Rising butt hinge question.

[Imagewerx]

I need to make something that works in the same way as a rising butt hinge,but I need to have some control over how much it rises against how many degrees you turn it.Is there a geometrical name for the shape or form involved,or is there anything else larger than a hinge that uses the same principle please?

 

[bernardgreen]

A rising butt hinge is a type of elevating screw with a very steep incline.

Another term used is spiral inclined plane or inclined spiral plane

 

[Burnerman]

Some sort of cam, maybe.....either a flat or plate type, depending on what you are intending to make?
John

 

[Dave54]

Depends to some extent how much linear movement you want for how much radial movement.
Face cam as John says, or a helix as in an old fashioned starter motor Bendix which will give a much longer movement per degree.

 

[noseall]

Spiral cam.

 

[Imagewerx]

Ok thanks for the replies everyone.

This is what I'm trying to do......

But a lot quicker than this as this is way too slow.This is done using four ultra miniature servos and is triggered by a proximity sensor.

The problem I have is very limited space.It all has to fit into a tube with 60mm inside diameter and a total depth of just 50mm.Roughly 30mm at the top is taken up with the switch and it's associated circuitry,while I only have about 20mm at the bottom in which to fit the lifting mechanism.It can be powered by either a normal rotary servo or a small pneumatic actuator which can only go horizontal as it is in the video.I need about 15mm of lift and fall but can work around how much linear movement I've got by changing pivot points.

 

[Burnerman]

Is there nothing in the world of the model maker which could suit you here.....a boat rudder servo, or something similar?
John

 

[Dave54]

How does the actual lifting mechanism work at the moment? Can you simply use faster servos?

 

[Imagewerx]

Is there nothing in the world of the model maker which could suit you here.....a boat rudder servo, or something similar?
John

I'm using robot servos anyway,it's the lack of space that's the problem for me. The idea to have to build it so it all fits inside the cup holder shown is self imposed,it doesn't have to but it's a challenge I've set myself.

How does the actual lifting mechanism work at the moment? Can you simply use faster servos?

Like this......



They had to be linear servos and after an exhaustive search these were the only ones any where that would fit where I needed them to.Hobsons choice I think it's called,when the only ones are the fastest ones.The problem is the motors in them are so small the only way to get in useful torque out of them is to gear them down a lot,run them faster and there'll be next to no torque from them.

I've got an idea in my head now how this is going to work,but I need to learn how to draw an Archimedes screw using Sketchup to get it made.

 

[Dave54]

Pretty neat as it is! Nice thing about it is that as it is ( I assume) the servos are self contained, and so require no lubrication, with the possibility of getting dirt in there etc.
I was going to say earlier that the trouble with "faster" is that it requires more power. Which presumably means bigger motor(s) If you're not careful you end up with a "weak" mechanism that sticks at the slightest thing.

 

[Imagewerx]

These servos run at a lower voltage than most servos do,in this case just 3.7 Volts which also limits their torque.The other problem with them is the feedback pots aren't very accurate so they don't all move at exactly the same speed or park in the same place.I had to buy six to get four that were as closely matched as possible.

http://www.robotshop.com/en/vs-19-pico-linear-servo.html

 

[Dave54]

Very neat as I said. Thanks for the link. Interesting.
Bodger Dave has to ask that (assuming) these are made to be able to be run on a Li-ion battery? Can you up the voltage without knacking the unit out?

 

[Imagewerx]

Very neat as I said. Thanks for the link. Interesting.
Bodger Dave has to ask that (assuming) these are made to be able to be run on a Li-ion battery? Can you up the voltage without knacking the unit out?

Thank you but no,a minimum of 2.5 Volts and an absolute maximum of 3.7 Volts.By themselves they'll be fine,but trying to get four to track with each other exactly and it has a bad attack of the judders.I'd guess they are designed to run from rechargable batteries,don't know how much current they draw so can't so how long batteries would last.