I'm glad to say that normally when I complete and deliver a project I rarely get it returned for re-work
Last year I made a lightweight box that fitted onto a sack truck to enable a disabled friend of mine to transport model cars that he builds and races. He gets about on crutches and previously used carrier bags to hold his cars, tools and radio gear which was not very practical and things could get damaged.
When he got a new mobility car (full size! ) the internal arrangement with the rear seats folded could not have been more awkward to get the box in and out of the car as virtually every protrusion on the back of the box caught on the various features of the less than flat/level loadspace.
What we needed was some form of sledge/skid runners to ride over the obstructions and make the box easier to get into the car.
This is what we came up with between us to fit to the back of the box. It needed to be as light as possible and yet rugged enough for the job.
The curved skids were the most challenging part and the methods used are written up here.
http://www.thewoodhaven2.co.uk/viewtopi ... =20&t=3821
The skids and lengthwise part of the frame are 20mm square oak and the other part are 18mm square with chamfered corners for a little bit of interest.
Each side is made of these pieces with mortise and tenon joints.
A bridle joint is used where the end of the curve meets the end of the frame straight and a scew will pass through both members into the box if the ere is any tendency for the laminated curve to creep at any stage.
A couple of lateral rails space the two skids 400 mm apart.
The complete assembly screw onto the back of the box.
and a couple of diagonal braces add some rigidity
All ready to go with a road test tomorrow
Thanks for reading
Bob