Author Topic: Green Twin Oscillator Cast/Build  (Read 24143 times)

MetalCaster

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Green Twin Oscillator Cast/Build
« on: July 27, 2013, 04:27:07 PM »
A little history about how I got into model building, and my approach to the same.
I have had a lifelong interest in steam engines, and build my first one as a 12th grade science project, along with a boiler that was about 18" dia, 36" tall, vertical fire tube type with injector.

Life has been busy since 12th grade, and I always had the intention of getting back to building steam engines and boilers.

My dad got into the modeling hobby about 2001, and build a ludicrous number of model steam and hot air engines, and some full sized ones too.
My intention was always to get with dad and build some models too, but again it was not to be.

About 2002, I was working as an engineer at a large firm, and a very ambitions and rather ruthless junior engineer pulled some corporate political strings, pushed out the head of our department, took over, and then fired the entire department to "clean the slate" and install his own loyal people.
He lasted about a year at that business, and then quit and took "his people" with him to start his own firm.

I decided that the old adage "Fool me once, shame on you, fool me twice, shame on me" was something I had to adhere to, so in 2003 I started my own consulting engineering business, and have been running it as a one-man operation ever since.
While the last few years have been nothing short of brutal, and one man in his own firm has to wear a lot of hats (I am the janitor, secretary, financial planner, marketer, draftsman, designer, you name it, I do it), there are some redeeming things about working for yourself, such as the fact that I have been the "employee of the month" every single month going on 11 years now.

My dad died in 2006, and so I accumulated his machine tools and shop equipment.
Building models seemed rather rudimentary to me, after all, dad made so many, and made it look so easy.
But it was anything but rudimentary.  I realized I was floundering in 2009 after getting the shop and equipment set up, so I discovered online model building forums, and began the process of learning how to machine engines from bar stock.

Several things became evident very quickly, which were 1. I sucked at machining.  2. Machining can be extremely tedious and boring for someone like me with a short attention span.  3. Machining engines from bar stock generally required machining anywhere from 50% to 90% of the metal off into chips which fall on the floor and fly in every direction, and have to be cleaned up daily.

I was bound and determined to make the brute-force method work for me, and so I drew a couple of my dad's engines in 2D CAD, and set about to build copies of them.
After a year or so of what seemed like banging my head against the wall, I decided there must be another way.

Offline awemawson

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Re: Green Twin Oscillator Cast/Build
« Reply #1 on: July 27, 2013, 04:37:37 PM »
And the "Green Twin Oscillator Cast/Build " ??????????????????????????
Andrew Mawson
East Sussex

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #2 on: July 27, 2013, 04:39:52 PM »
Several things became apparent at this time.
1. Too much metal was being wasted to get the part into the shape I wanted.
2. Too many tool bits were being worn out to make the parts.
3. The parts never really assumed the shape/appearance that I wanted them to have.

My dad had lamented that if he had enough space, he would have cast his engines.
I really did not have the space either, but I considered getting into castings.

Then I ran across Rob Wilson's work, got the 3D bug, and then discovered that with 3D, I could visually see the engine, as well as assemble the parts, and check for alignment, fit, and actually run the engine virtually.

So I decided to give the casting thing a go.
I tried a charcoal melt, to no avail, and then purchased a propane burner.
I melted aluminum first, and had pretty good success with that for a beginner.
I found a casting forum and leaned heavily on the information found there and in videos online, many by members here.
My funace design comes directly from Rob Wilson's (thanks again Rob).

You may ask, why does my furnace look so shabby, when Rob's looks superb?
Well, I quickly realized that while my interests in self-discovery are high, my time and money are limited, and I am no spring chicken, I only have a limited amount of time to make a go of the casting thing.
So my method has been to use the information available on the internet to maximum advantage to hone in quickly on workable (granded ugly) furnace, burner, equipment, etc.
Trade-off's don't bother me as long as the focus is on the final product, and so that has been my approach.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #3 on: July 27, 2013, 04:40:37 PM »
And the "Green Twin Oscillator Cast/Build " ??????????????????????????

I got to have a lead-up to the story of the green twin.
I will get there shortly.

Chafing at the bit are we?

