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Updated:  26-Sept-09


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John Williamson

A Home Designed or Heavily Modified & Re-Built Off Road Power Wheelchair,  that's small enough to use Every Day,  Indoors and in the house + car

Mk1 | Mk2 | Mk3 versions + Timeline

Mk2 version -  Parts 1 | 2 | 3

Detailed PowerChair Only Menu

This page? The final build. To turn this bit of fabrication and guesswork into the finished powerchair.

(Pic below is what we have so far below! Updated today: 28th May 09)

Still needs batteries, wiring loom, rear light cluster, arms and arm tops, about 6 bolts polishing and others replacing, a seat cushion the control pod and then programming...

Off road powerchair-base

This new Power Wheelchair will be finished to higher standard and using many better components than any new stock powerchair and for under 1700 (or $2500). And a little work.

The original plan (here) was to build a superior powerchair cheaply that would be small enough to allow me to sit at a normal table, (low seat height) and narrow enough to allow me to use in my van and in the house 24/7. And short enough and compact enough to allow great manoeuvrability in tight spaces like public loos etc. Well there are already no powerchairs like that out there that I could find. I have been looking and trying for ten years or so. So I built this (actually two) to use as my daily powerchair. 

Great! Everything now works way better than any stock powerchair and build quality is amazing because they don't care if it festers away and looks tatty. I on the other hand do! 

It just washes clean after a years road salt and abuse and looks brand new. Plus with all the C of C and programming changes (etc) these chairs were massively more controllable and usable than any I have tested.

But then I discovered the dog needs walking. He doesn't like concrete and the new powerchairs don't much like mud or steep grassy slopes... They lack off road grip and "floatation" so sink...  You should try sand! So a new project started... This one!

I already knew that the Power Wheelchair market couldn't match my own "non off road" modified chairs for performance/size/manoeuvrability/finish etc. Because that's why I was forced to build them in the first place. So I didn't even bother looking for an off road solution that could match the exact same size or build / finish quality!  There is however a close contender here although its seat is a bit high, and its too wide/long by a few inches. Finish is just the same as all factory powerchairs though sadly.

So now I had to keep all the same tight size and control parameters and big all day batteries etc and somehow shoehorn them in alongside a pair of 6 inch wide tyres! It was harder than you may think. That's a foot of rubber in a 26 inch wide power wheelchair! Almost half the chairs narrow total width is rubber. And I cant bear to see batteries or battery boxes hanging out of the rear as some powerchairs do it just looks awful! So I had a big problem.

Now all the gory details of HOW it was done are covered on the previous pages. This page will cover very quickly the construction of the powerchair once all the bits arrive back from the Powder Coater!  Every SINGLE part is powder coated. Every one. Even the ones you don't see.

Its now like a ready to build kit since we already built and machined everything and did a trial construction/build on the previous page. Its a no expense spared, (Still about 1/3rd the price of an inferior new powerchair!) with the best parts possible used and even brand new parts are sent for blasting and powder coating so they have a proper hard shiny long lasting finish that doesn't rust away over the first winter! 

Standard "Bought" Powerchairs have a finish that lasts months only before it looks permanently wrecked and has corroded bolt heads everywhere. I hate that!  These things cost as much as a car!  Which is also properly finished and protected to last many winters...

With this in mind it gets a pair of brand new motors +. gearboxes with the internal Cush Drive (motor couplings replaced from day 1 as shown here.  And EVERY bolt is replaced with a polished Allen bolt in stainless steel.

All bearings, wheel axles and other replaced parts are stainless steel versions. See here I don't like rust corrosion or failed parts. It also gets new upholstery, new thicker wiring loom, a new charging harness so as to allow my fast charging system to work (around an hour usually when required). 

When I need to go out I need to go. I cant just wait! And it will get a new set of AGM Hawker Odyssey batteries as these can handle the amps way better than GEL type batteries as well as allow fast charging without any problems. It will also get the same tubeless tyres (or if tubed then two tubes to each wheel). Punctures are not an option! Tubeless tyres (and low pressure balloon type tyres) suffer less from this anyway.

