I have a REMAP task to make a wheelchair fooplate wider, with up-folding extensions each side.
Looking for ideas/warnings.
The user is a 10 yr old lass with MD.
Wheelchair footplate, needs to be wider about 80mmm each side on a central 240mm and with an edge ridge so her feet don’t slip off the sides. (Or she'll grow crooked.)
Looking for ideas for sheet material and hinges. First will use 4mm mdf pattern, then full thickness ply prototype.
Underside of current footplate. Flat black part to be replaced, with side flaps. Currently ~250mm wide at centre, needs to be ~80mm wider each side. Tube steel to remain. NB this is not supposed to be stood on. Kid’s a lightweight 10yo.
Top to bottom as shown, plate is ~300mm. Round section steel ~25mm dia tube is a rectangular loop.
Pink line is proposed line of hinge/join.
Original material is a nice hard solid plastic, with a “routered” edge. Not sure what this is. Polyprop, HDPE, Nylon6 – dunno.
The footplate flips up as shown (in plane of paper/screen) so can’t be more than 12mm thick centrally.
The flaps have to hinge up out of the way so the user can get her legs round the sides, to fold the whole footplate up. The flaps would then be under the seat part of the chair - plenty of space. Flaps will have a ~19mm upstand at the edges.
12mm isn't much to work with, even if I fix an extra strip of 12mm. I've had a dozen+ ideas developing from plywood doing this:
First thought was to make it 24mm at the edge, (and put the piano hinge on top), but the steel tube gets in the way. I could only reiniforce to maybe 25mm.
But as I then thought, some fat geezer could still break it because there's no support under the flaps.
The flaps have to hinge up out of the way so the user can get her legs round the sides, to fold the footplate up. The flaps would then be under the seat part of the chair - plenty of space.
I priced a nice 3D printed footplate with clever strong hinges, at around £500. The wheelchair cost about £4k, (NHS pays) so that may be OK, but not if it's breakable.
So I'm thinking, put the flaps on sprung hinges, so they just go down if a large force is applied. Something sort of like this, where the spring is strong, enough to hold the flap up for normal use: (The spring would have to be magic, as drawn, to be strong & extensible enough, but it's doable.)
The side flap as a whole folds up at hinge A which is piano hinge (could be mounted flat, on top) . "Stick" is something I put in to enable the safety, anti-fat-bloke hinges as at B. Idea being the flap would bend down out of the way without over-straining hinge A. As shown it's magined made from 12mm ply glues together to make 24mm - the squares are 4mm.
I've thought about many kinds of hinges - soss, pin, counter-flap, cupboard catches.... Even 24mm isn't much. The steel tube gets in the way, I don't want great big gaps where the joins are, and have to consider what's going to be presented when the plate is folded up - many ideas have sharp bits which poke out. The whole thing shouldn't get too heavy or she won't be able to lift it.
The spring & its fixings shown could be inside the thickness of the plywood.
I've had a number of ideas with special bits of sliding metal plates and pins with springs on - which I don't have any way to manufacture.
Sheets of nice plastics like Nylon6 are available (~£30) but glueing, fixing screws strongly etc, are a bit of an unknown for me.
Comments? Ideas?
(Sorry I don't have any smart drawing software - this is done in Word)
Looking for ideas/warnings.
The user is a 10 yr old lass with MD.
Wheelchair footplate, needs to be wider about 80mmm each side on a central 240mm and with an edge ridge so her feet don’t slip off the sides. (Or she'll grow crooked.)
Looking for ideas for sheet material and hinges. First will use 4mm mdf pattern, then full thickness ply prototype.
Underside of current footplate. Flat black part to be replaced, with side flaps. Currently ~250mm wide at centre, needs to be ~80mm wider each side. Tube steel to remain. NB this is not supposed to be stood on. Kid’s a lightweight 10yo.
Top to bottom as shown, plate is ~300mm. Round section steel ~25mm dia tube is a rectangular loop.
Pink line is proposed line of hinge/join.
Original material is a nice hard solid plastic, with a “routered” edge. Not sure what this is. Polyprop, HDPE, Nylon6 – dunno.
The footplate flips up as shown (in plane of paper/screen) so can’t be more than 12mm thick centrally.
The flaps have to hinge up out of the way so the user can get her legs round the sides, to fold the whole footplate up. The flaps would then be under the seat part of the chair - plenty of space. Flaps will have a ~19mm upstand at the edges.
12mm isn't much to work with, even if I fix an extra strip of 12mm. I've had a dozen+ ideas developing from plywood doing this:
First thought was to make it 24mm at the edge, (and put the piano hinge on top), but the steel tube gets in the way. I could only reiniforce to maybe 25mm.
But as I then thought, some fat geezer could still break it because there's no support under the flaps.
The flaps have to hinge up out of the way so the user can get her legs round the sides, to fold the footplate up. The flaps would then be under the seat part of the chair - plenty of space.
I priced a nice 3D printed footplate with clever strong hinges, at around £500. The wheelchair cost about £4k, (NHS pays) so that may be OK, but not if it's breakable.
So I'm thinking, put the flaps on sprung hinges, so they just go down if a large force is applied. Something sort of like this, where the spring is strong, enough to hold the flap up for normal use: (The spring would have to be magic, as drawn, to be strong & extensible enough, but it's doable.)
The side flap as a whole folds up at hinge A which is piano hinge (could be mounted flat, on top) . "Stick" is something I put in to enable the safety, anti-fat-bloke hinges as at B. Idea being the flap would bend down out of the way without over-straining hinge A. As shown it's magined made from 12mm ply glues together to make 24mm - the squares are 4mm.
I've thought about many kinds of hinges - soss, pin, counter-flap, cupboard catches.... Even 24mm isn't much. The steel tube gets in the way, I don't want great big gaps where the joins are, and have to consider what's going to be presented when the plate is folded up - many ideas have sharp bits which poke out. The whole thing shouldn't get too heavy or she won't be able to lift it.
The spring & its fixings shown could be inside the thickness of the plywood.
I've had a number of ideas with special bits of sliding metal plates and pins with springs on - which I don't have any way to manufacture.
Sheets of nice plastics like Nylon6 are available (~£30) but glueing, fixing screws strongly etc, are a bit of an unknown for me.
Comments? Ideas?
(Sorry I don't have any smart drawing software - this is done in Word)