Edit:
I attended a concert one time and the musician came out and began talking incessantly, and finally someone yelled "Are you daft man, stop yammering and get on with the show", and he said "righto", and the show began without further ado.
« Last Edit: July 27, 2013, 05:13:38 PM by MetalCaster »

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #4 on: July 27, 2013, 04:44:15 PM »
So then one day, I was doing a group build on another forum, and a guy says "I am going to build a green twin oscillator" that I saw on Preston's services.

So he designed on it for a while, and I offered some ideas/suggestions, and it got complicated, and not wanting to see it all go by the wayside, I jumped into the design.

Luckily my wife was gracious enough to give up her two-car garage and half the driveway, and without even divorcing me (yet).

So I started in earnest on the green twin, and about a year and a half ago, I got the mother of all work projects, and all work on the green twin ground to a halt.
I am just getting to the point of catching up at work to begin on the twin again.

So here is where I left off with the green twin.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #5 on: July 27, 2013, 04:50:30 PM »
The design was eyeballed from the Preson Services photo, and turned out like this:

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #6 on: July 27, 2013, 04:55:02 PM »
I tried my hand at making a pattern for the flywheel, but my equipment and pattern making skills were just not ready for that.
A 3D print was dispatched, and it looked like this, made from the 3D design, and printed with the appropriate oversize for shrinkage.

Offline doubleboost

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Re: Green Twin Oscillator Cast/Build
« Reply #7 on: July 27, 2013, 04:59:21 PM »
You have my attention
Get on with it :lol: :lol: :lol: :lol: :lol: :lol:

John

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #8 on: July 27, 2013, 05:00:45 PM »
I was certain I could make the pattern for the base of the engine, and so I begain building one from balsa.
The first pattern went rather badly, and so I had to redouble my efforts and really pay attention to detail.

Here is my second attempt at the base pattern.

It is a hybrid affair with some of it printed in 3D and some of it made from balsa.
It was a parallel effort by two of us (the guy who originally decided he wanted to model the engine and myself).

I was quite proud of this group-effort, and all seemed to be going fine..............
(Note:  If you ever think things are going fine, just wait a little while and things will change.)


MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #9 on: July 27, 2013, 05:06:12 PM »
And the cylinder and some of the other parts were printed in various places around the world, and shipped in.

The best 3D print was the flywheel, but I did not have to pay for that one.
The cylinder and some of the other parts were made on an inferior 3D printer, and so lots of extra work to finish them (an ongoing process).


MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #10 on: July 27, 2013, 05:12:57 PM »
I started trying to learn all the strange new terms required for casting, such as cope, drag, sprue, runner, gate, shrinkage allowance, machining allowance, ect. etc.


I tried to melt cast iron with propane as I had seen Rob do, but no luck with that.
I had to find a better burner, and without the problems of vaporization of the propane tank.
I started playing around with kerosene and a paint sprayer, blowing huge flames across the driveway much to my wife and the neighbor's horror.

I built a very ugly but well functioning furnace, and build an oil burner from a cutting torch tip.
The cutting torch burner worked well, but required a heck of a lot of compressed air for atomization.

Then I ran across a Delavan siphon nozzle, and made a great duel-fuel (propane-oil) burner which melts cast iron like butter.

The cope/drag thing and moulding in general was very confusing, and I confess I hardly had a clue as to what I was trying to do other than fill the mould with molten metal.
Here is an early attempt at a cope/drage layout.  I would probably do it different now.
This is before I read the "Basic Gates and Risering" book.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #11 on: July 27, 2013, 05:34:40 PM »
One very critical casting term that I was aware of, but an idea that was further impressed upon me as I progressed was the all critical "draft angle".

Not a more important term in casting than that (in my humble opinion).

I attempted to cast the base in aluminum, and had a lot of trouble with the lower mould breaking off (the part that protrudes up into the bottom of the base).
I finally used a sodium silicate core in the drag, and petrobond in the cope.

But who would dream that you have to put weights on top of your flask to counteract the hydraulic forces, and so while I was on track for an excellent cast, the mould blew out, and the casting was ruined.

The sand used for the core was too coarse, and so the finish underneath was terrible.

I have made several other attempts at casting the base, using various sand types, mixtures, grain sizes, mould layouts, etc. and each has been a failure for one reason or another.  A good learning experience though, and I think I have the issues sorted out.


MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #12 on: July 27, 2013, 05:39:37 PM »
Another attempt at the base.

