Electric Wheelchair Design "hyperchair"

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Electric Wheelchair Design "hyperchair"

Post by admintrev » Mon Nov 25, 2013 7:22 pm

Hi Folks,
I'm working on an Electric Wheelchair design roughly based on the design on http://www.wheelchairdriver.com.
This design is Copyright, but may be reproduced for personal use.
My version uses the same tyres/wheels, but I'm making mine narrower and designed so that it can be broken down into parts all less than 10kg in weight.
Below are a couple of rough blender image of what it will look like:
hyper_chair2.jpg
hyper_chair2.jpg (22.35 KiB) Viewed 16634 times
hyper_chair1.jpg
hyper_chair1.jpg (25.63 KiB) Viewed 16634 times
So far I've assembled one of the wheels with the spun aluminium hegar rims and neoprene seal inbetween and it seals up OK. I've also made the quick release blocks, so that I can remove the wheel/motor asssemblies from the rest of the chair when dismantling it. I'm currently working on the front forks for the 10" diameter front wheels.
I'll add images as I get parts made, and some pictures of the finished chair when I get that far - at the moment the plan is to finish it by Christmas, so that I'll be able to get out and about with a bit more grip when the snow/ice arrives.
Best Regards
Trev

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design

Post by admintrev » Wed Nov 27, 2013 12:19 pm

Some of the bits and pieces:

Rear Rims, Hegar 2 x 6" Spun Aluminium Half 2.5" (2 off) and Hegar 2 x 6" Spun Aluminium half 2" from Hegar (USA) www.hegar4.com , £113.46 including delivery and duty:
chair_bits4.jpg
chair_bits4.jpg (28.99 KiB) Viewed 16630 times
Front Wheels, E300 Front Wheels for Razor E300 Scooter from razorbase.co.uk, £52.95 including delivery:
chair_bits3.jpg
chair_bits3.jpg (43.41 KiB) Viewed 16630 times
Rear Tyres, 2 x 15x6.00-6 4 Ply Kenda K500 Super Turf with K-SHIELD from allterraintyres.co.uk, £85.90 including delivery, shown inflated with Hegar rims fitted:
chair_bits6.jpg
chair_bits6.jpg (31.48 KiB) Viewed 16630 times
Gasket for Hegar split rims, 2 x Rubber Sheet 3mm Smooth Finish Neoprene 100mmx100mm from ebay(parki.babs2012), £2.54 including delivery, shown cut ready for use:
chair_bits5.jpg
chair_bits5.jpg (51.15 KiB) Viewed 16630 times
Rear Wheel Hubs, Aluminium Round Bar 3.1/4 Dia 150mm long from ebay(alum-droitwich), £30.41 including delivery, shown cut in half ready for machining:
chair_bits1.jpg
chair_bits1.jpg (47.06 KiB) Viewed 16630 times
Bearings (for castors),4 x Bearing R8 2RS SS 1/2 X 1 1/8 X 5/16 STAINLESS R82RS SS from ebay(bearingoptions), £22 including delivery:
chair_bits2.jpg
chair_bits2.jpg (43.72 KiB) Viewed 16630 times
The above items are the most costly items, I'll photograph more bits as I go along.

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design

Post by admintrev » Wed Nov 27, 2013 4:29 pm

Complete Parts List:

