project ATC(all terrain chair)

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looks like i forgot to drop this bomb....
of course theres alot going on since moms cancers come back for newyears....

anyway just going to copy pasta it...enjoy

the project mentaly started 25-30 years ago
physically started nov 6th 2020
primer laid dec 15th
viper red laid dec 18th
final assembly starts dec 21st
final assy finished mid day dec 23rd
final touches dec 24th

lets start with a bit of back story, i grew up riding, i was on race tracks before i could walk, my mother even rode a desert enduro while full on pregnant with me...ive always been on bikes got my z50 when i was 5 new off the showroom floor

the 80s were great, lots of weekends riding with mom n dad be is woods or sand

in 1988 mom was in a const accident and dissabled, a year later dad ran off, so its been since the mid 80s since moms been in the woods or out on the sand....its not like a wheelchair can get out there

30+years of me being her only caregiver has given me alot of insight into wheelchairs, including repairing hers over the years

this year for her b-day she got cancer in her leg and had to have it taken, but..shes cancer free now, but it really lit a fire of im running out of time to get this done

over the past 20+ years ive been stashing wheelchair parts and such tryin to figure out how to get her offroad even if its only short bursts, with the help of someone here. i finally felt like the project would be do-able, and ive gathered everything up ive stashed, dropped 200$ on stuff i didnt allready have including some water/laser cut parts and wheel adapters

so let the build begin, the goal is to have it done before xmas

 

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first off an old chair that we paid dearly for many years back, gave up our fully home restored 73 challanger as PARTIAL trade..yeah we still had to come up with more $$$ to pay the chair off, so..its kinda fitting it all starts with this old base to me

when ordering a wheelchair you pay pay a fortune for the "power base" which is to say its just a frame, motors and electrical, the power seat is an entirely separate purchase which again is a smaller fotrune, if memory serves when this was bought it was about 35k all said n done..prices have gotten better but not alot.............

i pulled this out a couple weekends ago and did a systems check on it, it may need to be re-"tuned" to get full power but its otherwise functional, braking system steering etc it works as it should, but without road testing it i cant be sure the "high/low" settings are still tuned....it looks like they are identical right now....but we should be able to get it tuned for 100$

 

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the pile of parts..most of it, but it seems like every time i turn around i find ive forgotten x bit of steel or some other minor bit of something

another power base to get measurements from, casters to hack up for the shafts and rake angle, 6 full sets of drive motors, the spare OE wheels n tires from my wifes 400ex, front hubs from a 300ex i picked up for 100$, 6 inches of amazon wheel spacers, still waiting on a 1/2inch spacer to go from the chairs 4x78 to the quad 4x110, chair swingarms and shocks, some steel, a bit of scafolding coupler....this piece is odd yes...but...i found tubing "close" enough to air grinder open to fit the caster bearings, the scafolding tube is a tad larger than the bearings, so i chucked it in the drill press and turned it down to bearing size to use as a stop

 

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casters up

this took me a good bit to figure out...seems simple enough right?....

first youve gotta figure out the stock rake of a chair, then translate that into a 22inch tire, modify the stock caster post to take a much MUCH bigger wheel n tire, the hard part here is 15mm axle....that took some digging and will have to be made from solid stock, but a honda XR axle could have been used.....id have killed for XT axles as it would have been a perfect fit with almost zero work

bored some 2x1 tube to slip over the caster stud, weled it squre then cut off the old faster bits, calculated the 3inch caster post to axle line offsetn calculated the tire to caster spacing, cut n weld it all together

 

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start of frame work

galvanized powder coated tube...not my first choice but...i couldnt argue with the tolerances to the caster bearing requirements, a couple hours of die grinder work to remove the internal weld seam and galzanization i ended up with a perfectly snug fit to the chair bearings

next up was to use a rubber drum from a die grinder on 2 die grinders to turn down the scafolding tube, the results were solid, a perfect carrier stop for the bearings...just neet to locate it and drill a hole from the outside to weld it in

 

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the frame itself, busted out on the past 2 days...only to realize that i overlooked the caster height vs the motor mount height vs swingarm mounts and failed to remember the rear wheels are 20's not 22's......needless to say i feel like i wasted yesterday

ive done soo many measurements of so many things and changed the design atleast a dozen diferent ways, that im not entirely surprised i overlooked something

the caster line to complement the HUGE rear tires had to be jogged out 6 inches so that ment a narrower than planned frame which offsets how the batterys will mount..it all snowballs.....

