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On 8/16/2020 at 8:31 AM, Turbocharger said:

After a smoky discovery that the heat sink tabs are electrically connected to the transistor outputs AND earth (oops)

Basic mistake :P

You can quite often get an "isolated" variant of the transistor which will have the heatsink tab electrically isolated from the terminals. Usually won't be quite as high a power rating for it though.

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A little more time spent building a programme structure (and chasing issues with code), I'll use the electric window switches either side of the 2002 dashboard as control inputs in the cab. They'll be nominally MENU/SELECT on one side and UP/DOWN on the other.

I've written a really simple routine which inflates or deflates each solenoid, and shows ^ or v on the display in the relevant corner. I can also equalise an axle left to right or one side front to back (open the axle solenoids, don't inflate or deflate), and here it puts = in the relevant corner of the display.

It's useful to be able to manually ping each solenoid but normally it'll set a target height for each wheel and have a routine which does the legwork. As it can only inflate or deflate at one time the routine will look at all four corners, decide whether the average is higher or lower than target, then run the relevant routine to inflate or deflate the appropriate wheels and show the change on the display. That's all for the next stage though, I haven't mounted height sensors yet. 

Right now I've got a controller where MENU takes you through seven modes, and SELECT will do different things in each mode to choose what UP/DOWN do. 

  1. Automatic - will set a target height and adjust to meet that, plus or minus a tolerance band. Up/Down will adjust the target height, then the control routine does its thing to best match that, and then rechecks.
  2. Lean - takes the target height from Auto, and up/down will offset the targets left/right.
  3. Pitch - same, offsets front to back instead.
  4. Calibrate - this will be to manually set the min and max heights for corners, rebalance one dicky corner sensor etc.
  5. Test - this tests the solenoid outputs, in a pattern, individually, pairs together etc, controlled by UP/DOWN. This should help with any diagnostics on the trail, listening for the click etc.
  6. Diagnostics - will page through different inputs and variables on the display using SELECT, then UP/DOWN.
  7. Manual - this uses SELECT to page through different options (all, front, rear, left, right, FR, FL, BR, BL, equalise across, equalise one side) and then uses UP/DOWN to activate appropriately.

At the moment only modes 5 and 7 are written - the others need height sensors (or me to have some patience...). This does mean I can control the solenoids in a meaningful way to make it dance around a little:

And an explanation of the controller, mostly for myself in lieu of formal documentation: 

Some pictures in action from manual mode (you get the idea):

 

Inflating the rear:

IMG_20200825_202524.thumb.jpg.e13faea6fa9b00abd76810f946403e4e.jpg

Equalising the right-hand side springs:

IMG_20200825_202542.thumb.jpg.66dc8ccfdc58f81d042fdfae8a7e2e99.jpg

Deflating just the front right bag:

IMG_20200825_202553.thumb.jpg.b3c6c818f4dc0e8acb735016f09275ae.jpg

Next steps are

  • to tweak the spring seats which I'm not happy with.
  • to check that the shocks don't allow the springs to overstroke (even if the controller starts exhausting them as the axles droop).
  • to fit 4x height sensors so that the control can move to automatic.
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  • 2 months later...

I like that alot.

3d printing can bring  a whole new world of pain.  I got 10 hrs into 14hr print fail last night.  Funnily enough it was an adapter to go from a disco 2 air spring to front turret inspired by thsi thread.

Are you printing in ABS or PLA?

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These are PLA. I've got a reel of ABS once I've finalised the design, but if it's working I'll probably just replace on failure. A friend runs a printer farm for a living so he's very aware of the failure rate. One of his machines is 6ft tall and has print times longer than a week, so regular checks prevent the spaghetti mess.

Interested in your adapter - I'm just using a vibration isolation ring and some Velcro to hold the top in place for the Disco2 springs - I've a bayonet at the bottom and the travel will be restricted by the shock so I'm not sure why it needs pinning mechanically at both ends. 

