Picture of 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.


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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

Picture of 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

Picture of Cutting and Mounting Arm

Step 4: Cutting and Mounting Claw

Picture of 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

Picture of 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

Picture of Putting it all together
After created the arm, claw and base pieces together to test out the movements and check if everything is working properly. Once assembled, we found that the syringe clamp was not well positioned. We cut a piece of cardboard to attach the syringe to another position, as shown in figure.

Step 7: Painting

Picture of 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.
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makershaker0511 months ago

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.

PeckLauros (author)  makershaker0511 months ago


moosaahmed7 months ago
plese give us measurements
PeckLauros (author)  moosaahmed6 months ago

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

moosaahmed7 months ago
what can it pick up in particular cause I have to do it in school
PeckLauros (author)  moosaahmed7 months ago

Some plush toys and some origami . The claw is not very strong . It was meant only to showcase the work of pistons in a didactic way .

moosaahmed7 months ago
can the claw pick up a chalk board duster
PeckLauros (author)  moosaahmed7 months ago

With a feel changes in design,i guess :)

kshitizc8 months ago

Thanks For Your Help. It will surely help me.

PeckLauros (author)  kshitizc8 months ago

No problem! Then Show us your arm.

jamie.parr.188 months ago

where did you buy the syringes?

PeckLauros (author)  jamie.parr.188 months ago

I bought at a pharmacy.

akshaygill8 months ago

this is awesome.. I really loved it

PeckLauros (author)  akshaygill8 months ago


makershaker0511 months ago

I do not need the demensions to each part but just out of curiosity, (hope I don't get killed like the cat), what is the size of the whole project put together? I don't even need exact numbers an estimation would even be fine.

Dullz1 year ago
Made a few changes but got the main idea from you, thanks! ;)
PeckLauros (author)  Dullz1 year ago


Dullz1 year ago
Wow thanks a lot, this design was AWESOME. Look at my profile picture, I'm finally finished with it.
Dullz1 year ago
Busy making it and it's really FUN!!!
PeckLauros (author)  Dullz1 year ago

Also enjoyed myself.

gholam1 year ago
nice design
PeckLauros (author)  gholam1 year ago


Dullz1 year ago
PeckLauros (author)  Dullz1 year ago


As simple as you and your brains rock
hashwanth1 year ago
i want the measurements of everything !!! please
PeckLauros (author)  hashwanth1 year ago
Hi! If I find the claw, I will put measures.
wow extraordinary
PeckLauros (author)  K S VigNesh1 year ago
3366carlos1 year ago
5 jalapenos!!
PeckLauros (author)  3366carlos1 year ago
vkz.soni2 years ago
plz can i know the size of the syringes used
PeckLauros (author)  vkz.soni2 years ago
Hi Sorry for the delay in responding. In this project, I used 3ml syringes. I do not know the size because I'm not home. As soon as I can, will check the size of them. Although size does not matter much. It depends on the size you'll want to build your mechanical arm.
mangomango2 years ago
Absolutely brilliant! I never would have imagined using syringes like that
PeckLauros (author)  mangomango2 years ago
Lorddrake2 years ago
5 stars :)
PeckLauros (author)  Lorddrake2 years ago
Thanks !
wilgubeast2 years ago
So awesome! This would make an awesome classroom kit if one had access to a laser cutter.
PeckLauros (author)  wilgubeast2 years ago
I agree!
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