the edges, and then made a cut. To refine the cut I used a grinding wheel to do that. Once the cutting is done I placed all the three-piece in the position to make the two sides square and then proceed for the next process.

Once three sides has been prepared for the welding I placed them over a flat surface. I clamped all three sides with c clamps and then measure the squareness. In this build, it is absolutely mandatory to do the measurements because once it's secured with welding and it went a little bit off then that might end up giving you an out-of-square clamp which we do not want. Then I made tack weld onto all the sides and allow them to cool and once they cools down remove the clamps. Then I flip the piece upside down so that I am able to weld onto the backside also. But before starting the welding it is absolutely necessary to keep the faces in line with each other and for that, I used a ruler and place them over the joints. Some are flat but some need to place down a little bit and to do that I used clamps and then made tack weld. Since in first glance at this stage the fixture looks a bit weaker in the middle section and that's why to secure them I cut a piece from a 50mm wide strip and made miter cut to it and made a tack weld by holding it with clamps then I flip the piece and felt that whether the piece is flush with the surface or not and it was flush and then start the full weld. I welded diagonally to avoid thermal distortion in the piece and after that again measured it with the help of a square and it's was good and didn't warp at all. In the fabrication, it's absolutely mandatory to go diagonally to avoid thermal stresses.

I also added a corner piece to the notched area to make it more strengthened. These are just offcuts from that miter joint which fits quite nicely.

Once the clamps are made I start the grinding work. First I grind down with 24 grit and when it's slightly above the surface I use a flap disk to make it completely flat and flush with the surface.

For effective work holding, I need to drill holes so that I can install tabs over which job can be placed during the work. Provide a spacing of 75mm between the holes and mark it onto the sides of the angle, then I center punch and drill down the holes and tap them with M8 thread tap.

Sometimes during the work, it's always not possible that we have a work table so in those cases, these tabs are extremely helpful and what they do is that they provide a flat reference to the job and with that, you are easily able to hold down and weld the job. I use a 25 mm 12mm thick piece of bar and I first divided it into 50mm long pieces and then made a mark for the hole at a distance of 15mm. I drilled 8.25 mm holes so that an M8 bolt can pass through it. Then I cut them into 50mm long sections with the help of a grinder. Off-camera I deburr the edges to make the pieces nice and smooth.

Since it's mild steel and often gets rusted in the humid environment I decided to paint it with orange and black paint. I first did one coat of primer and then one coat of paint with the help of a brush. Another advantage of paint is that it will avoid spatters to stick to the surface and kept it smooth.

After the painting, the clamps look quite good but I am definitely aware that it's not going to last long but for a little bit of time it looks fine.

Now the most obvious advantage is in framing by holding the job with clamps along the sides.

The second is that it's much easy to hold the round pipe also and able to maintain squareness with the frame and all that happens because of those tabs.

Last is that when you combine these pieces you are able to maintain the certain gaps within the limits of clamps if you placed them a mirror to each other while both the longer sides touching each other. Just by sliding them up and down, you can maintain a certain gap. I hope you like this and if have some suggestions then do let me know in the comment section down below.