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On 11/20/2020 at 9:35 PM, Turbocharger said:

These are PLA. I've got a reel of ABS once I've finalised the design, but if it's working I'll probably just replace on failure. A friend runs a printer farm for a living so he's very aware of the failure rate. One of his machines is 6ft tall and has print times longer than a week, so regular checks prevent the spaghetti mess.

Interested in your adapter - I'm just using a vibration isolation ring and some Velcro to hold the top in place for the Disco2 springs - I've a bayonet at the bottom and the travel will be restricted by the shock so I'm not sure why it needs pinning mechanically at both ends. 

Maybe when the pressure gets to low in the air spring at full drop, like the air spring makes vacuum and doesn't want to extend enough. That situation can accur when on low ride height and dropping the axle (when lifting the car resting on the chassis for example). 🤔

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Sorry been awol doing that DIY thing, ill try and sort some pics this week. I may ever retry the print now i have identified why it went wrong ( over heated stepper driver)

ABS gives off fumes, so might be worth friggin up an extractor if you don't already have one.

My adapter was purely to keep things located top end and i have the added issue of larger spring seats on the rear as its for a 130 chassis. On the front i have tried to use the turret bolt holes to hold the adapter,but i need to work how to hold the adapter and turrent without the load from the turrent transmitting to the adapter.

The rear i had planned some form of clamping ring that sits just inside the spring hanger, which pulls the adapter ring up tight. The adapter then swages down from the larger diameter to the disco size.

 

how does your radius arm bracket attach, is it a clip?

Edited by MECCANO
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I'm so impressed John!  You are exploring this in a much more methodical, scientific way than I did and I think it will yield a better result overall.

The experience I gained from going through the same process has served me again and again. 

Si

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So heres my adapters ( front only) i braved another print.

Unfortunately i havent quite got the air sping pin holes quite right and my support material needs cleaning up ( its fusing too well).

However, im now considering a 5mm steel ring at the base instead of relying on the plastic to retain the sping. The plate can then have studs welded for the turret, so it becomes a plasic sandwich instead of using the strength of the plastic to retain the turrent bolts.

from memory its a 5mm shell and 50% fill. 15hr print.

Stl file:

y4mwgs7WKBDOE2AWzRyu0R8mkqLVhrmEOTI65bHJ

 

y4mhlvFqT3_dTHgiR5JAFXpC0XRbiWKAK8pnE8Is

 

the actual print:

y4mQ_GLemsR9gIQIBuAK9iIZN_COpwKthXWCQnRz

 

y4m-UzVHw80Govdti-w9Ed4UQLjWhVP6MLpM8Rph

once ive trimmed the support material the pin should locate all the way through:

 

y4mabXkaKakZPqpYkpDsg8YJKxjUn73ofl3b8w51

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  • 2 months later...

Loving Meccano's approach. I've had a fallow few months because it's really cold outside(!) so I've been learning more about Fusion360 and getting better at 3D-printing stuff. It can dangerously become the answer to everything though, but I've found an economic source of MIG gas again too so we may be able to add metallic fabrication back to the arsenal soon.

My progress has taken much longer than the photos suggest - essentially I've put the electronics in a box and made three brackets; I'm hoping this is the bit where lots of effort doesn't bear much fruit. 3D printing brings a nice custom finish to this, though the jury's still out on whether it'd be adds value or if it'd be quicker to just buy something or fold up some metal.

Hoping-it's-temporary box for the sparky bits:

PXL_20210109_134616253.thumb.jpg.929add2025b7a17ae68e89afe29a6007.jpg

PXL_20210111_211248106.thumb.jpg.678d64ea4d350b334ff500f8a4395e09.jpg

 

And a few clamps to hang the solenoids off the cage to stop it wandering around.

PXL_20210221_162031360.thumb.jpg.e1e4643b0d891b812253c0fcb72a20d3.jpg

PXL_20210221_165955022.thumb.jpg.24e241787f6b61cb7c92e571c3335e20.jpg

Next to do is extend the solenoid loom and height sensor looms to reach the dashboard and put a neat little plug on them. I don't have the patience or steady hand for soldering so I've ordered a third-hand clamp thingy.

 

 

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