PollyMobiles Rebuild

[pollyp]

welded new mounts on the base beam to lift the printer and regain full Z-axis travel.

rebuild the frame, keeping it square as I tighten the nuts

building the X-axis assembly. all the 8mm leadscrew holes have been enlarged slightly so it spins alot looser

all assembled & moves nicely

some wiring needs redoing (extend the extruder cable. the pwm y-splitters only have 1 end with 4pins and the other with 3pins so will have to rearrange them)
and once fully working, it needs realignment & retuning but overall it looks mint

 

[infinity]

What exactly is left of the original printer? Haha nice job mate so neat looks factory made

 

[pollyp]

What exactly is left of the original printer? Haha nice job mate so neat looks factory made

not much lol.
just the controller, heated bed, 4 step motors and end stop switches.

 

[infinity]

not much lol.
just the controller, heated bed, 4 step motors and end stop switches.

If you can buy them separatly you could probably make\print your own 3d printers n sell em. These printers reproduce

 

[pollyp]

If you can buy them separatly you could probably make\print your own 3d printers n sell em. These printers reproduce

getting the makibox kit was a worthwhile investment to learn tons bout operating & designing my own printer.

some say time & money = knowledge & power.
now with this knowledge, if I myself was to start all over again into printing, yeah it'd be more economical to purchase all the bits seperately and build it myself.

technically my printer is purely at a experimental prototype stage, built from a prototype machine as a hobby
so nowhere near commercial readiness cos that requires a much higher level of quality control with a fixed-design accurate frame.

aye self replicating machines, much like biological cells

 

[pollyp]

ah bollux it didn't work.
I tried to connect the dual X/Y motors to the controller with y-splitters to test it and found some major issues.

the makibox D8 controller obviously only meant to run single step motors, so there's not enough juice to run 2 motors and overcome any mechanical friction without it skipping/missing.
the y-splitter lengthens the wiring abit which weakens the voltage to the motors and further worsening the weak signal.

bummer, unless I get a new controller that supports dual motors and start from scratch, this has been a wasted effort cos I failed to check if the board can run 2 motors :/
well this printer frames gonna gather dust and I gotta revert back to my last printer layout, rebuild that all over again

 

[l_jonez]

A few MOSFETs will sort that out.

 

[pollyp]

so essentially build an amp for the stepper motors? I got few old motherboards, wonder if the mosfets in them will work. no idea how to wire em up yet

 

[l_jonez]

Essentially yes, Google is your friend

 

[pollyp]

ah I almost had it working after figuring via code how to raise the step motor max current from 1600 to 2000mA, increase something called "current sense resistance" from 100 to 120mA and reducing the max travel speed from 4800 to 2000mm/h via command lines and it spins both motors without skipping

but then found the leadscrews are mounted slightly wonky on the motor shaft making the hot end shake so this design is dead in the water. tis a case of 1step forward 2step backwards, ah well :/

 

[pollyp]

from another thread I just added up all my spenditures to value kasandra and to simply turbo her costed me £2875
but then I added everything else from forged pistons, LSD, coilovers, etc and ohh my, it ran over £8k plus burning £2k of fuel & £320 engine oil annually
geez christ why am I driving this mobile bank as a daily?

 

[r-reg-sr]

Is that with insurance cost?

 

[pollyp]

Is that with insurance cost?

purely parts cost

 

[pollyp]

so the new frame was quickly dismantled to be stored/thrown away in garage

and prev layout rebuilt and working again

 

[Big_Andy_Redcar]

this morning i had a meeting in sheffield so the office had already got my tickets for 9am train from middlesbrough to arrive at 11am (originally wanted to drive there in my car but meh, work policy) and my other colleage would join me at yarm station.

So, you're another from the North East? Can you remember what length of red battery cable you used for moving the battery under the passenger seat? Thinking of doing this with my autotesting K11

 

[pollyp]

So, you're another from the North East? Can you remember what length of red battery cable you used for moving the battery under the passenger seat? Thinking of doing this with my autotesting K11

aye.

I brought 3m of 50mm2 welding cable to relocate the battery.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-16#post-439222

 

[Se@n]

How comes you had to grind them were they catching or something?