Show Standard Powder Coated Parts have arrived back. That's every single part, frame, ALL brackets, including any new parts and every single spacer.  Bolts will of course be polished stainless steel and greased on assembly. We want long lasting good looks that can survive the average British winter road salt and then just wash clean without damage.

The deep powder coating is much tougher than the thin paint that most of our bought powerchairs are graced with. And its so shiny and smooth so is easy to keep clean.

powdercoated parts wrapped up

Awaiting Unpacking -- Some new, some old, some home made (like about 3/4 of it)...

Powdercoated parts unwrapped

SOME of it unpacked. Not including frames, seat frames, and the new fabricated centre section.

Powder coated wheelchair wheels!

Powder Coated Wheelchair Wheels! medium | Powder Coated Wheelchair Wheels!  large

I unpacked the Show Standard Powder Coated wheels and wheel centres and fitted some tyres. These are Tubeless (less punctures) and also have a Kevlar reinforcing layer to further protect them from the dreaded flat tyre. These are the same size as the off road ones but better for summer on pavements, roads, off road when its firm ground. In the winter when the grounds soft we need the ones at the off road treaded ones for grip. Now look at all that lovely sidewall to give me a smooth soft ride. 4 to 5 psi is normal for these balloon tyre sizes. Or less if you are light.

Tyre (Tire) choices for these off road wheels I will show you the tyres I intend to use initially on the rear. As we already know from 1 they are big fat Off Road style tyres as used on 50cc Quad Bikes at the moment.

Tyres (Tires) is the whole point of this new powerchair. The idea being that they give a better ride due to the huge sidewalls and low pressure (4 psi) and their flotation on sand and soft ground is massively better. If I can fit them in and the chair is no wider then its all win win! Well with some careful engineering and a few grazed knuckles the total width is going to be a tough over 26 inches. That's as small as the vast majority if indoor powerchairs.

There are various TYPES of tyres available in these sizes. The Quad Bike tyres shown on the previous pages and here are 145/70 6.  This means 145mm wide, the aspect ratio is 70 percent, and it fits a 6 inch diameter wheel. And about 14.25 inches in diameter (measured). Different manufacturers vary a bit though. But they all look like balloons with rough open tread designed for the off road dirty environment.

The Lawn tyres also shown here and fitted above are 15x6.00 6.  They are designed not to mark golf courses and to be used on big lawnmowers and some golf carts. They are useful though and get used for other things too. Like wheelchairs! The size marking mean: 15x6.00 6  15 inches diameter outside, 6 inches width, 6 inch diameter rim size.

In the winter I want off road grip so that I can walk the dog here, go on grass airfields etc when its muddy or slippery so will use the off road tyres in winter..  Both Off Road tyres and the Lawn Tyres can be fitted to tubeless rims with the extra security from punctures that this allows. Or they can use tubes.

Since I have some spare wheels I have ordered a set of lawn tyres too. These are designed for pavement and grass but mostly when dry in the summer. The advantage over the off-road ones, is that they will wear much slower but more importantly for me is that they will help prevent punctures! And I cannot afford to get one...

I don't want to get stranded somewhere with a flat and no way to get home. These lawn tyres will be perfect then as they have a special Kevlar lining built in that massively reduces the possibility of punctures. Developed because local authorities cut the grass on roadside verges and public areas that are full of glass bottles and bits of metal...

off road tyre power wheelchair

145-70 - 6 off road & 15x6.00 - 6 lawn tyre medium  |  145-70 - 6 off road & 15x6.00 - 6 lawn tyre large

Compared both side by side. The off road style tyre which is 145/70-6  (for the winter for grip in snow mud and soft ground) and the "lawn" tyre (Kenda Turf) which is 15x6.00 - 6 for summer use. A different imperial sizing system is used. These actually measure 14.75 inches when fitted and inflated to 6 psi.

They are almost the same actual size and pretty much interchangeable (for our off road powerchair use) on our 6 inch diameter x 4.5 inch wide wheel rims.

