Chris's Build of Steering Engine

[Kim]

Nice crank shaft, Chris!

So where did you get those nifty taper pins and taper drill?  I assume they come as a matched set?

Kim

[Michael S.]

Hello Chris,

perfect look!

The crankshaft will last forever. I also own a few of these cone drills but they are much too big for model building.
There is another picture of the crankshaft, I don't know if I've shown it before, where you can see how the cranks and wedges of the eccentrics are in relation to each other.

Michael

[crueby]

Hi Michael,
At first glance I thought you had started your version of the model, then realized it is the real one!      Now that you have your shop back together, is a version of this engine on your list? You have a larger lathe, maybe do one larger?

You had not shown those pictures, thanks very much for them!
I would be starting on drilling the other taper pins by now, but we have another afternoon at the local pool to run the RC subs, which is forcing me to be patient and wait for the loctite to cure up properly.
Chris

[crueby]

Nice crank shaft, Chris!

So where did you get those nifty taper pins and taper drill?  I assume they come as a matched set?

Kim

Hi Kim,
I got them from McMaster-Carr, they sell both the pins and the drills and reamers. As I recall when I was looking for them most of the other sellers here carried the pins but not the drills and reamers, or vice versa. The first few models I just had the taper reamer to match the pins, so I used normal drills and stepped down through the hole with four different size drills at different depths, then used the reamer to join them up in one smooth taper. Worked well, but took a long time for each hole. I finally splurged on the drill during the Ward pumping engine build, glad I did, its a lot faster, though I still do drill a pilot hole to get the bulk of the material out at the size of the taper drill tip.
The taper pins come in different sizes, these are the 4/0 size. Each size comes in different lengths. On these I have two lengths, and it looks like they are the same size at the fat end, they just get narrower on the longer ones. They do make a very tight joint.
Chris

[Vixen]

........... which is forcing me to be patient and wait for the loctite to cure up properly.
Chris

I am quietly following and enjoying every move you make on this exciting engine. Your work rate is phenomenal. Waiting for the loctite to cure is probably the only way of slowing down you build progress.

Mike

[Kim]

Just looked those up on McMaster's website.  They don't give those bits away, do they? 

And interestingly, the drill bits & reamers are listed as 1" over 50" taper.  But the taper pins are listed as 1/4" over 12".  That's 1:48 rather than the 1:50 of the drills.  Why the difference?

Also, do you use the stainless taper pins? Or the 12L14 taper pins?

Thanks Chris,
Kim

[crueby]

Just looked those up on McMaster's website.  They don't give those bits away, do they? 

And interestingly, the drill bits & reamers are listed as 1" over 50" taper.  But the taper pins are listed as 1/4" over 12".  That's 1:48 rather than the 1:50 of the drills.  Why the difference?

Also, do you use the stainless taper pins? Or the 12L14 taper pins?

Thanks Chris,
Kim

The pins I have are the 12L14 ones (had to look up my order at McMaster to check that! ).  I never noticed the difference in taper, did a search online and found this:

Standard inch-sized taper pins have a taper diameter of 1:48 while metric ones have a taper of 1:50.

On the reamers, some are listed as 1:50 and some 1:48. For a 1/4 or 1/2" deep hole/pin, I doubt it matters at all, I have not been able to see any wiggle in the fit as I use the ones made with that drill bit. I usually tap them with a hammer to seat them good and tight - maybe with the 12L14 they are soft enough to adapt to the very slight taper difference?

Maybe some of the others with formal training in this stuff could enlighten us!

[crueby]

........... which is forcing me to be patient and wait for the loctite to cure up properly.
Chris

I am quietly following and enjoying every move you make on this exciting engine. Your work rate is phenomenal. Waiting for the loctite to cure is probably the only way of slowing down you build progress.

Mike

Where is that thumb-twiddling emoji?   
 

[Michael S.]