Rear Tyres
2 x 15x6.00-6 4 Ply Kenda K500 Super Turf with K-SHIELD
supplier=allterraintyres.co.uk
cost=79.9
delivery=6
total cost=85.9
Rear Rims
Hegar 2 x 6” Spun Aluminium half 2.5”
Hegar 2 x 6” Spun Aluminium half 2” + £24.04 duty
supplier=Hegar (USA)
cost=$100 (£63.83)
delivery=$40 (£25.59)
total cost=113.46
Front Forks
Pair of Front Wheels, Tyres, Forks from Betterlife Wheelchair
supplier=Ebay (yellabelly72)
cost=8.99
delivery=7.99
total cost=16.98
Front Wheels
E300 Front Wheels for Razor E300 Scooter ( 2 off )
supplier=razorbase.co.uk
cost=48
delivery=4.95
total cost=52.95
Motor Quick Release Blocks
Aluminium Square Bar – 2.1/2”x2.1/2”x125mm Long
supplier=Ebay (forwardmetals)
cost=11.99
delivery=7.29
total cost=19.28
Drill for Quick Release Blocks
Taper Shank Drill 7/8 Dormer 9” long
supplier=Ebay (rwdsharples)
cost=15
delivery=2
total cost=17
Bar for Quick Release Blocks
Bright Mild Steel Bar 5mm Dia x1000mm (4 off)
supplier=Ebay (ukfab12)
cost=4
delivery=4.95
total cost=8.95
plate for Quick Release Blocks
mild steel plate 250mm x 250mm x 3mm pack of 2
supplier=Ebay (ajdfansltd)
cost=7.4
delivery=6.2
total cost=3.4
Bolts for Quick Release Blocks
M6 A2 Stainless Steel locknut pack of 20
M6 A2 Stainless Steel Allen cap 35mm bolt pack of 20
M6 A2 Stainless Steel allen cap 20mm boltpack of 10
supplier=Ebay (abolt-fromtheblue)
cost=4.68
delivery=0
total cost=4.68
Rear Wheel Hubs
Aluminium Round Bar 3.1/4 Dia 150mm long
supplier=Ebay (alum-droitwich)
cost=30.41
delivery=0
total cost=30.41
Gasket for Hegar split rims
Rubber Sheet 3mm Smooth Finish Neoprene 100mmx100mm
supplier=Ebay (parki.babs2012)
cost=2.54
delivery=0
total cost=2.54
tube to extend freewheel bars
Steel Precision Tube 10mm O/D x 300mm long 2mm Wall
supplier=ebay (brilliant2buy)
cost=2.29
delivery=2.74
total cost=5.03
Bearings (for castors)
Bearing R8 2RS SS 1/2 X 1 1/8 X 5/16 STAINLESS R82RS SS
supplier=ebay (bearingoptions)
cost=22
delivery=0
total cost=22
End Mill for Quick Release Blocks
RDG 4 Flute End Mill 10mm
supplier=ebay (rdg355)
cost=7.2
delivery=0
total cost=7.2
17mm slot drill to make hub
Sherwood, slot drill, hss sc/sh 17mm
supplier=ebay (gaverltd)
cost=9
delivery=2.5
total cost=11.5
6mmx6mm hss tool for hub
HSS Toolsteedl 6mm x 100mm square tool Steel Bit
supplier=ebay (fordeight)
cost=3.25
delivery=1.15
total cost=4.4
16 off M8 washers for wheels
16 off Titanium M8 Washers, Lightweight
supplier=ebay (tibenn)
cost=16.42
delivery=0.5
total cost=16.92
20 off M8 bolts for wheels
20 off M8 Allen Cap Head Screw Bolt Stainless A2
supplier=Ebay (abolt-fromtheblue)
cost=3.44
delivery=0
total cost=3.44
Frame
7/8” x 16swg (1.62mm) 6 metres x 2
supplier=metals4u.co.uk
cost=39.312
delivery=0
total cost=39.312
joints between frame sections
1” x 18swg (1.21mm) 6 metres
supplier=metals4u.co.uk
cost=17.976
delivery=0
total cost=17.976
inner tube for bearings (castors)
1.1/8x14swg tube 3m
supplier=metals4u.co.uk
cost=18.9
delivery=0
total cost=18.9
tube for bearings (castors)
1.1/4x10swg tube 3m
supplier=metals4u.co.uk
cost=27.156
delivery=0
total cost=27.156
For retracting footrest 10mm dia bright mild steel round bar 3m
supplier=metals4u.co.uk
cost=13.332
delivery=0
total cost=13.332
For front forks
50mmx5mm mild steel bar (3 metres)
supplier=metals4u.co.uk
cost=28.524
delivery=0
total cost=28.524