The squarer lawn tyre is a nominal claimed 15 inch total diameter and the off road Quad bike tyre is 14.5 inches. That's a 1/4 inch or 6mm ride height change in use. Which can be ignored usually as long as you have 6mm clearance.

Its the same story with the width as the lawn tyres are a total of 1/4 inch or 6mm wider according to my ruler. That's about 3mm or 1/8 inch wider each side. So it too isn't important.  Both of these tyres are 4 ply (stronger than 2 ply which is most powerchair and mobility tyres) and tubeless should you wish to use them on a tubeless rim as I do.

 puncture proof tyre casing

Puncture resistant tyre casing medium  |  Puncture resistant tyre casing large

The grass / mower / golf kart tyres are designed for us!  Puncture resistant tyre casings are available at a small extra cost.  Ask yourself, why on earth don't the manufacturers all fit things like this as standard?

Maybe they don't care if we get stuck with no hope of rescue in a strange town at 2am. They will fit solid  tyres but they are crap!  Greater rolling resistance and much harsher ride and my back cant stand that. After all I just took me about ten mins finding these. And they are grey which looks "disabled" before it goes yellow a few weeks later and looks old too. Black tyres look better, and stay looking better with a quick wash and some tyre treatment (foam in a can!)

How puncture resistant? Well I found a forum post showing someone trying to puncture an old one from his dads mower with a scalpel just out of interest and he struggled.  And they are not even half as expensive as the nasty "mobility" grey tyres... Have you ever noticed how that word "mobility" doubles the price?  OK black tyres do mark carpets if they are wet. Or if the carpet is wet. So be careful!  I have a fully carpeted house (Bungalow actually) and white paints. There isn't a tyre mark anywhere and I have used black tyres for 12 years.


Fitting Motors medium | Fitting Motors large

New 4 pole motors/gearboxes fitted (with modified cush drives) so they don't fail as usual. And the alloy bars, rose joints etc. All freshly powder coated and alloy so light.  And the battery door complete with some reflectors as I don't want to die on the way back from the pub!

rose joints adjustable rods

Adjustable rods detail medium | adjustable rods detail large

Some better detail of the adjustable length rods that allow the ride height to change as I need. Of course that would mean a new battery door too!  But if I need to change it I can. Its set at the height its is because it then matches my other two powerchairs exactly. For transfers and because it has to allow =me to drive from it. All alloy, stainless polished bolts and powder coating of course! I want this thing to wash clean after the worst of the winter has had a go!  Shame the "real" manufacturers don't do the same.

fitting wheel

fitting wheel medium | fitting wheel large

Fitting the Tubeless (less punctures) and Kevlar lined (even less punctures!) tyres and powder coated wheels onto my home made adapters with polished stainless steel bolts.

No rough work here! I leave cheap thin painted finish and steel greaseless bolts and tubed 2 ply tyres to the manufacturers...

inside details of powerchair

interior detail medium | interior detail large

An "internal" view. As you can see the vast majority of the original powerchair has been thrown away. Only the main frame (the tubular bit) is original powerchair in this picture. And the 4 pole motors. But even the frame and the motors are modified a little...

powerchair wheel centre caps

Wheel medium | Wheel Large

Wheel centre caps machined from solid, (my trusty old lathe) but alloy so fairly light. Held on with a tapered countersunk Allen bolt as this centralises it.

caster wheel power wheelchair

Caster wheel medium | Caster wheel large

Front wheel. The wheel is from a "minibike" - cheap light and better designed  - off the bay of E. The bearings are Stainless steel. So they don't corrode and fail when they get water in them due to hair getting wrapped around the shaft. This is a common occurrence and I have heard many powerchair users complain about this. 

The wheels are powder coated of course, as are the alloy spacers... And the brand new caster forks are as well. They arrive with a thin dull coat of paint. They too use Stainless steel bearings in the frame.  I don't like corrosion and since these bearings are as cheap on eBay as the steel versions why not? . The wheel half bolts and the bolts holding the shaft are stainless steel.

