Diy garage gantry crane
Discussion
I'm thinking about building an overhead gantry crane in my 5m x 5m garage.
Initial idea was to use 2 x 5m Universal Beams (RSJ) supported by steel square section at each end with another sliding Universal Beam of the same size riding on top.
What sort of point load would I be able to safely hold if the beams were 127x76x13 for example?
The immediate use is for a fibreglass body (150kg) but ideally would want to use up to 250kg really.
Initial idea was to use 2 x 5m Universal Beams (RSJ) supported by steel square section at each end with another sliding Universal Beam of the same size riding on top.
What sort of point load would I be able to safely hold if the beams were 127x76x13 for example?
The immediate use is for a fibreglass body (150kg) but ideally would want to use up to 250kg really.
Edited by bagofjuice on Monday 29th October 08:28
Using the beam you are planning over than span would not be an issue from a structural integrity point of view, as in you will not break or drop a load of 250kgs.
However over that span the deflection you will see in the beam due to the travelling cross beam weight and load will probably be quite big so you could end up with the travelling beam trying to run to the middle of the side beams or the lowest point. option to alleviate this would be a mid point pillar which would half the span to 2.5m.
I could work out the deflection and stress in the beam but I won't be doing it for free, you could probably find an online calculator to give you the deflection over the span with a point load.
However over that span the deflection you will see in the beam due to the travelling cross beam weight and load will probably be quite big so you could end up with the travelling beam trying to run to the middle of the side beams or the lowest point. option to alleviate this would be a mid point pillar which would half the span to 2.5m.
I could work out the deflection and stress in the beam but I won't be doing it for free, you could probably find an online calculator to give you the deflection over the span with a point load.
Might be overkill, if you don't need too much adjustability side to side you might suspend a single beam down the middle of the garage then use a wheeled "truck" sorry no idea what to call this that rides the RSJ's lower edge. Just like some curtain rails.
Here, found it
https://www.ebay.ie/itm/1-Ton-Push-Trolley-Overhea...
Here, found it
https://www.ebay.ie/itm/1-Ton-Push-Trolley-Overhea...
If I've done my calcs right ( I used this), then the the two 5m end beams, centre supported, will have a deflection of ~1.7mm at the unsupported centres with ~350Kg point load.
The sliding cross beam (on rollers above the other two beams) also spans 5m (but unsupported in the centre) and will hold a rolling hoist - I've calculated a deflection of around ~9.5mm at ~250Kg point load in the centre.
A few questions:
- I'm a bit nervous about the calculations - Is the above in the ballpark of what you would expect?
- Do these types of calcs generally take into account the weight of the steel itself?
- What is the max acceptable deflection?
The sliding cross beam (on rollers above the other two beams) also spans 5m (but unsupported in the centre) and will hold a rolling hoist - I've calculated a deflection of around ~9.5mm at ~250Kg point load in the centre.
A few questions:
- I'm a bit nervous about the calculations - Is the above in the ballpark of what you would expect?
- Do these types of calcs generally take into account the weight of the steel itself?
- What is the max acceptable deflection?
It's too easy to input the the wrong figures/units in those free calculators, so I I decided to implement the calcs for point load deflection of some standard sized beams here: https://github.com/bagofjuice/engineeringcalcs/blo...
It should be easier to check the numbers assuming you're looking for exactly the same calcs as me. Hope it's of help to someone.
(some ability to update/run javascript/typescript required).
It should be easier to check the numbers assuming you're looking for exactly the same calcs as me. Hope it's of help to someone.
(some ability to update/run javascript/typescript required).
Edited by bagofjuice on Tuesday 13th November 22:48
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