Slowly casting up parts for a steam twin marine engine

[Artie]

This project has evolved over on HMEM, apologies to the guys who frequent both sites.

Basically my project is a reversing horizontal twin loosely based on My Westburys design, an example, which I believe belongs to Don-tucker over at HMEM.



Mine is destined for a large side wheel paddle steamer called the PS Pevensey which still operates today out of Port Echuca, australia largest inland river port. She will be 7'6" and radio controlled which poses a few issues for a steam engine.



And the scale plans...



The changes to the design are simply making the cylinders level, mounting them on either side of the boiler cover (more on that later) and making the crank a stand alone pylon type with 4 individual pylons, 2 in close next to the throws and 2 out wide as this will a long crank shaft.

I am a caster of metal so it was decided early on to make and cast the components and this thread is my journey so far... yes it would probably have been easier to use billet... but where is the fun in that?

Ill go through this quickly with a few pics per post... to break it up... firstly I have Mr Westburys plans but really dont refer to them much, its all in my head. To make this a sloooow revving engine set Ive increased the bore size from 19mm to 25mm (3/4 to 1 inch).... on with the show!

[Artie]

The cylinders, for a simple item it ended up being quite a complex (and touchy!) cast. The plugs in manufacture....





I hate the wood lathe...scares the hell outta me! A mate, John is doing the dangerous stuff, Ive got the camera..



This was made up of 2 pieces which were screwed together outside the machining area, so when it was parted off it fell apart...



Steam chest mounts and cylinder mount added...

[Artie]

Brass for the cylinders.

Ive never cast brass before so this is a steep learning curve. I decided to do what I know and cast a few in aluminium first to test the casting procedure and also work out the machining steps before I cut into a lovely lump of brass.. ended up casting 4 ali cylinders. before i was happy. Had a bit of sink back due to the larger volume of metal around the steam chest area. Solved that though, used a larger core.



Core mold.... simply split steel tubing...



Cores already baked... these are high clay content sand... ended up using a sugar based core which set harder and darker..



The foundry.. (shes showing off... doesnt normally do this...)



Packing the cope...





Ready to pour...



You will notice that I ve fitted a reducer plate to reduce the volume of the flask (box holding the sand together..), any bigger is wasted effort..

[Artie]

This is what came out of the sand... still smoking hot.....



Here you can see the sinkback that I mentioned on the right cylinder but problem solved on the left one. Its simply moving the holes that the molten metal comes in and goes out (sprues and risers)...

[Artie]

So with the design and procedural stuff out of the way..along came the brass....



It doesnt look very pretty when it emerges from the sand. In fact it looks like it was salvaged from the Titanic....

But use your imagination because this...



Can become this....



And it did, same cylinder a few days apart..... but Im getting ahead of myself here... casting brass.. it actually isnt a lot of fun... I much prefer working with aluminium.... Ali melts at approx 630 degrees celcius, brass at approx 950. I use steel crucibles for this and I have 2, a large volume unit which will pour about 3 litres of melt and a smaller unit of about 1.5 litres. Ive had these since I built the foundry some 26 years ago. Not any more.

The extra 300 or so degrees increases the strain on the equipment enormously, I burnt those two crucibles out in 4 pours and the new unit is looking decidedly second hand already.

I dont think I will do much brass work after this!

[Darren]

Excellent thread, really nice to see the successful casting there 

[Artie]

I have intentions of building another twin at some stage so I ened up casting 5 brass cylinders (1 reject)...



Take a look at the cylinder on the left, this is one month after polishing.... gee that was wasted effort... actually no it wasnt.. I had a blast...

To get to this level I made a mandrel to hold the cylinder, the cylinder was roughly chucked up in the 3 jay, one end faced off and the bore taken to 24.9mm and then mounted on the mandrel. It wasnt taken off the mandrel until its finished. The mandrel was simply taken from lathe to RT in the mill and back when required.

