Questions about pneumatics

[pekka111]

Is there a motorized switch for pneumatics? Manual switches (47223) require so much force that doubt they can be automated.

Do pneumatics wotk always with overpressure? So there is no reverse function with suck / underpressure?

[msk6003]

1. Don't have any offical motoried switch. Normal switch even look like need lot of torque but you can find some example of motorised switch on internet.

2. Current version of pneumatic is work only with overpressure way. You can create vacum using switch with cylinder like video under here but if you don't want it you need this part from very old set.

 

Edited December 30, 2024 by msk6003

[Jurss]

22 minutes ago, pekka111 said:

require so much force

If they won't work directly, they can be geared.

[2GodBDGlory]

These are good answers so far! Those switches you showed are very stiff, but there are ways to motorize them. Part bb0874 https://www.bricklink.com/v2/catalog/catalogitem.page?P=bb0874&name=Pneumatic Switch with Pin Holes and Axle Hole&category=[Pneumatic]#T=C is a newer switch that has an axle hole, making it significantly easier to motorize.

[pekka111]

Thanks for the answers! So with longer lever and gears you could move the switch. But now that I think of it, if you have the second motor for moving the switch, you can also use it for a second pump and have two separate lines? Inspired from msk6003's video, I tested connecting cylinders directly to each other. They work utilizing over- and underpressure, but that action seems quite stringy. But you could transfer movement in both directions with one motor that way. And by using springs.

 

1 hour ago, 2GodBDGlory said:

These are good answers so far! Those switches you showed are very stiff, but there are ways to motorize them. Part bb0874 https://www.bricklink.com/v2/catalog/catalogitem.page?P=bb0874&name=Pneumatic Switch with Pin Holes and Axle Hole&category=[Pneumatic]#T=C is a newer switch that has an axle hole, making it significantly easier to motorize.

Do you know if that switch requires as much force?

Edited December 30, 2024 by pekka111

[2GodBDGlory]

3 hours ago, pekka111 said:

Thanks for the answers! So with longer lever and gears you could move the switch. But now that I think of it, if you have the second motor for moving the switch, you can also use it for a second pump and have two separate lines? Inspired from msk6003's video, I tested connecting cylinders directly to each other. They work utilizing over- and underpressure, but that action seems quite stringy. But you could transfer movement in both directions with one motor that way. And by using springs.

 

Do you know if that switch requires as much force?

I don't quite understand what you're talking about in the first section, but it sounds like what you're looking for might be something like this autovalve mechanism:

I'm not sure if I've built this particular one, but I know I've used similar designs, and it allows for one motor to control one cylinder in both directions.

As far as force for that newer switch, I'm away from my Lego at the moment and can't test, but I'd say it's probably fairly similar, but because it's wider and better braced, it doesn't feel like it needs as much. It should be just fine for motorized switching.

[pekka111]

17 hours ago, 2GodBDGlory said:

I don't quite understand what you're talking about in the first section, but it sounds like what you're looking for might be something like this autovalve mechanism:

I'm not sure if I've built this particular one, but I know I've used similar designs, and it allows for one motor to control one cylinder in both directions.

As far as force for that newer switch, I'm away from my Lego at the moment and can't test, but I'd say it's probably fairly similar, but because it's wider and better braced, it doesn't feel like it needs as much. It should be just fine for motorized switching.

This in nice invention. I meant that because the switch is so tight, you have to have a long lever for it.

Btw I just got some new used switches and they are easy to work with and would work like in your video. The ones i got earlier are so tight that legos would break first. They are hard to move even by hand. Maybe they are faulty.

 

e: just noticed new/used switches have label "mould king" on the side :(

Edited December 31, 2024 by pekka111

[2GodBDGlory]

6 hours ago, pekka111 said:

This in nice invention. I meant that because the switch is so tight, you have to have a long lever for it.

