Calculate the strength/load capacity of an M2.5 threaded bolt?

[etompau]

If you're going to burden it with 100 kg, you'll likely have other problems than the bolt in the handle. The wheels don't look overly stable.

 

[Nyfniken]

You're supposed to just pull the load, not lift it. And the handle is fixed on two sides.

Imagine if you actually lifted it. That would be 50 kg per side. If you were right, you should then be able to break the bolt with just your hands...

 

[Volatyle]

It is very possible, but when I tried loading it, I notice that the bolt is by far its weakest point. There isn't a chance that it will hold. Also, my original thread isn't about more subjective assessments regarding the cart itself. What I was looking for was to technically support the argument that this part of the cart is undersized by demonstrating what a 3mm screw can actually handle in terms of weight (consider that the load is likely to exceed 100kg sideways with the leverage effect.

 

[snuttjulle]

The cart looks flimsy, I agree, with something that looks like hard plastic wheels etc. Load it with 100Kg and drive a bit over sticks and stones. Then submit a complaint. Just make sure to document these 100Kg so there won't be any talk about you overloading it.

 

[etompau]

Taking a quick look at Essve's specs for bolts, they state breaking strengths for M3 bolts as at least 1660 N, approximately 166 kg. How this is applicable to your cart, I'll leave unsaid.

 

[Rolle314]

The screw will shear off. And it will happen in two places, right and left. There will be two screw areas that will shear off. The question is what breaks first, the screw or the fastening? If the fastening is weak, deformation can occur and thereby affect the load drop. It can become complex to calculate. Agree on thoroughly testing at maximum load.

 

[richardtenggren]

So that can't be M3, then I should book an appointment with an optician!
I think more like M5, but a quick overall calculation gives;

Assume that the allowable shear stress is Ttill=0.6*Rm, which gives Ttill=0.6*800 MPa if we assume 8.8 quality. As for M3 is about 5 mm3.

F=m*a => m=F/a and F=Ttill*As =>
m=Ttill*As/a= 480*5/9.82~240 kg

But you have two setups... So it should hold

 

[Strontus]

The screw will probably hold, but the whole cart looks a bit rickety, so it's likely something else will give way if you load it with 100kg and drive around with it.