Titanium Assembly Lubricant (Molyslip Copaslip) £6.15 inc delivery (ebay) (Edit - added 12/03/2014)
Loctite 641 (To stop bearings rotating in housing) £0.99 + £2.60 delivery = £3.59 (ebay) (Edit - added 12/03/2014)

Spend So Far = 580.98 (Edit now includes 2 extra items above - 12/03/2014)

Dynamic OEM programming Dongle and Cables £150 inc delivery (ebay) (Edit - added 23/03/2014)
Using the Dongle, Cables and the Wizard software (free download) it is possible to change the max acceleration, max speed (up to 4mph for the controller/motors I'm using) and lots of other settings, which if set incorrectly make a chair a real pain to drive.

I've essentially set everything in "Drive Program 1" at its maximum percentage value, with the exception of Tremor Damping - which allows the chair to continue after you centre the joystick (horrible if set at its maximem), I've also left Load Compensation and Traction (%) settings at the default values as I'm not sure what the Traction setting does and the Load Compensation shouldn't be altered without taking electrical measurements.

Spend So Far = £730.98 (Edit 23/03/2014 now including Dynamic OEM Programming Dongle and Cables)

Not purchase yet:

powdercoating(bright green)

If done again would get Instead of front forks, as only bolts used
Sunrise Medical Quickie Caster Stem Bolt Assembly – Standard Length (0.5” dia 3 5/8” long)
supplier=epc-wheelchairs.co.uk
cost=21.86
delivery=?
total cost=?

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design

Post by admintrev » Wed Nov 27, 2013 5:26 pm

Hub drawing - done at a scale of more or less 1:1
chair_dwg1.jpg
chair_dwg1.jpg (70.09 KiB) Viewed 16628 times
This is a drawing I've done for the hubs to mount the rear wheels, I'm making it from aluminium - I'll cut the centre hole with a milling cutter, to get an accurate 17mm diameter hole and use a 6mm square HSS tool mounted on the toolholder on the lathe and move it in and out of the 17mm hole slowly cutting the keyway (with the 4 jaw chuck locked in place, so it cannot rotate) - the reason I'm using a 4 jaw chuck is because I cannot reverse the jaws on my 3 jaw chuck and the workpiece is too large to fit otherwise.

The actual depth required for the keyway is 2.5mm and that depth provides a tight fit on the axle shaft. (added 15/03/2014)

I'll try and add more drawings later.

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design

Post by admintrev » Wed Nov 27, 2013 6:31 pm

These are some drawings of the quick release blocks - sorry they are a bit rough, but they were only done in rough in a notebook, then scanned, the aluminium part replaces the motor position and is clamped with bolts to the frame, the steel part is bolted to the motor. The two parts are held together with a pair of 5mm rods with a vertical tube welded to one end to hold the two together - I'll post pictures of the completed blocks later, which should make this clearer.

This drawing shows an end view of the aluminium block showing where the holes need to be drilled - the block was then sawed in half - on the drawing that would be a horizontal cut half way up:
chair_dwg2.jpg
chair_dwg2.jpg (39.05 KiB) Viewed 16627 times
Another drawing showing the position of the holes in the aluminium block:
chair_dwg3.jpg
chair_dwg3.jpg (45.26 KiB) Viewed 16627 times
This drawing shows an end view of the steel "U shaped" part, the bottom 3mm is the thickness of the steel:
chair_dwg4.jpg
chair_dwg4.jpg (29.68 KiB) Viewed 16627 times
After cutting the aluminium block in half (carefully with a hacksaw), the six mounting holes were drilled to match the actual motor and counter bored to allow for the heads of the bolts using an end mill.

