Aluminaut Research Submarine 1/96th Scale

[crazygary]

Uh, I knew that!!! Just wanted to see if you did!! (LOL)
We kin be a bit "thick" but uhventchully git 'er dun!!!

If I did the Honey-dos first, there'd be absolutely NO time to play!!
Gotta diplomatically skirt a few issues now and again just to try to
maintain what little sanity I still posess!! ( What?? I still have some sanity???? Go figure!)
Thanks for the thought, though!! I*** it weren't fer IN-sanity, I'd have none at all!!

Got my feeble mind working on an improvement to Trouts syringe system. All I can tell ya is
it will involve machining a spool valve, from either nylon or delrin, and will have a couple of
o-rings for sealing purposes. I do, however, really like his idea with the landing gear retract
actuator!! Very cool!! Might could borrow that from him!! O.K., Trout??????

Crazygary

[trout]

Absolutely, borrow away. Plan B, if this piston did not work, would have been a floating piston with a pump that pushes the plunger. So, I look forward to your creation!

[He Who Shall Not Be Named]

Tom's actuator find is a good one -- many possibilities!

[crazygary]

A good find, for sure!!!!

I'm gonna research "micro linear actuators" and see what pops up! That's, basically, what Toms find is! Might could end up being the best available possibility, for the money!! Glad it works so well for ya, Tom!! Way to go!!!

Will let y'all know what, if anything, I come up with!

Tom, does your actuator incorporate any kind of limiting? That is, can it be set to move something a set distance, or rather, rotate its threaded shaft for a certain period of time, etc??
I noticed in your video that it's capable of making abrupt stops at either end of the stroke!! That's a good thing!!

[Subculture]

If you want proportional control, the cheapest and simplest way to go about this is to purchase a cheap 9 gram servo (about $2-50 from Hobbyking) and dismantle it. Use the electronics and feedback pot from that to control your tank. Make a lever 0.7 times the stroke of your tank and attach it to the pot via a control rod. You can use the motor with the servo to drive the tank, although the gearbox will need some tinkering, or use a third party geared motor with the servo amplifier. Gizmoszone.com is good for small geared motors.

[Slats]

If you want proportional control, the cheapest and simplest way to go about this is to purchase a cheap 9 gram servo (about $2-50 from Hobbyking) and dismantle it. Use the electronics and feedback pot from that to control your tank. Make a lever 0.7 times the stroke of your tank and attach it to the pot via a control rod. You can use the motor with the servo to drive the tank, although the gearbox will need some tinkering, or use a third party geared motor with the servo amplifier. Gizmoszone.com is good for small geared motors.

Not wanting to take this thread too far off topic but Andy is there some good basic "how to" information re using servo as proportional control that you know of for electrical dummies like me?

[Subculture]

Most normal sized servos have an amplifier board capable of driving a motor of about 2.5 watts. Monster sized servos or those with high output can probably drive a lot more, but I'm talking about the something like your common and garden S148.

If you strip the servo down inside you will find a board, with the servo lead hooked in. The motor and pot will be directly soldered to the board on some servos, or connected via flyleads. The motor will have two wires, and the pot will have three wires. All five will generally require extending. On the motor leads you need to hook up some limit switches to cut the feed when the piston reaches full and empty. These switches will also need some diodes soldering across them, so the tank can start in each direction when the swicthes have been actuated.

The limit in size for a piston tank powered off a normal servo amplifier board is about 40-50mm diameter. Adequate size for a main tank on a small boat, or as a trim tank on something larger.

The pots on servos tend to about 5k in value. So you can substitute the pot for another of the same value- perhaps you would prefer to fit a slider pot for instance, or a multiturn version.

[trout]

This conversation is not off topic and right in-line with what is going on. I have on my bench a servo, that I took out of the Gato, that is disassembled and being played with for ESC on the Aluminaut (there is a reason - later) and a ballast system that could be added to the Gato or Skipjack to give fine ballast trim. I will document what I find, but it is good to step back and revisit ideas. Tonight, I will see if I can put all my chicken scratch drawings into a understandable coherent presentation. I will need to turn some parts.

[Slats]

Most normal sized servos have an amplifier board capable of driving a motor of about 2.5 watts. Monster sized servos or those with high output can probably drive a lot more, but I'm talking about the something like your common and garden S148.

