Electric Wheelchair Design "hyperchair"

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Electric Wheelchair Design "hyperchair"

Postby 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 (22.35 KiB) Viewed 7107 times

hyper_chair1.jpg (25.63 KiB) Viewed 7107 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

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Posts: 21
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Re: Electric Wheelchair Design

Postby 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 (28.99 KiB) Viewed 7103 times

Front Wheels, E300 Front Wheels for Razor E300 Scooter from razorbase.co.uk, £52.95 including delivery:
chair_bits3.jpg (43.41 KiB) Viewed 7103 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 (31.48 KiB) Viewed 7103 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 (51.15 KiB) Viewed 7103 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 (47.06 KiB) Viewed 7103 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 (43.72 KiB) Viewed 7103 times

The above items are the most costly items, I'll photograph more bits as I go along.

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Posts: 21
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Re: Electric Wheelchair Design

Postby 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
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)
total cost=16.98
Front Wheels
E300 Front Wheels for Razor E300 Scooter ( 2 off )
total cost=52.95
Motor Quick Release Blocks
Aluminium Square Bar – 2.1/2”x2.1/2”x125mm Long
supplier=Ebay (forwardmetals)
total cost=19.28
Drill for Quick Release Blocks
Taper Shank Drill 7/8 Dormer 9” long
supplier=Ebay (rwdsharples)
total cost=17
Bar for Quick Release Blocks
Bright Mild Steel Bar 5mm Dia x1000mm (4 off)
supplier=Ebay (ukfab12)
total cost=8.95
plate for Quick Release Blocks
mild steel plate 250mm x 250mm x 3mm pack of 2
supplier=Ebay (ajdfansltd)
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)
total cost=4.68
Rear Wheel Hubs
Aluminium Round Bar 3.1/4 Dia 150mm long
supplier=Ebay (alum-droitwich)
total cost=30.41
Gasket for Hegar split rims
Rubber Sheet 3mm Smooth Finish Neoprene 100mmx100mm
supplier=Ebay (parki.babs2012)
total cost=2.54
tube to extend freewheel bars
Steel Precision Tube 10mm O/D x 300mm long 2mm Wall
supplier=ebay (brilliant2buy)
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)
total cost=22
End Mill for Quick Release Blocks
RDG 4 Flute End Mill 10mm
supplier=ebay (rdg355)
total cost=7.2
17mm slot drill to make hub
Sherwood, slot drill, hss sc/sh 17mm
supplier=ebay (gaverltd)
total cost=11.5
6mmx6mm hss tool for hub
HSS Toolsteedl 6mm x 100mm square tool Steel Bit
supplier=ebay (fordeight)
total cost=4.4
16 off M8 washers for wheels
16 off Titanium M8 Washers, Lightweight
supplier=ebay (tibenn)
total cost=16.92
20 off M8 bolts for wheels
20 off M8 Allen Cap Head Screw Bolt Stainless A2
supplier=Ebay (abolt-fromtheblue)
total cost=3.44
7/8” x 16swg (1.62mm) 6 metres x 2
total cost=39.312
joints between frame sections
1” x 18swg (1.21mm) 6 metres
total cost=17.976
inner tube for bearings (castors)
1.1/8x14swg tube 3m
total cost=18.9
tube for bearings (castors)
1.1/4x10swg tube 3m
total cost=27.156
For retracting footrest 10mm dia bright mild steel round bar 3m
total cost=13.332
For front forks
50mmx5mm mild steel bar (3 metres)
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)
total cost=?

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Re: Electric Wheelchair Design

Postby admintrev » Wed Nov 27, 2013 5:26 pm

Hub drawing - done at a scale of more or less 1:1

chair_dwg1.jpg (70.09 KiB) Viewed 7101 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.

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Re: Electric Wheelchair Design

Postby 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 (39.05 KiB) Viewed 7100 times

Another drawing showing the position of the holes in the aluminium block:
chair_dwg3.jpg (45.26 KiB) Viewed 7100 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 (29.68 KiB) Viewed 7100 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.

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Re: Electric Wheelchair Design

Postby 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 (42.82 KiB) Viewed 7099 times

chair_bits8.jpg (74.52 KiB) Viewed 7099 times

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Re: Electric Wheelchair Design

Postby 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.

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Re: Electric Wheelchair Design "hyperchair"

Postby 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 (50.2 KiB) Viewed 7093 times

After welding and fitting to the current chair:

chair_bits9.jpg (53.09 KiB) Viewed 7093 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 (18.36 KiB) Viewed 7093 times

chair_frame2.jpg (33.84 KiB) Viewed 7093 times

chair_frame3.jpg (30.88 KiB) Viewed 7093 times

chair_frame4.jpg (41.4 KiB) Viewed 7093 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.

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Re: Electric Wheelchair Design "hyperchair"

Postby 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 (46.7 KiB) Viewed 7087 times

chair_trial2.jpg (50.69 KiB) Viewed 7087 times

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Re: Electric Wheelchair Design "hyperchair"

Postby 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 (78.11 KiB) Viewed 6999 times

chair_trial4.jpg (82.23 KiB) Viewed 6999 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.

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