Not a bad attempt, but poured too slow with too small a sprue, and aluminum too cold.

The finish was better on the bottom.

Was still trying to zero in on pour temps, gating/risering, and numerous other things.

Offline tekfab

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Re: Green Twin Oscillator Cast/Build
« Reply #13 on: July 27, 2013, 05:41:25 PM »
Sorry to interrupt, what size of delevan nozzle did you use ?

Mike

PS Good stuff !

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #14 on: July 27, 2013, 05:44:41 PM »
This is a third attempt at pouring the base.

My Petrobond was getting a bit dry, so I mulled some 30 weight non-detergent oil into it (too much oil), and started getting erosion as the sand/oil mix failed.

This casting is probably usable, but I will save it and try to improve upon it.


MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #15 on: July 27, 2013, 05:51:30 PM »
I used the largest size, which is 1 gal/hr, but don't be fooled, with 15 or 20 psi for atomization, and 5psi on the fuel tank, you can move 4 gal/hr or more.

I will post my sketches on the siphon-nozzle burner,  use at your own risk.
I assume no responsibility for anyone's use or misuse of this information.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #16 on: July 27, 2013, 05:57:36 PM »
And one more page for the siphon burner, and some photos of the setup.

Sorry for the general messyness of my shop/driveway/equipment, etc, you will never see RobWilson-like quality in my equipment or setups, but hopefully I can make up for that in what I make (attempt to make).

The burner below is my first attempt with a welding tip nozzle, made in a single afternoon.

For me, it makes little sense to build a lot of quality into a piece of equipment that is experimental in nature, and has a high chance of not working.
Hopefully I can slow down and put a little more quality into the equipment once I get the basics figured out.
« Last Edit: July 27, 2013, 06:29:36 PM by MetalCaster »

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #17 on: July 27, 2013, 06:03:17 PM »
This is the Delavan siphon-nozzle burner used with a pressurized fuel tank (5 psi using an aquarium pump for safety and to prevent overpressure on the fuel tank, it does not take much pressure on the fuel tank at all, but too much will result in disaster).

It starts on propane outside the furnace, and then you can change it to diesel in a few seconds.

I simplified the tubulator (spin vane) upon a recommendation from someone on another forum, and used a simple sheet metal unit.

The first photos are starting the burner on propane out of the furnace (a test in the shop;  don't try this in your shop for carbon monoxide and other hazardous reasons).

Note:  The Delavan nozzle has an o-ring inside of it, and this item is cooled by the fuel flowing through the nozzle, as well as by the combustion air flow, but you should turn off the burner and pull it away from the furnace immediately after you turn it off to avoid overheating and ruining the o-ring.
« Last Edit: July 27, 2013, 08:52:00 PM by MetalCaster »

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #18 on: July 27, 2013, 06:14:00 PM »
And the Delavan burner up to speed.

Video here:

(How about that beer gut, and I don't even drink beer; can't due to celiacs).
In the video, the burner has been started with propane only, no combustion air, then a little bit of diesel is turned on, then a little bit of compressed atomization air, then immediately turn off the propane and leave it off, then turn on more compressed air, then more diesel. and finally full compressed air.

You will have to play aournd with this sequence and perhaps get the furnace hot on just diesel and some compressed air before you turn on your combustion air blower (I use a pour-man's blower, which is the output of my shop vac).

Under no circumstances should you ever use the propane other than for a minute or so during the initial start.
I am guessing you could make this a propane-only burner, but I have not looked at that yet, and don't like the vapor-pressure cold propane tank problems that generally are caused by high propane flow.

The 5psi pressure on the fuel tank makes the burner output constant regardless of fuel tank position, elevation, or fuel level changes in the tank.
So the burner is operated at a slight (5psi) fuel pressure, not really a siphon pressure.
The burner works fine as a siphon unit only with the exception of irregular output as the fuel level drops in the tank.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #19 on: July 27, 2013, 06:17:28 PM »
I had seen others melt cast iron online, and they make it look so simple.
The first time I tested my new siphon burner with my furnace, I was sure it would work well.

After 3 hours of red hot but very solid cast iron (not the slightest hint of liquid iron) wasting 4 gallons of diesel fuel, and endless fiddling about with adjustments, I was cursing the casting gods and Rob Wilson (not necessarily in that order) for getting me into such a mess.  (Sorry Rob, I take it all back now that things are working).
My wife politely excused herself to go run some much needed "errands", code name "he is pissed, I better slip out for a bit".

