Model Engine Maker
Supporting => Casting => Topic started by: Tjark on August 17, 2013, 05:23:19 PM
-
I thought it would be nice to make a tread about making new flasks.
I need a set off new flasks to cast some small cylinders for a Zenoah model engine.
So I will make a step by step how to process.
At first I have made from ply wood two plates.
Have glued an outer ring off 20mm triangle wood around the edges .
Now I have to mill some groves in the inside to hold the forming sand in place.
-
This looks to be an interesting thread. To see the procedure from the beginning. I'll be watching.
BC1
Jim
-
Milled the groves in one off the walls.
Now it’s a lot off filler and sandpaper work to get all the sites straight and flat.
Then its time for the shellacked finish.
-
To align the bottom and top half off the flask’s we need a alignment pin and hole.
There for I have made pin guide and glued this to one off the parts what will be the small site off the flask.
The sanding and filler work is been done and now I am putting shellac to all the sites.
Due to the shellac the parts will release more easily from the molding sand.
I do not know how many coats it will take to get a smooth finish, sometimes are three to four coats enough but it depends on the wood sort.
Hopefully it will be dry this week, it rains so now en then over here, so I can cast some parts off the flask’s.
-
Despite the bad weather I had a try to cast the first flask panel.
Had just enough time before it started to rain.
Not the ideal weather to cast very moist air outside.
Normally I do not cast in this type off weather because off hydrogen forming in the casting.
But I think for these flask sides it’s not that big deal.
First two pictures is the mold in very well used petrobond.
The next two pictures are the melting and pour the mold.
Despite the weather success at last.
The next update will take some more time, waiting for better weather and cast the other seven panels.
-
Made some progress today.
Casted three side panels and milled and drilled the outside panels.
I realized today that I had made the hinges for the alignment pins to far to the middle.
Maybe I mill them off and weld some new ones more to the top, I have to think about this.
When the weather is good I will cast tomorrow the last side panel.
-
Very nice flasks, Tjark.
Cheers, Hugh.
-
Hugh, thanks for your commend.
I am still not ready with them.
Have casted yesterday the last side panel and today I have assembled them almost.
To do list now is drill four 5mm holes and tapping four times M6 tread into them.
The flaps for the alignment I have renamed now as handles to lift the flasks.
Plan is to make a set off new holders for the alignment pins and bold them to the side panels.
Well work is waiting tomorrow so I will see if there is some spare time left to make some more progress.
Tjark.
-
They seem to be very deep flasks, Tjark. I'm looking forward to seeing what comes out of them. Rugby balls would fit, but you probably won't be doing them.
Cheers, Hugh.
-
Hugh I need the height, the flasks are not that big.
They are for casting small model engine cylinders.
The height is very handy to have more down pressure for the aluminum.
Tjark.
-
Hugh I have a picture included with the height dimensions
The small pattern on the side off the flasks has a little les height then the one I will use for the next cylinder.
I will cast it in standing position.
The inside dimensions are 15 x 18 cm and one flask has a little bit more height then 14cm.
This are the smallest flasks I have made so far.
Tjark.
-
Beautiful casting of the flask Tjark, one day I will have to try my hand at it. Just no enough time in the days to do it. I have been following and enjoying but also trying to learn.
Don
-
Thanks, Tjark.
-
Don, for me it was a lot off try and error in the beginning.
I could not get any help over here because there was nobody with some knowledge about casting.
I had downloaded a lot off books from the internet and bought some books from Steve Castain, http://stephenchastain.com/store/index.php?main_page=index&cPath=1 and two books from C.W. Ammen, The complete handbook of sand casting and casting Aluminum.
Specially the last book gives a lot off practical information.
How to build a good furnace you have to look at one off the books from Steve.
As base metal I use alloy car wheels, and for the casting molds I use several sand mixes.
I use sometimes green sand, oil bonded sand and sometimes a mix from sand and sodium silicate what will harden with CO2.
If you have the base together you will use the casting process more often to make parts.
It’s a lot cheaper then making things from solid material and you can make more detail to your parts.
Tjark.
-
Hi Tjark
A very interesting subject as I'm planning something similar down the track a bit.
I was interested to note you use car Mags, Does the Mag in mag wheels not stand for magnesium? :noidea:
I was offered a set myself but was a little concerned about the safety aspects.
Pete
-
The vast majority of car wheels are aluminum. There was a time that you could get a magnesium wheel, but they would turn black almost as soon as you got it, and of course, they were very expensive.....but the name stuck
It's probably a very safe bet that all modern mags are actually aluminum.
Dave
-
As Dave mentioned the magnesium wheels, those are to avoid.
Those are very dangerous when melting.
I have a engine builder in the back at my place who has built racing engines in magnesium and he is an expert in telling if I have an aluminum wheel ore a magnesium wheel .
I always let him take a look at the stuff and till now it all went good.
If you meld a magnesium wheel you will destroy your furnace.
Tjark.
-
Collected the last material to finish the casting flasks.
Some aluminum and stainless steel rod.
Have cut the aluminum to four rectangular bars 80 x 45 x 12mm and have to fit them to the sides off the flasks.
Then I will bore two holes in them and ream them to 10mm.
This is the diameter off the stainless steel rod.
Have to treaded the rods also but have to see what length they will have.
Tjark.
-
Newbie question. What is a 'flask'?
When I saw this topic I was thinking a hip or pocket flask for holding spirits.
Might be because I'm in the process of filling my internal flask with spirits. ;D
-
Carl, flasks are no more then open boxes who will hold the forming sand.
In casting terms they are called cope and drag.
The cope is the top flask and the drag is the bottom flask.
I have given these flasks some more height so that I do not need to extend the sprue (this is the place where you fill the mold with molten metal) and the riser ( this holds the extra molten metal for shrinking when the metal cools).
Tjark
-
Thanks Tjark!
-
Had some time today to work on the flasks.
My wife and I are busy with the bathroom, new shower cabin and Flore and wall tiles.
So not a lot off time left for the hobby.
Have made two plates for the aline pins on the site walls from the bottom flask.
If I have some more time tomorrow I will make them also on the top flask.
-
Hi Tjark
What is the blue paint on your Cope.
Some form of release agent ?
Pete
-
Hello Pete,
From witch picture is your question?
From reply19, this is an internet picture from I do not know the details.
I have put it there to inform what the drag and cope is off the flasks.
I have at the moment no pictures from my castings.
Will make a report from casting off some motorcycle carburetors in short time.
Have been busy with the owners pattern witch I have to modify.
You can see this on the picture, its an old type off motorcycle carburetor with a separate float chamber, this will be changed to a central float chamber.
The carburetor on the top is changed to get all the measurement details by hand.
Same for the float bowl on the left off the pattern.
From reply21, the bleu shine on the cope is the reflexion from the flash off the camera.
It was late when I took the pictures.
On the patterns I make myself I use shellack.
I use oil bonded sand as forming sand.
Between the cope and drag I use baby powder as parting powder and some weeks ago I got some parting powder from a big casting firm to try out.
Will be casting soon again and will try out the official parting powder, will see if this gives some advantages.
Tjark.
-
Hi Tjark
Top job on the carby :praise2: :praise2:
Yes it was reply nineteen I asked about, thanks Buddy :cheers:
Pete
-
Pete thanks for your comment about the carb, I had help from a professional pattern maker.
That makes things a lot easier.
Had some spare time so made the alignment pins to the flasks.
They are now ready for casting.
Tjark.