 

[pollyp]

How comes you had to grind them were they catching or something?
View attachment 45403

Before I had the pulsar discs lathed, yup they were rubbing on the caliper when warmed up.

 

[Se@n]

Do you have a pic off what the washers look like spacing caliper? @pollyp

 

[pollyp]

Do you have a pic off what the washers look like spacing caliper? @pollyp

Urm like any normal 1mm washer

 

[Se@n]

Ha ha what I mean is do they sit in between the hub & caliper? i asked for a pic cause pictures are worth a thousand words. @pollyp

 

[pollyp]

Ha ha what I mean is do they sit in between the hub & caliper? i asked for a pic cause pictures are worth a thousand words. @pollyp

Yes inbetween the solid hub & carrier to move it further out

 

[pollyp]

took out the passenger seatbelt reel to check why it's not returning

the explosive side can't be open easy

lets look at this side

pushed out the lockpin

it's just the inertia lock mech

when lateral force moves the weight, it pokes the latch out to trigger the stopper

not much I can service there but somehow after bolting it back onto the chassis, the return spring works again, meh

also recently noticed this rear seat latch had some issues locking

found out the bolt holding the lock to the frame has come out

it's such a tight space but eventually tightened the bolt back up and it work fine again

 

[pollyp]

Disassembling BC V1 rear damper

wanted to strip apart the broken rear dampers to have a look.

the top cap unscrews. the seal & housing is held captive by a c-clip and can be nudged down the tube but felt springy so there's definately still some nitrogen pressure remaining.
don't wanna remove the top without depressurising it or else the nitrogen will simply ram any remaining oil out onto my face

so at the bottom is a grub screw, removed with an allen screwdriver

no oil gushing out yet, but now it abit puzzling what this is. thought it was a ball bearing sealing against an o-ring so I poked it. it felt very spongy and still doesn't release any gas/oil

so resorted to drilling a tiny hole to pierce the tube & released all the gas

now I can push the top housing down to expose & remove the c-clip

top housing removed

piston shaft assembly out

the free floating piston was deep inside so I need to get at it from the other end. figured I could unscrew the base mount off with a pipe wrench & lots force

so I can push this bottom cap & floating piston all the way through

removed floating piston

and the bottom cap

this was the sealing rubber bung that I couldn't push

not much oil was left in the damper

removed the shaft seal

all the damper & piston disassembled. will soon measure & model all the bits

 

[andy]

did ya take things to bits when ya was a kid lol i did

 

[pollyp]

did ya take things to bits when ya was a kid lol i did

of course
whether destructively or not.
tis the best way to learn how stuff works, how they're designed & made, how to use tools, how to fix em and how to reassemble them better.
as a kid we obviously start off breaking alot of things but over the years with more knowledge, skill & experience we then begin to have a higher success rate of reassembling/fixing stuff.

 

[pollyp]

BC V1 Rear Damper Components

here are all the parts of the dampers

top cover

piston shaft guide with brass bush

rubber top out stopper

top out stopper mount

the piston main seal has this expansion slit

there's also these tiny piston bleed holes which I guess are for low speed moves

removed piston seal

main piston

floating piston

bottom cap with the nitrogen gas fill hole

lower mount

modelled every part in CAD

this is the top section with shaft guide & oil seal

main piston assembly

the adjustable dials control the amount of oil bled/bypassed past the main valves

bottom section

during bump travel the oil flows through the tiny piston bleed hole at low speed and through the multi-washer bump port valve stack (like a leaf spring) at high speed

during rebound, some oil flows through the piston bleed hole and some through the other rebound port valve stack

when I unscrew the damper dial to soften the setting, it opens the bypass bleed port so at low speed, some oil would flow through the bypass port as well as the tiny piston bleed holes

at higher travel speed the oil can't flow through the bleed ports fast enough so the oil begins to flow through the main valve stack

when the suspension goes beyond bumpstop and literally bottoms out the damper, the last thing the shaft hits is the floating piston, which offers abit of cusion from the nitrogen gas. any further force would cause the floating piston to crash down onto the bottom end with some damage.

when the damper tops out, a rubber stopper cusions the piston assembly from striking the top cap section

 

[yorkiesteve]