If you strip the servo down inside you will find a board, with the servo lead hooked in. The motor and pot will be directly soldered to the board on some servos, or connected via flyleads. The motor will have two wires, and the pot will have three wires. All five will generally require extending. On the motor leads you need to hook up some limit switches to cut the feed when the piston reaches full and empty. These switches will also need some diodes soldering across them, so the tank can start in each direction when the swicthes have been actuated.

The limit in size for a piston tank powered off a normal servo amplifier board is about 40-50mm diameter. Adequate size for a main tank on a small boat, or as a trim tank on something larger.

The pots on servos tend to about 5k in value. So you can substitute the pot for another of the same value- perhaps you would prefer to fit a slider pot for instance, or a multiturn version.

Thanks Andy - I appreciate that, but confess I'd probably need a diagram to understand it!

[Slats]

This conversation is not off topic and right in-line with what is going on. I have on my bench a servo, that I took out of the Gato, that is disassembled and being played with for ESC on the Aluminaut (there is a reason - later) and a ballast system that could be added to the Gato or Skipjack to give fine ballast trim. I will document what I find, but it is good to step back and revisit ideas. Tonight, I will see if I can put all my chicken scratch drawings into a understandable coherent presentation. I will need to turn some parts.

Thanks that would be excellent.
J

[crazygary]

Good info here, Subculture!!
Thanks, my friend!

[trout]

I did not get to the lathe, that will have to be this weekend to show the variable ballast tank.
The current ballast system does have a limiter to stop the servo. It is on the underside of the circuit board. In its original position on the retract, the metal nut that travels up and down the threaded rod has a tab that would travel between two push button switches. When I mounted the circuit board on the motor, I had to adjust the travel by making a plastic brick attached to a wire that was attached to the plunger. As the plunger moved forward, the wire pulled the styrene block forward until it touched the switch. When the tank was filled, the wire was pushed back, and so was the brick, until the block met the switch on the other side. Maybe this picture will help.

Does that make sense?
But to clarify a little on a servo being used for a ballast system.
Here is a small 9g micro servo opened up. There are three sections outlined in the picture circuit board, potentiometer, and motor.

The potentiometer has a post that comes out that normally would have a gear on it.

As the servo moves the servo arm, it is also moving the potentiometer. This varies the voltage (the pot. is a variable resistor) and the circuit board knows when to stop when it meets the high voltage limit or the low voltage limit. So, you could connect the motor from the current ballast system to this circuit board, then use the wire (that currently pushes the styrene block) to now move an arm attached to the potentiometer post that would let the circuit know when to stop at each end. Does this make sense? or am I making this clear as mud.

Now back to the build. I had a fear that these little ESC controllers did not have reverse. Even though I quickly tested them, I felt uneasy and wondered. Tonight I tested the ESC. They do indeed go forward and reverse, yessssss....

The pour shaft has not been cut off the props yet, so it is waving in the air, but the prop tracked straight. Now I am going to coat the ESCs in liquid electrical tape to keep the boards from shorting each other out while stacked and crammed into place.

[Subculture]

That is really a 5-6 gram servo, because it's using a pager motor. Don't expect too much from those. Fine for very small syringe based tanks, but wouldn't use them for driving a motor over 1 watt.

Do those pictures help fill in the blanks, John?

Norberts book has a whole chapter on piston tank design. Formulas in there that allow you to calculate how much wattage you need to power a tank.

Has a bit about the electrical side, including a circuit based on servo IC's with a beefed up output for driving larger motors. This is necessary if you want a larger tank like an Engel.

[crazygary]

Gettin' close to the water now, Buddy!! Looking good!!

My attempts to find something to improve upon your landing gear retract unit
have fallen into the hands of those who want me to mortgage my house!!LOL

Will be utilizing your excellent "find", and am planning to machine a piston
out of either nylon or delrin. A couple of o-rings to seal things off, a
few more positive thoughts, and we shall see what we shall see!!

Also like the heck out of your little ESC find!! Good stuff!

Thanks again for the "divine" inspiration!!

Will post my findings as I progress!!

[trout]

Subculture, thank you for the correction on the little servo. I did take this out of the 2.5 D&E sub-driver, and put in a 9g. in its place. I made an assumption.
crazygary, go for it, I am glad you got great information from this WIP. I know I was getting frustrated because no one was sharing the how-to info.
The proportional ballast will have to wait until I make a prototype and discuss some thoughts with Dave. Hewhoshallnotbenamed will kick me in the youknowwhere if this is really a dumb idea or not feasible. So, in order to avoid the public humiliation, I will do the background work first, then share.