Weighing something you cannot lift

[ruffrecords]

I am about to ship a fairly heavy mixer. It is too heavy for one person to lift but I need to weigh it to get a shipping quote. So I am wondering if there is a way to weigh it without lifting it all off the ground. And I don't have scales I can get it on.

What I have in mind is lifting it from one end and measuring the force required with a spring weigh gauge. The I repeat the process from the opposite end of the mixer (because the centre of mass is not in the centre of the mixer).

So I have two force measurements from which I need to work out the overall total weight. I did some algebra by taking moments about each fulcrum and solving as simultaneous equations. After some manipulation and cancelling out I came up with the result that the weight is just the sum of the two measured forces.

It is about 50 years since I was taught applied maths so I hope I got the right answer. I can show my working if required but this result 'feels'  right.

Comments?

Cheers

Ian

 

[Gold]

Most shipments aren’t strictly by weight. It’s a combination of weight and  dimensions. There are usually weight and dimension classes for shipping. If you contact the shipper they may be able to give you a range that you know  the mixer fits in.

 

[JohnRoberts]

If you have a long enough lever, and fulcrum (like see-saw), and know what you weigh, you could estimate unknown weight by how far down the lever arm you need to stand to budge it.

OR not

JR

 

[Tubetec]

Weigh the modules and the frame separately , or get a second pair of hands in to help out. A luggage scales might be easy and cheap to find.
I had to lift a small cast iron stove recently , around 62.5 kg and I weight around 72kg , managed to get it out of the back of the car ok , once I had found the right way to hold it .  If you absolutely have to do it on your own how about some rope ,a couple of pulley blocks and a step ladder as an A frame .

 

[ruffrecords]

Weigh the modules and the frame separately , or get a second pair of hands in to help out. A luggage scales might be easy and cheap to find.
I had to lift a small cast iron stove recently , around 62.5 kg and I weight around 72kg , managed to get it out of the back of the car ok , once I had found the right way to hold it .  If you absolutely have to do it on your own how about some rope ,a couple of pulley blocks and a step ladder as an A frame .

I don't have to move it on my own - my daughter will help with that. It is just weighing it that is the problem.

Cheers

Ian

 

[Gold]

You could hire  a crating company and have them take care of it. Problem solved.

I usually guesstimate  and wait for the bill. It’s easy for the shipping company to do. I’ve always told shipping companies that I can’t weigh a heavy piece . I give an estimate and that is usually close enough for them to do their thing.

Something like weigh a module. Multiply by number of channels. Add something for the frame and add 25%.

If you really want to weigh it you could do a pulley and a hoist with a counterweight. Seems like an awful lot of unnecessary work to me.

 

[PRR]

> the weight is just the sum of the two measured forces.

I *think*: only if the tilt is small or all the weight is at the bottom.

If the tilt is extreme or the weight is high, then you under-measure the total.

If you find a block of wood the same height as your scale, then the sum is valid.

Strictly the weigh-point should be close to the end, same on both sides, 2-point/line contact, which suggests two lengths of dowel/pipe to define the weight/counter points. However I doubt such fussiness is justified to get a Shipping Weight. As the USPO keeps reminding us, it IS what the carrier's scale says it is; you just want to know if it is nearer $100 or $200 (is it worth the cost?).