Hi Paul
Great strip down photos and CAD work, I'm surprised you didn't do an animated one too haha, I seem to have missed though where the damper failed because the last I read on this post your car had just passed its mot.
I know you put your car ( and suspension ) through its paces what with all the track days and long road trips and such, but how long would you say you have had the BC suspension ? And would you say it's been good value. I notice you drilled the damper body to release gas pressure, but if the seal had failed and oil was leaking out wouldn't the gas have escaped too ? Or where you just being super safe

 

[pollyp]

Hi Paul
Great strip down photos and CAD work, I'm surprised you didn't do an animated one too haha, I seem to have missed though where the damper failed because the last I read on this post your car had just passed its mot.
I know you put your car ( and suspension ) through its paces what with all the track days and long road trips and such, but how long would you say you have had the BC suspension ? And would you say it's been good value. I notice you drilled the damper body to release gas pressure, but if the seal had failed and oil was leaking out wouldn't the gas have escaped too ? Or where you just being super safe

thanks steve hehee I could've animated it all but would take abit more work moving the valves and I was only curious bout it's construction. now moving on to building the new 3d printer.

twas back in april where I discovered the rear left damper was all wet.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-128#post-718007

conclusion was the hardened chrome coating on that piston shaft within the working ride height range had come off for some reason (manufacture defect or normal wear tear? the other damper was perfectly fine) so the rough surface damaged the oil seal allowing the pressurised nitrogen below to force most of the oil out the oil seal.

I've had these coilovers for over 4yrs, made protective covers since day1, used daily in all weather, long road trips, afew dozen full day hard trackdays, many thous miles.
reliability-wise apart from that faulty left damper which I think is a chroming defect, and worn strut top pillowballs which is expected, the rest of the suspension is still working flawlessly after all that abuse.
so is it worth it? for definate 100%

when the shaft oil seal failed, the nitrogen gas down below only pushes the floating piston/oil out the seal till theres not enough pressure to force any more thick oil out the tiny gap.
I felt the top cap was abit springy so there's still pressure inside and it's obvious we wanna depressurise it before opening otherwise I'll get oil spraying all over.
I had no idea of how to release the gas at the time and now we can see it's pretty difficult, that rubber bung is on there tight. the alternative destructive safe way was to drill a tiny bleed hole followed by a bigger hole.

 

[Huggy444]

Hi Paul
Great strip down photos and CAD work, I'm surprised you didn't do an animated one too haha, I seem to have missed though where the damper failed because the last I read on this post your car had just passed its mot.
I know you put your car ( and suspension ) through its paces what with all the track days and long road trips and such, but how long would you say you have had the BC suspension ? And would you say it's been good value. I notice you drilled the damper body to release gas pressure, but if the seal had failed and oil was leaking out wouldn't the gas have escaped too ? Or where you just being super safe

I'd also recommend them, I've done 3 years of rallying on mine and there's been no problems at all very adjustable as well.

@pollyp .... Whilst I'm here, how low will the rears of yours go? Mine won't go much lower than say a 20mm drop.

 

[pollyp]

I'd also recommend them, I've done 3 years of rallying on mine and there's been no problems at all very adjustable as well.

@pollyp .... Whilst I'm here, how low will the rears of yours go? Mine won't go much lower than say a 20mm drop.

when I remove the springs, adjust damper mount to it's lowest point, jack up the axle till it's literally resting on the bumpstops,
the 15" rim would be 67mm from the arch / 277mm wheel centre - arch (83mm drop).
my static ride height is 100mm rim - arch / 310mm wheel centre - arch (50mm drop), 33mm bump travel

https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-32#post-472341

 

[Huggy444]

Yeah... Odd. Defiantly not a coilovers set up for 'mad lows' or 'stance'!

 

[pollyp]

Yeah... Odd. Defiantly not a coilovers set up for 'mad lows' or 'stance'!

nope these units are designed more towards performance & comfort.
cos of the extra length of the adjustable lower mount to allow the user to adjust bump / rebound travel for max performance, max comfort and prevent tyres from fouling the undercarriage whilst also providing enough stroke travel to maintain tyre contact, the geometry of these tall rear dampers limit how much the chassis could be dropped towards the axle beam.

check ur dampers travelling fully down and use the shorter BC bumpstop and not the thicker original micra bump covers

 

[Huggy444]

I'm definitely not on the bumpstops

I don't want lows for rallying anyway, it's just something I've noticed when I lowered the car fully for Japshow.

