METAL DOG CART_ Bicycle Accessory

Warning

This project involves the use of potentially dangerous tools, equipment, and materials, such as welding machines, angle grinders, and metal cutting tools. The construction of the dog cart must be carried out at your own risk.

Strictly follow industrial safety regulations, use appropriate personal protective equipment (gloves, welding helmet, safety goggles, hearing protection, and suitable clothing), and work in a well-ventilated and safe area.

The author is not responsible for any injuries, accidents, or damage to people, animals, or property that may occur during the fabrication, use, transport, or maintenance of the dog cart. Improper use of the final product is the sole responsibility of the user.

Materials

Metal:

1. 2" × 1" PTR steel tubing, 10.55 m total (2 sections / 6 m each)
2. 3/4" × 1/8" steel angle, 2 m
3. Type 41 metal cutting disc, 4-1/2"
4. Type 27 metal grinding disc, 4-1/2"
5. Leather work gloves
6. Clear safety glasses
7. E6013 welding electrodes
8. Expanded metal (diamond pattern), gauge of your choice
9. 1-2 Spray paint for metal (color of your choice)
10. 3/8" drill bit

Wood:

1. 4 boards (premium pine wood), 15 cm wide × 2.4 m long
2. Oil-based wood paint (color of your choice)

Hardware and other materials:

1. Galvanized hex-head self-drilling screws
2. 3 pairs of 2" hinges
3. Reflective tape, 1 roll
4. 2 bicycle wheels, 16"

Tools

1. Electric welder for basic metal work (light structural welding)
2. Appropriate safety clothing for welding and cutting operations
3. 4-1/2" angle grinder
4. Electronic welding helmet
5. Pencil
6. Tape measure
7. Magnetic welding squares
8. Angle square
9. Drill
10. face mask

Quick Welding Tips & Recommendations

1. Clean the material before welding

Remove paint, rust, oil, or dirt from the metal to ensure proper weld penetration and strength.

1. Use the correct electrode

Make sure the electrode is suitable for basic structural welding (e.g., E6013) and is in good condition.

1. Maintain a steady hand and proper angle

Hold the electrode at an approximate 10°–15° angle to achieve a uniform weld bead.

1. Avoid long continuous welds

Weld in short sections and alternate sides to prevent warping caused by excessive heat.

1. Tack weld first

Always tack weld the pieces before making the final weld to verify alignment and measurements.

1. Check angles and alignment frequently

Use magnetic squares and a tape measure to ensure the structure remains square during welding.

1. Allow the welds to cool naturally

Do not cool welds with water, as this may weaken the joint.

1. Wear proper protective equipment

Use a welding helmet, gloves, and appropriate safety clothing at all times.

Before starting the construction, it is essential to become familiar with the project drawings, paying close attention to the indicated dimensions and proportions. These drawings have been created using AutoCAD and will be provided to the reader; therefore, it is recommended to review them carefully to ensure proper understanding and accurate execution of the design.

Metal Cutting List

1. 4 pcs × 80 cm, 1" × 2" PTR steel tubing
2. 4 pcs × 60 cm, 1" × 2" PTR steel tubing
3. 4 pcs × 40 cm, 1" × 2" PTR steel tubing
4. 2 pcs × 20 cm, 1" × 2" PTR steel tubing
5. 1 pc × 75 cm, 1" × 2" PTR steel tubing
6. 2 pcs × 25 cm, 1" × 2" PTR steel tubing
7. 2 pcs × 55 cm, 1" × 2" PTR steel tubing
8. 4 pcs × 15 cm, 1" × 2" PTR steel tubing
9. 2 pcs × 40 cm, 3/4" × 1/8" steel angle
10. 2 pcs × 45 cm, 3/4" × 1/8" steel angle
11. 2 pieces (42 cm × 72 cm), expanded metal (diamond pattern)
12. 1 piece (55 cm × 42 cm), expanded metal (diamond pattern)

Wood Cutting List

1. 3 pcs, 53 cm × 15 cm, premium pine wood
2. 5 pcs, 54 cm × 15 cm, premium pine wood

To cut the PTR steel tubing, it is necessary to use an angle grinder equipped with a metal cutting disc. During this process, protective gloves and safety glasses must be worn at all times to prevent injuries caused by sparks, burrs, or metal fragments.

*It is recommended to complete all required cuts at the beginning of the project in order to optimize time and ensure a more efficient construction process.*

1. Mark the angle clearly using a square or a bevel gauge.
2. Use a guide (a miter box or miter saw) to keep the angle precise.
3. Secure the piece firmly with clamps to prevent movement.
4. Cut slowly, letting the tool do the work.
5. Test the cut on a scrap piece before cutting the final material.
6. Lightly sand the edge after cutting for a better fit.
7. Work safely: wear safety glasses and keep your hands away from the blade.

