Chris's Build of Steering Engine

[crueby]

Hi Michael,
Question for you on the real engine. When playing with the model and turning the ships wheel back and forth, I noticed that the rudder position indicator was angling off to the left when turning the wheel to the right, and right when turning the wheel left. That puzzled me, and made me go back to the pictures of the real engine to make sure I didn't install something backwards.

All is on the same sides as on the real one, but in looking very close at the pictures, I think I can see that the threads on the upper shaft that move the rudder indicator are left-hand threads. Is that correct? The worm gear on the upper shaft that moves the control nut is a right-hand thread, that one is easy to see since it is much larger pitch, but the smaller indicator thread appears to be left hand. Can you confirm that for me?
If so, I have two options. Well, three options - leave it as is and know that the pointer moves opposite, turn the dial plate and pointer 180 degrees so it points at what direction the ship is going to turn, or remake the threaded collar on the upper shaft as well as the square nut that rides on it to be left handed thread.

[crueby]

First step on the crankshaft is the section of worm gear in the center that turns the front wheel. Cut off a length of the Acme threaded rod, trimmed to length, turned in the ends, and drilled/bored to fit the stock used on the crankshaft:

The worm section will be drilled/reamed for a taper pin to hold it in place. Here it is held up to the engine to show how it engages the wheel. The crank webs will have a matching round boss on the side facing the center, between that and the narrow section at the ends of the worm the shaft is prevented from moving sideways under the load of turning the gears and rudder.

[Michael S.]

A little test:

<a href="https://www.youtube.com/watch?v=wtX3eNemYGQ" target="_blank">http://www.youtube.com/watch?v=wtX3eNemYGQ</a>

There is also some dead gear Insolvenz here.

[Michael S.]

The pointer goes in the direction in which the steering wheel is turned.
Then you need a left-hand thread?

On the large machine, the levers are splined to the shaft. The screws you use also work and you can find out the correct position better.

The bronze carrier ring has no play at all in the groove.

Michael

[crueby]

The pointer goes in the direction in which the steering wheel is turned.
Then you need a left-hand thread?

On the large machine, the levers are splined to the shaft. The screws you use also work and you can find out the correct position better.

The bronze carrier ring has no play at all in the groove.

Michael

Great! 


So, looks like I need to change it to a left handed thread. Or extend the slot in the front wall to the other side and put the gear rack on the other side of the post, which would make the pointer move the correct way.




When I added the screws to the arms, I drilled and tapped through the arm and the cross bar, so its like a pin.


 

[Admiral_dk]

Shame about the "Links Gewinde" - most of Us don't realize it just by looking at them .... but it will be one of those details you probably will remember much longer than other details 

Otherwise great progress 

I wouldn't worry about the fact that you have a Hysteresis - as almost every single kind of servo has one, in order to avoid too much 'Action' / energy consumption, etc.

    

Per

[crueby]

Shame about the "Links Gewinde" - most of Us don't realize it just by looking at them .... but it will be one of those details you probably will remember much longer than other details 

Otherwise great progress 

I wouldn't worry about the fact that you have a Hysteresis - as almost every single kind of servo has one, in order to avoid too much 'Action' / energy consumption, etc.

    

Per

Yeah, the left hand thread detail was there in the pictures but I never looked close enough to notice it. Its amazing how much detail a picture can have, on all of the models I based on real machines there have been details that I am still finding long after the builds!
Just took a look at the model, and widening the slot in the wall and swapping the gear rack to the other side is not an option, it would interfere with the valve linkages. So, I'll have to see if I can find a suitable left hand tap/die to remake that cylinder on the upper shaft. You are right, its one of those little details that would annoy me!
You are right about the servo behavior, without some of it they would sit there and quiver back and forth constantly!

[crueby]

Got a good start on the crank webs this morning. The finished webs are between stock sizes for width/thickness, so I picked the next size up and cut two lengths, enough for all four webs. The two pieces were clamped together and drilled for the shaft holes. Each pair in the stack will be kept together and in this same orientation to keep the holes aligned and everything even.

Two short pieces of the crankshaft stock were filed slightly to make them an easier sliding fit, then cut off from the bar to use as alignment pins during the next steps.

Set up in the mill, and trimmed the ends square and took passes down both sides to get the width down to the desired dimension.

Made the cut down the center to split the pairs apart, and trimmed the cut edges too

Here are the web pieces so far. Next step will be to take each one down to final thickness. After that can look at the shaft/pins. The joints will all be drilled/pinned with taper pins. Have to remember to put the worm gear between the webs before the final assembly!! 

[cnr6400]

 

[crueby]

Thanks Jeff!

Got the webs thinned down, took cuts on both sides of each:

Webs so far:

In the photos of the real one, I can see that the ends of the webs are radiused, with the center point at the center of the shaft at the other end. That could be done either on the lathe or on the mill with the rotary table. I'll set up an arbor for that next time...
 

[Michael S.]

Top work 👍

The crank pieces only with pins or also glue?
I would have used Loctite.

Michael

[Michael S.]

Yes, the ends of the crank pieces are rounded.
I see now that the crankshaft is rounded at the transition to the crank. I think this is done so that there are no breaks at the point. The bronze bearing shells are also rounded there.

Michael

[crueby]

Top work 👍

The crank pieces only with pins or also glue?
I would have used Loctite.

Michael

Ah - yes, forgot to mention the loctite. Whenever I do one like this, I first assemble with Loctite retaining compound and alignment blocks/clamps while that sets. Then I drill for the taper pins, and tap them in with another drop of loctite, trimming them off flush.
 

[crueby]

Yes, the ends of the crank pieces are rounded.
I see now that the crankshaft is rounded at the transition to the crank. I think this is done so that there are no breaks at the point. The bronze bearing shells are also rounded there.

Michael

Rounding those inside corners would keep the stress points down, I never noticed that, plus the bearings would have to be rounded there to match. Nice detail!  On the model that would be tough to duplicate, given the way the pieces are assembled. I do need to add the round plate next to the crank web that acts as a thrust bearing against the forces of the worm gear.  Its great having the photos of individual parts during restoration!

[Kim]

Getting started on the engine!  How fun is that!  You're moving at breakneck speed, Chris!  (as always!) 

Kim