The long damper travel is brilliant for rallying though, allows them to keep grip on the rutted surfaces

 

[pollyp]

I'm definitely not on the bumpstops

I don't want lows for rallying anyway, it's just something I've noticed when I lowered the car fully for Japshow.

The long damper travel is brilliant for rallying though, allows them to keep grip on the rutted surfaces

have you tried verifying ur suspension geometry can reach the bumpstops by jacking the axle up without springs or panhard connected?
if the cars weight can't push the unsprung suspension down to the bumpstops then something in the geometry or bushing is binding. loosen all trailing arm inner bush bolt, position suspension at new ride height then retighten the bush bolts to reseat the inner metal bush insert so the rubber bush ain't so twisted/binded.

if the unsprung suspension can drop on the bumpstops (assuming that the ride height at point where it rests on the bumpstop is lower than ur target height) but when the adjustable rear spring seat is set fully down and the ride height still cannot reach ur target height, the main spring is either too hard and/or too long.
either soften the rear spring rate or reduce the free length of the spring (custom made, custom reformed, or unadvisibly cut it which will raise spring rate too)

adjusting the panhard rod to fit & keep the axle centered at the new static ride height is the last step

 

[Huggy444]

Thanks Paul!

Lots of bits for me to tinker with over half term (week off school, woo!). I'll update my blog with results when I get around to it.

 

[pollyp]

Since the printers original mechanism of using intersecting rails was prone to being too slack or binding,
and the parallel dual motor design required too much current from the control board, hard to keep aligned and leadscrews were wonky,
now I spent afew weeks redesigning it from scratch going a different route by keeping all the XYZ motors/sliders seperate, using stiffer 8mm rails, mount the Extruder motor over the hotend to eliminate the bowden tube and all the leadscrews are aligned inbetween the linear bearings so they move the assembly via its CoG to reduce any binding.

Printer 26
Extruder motor & slider rails aligned vertically & Z axis motor pulls the frame from above but during movement the leadscrew would foul the Y axis assembly & pulls the frame from off-centre.

Printer 28
Z motor pointing upward so the leadscrew doesn't foul with the Y axis assembly. Stiff thin frame keeps the CoG of all the Y / Z axis & Extruder motors aligned but access to the Y axis motor was blocked.

Printer 29
Cleared the frame for accessing the Y axis motor but there's alot of wasted frame space.

Printer 30
Z axis bearing mounted slightly offset to clear the Y axis motor for a shorter chassis frame but the Extruder motor mounted top-heavy high above rails could cause binding. half upper main frame support as an attempt to save material.

Printer 31
Changed to full box frame for rigidity.

Printer 32
Mount rails horizontally with leadscrew under the Extruder motors CoG to reduce stress but assembly would cover the bed

Printer 35
Swapped the hotend to the front for easy access and unobstruct the bed. Develop new pull-type extruder tensioner.

Printer 36
Utilising longer LM8LUU linear bearings for reduced binding. One used for aligning the mounts Y/Z axis while other bearing is only for the X axis. Extruder motor fan mounted at the rear.

Tried printing the mount but the long print in cool room temps developed alot of serious splitting.

Printer 39
Mount the Y axis motor closer inward to utilise more of the available screw thread. Extruder motor fan mounted to the side. Linear bearing for the heated bed frame mounted further inward to clear the beds adjustment screws.

Printed the mount but it still cracked, so I manually filled the cracks with hotend, grinded & smoothed but concerned bout the amount of flexing between the two long linear bearings.

 

[pollyp]

Printer 40
Added some bracing between the two linear bearings and tried printing it with an external shield to help control heat & cracking, but it still warped.

Printer 42
Stiffened the rear of the frame to stop it swaying.

Printer 43
Moved the Extruder motor inbetween the sliding rails vertically with the leadscrew below but the big offset distance between the bearings could cause binding.