In one final act of desperation, I turned on 100% oil, compressed air, combustion air, and sealed the burner tube to the furnace entry hole.
I fully expected the burner to extinguish itself with so much input, but low and behold, the cast iron began to melt very quickly.
The neighbors wondered what all the shouting was all about, but the first cast iron melt is a big deal (Routine for some perhaps, but a very big deal for me anyway).
I had the high-five myself since the wife was away shopping. (Edit, my wife reminded me that she was actually there, so I guess my memory is not so good).

So I poured the flywheel using Petrobond for the mould.
Little did I know that Petrobond does not really like cast iron temperatures, and so some of the mould failed, but the pour was successful enough to verify that I could melt and pour iron.

I used big honking weights on top the flask to keep the mould from rupturing.
I need to add a band around the top of my furnace to keep the refractory from cracking, that furnace was made from a cut-up 55 gallon drum what was welded back together Frankenstein-style, with more than a few gaffs and pitfalls in the construction prcess.  It does work though; maybe the next furnace will be pretty.

In the last photo with the furnace lid open, the burner is running flat out, and without a hint of smoke, so the combustion is very complete.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #20 on: July 27, 2013, 06:27:26 PM »
A seemingly maze of hoses for the burner, but well worth the trouble to get such performance.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #21 on: July 27, 2013, 06:33:07 PM »
This cast iron pour was the flywheel for the green twin.

The sprue, runners, gates, etc. are very sloppy and not necessarily the way they should be optimally, but I did not expect a successful pour anyway, it was all just to see if I could actually melt gray cast iron.

The surface finish varied a bit from top to bottom, not sure what that was about, and I can't remember which surface was better, maybe it is apparent in the photos.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #22 on: July 27, 2013, 06:34:57 PM »
And here is the machined rim face.

Not too bad other than the sand inclusions on the back, which I think is a problem that can easily be resolved by not using Petrobond.

And better than I thought I would get for a first attempt at iron.

No hard spots, surface easily cut with carbide bit, no hard inclusions.
The 100 dollar question will be "can I repeat this?".

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #23 on: July 27, 2013, 06:42:14 PM »
The local metal museum uses both water and resin-based self-hardening sand systems, with a manufactured fine round grain sand.

I decided to try the manufactured sand and the resin system.  The resin system has fumes that you do not want to breathe for any reason.

So this is as far as I got, and I can't even remember how long ago this was, perhaps a year or more, when the big work project started and the green twin project came to a screeching halt.

Hopefully we can get this project underway very soon, and stop taking about casting, and actually cast some metal.

Below is the river sand available in abundance around here, and the lighter colored manufactured sand.
The fine sand and binder system will require careful venting, since the permeability of the sand/binder mix will be low.
The local metal museum used this sand and binder with great success, so I have full confidence in it once I get through the learning curve.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #24 on: July 27, 2013, 06:50:17 PM »
And a cupolet cast iron pour at the local metal museum a few weeks ago.

The iron was really flying, it was very interesting to watch.
They have guys working there who use to work in foundries, and I pick those guys brains every chance I get, its an invaluable resource.

Videos here:






They poured several hundred pounds of cast iron the other day at the museum.
All using old radiator material.
No sign of gassing in any of the castings.

They do use an additive, but that is to add fluidity to the pour, since all their work is ornamental in nature.
I need machinability above all else, so I don't use any additive, but I did not have any problems with fluidity.

I think the ladels they are are insulating, since they seemed to stand around using the aditive, stirring, and skimming for a long time before pouring, and still the metal pours like ice tea.

Well, until I can get out and cast again, that is all I have for now.
Happy casting folks.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #25 on: July 27, 2013, 07:04:38 PM »
And did I mention that if you get too excited and open your petrobond-rammed flask too soon after pouring cast iron, the cloud of smoke that is generated will burst into flames and singe off most of your eyebrows (the excitement was suppose to be over, so no face mask).

Well, it will.
Lesson learned.

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #26 on: July 27, 2013, 10:11:51 PM »
So far, my gating and risering have been rather crude, and as someone mentioned, you don't need a very sophisticated gate and riser system for models, but I do have some larger castings in mind, as well as some match plate work I want to do, so it is important for me to try and understand how to get a functioning system.