Chris, I think I will definitely build the steering machine as a model for myself one day. At the moment I have other construction sites. But I keep a watchful eye on a suitable worm wheel, which I can get as a ready-made combination. That also sets the standard. I will prepare it in the long term.
And I will watch you with excitement and learn with my eyes.

Michael

[cnr6400]

After a half hour trying to find the thumb twiddle emoji    I got the old gonkulator out and figured the angle difference between 1:48 and 1:50 pins is only .047 degrees. On a 6 mm long pin that only makes .0049 mm difference on diameter. I don't expect that would make a perceptible difference in feel while installing a pin. One knock with a small hammer and it's driven well I'd say. (the scratches and pits in much of my work are deeper than .0049 mm.) 

[derekwarner]

Sorry.....old Vickers 4.5" twin mounts had dozens of BS taper pins installed......naturally as noted, 1:48 BS pins require 1:48 taper reamers

Same for Continental applications, ISO 1:50 pins require 1:50 reamers

Many years ago [in a previous life] I supervised a refit on HMAS Parramatta's Vickers 4.5" gun mount

In the UK [in years goneby], Gun builder supervisors inspected a bluing of every tapered pin hole taper, prior to hammering home.

[the amount of protrusion [height] of the head of a BS taper pin was also toleranced

From this you can see a BS pin could never be inserted to an ISO taper hole.........

Derek

[crueby]

Well, if I ever start building a full size machine gun I will be sure I have the matching drill.  For these models, with a 1/4" or 3/8" long pin, its working perfectly!

[john mills]

the  cheap imported machines have taper pins to align parts it would be obvious they don't know
i found pins fitted or not from just in the hole to drive welling with may be a 10 lb hamer  the holes just drilled with a hand drill at any angle
in any position.these are a printing machine and a laminating machine for 1500mm wide web   just horrible and now were near suitable for
the work.
john     

[crueby]

Continuing on with the crankshaft, the taper pins were drilled/installed last night, and this morning were cut off and milled flush with the surface:

Then, after a LOT of double checking the photos from Michael to make sure I had them on the proper sides of the shafts, I milled in the keyways for the eccentrics:

And the nearly-complete crankshaft set on the engine (no bearing blocks made yet)

Now, to make sure that I was interpreting the photos properly, and that the screw threads were all in proper direction (after the slight goof with the indicator threads for which a new left-handed tap/die will be here this week), I did a test. I marked where the eccentric goes on the shaft from the photos, then used the valve porting diagrams I showed before plus actually turned the wheels on the model to see which direction things went, making notes along the way. All looked good so I went ahead and cut the keyways.


For those of you who like technical details and really really want to follow along on the mechanism, here is the sequence the parts go through (hang on, its easy to get dizzy)

• Steering wheel is turned to the right, as viewed from the back of the engine where the helmsman would stand
• That turns the upper inner shaft clockwise as viewed from the back
• That moves the control nut back towards the helmsman
• Which tips the crank arm, pushing down on the control valve rod
• which opens the upper port in the control valve to steam and the lower port to exhaust
• That matches the porting diagram shown the other day labelled 'reverse direction' which shows that the upper port with steam connects to the inside of the piston valve, giving it inside admission
• That moves the crankshaft counterclockwise, as viewed from the right front of the engine
• That moves the worm on the crankshaft left as viewed from the front of the engine
• That turns the lower shaft counterclockwise as viewed from the back of the engine
• As the lower shaft turns, the sprocket on it turns as well, pulling the chains on the right and moving the rudder to the right as well
• Which turns the upper outer shaft clockwise as viewed from the back of the engine
• Which makes the control nut forward again
• Which moves the crank arms to pull the valve rod back up to the 'off' position, stopping the engine!

Whee!  As the old textbooks would say, the sequence when the steering wheel is turned to the left is left as an excercise for the reader!   

[RReid]

Whee!  As the old textbooks would say, the sequence when the steering wheel is turned to the left is left as an excercise for the reader! 

That's OK. I'm just auditing this course, and don't have to do the homework!