Team Saint Robot Builds

[craig_colliass]

I have been preparing some motor gearbox units NPC74

IMG_0819.jpg

One done the other to go.
For some strange reason the motors have the thinnest wires connected to them, evidently this has been a problem with these motors for a while, I have doubled up the cables so there should no longer be any problem they also have an elongated case at the back for encoders and similar as I am not fitting that, the aluminium casting has been cut down and the end plate refitted. when I got these motors I thought they were rated at about 1hp similar to the Boshes but they seem to be about 1.7hp so that was a nice surprise the smaller ones are the 1hp units.

[craig_colliass]

Nearly finished the other motor
IMG_0822.jpg
Have been bedding in the brushes the motor draws about 5Amps at 24v with the gearbox attached, that is not too bad running with no load for a motor that is about 1.25Kw
IMG_0823.jpg

[daveimi]

Are these the units the marketplace sells as "T74's"?

[craig_colliass]

Yes they are I don't know how good they are going to be as they aren't used much this side of the pond. The specification looks OK.
24v motor no load speed at the drive coupling is nearly 250rpm with a reduction of 20:1 this gives a motor speed of just under 5000rpm! the gearbox innards look like they can take some stress but you don't know till you try to break something I am fitting a 20 tooth sprocket to connect to the 40 tooth sprocket on the hubs, this will give them a reduction of 40:1 (Saint has about 34:1 at the moment)
they are to go into either Saint or Gabriel. the only thing to watch with these motors is they have very thin bolts holding the motors together so I will have to support the end of the motor somehow. If you don't try you won't know.

[daveimi]

I'd been looking at these, like the way you can just bolt them on.

[craig_colliass]

hopefully they will work out OK but you never know how they are going to be until you try them.
I don't know if the output shaft is that well designed for direct connection to the wheels even with the hub plate you can get for them. to get 10mph out of them the wheel diameter would be about 350mm similar to Maelstrom.

[Max]

Many thanks for the information, I have just ordered one and will see what its like.


[ATTACH=CONFIG]5014[/ATTACH]

Above is my first attempt at Pneumatic Muscle. the initial results are quite promising.
Operating pressures seem low about 40-60psi
Contraction is around 15-20 % of effective length, and the force though not measured, is sufficient to over power my or anyone's ability to stop it, so far. the diameter is 15mm and length just over 100mm.

I hope to take it to Maidstone so if you are there we can show anyone who is interested.

Craig

Not that it's a competition Craig but mine's bigger! :

http://youtu.be/2rsBqIPrhTA

[razerdave]

I resisted it Craig... Nice to see something different

[craig_colliass]

Everyone's in on the act!!

Looks good what is it for?
Specification?
weight lifted
overall length
stroke
pressure.

I am thinking of making one for a weapon actuator just to see how it dose

and Dave yes you were the only one who tried to stop it and did.

[Max]

I made it just for testing to see if I could power a weapon with it, maybe a lifter or grabber.
It's made the same way as yours but with a regular bike inner tube (about 30mm diameter), 450mm long and has a stroke of around 80mm which is a bit pathetic! Braided hose goes from 30 to 45mm. In that video it is lifting around 100lbs at which point we ran out of weights to put on it. Looked like it could lift a bit more but as more load it put on it contacts less.
Was running at around 80psi but there was a leak somewhere so that kept dropping rapidly.
The encaps were made from aluminium and had a groove machined into them to provide more grip for the jubilee clip.

I wonder if you used stainless steel braided hose if you could run off full pressure CO2? Wouldn't want to be around during testing though!

[craig_colliass]

Started some modification to Gabriel I have got to fit different motor gearbox types into the robot, brackets made up, but need drilling in the right place, but I don't want to do this until I have the sprockets machined to fit, as it never pays to guess these things.


IMG_0845.jpg

The wheel axles have been moved further back by about 45mm this should give the robot more counterbalance force this in turn should make the hammer weapon more effective. I hope to get the major part set up by the end of January.

[daveimi]

That's a pretty chassis!

[craig_colliass]

The sprockets have now been machined and fit well on the output shafts on the gearboxes, they are fitted in reverse this is to bring the load closer to the output shaft bearing, reducing the load on the bearing.
Axle robots tends to kill transmissions quickly, so any help in design is always going to help reliability.


IMG_0854.jpg

IMG_0855.jpg

IMG_0856.jpg

[craig_colliass]

I have been doing a little bit more on the pneumatic walker project.

IMG_0858.jpg
As you can see on the above picture the actuator basic size has been fixed at about 80mm long in total this gives an unloaded contraction of just over 10mm. the actuator is anchored via 8mm bolts one of them has a hole drilled through for the pneumatic fitting this makes the construction of the actuators simple.
the problem I still have to address is the air leaks where the clips are they aren't big, but I have to reduce leaks to a minimum to get the robot to move at any useful speed.

IMG_0859.jpg
The valves I hope to use are 5 way with an actuating arm on the top, like a micro switch. The main reason for this is speed, the gait time should be less than one second I don't think a solinoid v/v will like operating 300 times in one fight!

IMG_0860.jpg
The compressor has been stripped down and a pressure control switch fitted I don't like the arrangement at the moment as the relay tends to feather causing it to get hot more work needed on this I think.

[maddox10]

An industrial solenoïd of a pneumatic valve, like Festo or SMC, can handle 10 actions a second and more.
(at my work, programmed minimum response time is 50 milliseconds)

That the rest of the setup can have problems with that is another matter.