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Author Topic: A Greek BIREME  (Read 23445 times)

ballastanksian

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Re: A Greek BIREME
« Reply #75 on: July 17, 2017, 04:03:28 pm »

Put a thread on each end and a threaded collar onto the ends of the mechanism and screw them in. You could do it with an electric screw driver so you don't get RSI from twisiting your wrist a multiple of 60 times.

Just out of interest, how wide if your Bireme with the oars?

Whatever happens, she looks great, and as per usual you have rocketted along with her  :-))
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Tug-Kenny RIP

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Re: A Greek BIREME
« Reply #76 on: July 17, 2017, 08:25:26 pm »


No problem Ian, as they will be fixed in.  The total width is measured at 21 inches so it's not too bad.

Today I re-sanded the hull again and added some extra filler,  as I could see blemishes, so it had to be  re-sprayed again in more red oxide.    (Told you I loved the stuff   ok2).



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ballastanksian

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Re: A Greek BIREME
« Reply #77 on: July 18, 2017, 08:52:59 pm »

There's nowt wrong with a dab of red oxide:O) 
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Martin [Admin]

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Re: A Greek BIREME
« Reply #78 on: July 21, 2017, 06:07:04 am »


Soon Kenny, soon! -
https://youtu.be/lzveezi5vVs
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RAAArtyGunner

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Re: A Greek BIREME
« Reply #79 on: July 21, 2017, 07:47:15 am »

Just like in the movies  O0  O0
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Re: A Greek BIREME
« Reply #80 on: July 21, 2017, 08:47:01 am »

It reminds me of the old Dave Allen joke, about the galley slave owner who likes to go water skiing on Sundays.
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Re: A Greek BIREME
« Reply #81 on: July 21, 2017, 10:00:10 am »

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Re: A Greek BIREME
« Reply #82 on: July 21, 2017, 10:22:49 am »


Thanks guys.  Well immersed into the subject now.   %)

I am at present designing the  'rowing mechanism'.  I have all sorts of systems on file and plan to make it as realistic as possible.  Several versions have been tried and rejected as there's more to this than meets the eye.

It has to be a parallelogram action with rounded corners and slightly slopping sides,  with enough force to shift 60 wooden blades in the desired way, forward and backward.  When that's done, we have to make two sets  (one for each side) which can be run independently or together as the need arises.  I'm certainly getting through the Whisky bottle.    {-)

Cheers

ken


 
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Colin Bishop

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Re: A Greek BIREME
« Reply #83 on: July 21, 2017, 10:38:45 am »

Don't you wish that the ancient Greeks had invented the paddle steamer Ken - soooo much easier.

Colin
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Re: A Greek BIREME
« Reply #84 on: July 21, 2017, 10:45:40 am »


Didn't they have giant wheels that people walked uphill inside of .    :}

ken
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tigertiger

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Re: A Greek BIREME
« Reply #85 on: July 21, 2017, 11:16:33 am »

Thanks guys.  Well immersed into the subject now.   %)

I am at present designing the  'rowing mechanism'.  I have all sorts of systems on file and plan to make it as realistic as possible.  Several versions have been tried and rejected as there's more to this than meets the eye.

It has to be a parallelogram action with rounded corners and slightly slopping sides,  with enough force to shift 60 wooden blades in the desired way, forward and backward.  When that's done, we have to make two sets  (one for each side) which can be run independently or together as the need arises.  I'm certainly getting through the Whisky bottle.    {-)

Cheers

ken


Hi Ken, you may have already considered this.
Beyond the basics but this may make life easier.
If you can find someone who can program an Arduino for you, and you use stepper motors.


For each row/side of oars.
Position 1: Oars out of the water top of stroke. For coasting (turning if opposite side in)
Position 2: Oars in the water bottom of stroke. Braking (handbrake turns if opposite side out)
Position 3:  Row forward, normal speed
Position 4: Row forward, slow
Position 5: Row backward, slow. (playing with 4 and 5 allows turning the boat in its own length)
Position 6: Sync port and starboard in position 1. Start position and fail-safe.


Just thinking out of the box. But having some way to put the oars back into some 'start position' would be useful I think.
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Tug-Kenny RIP

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Re: A Greek BIREME
« Reply #86 on: July 21, 2017, 12:08:54 pm »


I am looking into this idea but first fancied all the mechanical ways of achieving the same result.

I can see why technology has taken over.   %)

ken
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tigertiger

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Re: A Greek BIREME
« Reply #87 on: July 21, 2017, 05:00:50 pm »

The mechanicals will still be the same, just controlling the motor will be programmable instead of micro switches. :-)
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Re: A Greek BIREME
« Reply #88 on: July 24, 2017, 08:46:52 pm »

I am now deep into work on the rowing system. 

Enquiries have been made on the 'Radio Equipment section'  about servos to control the up and down movement of the oars. At the moment I am going with mechanical means of control but hope to graduate to Arduino computer control at a later stage  ( another bigger model ?)


The OARS will be connected to push rods that are connected at their base to a horizontal strip which controls their action.  At the beginning of each stroke the servos will push the whole strip up whilst the oars travel horizontally and then down for the return movement.

Here are some pictures of the build so far. This represents 2 days work so far and it shows the oblong ends for insertion of Oars which have been fitted to the pusher rods. The Oar count has been reduced by one on each side as it looked odd when all the oars were fitted into the boat.  The front oar was a long one and the rear oar was a short one.  It looked so out of place ??  The bottoms of the pushers will be cut off flush, now we know their heights.   ok2


 


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Re: A Greek BIREME
« Reply #89 on: July 26, 2017, 10:02:37 am »


Huston...... we have a problem.       %)

After making all the oar mechanisms and dry fitting them, I found I couldn't rotate them in the required fashion.

