fabricating a moveable base - need help!

[imageel]

I have a heavy cast iron spindle moulder which I need to make a moveable base for since it's too heavy to lift/push around (am guessing +300Kg) and which needs to have retractable wheels so that when stationary can spread the load over my suspended workshop floor. For the design I am planning to copy the designs used by others where two rear wheels are pivoted in the vertical plane so that levers can be used to lower them whilst moving, and a 3rd pivot at the front to accept a levered dolly/pin again wheeled (am thinking pallet replacement wheels which seem reasonably cheap)

The question I have is this - I planned to use seam welded oblong section 30x30x3mm like this http://www.metals4u.co.uk/Mild-Steel-Box-Section/30mm-x-30mm-x-3mm-Mild-Steel-Box/49/2299/detail.asp

Will this be strong enough? - it will be welding it together and am planning the base to be approx 800x800 square infilled with ~75mm ply

I have tried using some of the online beam deflection tools, but can't seem to get sensible answers :-(

Any advice gratefully received,
Ed

 

[Hutzul]

I have a heavy cast iron spindle moulder which I need to make a moveable base for since it's too heavy to lift/push around (am guessing +300Kg) and which needs to have retractable wheels so that when stationary can spread the load over my suspended workshop floor. For the design I am planning to copy the designs used by others where two rear wheels are pivoted in the vertical plane so that levers can be used to lower them whilst moving, and a 3rd pivot at the front to accept a levered dolly/pin again wheeled (am thinking pallet replacement wheels which seem reasonably cheap)

The question I have is this - I planned to use seam welded oblong section 30x30x3mm like this http://www.metals4u.co.uk/Mild-Steel-Box-Section/30mm-x-30mm-x-3mm-Mild-Steel-Box/49/2299/detail.asp

Will this be strong enough? - it will be welding it together and am planning the base to be approx 800x800 square infilled with ~75mm ply

I have tried using some of the online beam deflection tools, but can't seem to get sensible answers :-(

Any advice gratefully received,
Ed

I recall making a similar base about 15 years ago when I was a fabrication engineer for ten years. I recall using 40x40x5mm which I believe would be strong enough for what you need.

Good luck

 

[siggy_7]

30mm box has very little resistance in bending as the maximum distance from the neutral axis is only 15mm. Bending resistance increases with the cube of the vertical dimension, so moving from e.g. 30mm to 60mm you would increase your strength in bending 8-fold. I would move to a 50x25 profile with the longer dimension vertical, on that site the price isn't much different. Provided you can weld it, wall thickness won't be that important - 50x25x2.5 is listed at £26.99 for 3m which is only a pound's difference to the section you linked to, and will make the world of difference to the stiffness of the base.

 

[imageel]

Thanks for the replies - I'll look to up the profile size as suggested
Cheers
Ed

 

[Lons]

Can't you use 50 x 50 angle iron. Very strong and easy to weld or bolt together. Flat plate across the corners to fit the wheels and support the feet works very well.

Bob

 

[Limey Lurker]

Can't you use 50 x 50 angle iron. Very strong and easy to weld or bolt together. Flat plate across the corners to fit the wheels and support the feet works very well.

Bob


That's the way I'd do it, too! Also, there's no danger of the machine slipping off the base.