Btw I just got some new used switches and they are easy to work with and would work like in your video. The ones i got earlier are so tight that legos would break first. They are hard to move even by hand. Maybe they are faulty.

 

e: just noticed new/used switches have label "mould king" on the side :(

Yeah, Lego ones have variable stiffness. Brand new ones are often very stiff, but they get broken in over time. I've had good success with Mould King pneumatics in general (though you need to glue the heads onto the shafts of cylinders), but their valves were one thing I didn't need from them, so I don't know how they'd work.

[pekka111]

On 12/31/2024 at 11:41 PM, 2GodBDGlory said:

Yeah, Lego ones have variable stiffness. Brand new ones are often very stiff, but they get broken in over time. I've had good success with Mould King pneumatics in general (though you need to glue the heads onto the shafts of cylinders), but their valves were one thing I didn't need from them, so I don't know how they'd work.

Good to know that genuine switches might get looser over time.

[allanp]

14 hours ago, pekka111 said:

Good to know that genuine switches might get looser over time.

Proper Lego ones aren't usually too stiff unless they have been left for a while not being used. sometimes both valves and pneumatics can stick on the first few operations after storage.

I'd like to try a silicone oil from a bottle but so far have just used a spray can of silicone lubricant. I spray a bunch into the cap and then use it from there, either carefully dripped into the ports or down the side of the valve or applied directly to the pneumatic rod. Be careful not to get it on the outside of any ports though as it can make the hoses slide and pop off easier when under higher pressure. This will help a lot with the sticking as well as keeping the rubber seals supple. I usually have a spray can of silicone lubricant, it's great to have handy around the house for lubricating sticky curtain rails, windows mechanisms, bicycle (doesn't trap dust/dirt on the chain like oil would) or also for use on the car door seal rubbers as it stops them sticking in winter. 

Edited January 3 by allanp

[LegoTT]

On 12/30/2024 at 10:48 PM, 2GodBDGlory said:

 

 

Being an autovalve it's a motorised switch AND a pump.

If you want multiple motorised switch and only one pump a smaller way to go is worm gear and 24t gear.

I don't know if in this example the switch was tweaked tough, indeed switch can be made more smooth :

 

 

You can see in this example that there is one more version of switch, I think that the first one (without pinhole) is the stiffest.

 

The previous example didn't use the oldest switch, you may have one because it's so stiff, but here is a contraption proving you can switch it with the worm gear / 24t gear combinaison even with the weakest lego motor :

 

 

 

[Brickthus]

The newer switches are a bit stiffer than the oldest ones with studs.

The longer cylinders help to provide more leverage for pneumatic automation.  A single cylinder can push up to 5 switches and the new type of switches with the nozzles on the bottom are easier to build as a compact bank.

This robot uses 7 cylinders and 17 valves (some in banks of 3 or 4 as a back-pack) in a 14-step sequence to sign "JOY" in semaphore:

I tailored the length of the levers to align the cylinder travel with the valve lever range.  A #2 joint plus a hole with 2 axles plus a #1 joint is the right length.

Mark

[pekka111]

I'm not getting notifications from this thread... Worm gear is good idea, that is probably best way to produce the required force for the switch. I have the ones with two holes.

e: This could also work: https://brickset.com/parts/4528037/linear-actuator-10-15-m

Edited January 10 by pekka111

[pekka111]

On 1/4/2025 at 7:43 PM, Brickthus said:

The newer switches are a bit stiffer than the oldest ones with studs.

The longer cylinders help to provide more leverage for pneumatic automation.  A single cylinder can push up to 5 switches and the new type of switches with the nozzles on the bottom are easier to build as a compact bank.

This robot uses 7 cylinders and 17 valves (some in banks of 3 or 4 as a back-pack) in a 14-step sequence to sign "JOY" in semaphore:

I tailored the length of the levers to align the cylinder travel with the valve lever range.  A #2 joint plus a hole with 2 axles plus a #1 joint is the right length.

Mark

Got any video?