That is to say, they have to move along the horizontal plane a distance and then drop down a distance, and move back along another horizontal plane and then move up towards the start position.

The reason for the failure was that the Oar holders were square and NOT elongated.   Please see pictures.  Now we don't have enough material to complete this re-design.

This now means that I have to make a modified set with a vertical section to allow the oars to pivot up and down.  I also have to make a better bearing system which allows them to turn with minimal resistance whilst keep the blades in a vertical position in the new vertical slots.

Please don't complicate things further by mentioning  'Feathering the blades'   {-)    as I'm sure they ancient mariners weren't aware of these things.

Onwards.

ken



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ballastanksian

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Re: A Greek BIREME
« Reply #90 on: July 26, 2017, 10:42:33 am »

If the oar holders could swivel in the wooden beam then that would cure one of the issues you are having especially if you can reuse the existing ones.

I would solder a small washer onto the holders just above where they exit the beam, and have a small pin below to keep them in place, perhaps with another loose washer, or solder the washer in place once the holder has been poked through. Making the loops bigger and then putting a pin through the outer most end of the oar stock would then allow them to swivel in the vertical as well How wide are the oar stocks?
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JayDee

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Re: A Greek BIREME
« Reply #91 on: July 26, 2017, 10:44:59 am »


Hello Ken,


It would be easier to make an Oar setup using just ONE Oar.
Get it to work OK, then make all of the others the same way.
Would be a lot quicker and easier than getting things wrong on dozens of them.
The Engineer in me is coming out !!!.
Very impressed with what you are doing.


John.  :-)) :-)) :-))
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Tug-Kenny RIP

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Re: A Greek BIREME
« Reply #92 on: July 26, 2017, 10:53:25 am »

Thanks guys.

Ian has the right idea.  I used solder as a quick way but washers would seem smoother.  I shall discontinue the wood beam as it might swell during use, so aluminium is the way to go.

Yes it was silly to proceed with them all, but hey,  that's the fun of it all and I do like my mass production.

We haven't come to holding the oars in position yet, so we have think of a way of stopping them sliding out.  Maybe the pins as sugested.

Cheers

ken
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C-3PO

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Re: A Greek BIREME
« Reply #93 on: July 26, 2017, 03:36:24 pm »

Ken,

Looks like this type of servo movement/control might help?

A very quickly cobbled together experiment - in this example only one servo is moving at any one time - one waits until the other has reached it's destination - clearly in real life the oars ( hence servos) would for some part of the travel be moving in both planes at the same time - this is possible just needs to be translated from the real world into code :)

I am using the Arduino Uno as it was readily available - this could equally be the smaller Arduino Nano - approx cost 4 delivered

Youtube video link - https://youtu.be/Fe8goLPlOjE



The program code that is making the servo's move is below:

Code: [Select]
#include <VarSpeedServo.h>
VarSpeedServo myservo_1;
VarSpeedServo myservo_2;
 
void setup()
{
  myservo_1.attach(3);
  myservo_2.attach(4);
}
 
void loop() {
  myservo_1.write(1000, 50, 1);
  myservo_2.write(1000, 75, 1);
  myservo_1.write(1700, 50, 1);
  myservo_2.write(1700, 75, 1);
}
 

Regards
C-3PO
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Tug-Kenny RIP

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Re: A Greek BIREME
« Reply #94 on: July 26, 2017, 09:25:32 pm »


Fascinating.  I've bookmarked your film for future reference.  The plan is to use a servo at each end of the pusher bar to drop the bar a certain distance and then restore the bar back to the top whilst a geared motor is pushing and pulling the bar a certain distance fore and aft via a linked rod.  I'll show details as I progress.

Today was spent working on a 2 new bars and swivel systems for each oar.

Cheers

ken


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derekwarner

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Re: A Greek BIREME
« Reply #95 on: July 26, 2017, 11:07:08 pm »

Now that Arduino functionality by C-3PO sure looks like the heart of the 2 x dual system movement for you Ken
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Re: A Greek BIREME
« Reply #96 on: July 27, 2017, 09:16:35 am »


Yes, it does look smooth Derek.

C-3PO, does it speed up in sync with the speed control  ?

ken
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C-3PO

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Re: A Greek BIREME
« Reply #97 on: July 27, 2017, 10:15:45 am »

Ken,

If you want the Arduino to read your RX throttle channel and react to the throttle change to speed up the servo's that is easily achieved. You would not need a traditional ESC as we are only controlling the servos.

The sweep motions can be as simple or as complicated as you want. EG. you may say you want the total travel of servo one to be 90 degrees - you may want the first and last 10 degrees to be at a slower speed to the main travel. You can specify a completely different movement for the other servo. You may want a pause once the oars have entered the water before the stroke starts....so in theory you can animate this as per your imagination.

Indeed you may need 4 servos- 2 each side - you could even include reading the RX "rudder" function to make one side stroke go faster than the other, or maybe just one side moving ....

So I think you can see that this can be as simple or as complex as you want :)

PS If you want to add some whistles and bells you could even synch a sound(s) with the stroke rate - did the Greeks chant/drum beat as they rowed?

https://www.youtube.com/watch?v=WXh1tW16V-8

C-3PO
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Re: A Greek BIREME
« Reply #98 on: July 28, 2017, 10:03:11 am »


     
I just choked on my corn flakes.................

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Re: A Greek BIREME
« Reply #99 on: July 28, 2017, 10:06:29 am »


To continue...  I have run out of 2mm brass tubes so went shopping yesterday..  None left I stock.  Now I'm stuck in limbo until I come up with an answer.

ken
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