Good evening from germany

[cabr]

Hi, my name is Carsten. I pick up this forum searching the web for information about steamboat models. I bought a plan from "VTH Verlag" because my friend has build a pool and on a sunny evening the clear calm water and banjo music from radio inspired me to build a steamboat like the one in "Life on the Mississippi", just for fun. Now the hull is ready and I'm searching for information's about drives. I my plan there is a gear on the wheel, but this looks horrible. So I look for a method to imitate a pitman drive using electric motor. I'm engineer of information electronics and i build some working aircraft and shipmodels , but i haven't any idea about the mechanical problems. In other publications I read something about linearmotors to imitate the pistons and cylinders of an steamengine. This sounds like a thing I understand. Also the use of two linear servos and a microcontroler to operate them seems possible to me. My technical equipment is limited to normal tools, no machines for metalworking, but programming, soldering, electronics and all these things.

That's enough for today and introducing myself. Sorry for mistakes, reading, writing and speaking English are totally different things and many mistakes are the result.

ciao, Carsten

[Bierjunge]

Hallo Carsten, herzlich willkommen im Forum!

So I look for a method to imitate a pitman drive using electric motor. I'm engineer of information electronics and i build some working aircraft and shipmodels , but i haven't any idea about the mechanical problems. In other publications I read something about linearmotors to imitate the pistons and cylinders of an steamengine. This sounds like a thing I understand. Also the use of two linear servos and a microcontroler to operate them seems possible to me.

Everyone has his own preferences. I as mechanical engineer would prefer a simple mechanical solution... But as you like. I don't know if you can find suitable and cheap linear actors. And I don't know either if the gearing of linear servos is designed for continuous operation. And as highly geared transmissions tend to be self-locking, you should take care to operate them exactly as sine movement with 90 deg phase delay, in order to avoid jamming or even damage of the gears if one servo tries to fight the other, as both are mechanically linked...

I think the conventional approach would be easier, to use one drive motor acting on an internal layshaft, from which the rotation is transmitted to the paddlewheel via the pitmans. There are more or less intelligent solutions to achieve this, a few of which I have tried to examine at http://www.paddleducks.co.uk/smf/index.php?topic=2838.0. I would suggest either variant 6 or 4 1/2.

Sorry for mistakes, reading, writing and speaking English are totally different things and many mistakes are the result.

The same applies to me, but I hope we can understand each other...

Liebe Grüße, Moritz

[scotfriend]

Hallo Carsten, schön einen weiteren Deutschsprachigen Modellbauer bei den Paddleducks begrüssen zu dürfen.

Gruss aus der Schweiz, scotfriend

[Eddy Matthews]

Hallo Carsten, schön einen weiteren Deutschsprachigen Modellbauer bei den Paddleducks begrüssen zu dürfen.

Gruss aus der Schweiz, scotfriend

HUH? Have we changed languages on here? That's me stuffed then..... 

Eddy

[scotfriend]

HUH? Have we changed languages on here? That's me stuffed then..... 

Eddy


No no we haven't chanced the language but i want to force you to learn a wee bit of german

Regards Hans

[Eddy Matthews]

The limit of my German is "Vorsprung Durch Technik" and that's only because of the Audi adverts on TV!

You'll have to teach me some in september Hans

Eddy

[cabr]

I think the conventional approach would be easier, to use one drive motor acting on an internal layshaft, from which the rotation is transmitted to the paddlewheel via the pitmans. There are more or less intelligent solutions to achieve this, a few of which I have tried to examine at http://www.paddleducks.co.uk/smf/index.php?topic=2838.0. I would suggest either variant 6 or 4 1/2.

I afraid you're right. I've read your posting before. But a few questions: Is it possible to use only one pitman arm ? I think the deathpoints are the problem, is'nt it ? The slotted holes on the cranks in var 2 are needed because of the mechanical tolerances of the cranks and arms on left and right side of the paddlewheel to avoid jamming ? Do you think, a functional curved link like the one in var 6 is build only using a 'Dremel' driller and file from 1 mm aluminium or brass ?   

But this all is eventually better moved to a new thread at Paddlewheels/Drive Systems ?

Ciao, Carsten

[Bierjunge]

Hi Carsten,

a few questions: Is it possible to use only one pitman arm ? I think the deathpoints are the problem, is'nt it ?

Exactly. If both cranks are ad dead center (e.g. pointing forward), the rear crank wouldn't know whether to turn forward or backward...

The slotted holes on the cranks in var 2 are needed because of the mechanical tolerances of the cranks and arms on left and right side of the paddlewheel to avoid jamming ?

To avoid jamming, yes, but not due to tolerances, but to kinematics: Imagine that both starbord cranks are pointing forward (dead center), the stb pintman is in stretched horizontal position. It is evident that the length of the pitman assembly (distance between holes) has to be exacly the distance between wheel shaft and layshaft.
But in this position, both port cranks are vertical, and thus the port pitman(s) in diagonal position, making them effectively shorter: In Var. 2, the distance between the holes would now be only 2*SQRT((l/2)²-r²), with l being the distance between the two shafts, and r the crank radius. See the contradiction? If this isn't taken care of by either long holes (making the movement jerky) or built-in elasticities, it would lead to jamming and/or high friction and wear.
By the way, in my opinion Var. 2 is the worst one, because it has no kinematic advantages over the simpler Var. 3, having exactly the same (bad) kinematics.

Do you think, a functional curved link like the one in var 6 is build only using a 'Dremel' driller and file from 1 mm aluminium or brass ?

I would prefer the classic approach, using a coping saw (Laubsäge) and fine files. I would further first mount the plate (not slotted yet) of Var. 6 to the pitman, and then scribe the two lines for the slot with a large compass exacly circular around the pitman's rear hole. Then the slot can be sawed and finished.
Alternatively, maybe you could fix your Dremel in some kind of compass (to be built) to guide it exactly circular around the pitman's rear eye, but with these milling cutters, there's always the danger to walk away from the intended trajectory if it isn't guided very rigidly.

But this all is eventually better moved to a new thread at Paddlewheels/Drive Systems ?

Eddy, your turn...

Regards, Moritz

[andy]

Hi,

no chance to hide a little cogwheel drive in the static arm, carryingthe stern wheel? And then the piston rods only being moved as imitation? You also could use an screw- drive with a little cogwheel on the end of the axle of the wheel. screw drive integratd into the arm, cogwheel in the bearing and drive shaft also integrated in the arm, having a diametre of about 3mm maximum???
Andreas

[mjt60a]

The thought has crossed my mind that it'd be possible to fit a 'fake' valve eccentric on one side of the paddleshaft and a crown wheel and pinion on the other with a drive shaft running between the paddlewheel and the support structure...could work!
...for operational pitmans though, do we still have pics of towboat joes mechanism on George M Verity? that has to be the best I've seen (made my meccano version look like the piece of junk that it is!)

[Harold H. Duncan]

Hi Carsten,
A belated welcome to paddleducks.
Have been a member here for only a short while myself, but a great site, and a great bunch of people.
Just love your little logo at the bottom of your post !
Have used a similar logo hidden away on most of the drawings I have produced over the years, but mine is not as cool and imaginative as yours. Well done, and am sure your models reflect this same gift.
regards
Kiwi
ps
my attached logo is a very good likeness of myself - unfortunately - even when I was a young tacker.