Slowly casting up parts for a steam twin marine engine

[Artie]

A shot to help with scale. This is a little larger than you typically see around here.



Cheers

Rob

[Bernd]

Very nice Rob. 

That's going to be some machine judging from the size of that crank check in your hand.

Bernd

[Artie]

Yes Bend, it certainly is. I am hoping its an impressive unit whn operating. thats why its being made to easily remove and bench run. I wanna see it! Sadly its buried in the superstructure of the boat with a fairly small viewing area.

Also would be hard to display the boat indoors as its a full 7' 6" long.

Cheers

Rob t

[Bernd]

Yes Bend, it certainly is. I am hoping its an impressive unit whn operating. thats why its being made to easily remove and bench run. I wanna see it! Sadly its buried in the superstructure of the boat with a fairly small viewing area.

Also would be hard to display the boat indoors as its a full 7' 6" long.

Cheers

Rob t

I should have gone back and looked at the size of the boat. That would have told me the story. 

I'm just follwoing to many projects to remember if I follwed everyone as it progresses.

Bernd

[Rob.Wilson]

Hi Rob 

7' 6" long     thats some size craft 

Cheers Rob

[Artie]

Yeah Bernd, I do know what you are saying... som much to do ...so little time...

Rob W.. yeah...its a little like Aus...everything is bigger..... 

Im at somewhat of a crossroads right now... I need the boiler to be in place to go on. While im doing this there area few other bits I can do but most is reliant upon this.

Decision decisions... I have materials for both a steel and a copper boiler... so far I have swayed back and forth about 2475 times... each has its advantages and disadvantages....

Right now Im thinking copper...

Mainly because I can silver solder it myself, whereas a steel unit requires a certified boiler maker to weld it. The drawn (seamless) steel tubing I have is a little too large for the engine aesthetically and the codes requirements for the construction of a copper boiler are a whole lot less onerous as this size tubing falls into the subminiature category where as the steel size is in the miniature category.

The drawbacks of the copper are that it is a fairly small capacity and will require topping up for any extended periods of running unless I build the pump Edgar W, lists in his plans. I am making provision for this by building the eccentic onto the crank. It wont be accessible afterwards and I dont really want to do a split eccentic.

The capacity of teh steel boiler is what is making me keep coming back to it (therefore the simplicity....ie no pump or water reservoir in the hull).

However..copper it is... I think.....

A couple of pics of the mock up I have been fiddling with to determine the 'looks' of the unit..... ignore the timber blocks...

Copper...(verdis and all!)... the copper boiler is a little small in looks and this will allow me to put a cover over it with teh scale details added and this will also act as an insulator retaining the heat to a degree and increasing it efficiency..





Steel...





Copper copper copper...

Just FYI, subminiature regs require the boiler to be 75mm dia or less, 1000cc capacity or less and an operating pressure of up to 75psi. The premise is that these 'little' boilers wont have the capacity to be used in trains which can tow passengers or an engineer..therefore they wont be in extremely close proximity to persons when they explode... (thats my extrapolation.. ).

Therefore they are a lot simpler to build...


Cheers Rob

[Rob.Wilson]

HI Rob 


I like the arangment of the engine room , with the cylinders either side of the boiler  , any chance of a shot of that part of the drawings ,,,,,,,,thats  if it ok to do that .

Will you be doing a casting for the bed plate ,to mount the cylinders and cross head guides ?   


Cheers Rob W

[Artie]

Hi Rob, sorry for the tardy reply, been away again.

Bed plate, really hadnt thought about that component yet. Have now... I was going to use the sheet in the picture to mount it all up and do the cast plate IF that wasnt satisfactory..... but..... now  am thinking that the sheet has NO place in the company of so many cast or scratch built components.... cast it is... and soon.......

Cheers

Rob T

[Rob.Wilson]

Hi Rob  

cast bed plate would be a very nice touch , like you say you already have alot of very nice cast parts  ,IMO would be a shame to mount them on a plain plate

So whats it to be copper or steel ?  

Regards Rob W

[Artie]

I like the arangment of the engine room , with the cylinders either side of the boiler  , any chance of a shot of that part of the drawings ,,,,,,,,thats  if it ok to do that .

 Hi Rob, back home again, mate there really isnt a lot of corellation with regards to the 'plans' and the engine Im building. I started this thing with basic dimensions from Edgar Westburys engine, an example can be seen here:



So you can see Ive deviated greatly from the engine. Actually Ive vaguely replicated what the boat has and found a plan set that will supply the technical data I needed...thank you Mr Westbury.