The washers are anodised aluminium alloy. They will be black too when they arrive...  The casters are modified, as the wheel shaft is now10mm stainless steel and it now passes through the caster forks after drilling. This means all the loads go direct from the shaft to the caster fork. The stock setup was designed by my mum. It puts all the loads through the bolt which then "had a tendency" unsurprisingly to come loose... So in true wheelchair style they added a tab washer to stop it coming undone rather than fixing the real problem... A rusty hex bolt and tab washer looks great!  Not. And we pay as much for a powerchair as a small car...

Powerchair off road part built medium | Powerchair off road part built large

So that leaves us up to here! Time for the pub. More tomorrow. These tyres by the way are my "dry" tyres. The real off road ones are for winter. They are the same size and I have two sets of wheels so will just swap over for the winter in about October...  They will still have the "balloon tyres smooth ride" with those soft sidewalls and will be  just as good on soft ground with great floatation at say 5 psi. I still cant believe its only a fraction over 26 inches (26.25) with these huge tyres on. Since they are 6 inches wide rather than the 145mm wide with the other off road tyres further up the page. But it is according to my ruler.

We got the seat and backrest and all of its various brackets and other parts crewed together! And fitted. All of about ten minutes! And the home made footplate is also reassembled and adjusted. All of these parts -- even where brand new -- have been heavily powder coated and all assembled with polished stainless steel bolts. It will look good for longer than I am around...

Looks strange at the rear without those lights fitted behind the seat. Leaves a big open space. They will be last. Notice the new anti tip wheels fitted to the shortened mountings. Every inch of manoeuvrability matters hence the smaller wheels and the shorter distance behind the wheelchair. Also notice that the most rearward part of this powerchair is my head. No great big box hanging out of the rear like some powerchairs...

And the arms once fitted measure 26.25 inches wide max, the same as the tyres do from side to side. So the whole chair is narrow too. And it has no corners...  Look at the tiles. 12 inch square.  It fits inside of two tiles and only the bulge of the sidewalls protrudes. That's narrower than most normal outdoor/indoor powerchairs.  Even with the fat tyres.

Something wrong with the photos colours here but you get the idea! Its minimalist light as possible and still needs its arms, a cushion, its batteries etc etc... Will look better soon! But look at that huge squashy sidewall. That tyre inflates to about 4 to 5 psi in use. It gives the sort of ride I have dreamed of for years in an all day powerchair. Smooth. I have tested a dozen so called "suspension" powerchairs. Its all marketing they barely work. These tyres deform so much over say a hammer left on the workshop floor that the chair doesn't rise as it rolls over it. Is as if its not there. That's got to give a smother ride over any surface than normal "hard" thin tyres do on a normal powerchair.

Anyone worried about the complexities of powerchair wiring needn't be!  This is half of it... These bolt to your batteries and plug into the mysterious complicated "module" under the seat! That's half the wiring done then...

The other half consists of two equally simple plug in bits of cable that go from that same module to the motors... Then plug in your control pod and away you go... You cant even do it wrong as the plugs are all different. Well ok you can plug the wrong motors in (reversed) or one motor the wrong way around but you soon figure out that's wrong as you spin in circles or go in reverse instead of forwards... Really all the complex talk by the manufacturers and tech guys is bull.

Here's that mysterious controller module! In this case its a Penny and Giles 100 amp "Pilot Plus" with some extensive reprogramming at the OEM level. To make it do what I want rather than what some safety Nazi thinks I should want.

Basically it now works proportionally and accurately with zero damping or delay on all parameters. For details see the original powerchair pages (Page 6 I think...)  Its mounted on a custom plate under the seat on the modified seat frame... This is looking upwards from the footplate.


(Part 1 | 2 | 3 )  To see how and why + what was involved see the previous sections!  To see it finished see the last section...

And the MK1 Original Powerchair build here - all 6 pages!

Lithium Ion Batteries for Powerchairs and Scooters




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