the frame itself..to keep things simple is is 3x1.5 ALL the steel in this is off the reminant pile of a local steel yard that i love to use..so i pay a lil more than scrap for it all, so more often than not my designs are tweaked based on what i find in the pile, that said i lucked out and found a bunch of this tube

shooting for an adjustable track width from 32-44 and an adjustable wheelbase from 36-48, as im thinking ahead a so she can use it localy go hit the park etc fit on sidewalks"just" and really stretch it out for stability when actualy offroad

the mockup below shows my mistake in calculations of the wheel heights

 

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the best thing about a car lift as a welding table and mock of table....ADJUSTABLE HEIGHT...being 6'4 any ole table would pretty well be in a crap spot most of the time, with the lift i adjust on the fly and am always comfortable

anyway, with the casters done and wheels mocked i finaly got to see where i was headed, and promptly noticed ive got a 7inch problem....so....Z the frames to fix it

cut everything and squared and tacked it all back up and called it a night...unsure if ill be back at it tommaro or not...ive got new PT for a screwed up shoulder

end results ill be painting this beast viper red as..well..i have a bunch of old PPG, and its "close" to honda red...and mama only rode hondas and get some white honda lettering

"if" i can find someone to do a seat back cover id kill to get it done in blue vynle aka 80s honda style

 

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full on frame attack

finished up the Z of the rails, ground flush and rolled into another mockup to verify measurements, next steps and get a general feel for it, loose numbers looked good enough to press on

 

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motor and axle mounts

with the previous mockup done, it set in motion all the calculations for the motormounts and swingarms, which in itself i had to add complexity...with a want to be able to stretch and shorten the wheelbase from 36-44inches, multiple hole sets , mapped out the night before, but finalized by the mockup, which showed me some issues id have to fix, like the side offset for the wheel to sit "close" to the rails without hanging out farther than it needs to be, while being balanced to the caster centerline as well

all said n done it went well enough but then pointed out a minor issue ill adress later

 

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with the mounts made it came time to locate them, to which i almost screwed up big..seeing the front mount hole as axle centerline....which its not by a long shot, locate weld flip weld, set aside duplicate on second rail, the "post" clamped to the front allowed me to get exact measurements ignoring the whole z angle

 

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main rails are basicly done, aside from connection slides to each side so the track width can be adjusted by 12 inches, and a minor tweak to the swing arm slides

still to be determined how much extra rail i will leave hanging out the back..so it just stays till im closer to done

 

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frame tie sliders

so heres the deal, the plan requires the ability to "wide track" it for maximum stability offroad, but "narrow track" for sidewalks and trips to the park etc, ie summer in town, sounds simple enough but the trick is that the batterys and power seat unit need to stay centered, so things get kinda weird in a hurry, as much as id love to draft it all out in advance, the amount of variables dictates mock up n test

so i used some roll cage tubing and some plate, 13inch center tube 6.5 inch outter tubes for a total of 6inches of safe wider track

 

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gut it to the bone

with all the critical and usefull numbers pulled from the old chair, it was time to split the power base from the power seat, which showed me some funny bits, the seat is canadian the base is US, everything on the seat is steel and HEAVY thick stuff, everything on the power base is mostly aluminum, some intrestingly odd warning labels, some...well hidden, as well as a final shot with the with the stock tires the stack of new rubber

with the seat base "loose" i will be able to start seat mockup which partly dictates where the sliders need to be

 

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didnt like the 2mm of slop in the sliders so i stitched some sheetmetal to it, then re-mocked everything up

after some initial tests it looks like i need more of that 2mm of slop back to get a smoother slide....overthinking things bites me in theass sometimes.....however the mockup shows promise and is one stout monster

 

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on a side side side note, me n mom share a memory from way back

we were out at sand lake, the sun had gone down and we had been riding out on the beach, her on her mr175 me on my z50, we headed for the truck, which ment up a steep sand hill and across the flats and mom had to cut a guy off neer the top of the hill to keep him from trying to run me down on my z50, mind you z50s dont have lights, so no way he could have really seen me..and back then "flags" were not required

that said, ive managed to find and build a newwer z50 some years back, i figure the first time i take her out to sand lake, ill sneak my z50 along and blast up beside her on the hill.....idealy, tho id kill to finish the restoration of the 1980 z50 that i got some time back...i got screwed on the deal as the ebay seller didnt bother to mention the bike had been in a bonfire.....but it was more important to me just to have a 1980 z50 to build from....so maybe just before summer i can get it built up and get her out on the sand if all goes well.....thats my plan anyway.....if not ill sneak the newwer one out..just need tires n spokes