I heard from one casting kit guy who had his match plate sent back to him from the factory because it would not pour right, and he had to rework the runners on his match plate and send it back to the factory a second time.

I have studied the Navy Foundry Manual, the Gates and Risering book, and several other old casting books.

The methods are as varied as species of dogs, but what I am after is a relatively simple gate and risering system that serves the intended purpose, ie: prevent air aspiration in the sprue, reduce turbulence to a minimum using a sprue basin and tapered runners (too much turbulence and pouring too fast can entrain air in the melt), provide a dead end to trap lose sand, tapered gates above the runner to provide a maximum of slag skimming, provide equal pressure at each gate by varying the size of the runner (if necessary for larger castings), provide risers where required for shrinkage control, install gates located at the largest part of the casting, if necessary usee some form of solidification control like a cold shunt, or at least be aware of potential solidification problems which can crack your casting in half, and venting the air and if using water-based sand, steam from the core and mould.

Here is what I have so far for a disk shape such as a flywheel.
Have not tried it yet, but am working in that direction.
« Last Edit: July 28, 2013, 04:14:01 PM by MetalCaster »

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #27 on: July 27, 2013, 10:20:03 PM »
They have mould-filling computer simulation programs now which allow simulation of various mould, gate and risering configurations.

While I don't need the program, it is important for me to be able to visualize metal flow, temperature gradients etc. so at least I can think in terms of what is happening in the mould.



The video mentions that if you try and fill a mould too fast, the air and or steam may not have time to escape, and also filling the mould too fast can cause too much turbulence, and entrain air.

And this video is amusing, since this is the mistake I made, no weights on top the flask.
And it is hilarious, some guy asks "what kind of sand is that?".  The guy answers "petrobond", but it is just a simulation, there isn't any real sand.  Its just pixels on a computer screen.   :lol:

« Last Edit: July 27, 2013, 11:13:26 PM by MetalCaster »

Offline Jasonb

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Re: Green Twin Oscillator Cast/Build
« Reply #28 on: July 28, 2013, 02:38:08 AM »
Good to see you back on this one Pat, look forward to seing some more progress now we are upto date.

J

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #29 on: July 28, 2013, 12:12:09 PM »
Thanks Jason-

It is time to do some more castings.

Pat J

Edit:  This engine really does not seem to draw much interest here.  Maybe its all been seen before, or too long winded, or just no interest in steam, not sure.
« Last Edit: July 28, 2013, 02:48:42 PM by MetalCaster »

Offline dvbydt

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Re: Green Twin Oscillator Cast/Build
« Reply #30 on: July 28, 2013, 02:41:56 PM »
Good luck with this project, I envy your ability to think BIG. That same engine inspired my little engine that I detailed here:-
http://www.homemodelenginemachinist.com/f31/twin-d-oscillator-12744/

Ian

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #31 on: July 28, 2013, 02:52:13 PM »
Thanks Ian-

Your build looks great, nice engine.

My wife complains sometimes that I have to do everything on a big scale, but for me big is a 12 foot flywheel.

I have had serious conversation with my buddy and co-contributor on this engine about building it full size with a 12" dia. flywheel.

But I need to get this 1/2 size one done first.
Crawl before you walk, walk before you run, as they say.

Offline NickG

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Re: Green Twin Oscillator Cast/Build
« Reply #32 on: July 28, 2013, 02:59:56 PM »
Pat that looks a nice design of oscillator. Well done on the casting it is looking good, bet it was some moment when it started to melt! is it usually the case that you need so much fuel to carry out these melts?
Location: County Durham (North East England)

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #33 on: July 28, 2013, 03:07:05 PM »
Thanks Nick-

I was really beginning to wonder if I would ever get iron to melt.
It can be a bit of a trick if you don't know what you are doing, and at the time I definitely did not know how to adjust that burner.

It was a Hallelujah moment for sure.
I could envision the clouds parting, and the sun rising majestically, the sound of the angels singing the chorus waifing town from the heavens;  sort of hard to describe the feeling; I had dreamed melting iron for years, but really did not think I would be able to pull it off, and had been told by more than a few to not even attempt it, it was too dangerous.