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design

Post by admintrev » Wed Nov 27, 2013 7:42 pm

These are a couple of photos showing what the quick release blocks look like:
chair_bits7.jpg
chair_bits7.jpg (42.82 KiB) Viewed 16626 times
chair_bits8.jpg
chair_bits8.jpg (74.52 KiB) Viewed 16626 times

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design

Post by admintrev » Sat Nov 30, 2013 11:47 am

Parts not listed so far:

Right motor model no:1444870
Left motor model no: 1444871 Available as pair on ebay for approx £150

Dynamic Shark Controller DK-PMB01 approx £50 on ebay
Dynamic Shark Basic Remote for drive only DK-REMD01B approx £50 on ebay

2 off Standard support bracket assy part no:1517047: will do drawings and make from steel

Back Canvas Black Bird 43cm 17" part no: 26003921BKB: will make from vinyl or faux-leather

Padded Seat Cpl Black Bird 43cm 17" part no: 1512365 - plywood sheet, upholstery foam and covering?
Seat Bracket Kit part no:1512361 : will do drawings and make from steel

If you have a donor chair the above bits won't be needed.

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design "hyperchair"

Post by admintrev » Fri Jan 10, 2014 5:25 pm

The front wheels need new forks as they are wider and a larger diameter, the forks have been made from 5mm mild steel plate:
chair_dwg5.jpg
chair_dwg5.jpg (50.2 KiB) Viewed 16620 times
After welding and fitting to the current chair:
chair_bits9.jpg
chair_bits9.jpg (53.09 KiB) Viewed 16620 times
The tubular steel frame is made up mostly of 7/8 inch diameter steel, the bits that make up the frame are as follows:

Diameter Length Cut angle 1 Cut angle 2
A Cylinder.003 0.875 7.35 90 45
A' Cylinder.002 0.875 7.35 90 45
B' Cylinder.061 1 3 45 up 45 horizontal
B Cylinder.062 1 3 45 up -45 horizontal
C Cylinder.001 0.875 5.5 90 45
C' Cylinder 0.875 5.5 90 45
D Cylinder.004 0.875 5.2 45 -45
E Cylinder.006 0.875 5.2 45 90
E' Cylinder.005 0.875 5.2 45 90
F Cylinder.036 0.875 7 90 90
G Cylinder.008 0.875 12.795 45 down -40 horizontal
G' Cylinder.007 0.875 12.795 45 down 40 horizontal
H Cylinder.014 0.875 16.945 45 -45
I Cylinder.027 0.875 6.681 90 45
I' Cylinder.029 0.875 6.681 90 45
J Cylinder.028 0.875 5.598 45 down -45 horizontal
J' Cylinder.016 0.875 5.598 45 down 45 horizontal
K Cylinder.037 0.875 10 90 90
L Cylinder.033 0.875 6.33 90 45
L' Cylinder.034 0.875 6.33 90 45
M Cylinder.031 0.875 4.438 90 45
M' Cylinder.032 0.875 4.483 90 45
N Cylinder.030 0.875 4.5 90 90
N' Cylinder.015 0.875 4.5 90 90
O Cylinder.018 0.875 3.346 45 90
O' Cylinder.017 0.875 3.346 45 90
P Cylinder.009 0.875 2.114 50 -50
Q' Cylinder.010 0.394 10.5 90 90
Q Cylinder.011 0.394 10.5 90 90
R Cylinder.019 0.875 1.75 45 -45
S Cylinder.038 1 3 90 90
S' Cylinder.039 1 3 90 90
T Cylinder.021 1.4 3.15 90 90
T' Cylinder.022 1.4 3.15 90 90
U Cylinder.020 0.875 2.912 90 90
V Cylinder.035 0.875 4 60 30
V' Cylinder.013 0.875 4 60 30
W Cylinder.012 0.875 7 30 -30
X Cylinder.042 0.875 8.038 90 90
X' Cylinder.043 0.875 8.038 90 90
Y Cylinder.045 0.875 9.35 90 90
Y' Cylinder.044 0.875 9.35 90 90
Z Cylinder.047 0.875 23.388 45 -45
Z' Cylinder.048 0.875 23.388 45 -45
AA Cylinder.071 0.875 15.946 45 -45
AB Cylinder.046 0.875 15.75 45 -45
AC Cylinder.059 1 3 90 90
AD Cylinder.055 1 3 90 90
AD' Cylinder.056 1 3 90 90
AE' Cylinder.040 1 3 90 90
AE Cylinder.041 1 3 90 90
AF Cylinder.058 0.875 9.375 90 45
AG Cylinder.060 0.875 2.25 45 90
AH Cylinder.049 0.875 19.5 90 90
AH' Cylinder.050 0.875 19.5 90 90
AI Cylinder.054 0.875 11.5 90 90
AI' Cylinder.057 0.875 11.5 90 90
AJ Cylinder.051 0.875 15.75 45 -45
AK Cylinder.053 0.875 1.375 45 90
AK' Cylinder.052 0.875 1.375 45 90