 

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i managed to put in a lil time, mostly brainstorming some issues

so heres the deal...anyone whos seen a wheelchair will note that your feet ALWAYS sit forward of the front wheels...which...offroad is an obviously bad idea
but theres multiple factors here...length and width by law is basicly required to be no wider than 30 inches and no longer than roughly 24(not counting your feet)....its not the chair design but the laws to make sure they fit in buildings etc...now..i could ramble on about how pretty much no store follows these laws beyond the doors.....but i wont bore you all to death

this chair doesnt need to follow any "rules" so first and formost in my mind is stability second safety , because stability makes safe...third is capability...after those its about "fit" as in how do i make X work here

so when you have a seat you have to have room for legs and feet...in this case ive only gotta make room for 1..but 1 in the way is just as bad as 2 in the way..its still the same problem.........
so with the MASSIVE casters up front this means you have to either
A: raise the seat about 18 inches to clear the frame and caster
B: move the seat back and up "just enough" to get frame clearance
C: "bend the leg" and then build to fit

now see im looking at building B, with adjustment for C as im unsure that C is good for bouncing...but the differance would be the ability to sit another 8 inches lowwer in the frame...so its pretty huge

now with all this im certain someones going to atleast mention or think CG...yeah raising the seat on anything else would throw the center of gravity off....however...in this case let me thro some numbers out there
batterys are just above the bottom edge of the rim line @50LBS EACH with a minimum of 2, but building it with the ability for 4
wheels, tires and hubs is roughly another 100lbs....again down LOW
the drive motors and gearboxes are another 40lbs total

so minimum weight WITHOUT the frame is lets say 250lbs, with a max weight of 350lbs...all of which is CG'd at about 8-12 inches off the ground....that doesnt take into acount the frame which the bulk of is below the top of the tires

so yeah CG....this thing couldnt roll over if it tried

seat height in this case is a combination of aesthetics crossed with "feeling safe"..obviously the higher i make mom sit the more unsafe shes going to feel

so anyway..too wordy..have a couple mockup pics..all of the steel on top of the frame is just for "spacing" of the seat to get a feel for leg rest clearances which dictates minimum height...which at current standing is enough for C but 8 inches short for B

 

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top half attack

with the design of the setup to be able to adjust track width, the upper half will stay "centered" while the frame rails will slide everything out, this means the battery boxes, seat, power recline, electronics etc all need to be mounted to the mid/upper section.....

with everything on the rails basicly finalized, and the mid/upper section planed i attacked at full tilt

located and welded in all the tube extensions and plates, tweaking and adjusting till all 3 sets slid easily, while adding in a slight "rake" to it all as the seat will have to be semi high
after getting them welded in i took to welding all 3 mid sliders together and started forming the base frame to mount everything off of, initialy i wanted to get the seat LOW as possible, but with the power recline motor forcing a need for X amount of space i found a compromise that should work out fine

 

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with the base tacked it was time for another test fit of the seat unit to see what options and tweaks id need to make

special note, im using the left foot rest on the right side so that it sits outside the rail for measurement sake, thus you can see the interference issues

these shots pretty much tell the story, everything fitting up better than planed, a few minor tweaks and all will be good

 

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just a lil more

a few more tacks and full welds....then it was time to split the rails and slide out the mid/upper so i could rotate and such for full welds, as well as simply making it easier to work with...it slid off real nice and easy...in fact better than i could have ever hoped for

back cut a section of tube so the OE recline motor mount could be used..mind you i had to notch it slightly but if it ever needed to go back into a normal chair no one would be the wiser

its actualy so much finalized that holes have been drilled for the seat base and motor, i need to make some spacers for the seat mount but its otherwise good, some cleanup will still be required obviously..but....im pleased

did some end capping and strengthening before pulling it off the bench......it probably wont go back up untill i do a full mockup as i will be making side panels and such from ABS sheet

slid off a lil extra work and whipped up the first of the pair of battery box trays....not bad for blowing my b-day to work

 

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been a long few days

dr apt's at the asscrack of dawn, with mid day apts mixed in only to run to the other side of the state for another dr apt....add into that fresh puppy training...which...translates into mid sleep wakeups, as well as totaly re-teaching my wife since shes never had a big dog as a puppy..so..im training 2

anyway i got a shipment in and...whoa im pleased