It was sort of like this (at least in my head anyway):


Well it is dangerous, but that's life I guess.  If you do the research, and study the dangers, and take the necessary precautions, and you have a technical flair, you will be fine.  If not, you may have trouble.

Offline dvbydt

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Re: Green Twin Oscillator Cast/Build
« Reply #34 on: July 28, 2013, 03:10:05 PM »
I will be following your big build with great interest.
My Dad served his apprenticeship as a Millwright on Clydeside, shipbuilding. The spanners to tighten the nuts on the boiler stays were 6ft. long!

Ian

Offline NickG

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Re: Green Twin Oscillator Cast/Build
« Reply #35 on: July 28, 2013, 03:34:14 PM »
Great stuff. The only time i've cast anything was for a couple of simple loco parts. I made the pattern myself and my dad used to work in a school as a design technology teacher so we went in and used the crucible he gad in his classroom! We only cast in aluminium though and i was surprised how much heat even that needed - nothing compared to iron i guess. He said he bought some bronze or gunmetal to try once but it wouldn't get hot enough!
Location: County Durham (North East England)

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #36 on: July 28, 2013, 03:38:48 PM »
Sorry to interrupt, what size of delevan nozzle did you use ?

Mike

PS Good stuff !

Feel free to interrupt at any time.
I post this stuff on here for others to see and comment on.
Any/all feedback/comments are more than welcome at any time from anyone, and much appreciated.
« Last Edit: July 28, 2013, 06:44:41 PM by MetalCaster »

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #37 on: July 28, 2013, 04:25:34 PM »
Great stuff. The only time i've cast anything was for a couple of simple loco parts. I made the pattern myself and my dad used to work in a school as a design technology teacher so we went in and used the crucible he gad in his classroom! We only cast in aluminium though and i was surprised how much heat even that needed - nothing compared to iron i guess. He said he bought some bronze or gunmetal to try once but it wouldn't get hot enough!

Thanks Nick-

Glad to see the interest.
In the old days, it seems like almost everyone had shop classes.
I never got to take shop classes in high school, it was considered beneath those people who ran the school.
When I went to college, I took a number of shop classes in metal working, woodworking, welding, etc., and those were the most interesting classes I ever took, but they did not have metal casting.
It is a shame they don't teach more of that sort of thing.
People don't like to get their hands dirty.

We did get to take a school tour of the International Harvester foundry which was still in business in this area at the time (1978), and I vaguely recall a huge process with tons of green sand, and iron flowing out of giant ladels.  I wish I had known more about what I was looking at during that visit, I would have learned more.  I do recall that one item they manufactured was the front axle for a large truck, and I presume it was made from maleable iron.

Melting iron is really quite easy, but you really need a good setup, high temperature refractory, iron-rated crucibles, a stable burner calibrated for the correct btu input into the furnace size that you are using, etc., and it can be rather tricky to discover that information online or anywhere else.

Pat J

Offline tom osselton

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Re: Green Twin Oscillator Cast/Build
« Reply #38 on: July 28, 2013, 07:00:44 PM »
I wouldn't worry about interest a lot are lurkers including myself. Still gathering equipment to set up a home shop and gathering knowlege for builds and machining operations. I am at that point now where I have to get on with it I have the machines and am starting to build a furnace using a beer keg and fiber blanket like Ironman's video. I have cast aluminum back in school one time shot for some handles, Im 60 now lol my son has been bitten by it he has completed his 1st year training at sait and had his teacher help him cast some pillars for my dad'engine build so he is eager to get into casting.

Tom

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Re: Green Twin Oscillator Cast/Build
« Reply #39 on: July 28, 2013, 07:59:01 PM »
Tom-

I guess everyone likes attention, myself included.
Sometimes I wonder if there is anyone out there in model engine land, but then I am the king of lurkers too, so what can I say.

And speaking of kings, ironman is the king of cast iron, but I think there are a few here and elsewhere that perhaps can start the journey he has been on for 20 years, and perhaps rival some of his work.
I know Rob Wilson has done some iron a while back (perhaps more recently), and is actively involved in a cupolet build, which is capable of making bucketsful of molten iron fast.

It is easy to get bitten by the casting bug, that is for sure.
I have found few things as addictive as pouring molten metal.  Be cautious with the fumes though, you can't necessarily see them, but they can cause some serious damage.