To begin the construction of the dog cart, use the reference image and the provided drawings as a guide. Based on these, make the required 45° cuts on the corresponding pieces, ensuring that all indicated dimensions are respected.

The chassis assembly is carried out in the following order:

1. First, assemble the main rectangular frame of the largest size.
2. Next, position and weld the central cross, which provides rigidity and structural support.
3. Finally, assemble and weld the side rectangles, making sure they are properly aligned and symmetrical with respect to the main frame.

To ensure that all corner angles are at 90°, it is essential to use magnetic squares during the welding process. These help maintain proper alignment of the pieces and ensure the symmetry and stability of the chassis.

*Grinding is a fundamental step to achieve clean, safe, and well-finished work. Grinding the welds allows the removal of burrs, excess material, and irregular weld beads, improving both the aesthetics and functionality of the structure. Proper grinding also facilitates paint application and reduces the risk of sharp edges.*

Once the chassis is solid and properly ground, we will continue with the structure. To begin, we will raise the frame by placing the 40 cm PTR sections at the corners at a 90-degree angle, using magnetic angles to ensure proper alignment.

Following the structure, what we will do next is place the remaining pieces, using the images and plans that I will provide as a guide. Make sure to make 45-degree cuts where required, and use magnetic angles to achieve the necessary symmetry.

In this step, we will use the 3/4" × 1/8" steel angle. The measurements are the same as the ones you already cut; the only thing you need to do is cut the corners at a 45-degree angle. It is important that you do this on only one side, as shown in the image; otherwise, it will not fit correctly.

For the wheels, we will also use the 1 × 2" PTR. As shown in the images, we will cut it into an “L” shape. This is very important, since this is where the wheels will be mounted.

This piece is very important, as the hook for the bicycle will be attached to it. It has this design because of the shape of the bicycle model used; if necessary, you should adapt it to your own bicycle.

In this step, once the main structure is fully assembled, install the expanded metal (diamond pattern). Cut the metal using an angle grinder. The required measurements were provided at the beginning of this instructable:

1. 2 pieces (42 cm × 72 cm) of expanded metal (diamond pattern)
2. 1 piece (55 cm × 42 cm) of expanded metal (diamond pattern)

Make sure the pieces fit properly before fixing them to the structure.

The installation of these mesh panels is very simple. It is important to place the mesh on the inside of the cart, from the inside outward; otherwise, the welds will be visible from the outside, which would negatively affect the final appearance.

*Remember that every time you finish welding, you will need to use a grinding disc to clean and smooth the weld.*

These are the steps I recommend you follow. Installing hinges can be a difficult task, so I recommend staying focused and exploring which method works best for you.

1. Place the door in its final position and secure it with clamps so it does not move.
2. Position the hinges where they will be installed, making sure they are properly aligned.
3. Mark the points where the hinges will be fixed.
4. First, tack weld the hinges with small welds to check that the door opens and closes smoothly.
5. Once the movement is correct, complete the welding.
6. Grind the welds to leave them clean and smooth.

We will prepare the wood pieces we already have. I recommend that when purchasing the wood, you ask for the required cuts to be made at the store, so you need fewer tools and save time.

What we will do next is sand all the wood pieces, starting with 100-grit sandpaper and working up to 400-grit.

Once the wood is well sanded, paint it. My recommendation is to apply the paint using cotton waste (rag) and thick latex gloves.

It will be necessary to apply at least two coats of paint.

Once everything is welded and properly ground, we will move on to painting the cart. I used a compressor and a spray gun, but you can also use metal spray paint cans in the color of your choice.

I recommend wearing a face mask and working in a well-ventilated area.

You will need approximately 1 to 2 cans of paint.

To install the wooden floor, it will be necessary to drill holes in both the wood and the metal. It is recommended to place the wooden boards in their final position and perform all drilling with the pieces already assembled. A drill with the appropriate drill bit will be used. Once the holes are made, insert the self-drilling screws to secure the boards, completing the base of the cart.

We will continue with the installation of the wooden panels on the door. The process is the same as before; however, the self-drilling screws will be inserted from the metal frame, going from the outside toward the inside.

First, drill the holes through the metal frame and into the wood using a drill with the appropriate bit. Once the holes are made, insert the self-drilling screws to secure the wood in place.

*For this step, the hinges should already be installed, making it possible to mount the door and check its proper operation.*

To ensure that the door closes properly, it is recommended to install a door latch. In this case, it was fixed using “No More Nails” adhesive (or any adhesive of your choice), making sure it is positioned correctly to achieve a secure and functional closure.

For this final step, we will install the wheels on the cart. It is important to properly tighten the nuts so the wheels do not remain loose. Once the wheels are mounted and securely fastened, reflective tape will be applied to increase safety.

In case of any doubts, it is recommended to review the production drawings. These were created by me using AutoCAD and will be included to make the fabrication process easier.