Some STW genuis needed.. height alarm for car lift

Ir sensors about 6 inches from ceiling, when sensor is cut the ramp stops...no idea how that would work though.

Beam break sensor will do that. They are pretty standard fittings for cutting the power to machines to stop someone sticking their hand in.

Was looking for optical switches,  do you have link to a kit? I supect theyll be 12v with a 230v relay?

If you want to go down the sensor route, then I’d look for lift door detectors, but mount them horizontal (rather than vertical as they’d be on a lift door)

This way you get cover across the whole footprint of a car roof, rather than a line across it.

search weco door detectors. They are a big supplier in the industry.

Otherwise I’d put a limit switch with long roller arm above that the roof hits and as the roller touches the car roof and rotates the arm it cuts out.

Sounds obvious, but whatever solution you go for, wire it in series with the up button. You don’t want it as an emergency stop as that will stop power to the up and down buttons and you’ll not get the ramp to lower ?

Big push button on a switch box. Flexible cable. Magnets.

Throw it on the roof of the car.

Sorted.

I know I’m spoilt but…

You're spoilt 😉

Many years ago my FIL had a number of industrial units - one of which become empty when the body repair shop in there closed very suddenly leaving a lot of kit.

I had the opportunity to get a proper 4 post lift for free but, despite having room for it in my barn, I decided against it as I didn't really think I'd have enough use for it and the installation would have been quite spendy.

I did have the engine hoist, large battery chargers and an excellent metal workbench though.

Beam break sensor will do that

+1 also used on electric gates etc.  Think pretty hard about what is going to be the first thing to hit the ceiling though, I can imagine a few crushed ariels, roof racks, etc

Beam along the length of the car could work but sounds like a lot of effort and overly complicated. Keep it simple.

I'd be looking at some sort of physical stop, if it's a scissor then a stop on the drive.

Even simpler, hang a pole along the length of the car, when the car hits the pole stop lifting. If you want to complicate it hang it on spring loaded switches that turn on a light when one or both lose tension.

Tape a ballon to the ceiling, it it pops, take your finger off the up switch.

Something like this:

https://amzn.eu/d/7MSF4xt

Just a Google hit but this is the sort of thing I was thinking. I see in the reviews someone is using it exactly like you want.

You need a Canary alarm. When the tweating stops it’s at max height.

Alternatively a couple of bells with tennis balls below?

You don't know what the highest part of the car is. Could be the roof, could be the bonnet that you've opened.

As oldschool says, you need a sensor that covers the whole footprint of the car, not just where you 'think' is the highest point. I've used curtain sensors before, to stop people getting hit by a robot. Fairly cheap from Aliexpress (not sure I'd trust one) or expensive if a fully approved one, like  https://www.keyence.com/products/safety/light-curtain/

Ive a scissor lift on order for my garage.

I'd be interested to know what model you're getting.

Plastic grid above car connection to a long bar that sits just below the switch.

When any part of the car hits the grid it lifts and a drop down bar also goes up  and knocks your finger off the up button

Like a big version of a puppet controller with a length of electric conduit on one of the legs .oval slot allows access to button till it's nearly at ceiling height when the up switch is blanked out

Beam break as above
, or maybe a proximity sensor on the roof above the ramp, I used a 12v one off eBay to drive a cat squirter

Use the AI visual feedback solution.

Look the the car when it's near the roof hit the stop button.

I'd paint a danger zone at the top of a couple of walls and position a couple of mirrors where you can see the zones while raising a car. As soon as the highest point visibly breaches the zone, stop

As oldschool says, you need a sensor that covers the whole footprint of the car, not just where you ‘think’ is the highest point. I’ve used curtain sensors before, to stop people getting hit by a robot.

Which highest bits wouldn't trigger a centreline longitudinal sensor... Gullwing door?

Fit the controls to a cable. Lie face up on the roof.

My car has the roof bars and one bike rack permanently fixed to one side, rack (or an attached bike!) will be highest point in the unlikely instance of the roof box being up there too.

Tbh if you aren't remembering to remove a bike from the roof before lifting the car up then you probably shouldn't be working on a car.

Claymore clacker taped to the highest point of the car with the Claymore pointed at the fool with the up button?

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@fruitbat sent you a pm

Which highest bits wouldn’t trigger a centreline longitudinal sensor… Gullwing door?

As midlifecrashes says any bike / kayac etc rack etc is not usually centred but becomes the highest point even without the bike/boat attached.  not sure how scissors lifts deal with different widths of car, but it seems likely they dont precisely centre the car so the little fin at the back (with antenna etc) would be on centre for some cars and not others?  I’ve no fin on an MG5 so the roofbars (even with no bike racks) are a couple of cm higher than the back door.

question for me would be do you wire in series (which probably causes you warranty issues) but is a fail safe or just wire to an alarm?  Some cars still have flexible aerials (not sure if can just be unscrewed) which will leave you about a foot short of the ceiling if it’s a cutoff, but with care you might ignore that on an alarm…

Stick a load of whoopee cushions to the ceiling!

Tbh if you aren’t remembering to remove a bike from the roof before lifting the car up then you probably shouldn’t be working on a car.

Or driving into a garage or car park…