Keep us informed of your engine building and casting progress.

Pat J

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Re: Green Twin Oscillator Cast/Build
« Reply #40 on: August 05, 2013, 11:20:21 PM »
Layout out the runners and gates for most of the parts for the green twin.

Offline NickG

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Re: Green Twin Oscillator Cast/Build
« Reply #41 on: August 06, 2013, 03:32:47 AM »
Looks good!
Location: County Durham (North East England)

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Re: Green Twin Oscillator Cast/Build
« Reply #42 on: August 06, 2013, 12:26:33 PM »
Thanks Nick-

I am working on the core boxes for the cylinder support and the ports and passages in the cylinder.
I want cored ports and passages for this engine if I can make some that are that small.

The passages will be similar to those shown below, but I think I will reverse the sweep in the passage below the port from covex to concave.

I am going to attempt at least one of this engine in all cast iron.
« Last Edit: August 06, 2013, 01:07:32 PM by MetalCaster »

Offline doubleboost

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Re: Green Twin Oscillator Cast/Build
« Reply #43 on: August 06, 2013, 04:26:59 PM »
This is going to be good
Nice drawings looking forward to the patterns & cores
John

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Re: Green Twin Oscillator Cast/Build
« Reply #44 on: August 07, 2013, 11:21:07 AM »
Thanks John.

Here is the core box I came up with for the passages/ports, made from scraps of brass, bronze and copper.

It needs a little refinement, but I did have some success with it.

Using a very fine sand and sodium silicate/CO2.

Offline NickG

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Re: Green Twin Oscillator Cast/Build
« Reply #45 on: August 07, 2013, 12:17:40 PM »
Wow will be really impressive if you can cast the ports in, will require less machining.
Location: County Durham (North East England)

MetalCaster

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Re: Green Twin Oscillator Cast/Build
« Reply #46 on: August 07, 2013, 03:31:54 PM »
I hope I can pull off the cast passages.
We shall see.

I got into castings because I was tired of the brute force method of machining engines from solid bar stock.
My patience is not so good as far as machining, and so my thoughts were that it is easier to make and machine patterns, and then I can hopefully subtract most of the tedious metal machining work out of the mix.

And I have often not been satisfied with the casting quality of others, and I prefer cast iron parts.
Sometimes the high quality casting kits are more than I want to pay.

I made the core box and core today for the bore.
« Last Edit: August 07, 2013, 04:03:13 PM by MetalCaster »

Offline doubleboost

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Re: Green Twin Oscillator Cast/Build
« Reply #47 on: August 07, 2013, 05:04:51 PM »
This looks good
Nice bit of wood working  :bugeye: :bugeye: :bugeye:
John

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Re: Green Twin Oscillator Cast/Build
« Reply #48 on: August 07, 2013, 06:40:43 PM »
Thanks John. luckily the metalworking skills I have learned in the last few years translate well to wood.

I use the same bits, machines, etc.

I added core prints to allow the passages to be glued into the bore core with furnace cement.

Slowly coming together on the coreboxes.
I need to grind on that passage corebox a bit to get a consistent thickness passage.

One more corebox to make for the outer support.


Offline Meldonmech

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Re: Green Twin Oscillator Cast/Build
« Reply #49 on: August 08, 2013, 03:47:09 AM »
Hi Pat,
           An interesting project, but a lot of your thumb nail pics need resizing anything over 800x 600 does not enlarge correctly. Check some of your larger sizes, and you will only get a part of the pic. I made the same mistake when I started posting.

                                                          Cheers  David

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Re: Green Twin Oscillator Cast/Build
« Reply #50 on: August 08, 2013, 10:12:38 AM »
Hi David-

I try and resized them to 100k or less.
More than that and they can get a bit grainly.

Thanks for the feedback.

Offline ironman

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Re: Green Twin Oscillator Cast/Build
« Reply #51 on: August 09, 2013, 09:46:01 PM »
Mine would sometimes break. Lets hope that yours are successful.

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Re: Green Twin Oscillator Cast/Build
« Reply #52 on: August 10, 2013, 10:02:01 AM »
There is a bit of an art to making sodium silicate cores.

I have been experimenting with different percentages of sodium silicate, between 3 and 4 percent by weight of sand.

I have a core I made last week, and it is as hard as granite, and then another one that fractures easily.