Drawings showing the location of each piece are below:
chair_frame1.jpg
chair_frame1.jpg (18.36 KiB) Viewed 16620 times
chair_frame2.jpg
chair_frame2.jpg (33.84 KiB) Viewed 16620 times
chair_frame3.jpg
chair_frame3.jpg (30.88 KiB) Viewed 16620 times
chair_frame4.jpg
chair_frame4.jpg (41.4 KiB) Viewed 16620 times
The overlap of tube A and B ( also A' and B') is 1.75 inches - this could vary, depending on what motors are fitted.
The distance from the centre of F to the centre of H is 4.5 inches and from the centre of F to the centre of K is 8.35 inches. This should leave a suitable gap for the batteries.

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design "hyperchair"

Post by admintrev » Sun Jan 19, 2014 11:58 am

The new front forks and tyres are being tested on a standard chair as the new frame isn't finished, after accidentally running one of the front wheels along a raised surface (the rest of the chair bieng on the flat) the top section of the front fork (5mm steel plate) became distorted either side of where the bolt goes through it. Therefore I'll be welding an addtional piece of 5mm plate under each of top bits of the front forks to reinforce them - this will hopefully make them strong enough.

The front bearing housings still needs machining on a lathe, however I've done an assembly test showing the fitting of the front wheels etc:
chair_trial.jpg
chair_trial.jpg (46.7 KiB) Viewed 16614 times
chair_trial2.jpg
chair_trial2.jpg (50.69 KiB) Viewed 16614 times

admintrev
Site Admin
Posts: 21
Joined: Mon Nov 25, 2013 6:04 pm

Re: Electric Wheelchair Design "hyperchair"

Post by admintrev » Thu Mar 06, 2014 6:53 pm

The aluminium hubs are still a work in progress (the keyways need cutting and then then they need reducing in size [to save weight]).
The photos below show the aluminium hubs in use (non-functional as the keyways still need cutting) along with the rest of the frame assembled to verify the cutting length for the vertical elements to support the seat structure:
chair_trial3.jpg
chair_trial3.jpg (78.11 KiB) Viewed 16526 times
chair_trial4.jpg
chair_trial4.jpg (82.23 KiB) Viewed 16526 times
The frame including the aluminium quick release blocks and the front wheels is currently 10.1kg and the front footrest still needs attaching.
Once the chair is complete, it may be worth re-making the back section of the frame as when it was initially welded, some problems with the welding were encountered and so extra weight was added that shouldn't be there, re-making that section is likely to reduce the frame to the 10kg target weight.
The two wheel/motor assemblies have been weighed at 9.8kg and 10.1kg (one of them is longer than the designed width and needs cutting down slightly) and once they have been turned down to the designed shape the assemblies will be considerably less than the target weight of 10kg.

Post Reply