Printer 44
Rearranged the sliding rails & leadscrew to be close as possible together vertically to reduce binding & space and turning the Extruder motor sideways to keep its CoG close to the rails.

Printer 45
Tried adding an extra tube across the top of the Y axis frame to support the Z motor rather than a thin plate steel but the 15mm vertical L bars holding the linear bearings were too small.

Printer 46
Construct a small tubular frame around the Z axis motor to secure it solidly.

 

[pollyp]

With the design finalised, time to build it.

Ordered some 8mm bearings & rods.

Printed & smoothed the new hotend mount.

Was looking for a stiff coilspring over the M3 screw to tension the filament extruder motor pulley, found some from ball point pens. Tried running the extruder but the springs were too soft and the gear slipped so resorted back to a piece of rubber.

New hotend mount with bearings, tensioner & leadscrew nut.

Cut some 16mm square tubes as accurately as possible.

Used a picture frame as a jig to keep it all square, made the base frame

Then the sides

and welded it all together

To make the adjustable rod ends, cut some 10mm tubes

and weld em to M6 nuts

All the frames complete

 

[pollyp]

Assembling the Y axis frame

Fit bearings on the bed frame and onto the main frame

Install Z axis bearings

Followed by the Y axis frame

Fit Y & Z axis motor

Fit extruder motor

Trim the old bowden tube this long to fit in the mount like this & locked in place

Organising all the wiring route

Hot glue the end-stop switches in

and yay hey presto a very fine piece of 3D printer

Began afew test configuration prints and ohh boy she prints sooo straight & accurate now it's awsome

This piece would've been near impossible with the old setup but it's now possible

 

[Huggy444]

Very nice work Paul, I'll have to get you to make me some random stuff haha yeah

 

[pollyp]

Very nice work Paul, I'll have to get you to make me some random stuff haha yeah

it's like when u just learnt a new skill to weld, cut,fabricate,program, etc you just can't wait to see what you can make.
only limited by ur imagination and how well u can model but it ain't a cheap hobby with all this ££ rebuilding & tinkering but abit more affordable than playing with special car bits

 

[Huggy444]

it's like when u just learnt a new skill to weld, cut,fabricate,program, etc you just can't wait to see what you can make.
only limited by ur imagination and how well u can model but it ain't a cheap hobby with all this ££ rebuilding & tinkering but abit more affordable than playing with special car bits

I've done it before, years ago albeit, still have solid works at home.... I'll have a play later
So the cars gone on hold for a bit i take it? Keeping it as it is for a little while

 

[pollyp]

I've done it before, years ago albeit, still have solid works at home.... I'll have a play later
So the cars gone on hold for a bit i take it? Keeping it as it is for a little while

yup she still works fine enough to get me around, we had our fun for the yr so its just maintaining her over the winter while I now focus is purely on sorting out my career & income before considering spending any more on her.
cos of her high parts value, high maintainance, high risk & running cost, I may have to consider getting another car preferably k11 as a normal eco daily parked on street for when I have to move away for work.

 

[SuperUno]

With your ability to create such CAD drawings you must be able to get a job somewhere using those and your engineering skills...

 

[pollyp]

With your ability to create such CAD drawings you must be able to get a job somewhere using those and your engineering skills...

fingers x

 

[pollyp]

tried printing these slim plastic clips to hold down the glass bed rather than the bulky metal clamps

they hold briefly but the high temps make em soft n loose so went back to metal clips

replaced the loose bolt & spring bed support with nut & bolts to reduce any slack in the bed movement

my glove box latch needed replacing so printed another one

wanted to finally enclose the printer to retain heat and reduce the amount of ABS plastic shrinkage/warping/cracking on big prints so got this 4mm double wall polycarbonate roof sheet from B&Q that's stiff, insulating & kinda translucent to look through

cut the panels to fit over the frame. propped the filament spool on top

fed through a hole

power & usb plugs through the rear holes

printing at the mo and it does a good job keeping it hot inside

 

[wehey]

Just out of interest, what are the running costs of a 3D printer like?
I used to be a 3D Cad draughtsman and have been interested in giving this a go for a while.

 

[SirChris]

That's a Clever setup

 

[SirChris]

Case defo smarts it up. Gets some neons in there.. Serious.

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