I need to figure out how to get a consistent hardness to the core.

Too much sodium silicate and you cannot force the CO2 through it.
Too little sodium silicate and the core is too fragile.

Offline ironman

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Re: Green Twin Oscillator Cast/Build
« Reply #53 on: August 11, 2013, 08:24:10 PM »
Have you tried using a microwave oven? Gassing them can be hit or miss if they are not gassed properly.

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Re: Green Twin Oscillator Cast/Build
« Reply #54 on: August 11, 2013, 08:51:07 PM »
Nope, I have not tried that.

I can't pull the core from the pattern without hitting it with the CO2.

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Re: Green Twin Oscillator Cast/Build
« Reply #55 on: August 13, 2013, 11:50:59 AM »
Snap flasks made yesterday, and runner/gate arrangement glued together.
This flask will be used to make multiple molds.
The mold halves will be glued together and poured without the flask being present.

Using bound sand, so the flask is only 4" tall total height (cope is 2" and drag is 2").
The photos show the cope and drag stacked.

Pour basin will go in the blank spot along the runner left of center.

When I get the cores completed, it will be time for a cast iron pour attempt, weather permitting.
We have been getting a record amount of rain this summer.  Generally we get little or no rain for about 3 months in the summer.
It rains almost every single day here.

Offline tom osselton

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Re: Green Twin Oscillator Cast/Build
« Reply #56 on: August 13, 2013, 12:54:08 PM »
Looks like a lot to cast how big is your crucible?  That is huge I would hate to see you make a short pour. Could you split them into two halves it could still be the same mold but would ensure against a short pour you still have to fill the sprue and riser too.  I don't want to sound negative but it seems like a lot.

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Re: Green Twin Oscillator Cast/Build
« Reply #57 on: August 13, 2013, 05:03:43 PM »
Tom-

Not a problem, I use a #30 for cast iron.
Brim full I think is around 100 lbs. of iron.

I will probably try and pour around 60 lbs. this time, and fill three of those molds.

I have a pouring cart almost finished.
I have hand poured with the #30, but it is a bit of a bear to handle, and for this much metal, I will be using the cart.

I saw a commercial cart online several years ago, which is where I got the idea, but I noticed that ironman uses a similar cart with great success.


Offline tom osselton

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Re: Green Twin Oscillator Cast/Build
« Reply #58 on: August 13, 2013, 06:18:08 PM »
A # 30 dam!!  going to have to call you herc !   :) well if you have to lift that much by yourself I think I would redo or make another that raises the furnace to expose the crucible then just latch on with Ironmans wheeled pouring doohicky. I just finished putting the fiber refractory in mine still have to coat it with zircon after I do my coffee. It is 11"wide and 13 1/2 tall inside so now I can figure what size crucible to get. I should weigh dad's cylinder's and get a good guess on that although the base would probably take more.
Anyways good luck with the pour!  :thumbup:

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Re: Green Twin Oscillator Cast/Build
« Reply #59 on: August 13, 2013, 08:27:10 PM »
I hand poured with about 20 lbs of iron in it, but that was just because the cart was not finished.

I also have a crane for lift out.

I know someone who is using a #50 I think.
I think he is running a two man operation.

I forget my furnace dimensions, I think 15" tall.

Thanks, I am looking forward to this pour, and hoping it goes well.

Offline tom osselton

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Re: Green Twin Oscillator Cast/Build
« Reply #60 on: August 13, 2013, 08:46:49 PM »
Ok this is the one I thought was a good design 

   


it would be a lot safer.
« Last Edit: August 13, 2013, 10:40:51 PM by dsquire »

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Re: Green Twin Oscillator Cast/Build
« Reply #61 on: August 13, 2013, 08:59:18 PM »
Just wear leather shoe covers, or some heavy boots.

I wear a lot of leather.

It is not that difficult to lift a crucible out of a furnace, and if you use quality crucibles, then breakage is not much of a danger either.
Special furnaces like that are just not necessary in my opinion.

And you should inspect your crucibles before each pour to make sure the are in good shape.

This is me pouring about 20 lbs. of iron.
Don't forget to put on your leather shoe covers (don't pour in lace-up shoes like I did, not a good idea if you like your feet).

   


« Last Edit: August 13, 2013, 10:44:06 PM by dsquire »