How to install gas strut to soft close wooden box lid?

[jarko]

I've made a wooden box with a lid, which will be used by young children (inspired by this YouTube short: https://www.youtube.com/shorts/b82yN588qzc).

I want to make the lid soft close, to prevent mishaps with fingers, and the lid is too heavy to be soft close with regular soft close hinges/cupboard braces - so I want to use gas struts.

I want the lid to have an 80/85 degree max opening, the box depth is 400mm, the lid depth is 33mm and the lid length is 357mm.

I measured the length of the opening and ended up purchasing two 325mm struts (https://www.bunnings.com.au/goliath-325mm-150n-black-gas-strut_p4230058) and brackets (https://www.bunnings.com.au/goliath-20-x-25mm-stainless-steel-gas-strut-bracket-with-ball-stud_p4230... / https://www.bunnings.com.au/goliath-10mm-ball-end-bracket-strut_p4230085).

But when I installed the struts (like in the video), the lid wouldn't close. I also tried using a calculator online (https://www.gasspringsshop.com/gas-spring-calculator/) and had the same issue (it recommended a 332mm strut which likely impacted the placement locations).

I've uploaded a picture (the strut is currently not connected to the base since the lid then doesn't close) - can anyone help me understand what I am doing wrong here?

[EricL]

Hello @jarko 

Thank you for sharing your question about your gas struts for your children's wooden box lid. 

The reason your 325 mm struts would not allow the lid to close is simply that their compressed length is still too long for the short distance available between the mounting points when the lid is shut, which means the geometry can never work no matter where you place the brackets. Toy boxes and storage chests with shallow lids like yours almost always need shorter gas struts because the mounting points move very close together as the lid closes, and the strut must be able to fully compress within that space. 

In practice, struts in the 180–250 mm range work far better, and several Bunnings options suit this style of box: the Goliath 185mm 100N Black Gas Strut, the Taskmaster 265mm Pneumatic Furniture Gas Stay, and the Prestige 250mm Silver Pneumatic Stay. To choose correctly, close the lid and measure the shortest distance you can realistically achieve between a mounting point on the lid frame and one on the box side; the strut’s compressed length must be less than this measurement or the lid will never shut. 

The 185 mm strut usually fits compact geometries most easily, while the 250–265 mm options can work if that closed-position distance is long enough and you want a wider opening angle. Once you select a strut that can physically compress within your available space, mount the lid bracket roughly 70–120 mm from the hinge and the body bracket 70–120 mm below the top edge so the strut sits at a gentle angle when closed, giving you safe, smooth soft-close behaviour for children.

Let me call on our experienced members @Noyade, @Dave-1, @AlanM52 and @Nailbag for their recommendations.

If you need further assistance, please let us know.  

Eric

[AlanM52]

Hi @jarko,

Looks good and I like your pocket holes.

Looks like you need to drop the strut down and make a spacer block.

Here is another dad that made a kids toy box.

Did the instructions say to mount with rod up.

Maybe have a look at this video.

With little fingers in mind I would replace those back hinges.

Galvanised Piano Hinge.

Cheers

[Nailbag]

Hi @jarko 

The last time I had to install a pneumatic strut was also for a toy box and remembered how difficult it was. But it was important so little fingers didn't get smashed so, I had to persists.

The first point is which @AlanM52 has pointed out is to change the hinges to piano. This will prevent the lid from twisting as it's pulled down to close which, works against the strut pressure.

The next is length of the ram which, @EricL noted to use a shorter one and of the right lifting power and mounting points. I would follow his advice on these points.

Nailbag

[Dave-1]

Good Morning @jarko 

Well I just learnt a new thing I havnt install gas struts on anything as yet but will file @EricL's @AlanM52 's and @Nailbag 's words away as they make a lot of sense.

Dave