Hydraulic Arm




This hydraulic arm was a homework for my daughter's school. The idea was to create a toy from recycled materials. Hope you enjoy.


Step 1: Materials

- Pieces of cardboard
- 8 syringes
- 1,5 meter hose (aquarium pump)
- 15  Plastic clamps
- 2 screws with 3 washers and 4 nuts
- 1 piece of wire (clothespin)
- 1 wooden stick
- Water, paint, glue, knife, ruler, etc..

Step 2: Planning and Cutting

We made two drawings of what would be the arm and joints. This allowed us to readily quantify the material being used.

After choosing the model that we would use, cut the pieces (not much criterion measurements) as shown in picture.

Step 3: Cutting and Mounting Arm

Step 4: Cutting and Mounting Claw

The gripper is designed to move just one piece. It was more simple.
The "finger" was pasted fixed and mobile was seated on a shaft made with a piece of wooden stick that had a piece of cardboard cut in a circle glued on top so as not to leave the place.

Step 5: Cutting and Mounting Base

The base was made from two pieces of cardboard in order to support arm and accommodate syringes in the same set.

The movable part has two holes:

- One in the center (to be able to rotate the base)

- The other end (to link the syringe and allow movement)

The syringe was attached to another piece of cardboard to keep the same level of mobile base.

After verifying the limits of movement, we fix the syringe with the clamps.

Step 6: Putting It All Together

Aftercreatedthearm,clawand basepiecestogetherto testoutthe movements andcheck if everything isworking properly.Onceassembled, we found thatthe syringeclampwas notwell positioned.We cuta piece of cardboardto attach thesyringeto another position,as shown in figure.

Step 7: Painting

After completing the check and corrected minor errors, disassembled the arm as far as giving and paint. After the paint dries, put together definitely.

Step 8: Filling the Syringe

We chose four colors to color the water and fill the syringes.
Fill the hose and then put a syringe (without air inside - close) on one end. Fill another syringe (not filling all) and put the other end. Check the operation.

Step 9: Final Result

I hope you enjoyed.

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65 Discussions


4 years ago on Introduction

I favorited this as soon as I saw it. I really love the idea, and the vibrant colors! Thank you for the time you spent making this instructable, I really enjoyed it and was educated in hydraulics through it.

1 reply

2 years ago

cool is it okay if I use this for my science fair project

1 reply

Reply 2 years ago

No problem! No problem. I suggest reinforcing the claw arms with popsicle sticks, for example.


3 years ago

Cool, mine turned out perfect! Thanks for showing me and some others a good step-by step process into making this. I plan to take a picture of it and post it on here as well.

1 reply

Reply 3 years ago

Thank you for enjoying the work . Here at Instructables have many good works . As soon as I can, I come back to post more .


3 years ago

Wow, that's a lot of work you put into this project! It really fascinated me, so I will be looking at more of your projects!! Thanks for publishing it :D


3 years ago on Introduction

i had something like this before. then i broke it with over pressurizing it.

so i might build this. becuses it doesnt need to be pumped up.

1 reply

Reply 4 years ago on Introduction

Hello . Unfortunately this is an old project and I missed the measures . Will depend on the size of syringes you buy.


4 years ago

what can it pick up in particular cause I have to do it in school