Ive turned the configuration around, my valve gear is 'outside' the conrod. I figured that this 'needed' to be seen, why hide it away?

As before, been away for work so not much progress..... lets see if I can get some shop time this week.

Cheers

Rob T

[Artie]

And its copper.... 

[Rob.Wilson]

Hi Rob 

Good to see you back ,,,,,real pain in the butt when work gets in the way  ,,,,,,,,, So the engine is of your design      ,,,,,,, Lookin Great 

Regards Rob

[Artie]

Hi Rob, its all good, I count my blessings when  have 'too much' work, some of our mates on here dont have work.


A little update, not too much, decided to try out Bogs (thanks John) d bit reamer design. Its my first ever attempt at such a tool so it was a learning curve and fun. The fact that it was a success is also a bonus.





I took the shot with the refection on purpose... that was a test piece and the finish was extraordinary. Worked a charm. reamed the brass conrods out and then did the crank cheeks. I used a product over here called bright steel, simply a slightly better quality mild steel rod. Sized it up and used a hardening compound called Hardite. This is a tin we got from the fellow who owned the workshop before I and my partner bought it. It was ancient then and that was back in 1985.

Anyway, the resultant case hardening was ok for the brass but not quite good enough fopr the steel. It did the job but I had to resharpen the tool after each hole. I call this a success and the holes are damned accurate....

Also decided to add a little more detail to the conrods and milled the centres out by 2 mm leaving a centre thickness of 2mm (overall was 6mm)









Now just got to do a little sanding and filing to remove the tool marks. I used the ball nosed cutter for the entire process but I realy should have profiled the sides then changed to an end mill to remove the centre material. It left a lot of small marks which now need removing (see pics).
I like the 'real engine' effect and its certainly only bling detail... but i enjoyed myself.....

Until next installment...

Rob

[Dean W]

Hi Rob;
Things are getting along well for your build.  Looks like the D bit did the trick.  I like those things.  They'll sure get you out of
a pinch for odd sized tooling.
That case hardening product you used must work pretty well if it let you cut steel with a mild steel cutter! 

Thanks for he update.  Glad you've got some work!

Dean

[Artie]

Hi Dean, yes Im a fan of these, I have a set of adjustable reamers so this was an experiment in 'can I do this', happily I can and now have a whole new skill set.

The product is called Hardite as I said, its very old and requires the steel to be heated cherry red and dipped into the powder which melts and boils around the bar. According to the side of the can the hardness you require is in proportion to how often you repeat the above process. I assume this is within reason.... this bar can only get so hard I am assuming.

This is a description for this steel from a supplier here in Aus, Atlas Metals... its a lot better than your average mild cold rolled.

"Bright steel bars are carbon steel which has had the surface condition improved over the hot rolled finish supplied by the steel mill. Advantages achieved include improved machinability, enhancement of physical and mechanical properties and improved dimensional tolerances and straightness."

Im on the lookout for drill rod over here but none of the suppliers I contacted knew of it. We have a Carbon steel, Silver steel and an Alloy steel available, I wonder if its any of these... anyone know?

Rob

[sbwhart]

Rob

Drill rod as called in the US is the same stuff we call silver steel in the UK so I would imagine the silver steel you've located is drill rod this can be hardened.

Stew

[Artie]

Hey all, Im alive, no..... I know..... you didnt miss me....story of my life 

Havent had a lot of engine time for a variety of reasons. What time I have had has been making tooling and learning to operate the shaper, (love the shaper...  ).

Today I waved goodbye to lawns, painting, fence repair, car washing, travel and headed down to the shed...... its MY time......

What I have had is time to think about the parts which are next on the list.... eccentric sheaves and rods for the valve gear.

Ive decided not to use Edgar T Westburys design on this one for a couple of reasons, the main issue was the complexity. I think this thing could be made better, simpler.... remember im using the design as inspiration for my own engine.... Im not producing the engine verbatim....

Ive decided to make the valve gear rods in one piece instead of three piece as per the plans. Im splitting the eccentric sheave to allow this, as per the pics that follow.... the eccentics.... (4 of)...



These are one piece by the plans so Ive used a removeable side plate held in place by three screws. This allows the rod to be a one piece unit with no removeable big end cap and as this is only 4mm wide... that would make it unecessarily fiddly...(IMO)



Im a great believer in simplicity and I dont like complex items for complexity's sake.... not saying thats Edgar's reasoning... I just think I have found another way that suits me.



So, by making this item with a removeable side plate...



I can make this item in one piece and less complex....







Hopefully tomorrow is the one piece valve rods (4 of), if I can get those done Ill be more than happy....