[Darren]

Couldn't you drill and plug the dimple? Be a shame to loose it ..

[Artie]

Hi Darren yeah its been a fun project, more to go though.....

I have one cylinder finished and have left the others in a semi finished state until I have all the components to seal them up (end plates pistons etc).

[Artie]

Do you mean the sink back area? If so that was only a test piece in ali, it was always meant to go back into the pot. It didnt happen in brass which was the whole reason for doing a few test pieces in ali... casting that is really easy (in comparison..)...

[Artie]

Well that was an epic few weeks to get to that point and I must say that Im a little 'over' casting brass so I decided to move onto the next piece on the list, actually it wasnt next but it was aluminium so I moved it up the list to give me a break...

The pedestals for the crank used my CAD system to design them up... thats Cardboard Aided Design... I actually do have Alibre but for simple 2 dimensional stuff this was just too easy..

So using 3mm MDF and building up with atimber we ended up with these....







And straight out of the sand.. (again, still smokin)



Sprues and risers trimmed off...



Further triming but not yet finished, havent machined in the crank journal yet, will wait til I have the 4 of them cast and sized and do them all in 1 pass.

[Artie]

And thats where we stand today, next is the cross head beds in brass and the cylinder end caps also in brass. Crank will be a built up unit and the boiler is a thread in itself as I wish to use this thing in public it needs to be insured against public injury and that means joining the local steam club and buiulding a boiler that conforms to the AMBSC codes (Australian Miniature Boiler Safety Committee).

These are quite onerous and I have already changed from steel to copper in the planning stage.. unfortunately I had already sourced the steel tubing...

Ill update this as I go along.. but it wont be fast due to various commitments..

Cheers all

Artie

[Artie]

A short up date, had a couple of hours to spare today so I cast up the remaining 3 pedestals, actually I cast up 5 as I had a couple of failures. The first 2 had bad sinkback where the outlet sprue joins the top block, the previous 2 were perfect, its raining here and with the high humidity things change when casting. I altered the pour method and sprue locations slightly and all was well, the next 3 were great....



These will have main bearing caps made and mounted and then they will be bored for the crank. I plan on using a D bit reamer to size it (thanks Blogs) and shim if necessary (im hoping not).

Once rough sized these will all be clamped together and final machining will occur as a unit.

If anyone has any questions or suggestions to help improve the process, please fire away!

[Rob.Wilson]

Very nice Rob  great to see 

Keep it coming 


Cheers Rob

[Artie]

Thanks Rob, Ill be away working for a week so wont be able to touch it until I get back... I think I may need a tiny collapsible mill I can fit in the boot of my car. Im itching to size these things up and a week is a long time without a metal munching fix.... 

[Bernd]

Artie,

Nice thread you have going here. I like the casting bit. I started a Gingery foundry many years ago. Just melted some ali and poured into ingots. That's all I've ever done.

A few questions about pouring brass. What do you use for ingots? Any old scrap brass or do you use a know alloy? Do you add tin to the melt before pouring? I hear that the tin boils out as the melt gets near pouring heat.

In quiring minds need to know. 

Bernd

[Dean W]

Oh, this is some very impressive work, Artie.  Very interesting from my end, the way you are doing things here. 
From the looks of things, have you been doing this for a while? 
It's the last bit of voodoo that lets the home shop guy be completely independent from design and material shape requirements.
Top job!  Thanks for the pictures and explanations!

Dean.

[Artie]

Artie,
What do you use for ingots? Any old scrap brass or do you use a know alloy? Do you add tin to the melt before pouring? I hear that the tin boils out as the melt gets near pouring heat.

In quiring minds need to know.  

Bernd

Hi Bernd I use scrap items and ingot them ahead of time. Brass is really cruddy material and makes a huge amount of dross due to the tarnish which builds up quckly, therefore im not mucking around trying to remove crap during a stressfull pour, same with aluminium, its all turned into ingots before I need it.