Its nice to be back... had a ball in the shop today... By the way...its amazing how much time lil parts can take to make.......

[Artie]

I should mention that I can do this because Ive turned the engine inside out... that is, the eccentric sheaves and valve rods are are outside the con rods, unlike the  original design which has these hidden away in the centre of the engine.

In this way the one piece valve rods can be threaded onto the crankshaft and then onto the sheaves where as in the plans they MUST be the 3 piece design to allow assemby.

In my opinion, these reciprocating moving items are part of the mystique which makes these engines almost hypnotic.... why hide this detail away inside the frames?

Cheers again

Rob T 

[gingerneer]

I like the idea for the eccentrics. Its some thing that i could work in to the engine that i am building.

William

[Rob.Wilson]

Lookin good Rob 

Wondered what you had been up to 


Rob.W

[Artie]

Hi all, the eccentrics are finished and pictured here mounted on a piece of the rod to be used for the crank. Some finishing required to remove fine burs and smooth/polish it all out. A 4mm grub screw locks them to the shaft. I had to make a new tap holder for the tapping tool as this size tap had a larger shaft than the first 4BA tap (see here http://madmodder.net/index.php?topic=2929.0).

I didnt take pics but the first eccentric took 45 mins (make tool etc) and the rest took only 10 mins each to finish. This entailed, mill flat, change tool for drill, then change again for tap pilot. This ensured that the alignment didnt alter. So I had to do this whole process 4 times.

This required setting the eccentric to its required orientation, mill a small flat at 4mm, then drill to 3.2mm and the tap in the holder to 4mm by 0.75mm pitch.



I am making the crank in two parts with a joiner in the centre. This was decided when I wasnt sure whether to use the water pump which Edgar T describes as possibly necessary for his design. This requires an eccentric sheave much the same as those for the valve gear mounted at the centre of the crank. If my crank is one piece it must be added now. If two piece I can add it later if necessary.

Therefore I need a joiner. I am also making the shaft that mounts the paddle wheels as as seperate units and these will run on bearing blocks mounted in the hull. These joiners will allow shock reduction (not necessary) but more importantly are flexible and will allow misalignment if I happen to build some in unwittingly.

You can see how these will look once done. These will be mounted to a one piece shaft as seen here, some release agent will be used to coat the shaft and then RTV silicone injected into the gaps and smoothed out. Once set this will supply a flexible one piece joiner.







I had the RT mounted on the mill and the 4 jaw on it. A shaft is centred in this and the aluminium blanks are tapped with grub screws and mounted on this shaft.  A 3mm end mill used to machine most of the material away to leave 4 'blades' which fit into corresponding blades on the mating piece.

I was going to be moving onto the rods which mount on the sheaves (eccentrics) but decided to stray... hence the joiners today.

Until next time... cheers all....

Robt T

[Artie]

I finished the flexible couplings last night and a couple of pics to show how they turned out....

I used wax as a release agent and alos cleaned everything with brake cleaning chemicals. Stuff is aggressive as hell but removes all oils and greases. Then positioned everything ont he shafts and lightly nipped up the retaining screws, injected the rtv silicon and smothed over with a wet finger.. the crank webs make great holding jigs...







And now set.. will leave in shaft for a few days to ensure its as strong as possible.

[Stilldrillin]

Really enjoying this build Rob. 

Love your flexi couplings. Well done! 

David D

[Artie]

Thanks Dave, Im really happy with the result.... and I should mention that I machined the aluminium rod up from a piece I had cast up some tiem ago. No pin holes nice and smooth to machine... this is that 6061 that I got as scrap fire extinguishers..... truly rolling my own..... I got the idea from the rear wheel of my Ducati when taking it off to change a tyre... cush drive? ..... mmmm.......



Tonight I had a play with the crankshaft... remember this will have one of these couplings in the centre as well so this is assembled way too wide and Ill cut it down to suit when Im ready to do so....

Progress.....





This is lightly pressed together, not enough to ensure it wont move though, so ...... do I drill tap and fit grub screws (leaning that way, makes it dismantleable for whatever reason)? Or do I silver solder? If I solder Im going to have to relieve the fit so the solder can penetrate....

I am after advice here folks.... thanks in advance.....

Cheers Rob T

[Artie]

A brief pic...just to prove that the wax worked as a release agent.... as I had hoped.... relieved..... these seem strong and quite flexible.. Ive pulled bent twisted them.... Ive have started to think that they may well work... never in doubt.....





Next couple of weeks are they travel/work cycle... Ill be quiet for a while..... until I get back...

Cheers Rt