Its zinc which burns out of the brass, but if you are gentle and dont overheat it too much it wont be an issue. Incidentally try not to breath the fumes which come out of the foundry when melting brass, you will end up with the zinc shakes...not nice im told...

Glad you have found it of interest...

Hi Dean yeah had the foundry for near on 26 years now, it was put away for many years while I raised a family...same old story. Got it out a few years ago and got back into it. Having a blast, and you are correct in that ANY size of stock I need I can have within an hour or so... as well as the casting of items such as the pedestals.

Cheers Artie

[Bernd]

Thanks Artie. I've heard about the fumes.

Bernd

[Artie]

Just a little more, been away working for the last week so keen to at least achieve something. I need beds for the cross heads and end plates for the cylinders. I could just buy the stock for these but I doubt if anyone keeps the required size in town and if it was ordered it would cost a fair bit. So I cast them up. Nothing special, basically holes in the sand. A flat piece of pine for the beds and caps off spray cans for the end plates.

The beds were cast on end, so I put in a pour hole to allow any gases to escape without bubbling the molten metal. I also cast this just over the brass melt point, I think I have learnt something today, dont get brass too hot, if you go back and look at the finish of the first piece of brass that I cat, this is heaps better... heat may be the issue..

Cost about $3 in gas and about 1 hour, scrap brass I get for nothing from a friend who has heaps of it.

[Artie]

A quick shop session tonight, not much to show for it, one cross head bed almost done and one plate roughly sized up.... amazes me sometimes how slow I can be in the shop.

I was discussing with a mate recently about this... he was about to cut a gear on the shaper.. but he had to build a table extension first, scratch one full day.... hadnt even began to cut the gear at that point.... ended up with an exceptional result though..

I had a fun time with my fly cutter, just wasnt happening right.... after much fussing I reground the apparently sharp cutter.. bingo.

ok ok pics... sorry about the fuzzies, picking up replacement camera tomorrow... this one stopped focussing... best I could get tonight...





And for those who are interested, this is Isis, shes and a Centralian Python (aussie sheila) and about 2 years old and 3 feet long. She lives in the kitchen and watches us with very hungry eyes... im glad shes not bigger... (belongs to my daughter who has just moved back home.... ah well...)



Again, sorry bout the blurries.... all good tomorrow!

Rob

[Artie]

Howdy guys, cameras back on line (finally) and I have a little progress to report. I did say alittle progress. Seems that work keeps getting in the way of late...

The last pics showed the crosshead beds in rough form, these are now almost finished with the studs to be drilled and fitted and the oiler cups to be made. Also have the bosses to make and silver solder to the slide plates for the piston rod and conrod little end.

Studs and nuts (4BA) where ordered last week but still havent arrived as yet. Ill put these aside til they do and move onto the cylinder end plates





You may remember these being these not so long ago...



You ever have one of those days? Went to the shelf to grab the strips to retain the slider. These are 10mm by 3mm strapping. Cant find it...anywhere. I dont think I used it for anything. Ok zip down to the hardware store where I bought it as the shops are still open.... nada... out of stock. Only one thing for it....






Damn... did that take some time....

Also got the pedestals roughed up, all critical sizes are done, now just got to 'pretty' them up 



Thaz it fer now.... until the nex instalment.. Cheers  Artie

[Dean W]

Hi Artie;
You mention "not much done" a time or two, but from someone who doesn't know casting (me), it looks like a lot!
It's become quite an impressive project already.  I'm enjoying your thread, that's for sure.
Thanks for the write-up and all the pics!

Dean

[Artie]

Lots of holes drilled, tapped and square with NO breakages .... pilot driver works beautifully. One part down, dozens to go....

[Artie]

It needed oilers! So it got em....





Got another job, this is a little adapter set for a hoist, for higher cars like 4 wheel drives. A short set and a longer set.... a mates doing the cutting and creating LARGE swarf.... kinda cool....