Casting fun

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
It's been quite a while since I fired up the furnace . This weekend I finally had the time
to melt som ali , make a few moulds etc .

Here's the first . This beautifull flywheel was designed by ken brunskill . He mailed it to me , and I just scaled it a little
and put on some pattern draft .
3D printers are the perfect tool to make patterns . No matter how complex the shape is , as long as "rules" for a pattern are
observed it'll turn out ok .
Just imagine how much work it would have taken to make a wooden pattern .

The pattern printed in pla , no surface treatment was done apart from dusting it with parting powder .
DSCN0103.JPG



The casting , actually this is the second casting , I did two of them .
The second casting turned out better then the first one . The feeder is in the middle , and four risers on each "corner "
This one has almost no pitting , but still quite some flashing at the parting line .
I guess I'm still a bit clumsy when pulling the pattern from the sand . Or my homemade sand isn't the best quality .
Flywheel will be used on an atkinson differential engine .... someday :)
DSCN0105.JPG


Couldn't resist . I cleaned up and machined the first casting . Turned out quite OK altough there is some pitting and a few little blow holes .
I'll make a poly v-belt pulley out of this one to power a gear pump I'm building .
DSCN0104.JPG
 

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
One of the first castings anyone doing foundry work will probbaly make .
A sand rammer . Altough I've used a hammer handle for several years now to make my moulds .
This rammer was designed and given to me by myfordboy .
If you want to learn or to know more about foundry work , pattern making and all that goes with it do check myfordboy's youtube chanel .
Hundreds of very informative video's there .

The pattern was printed by a friend of mine , and he has a small build plate so it was done in two pieces .
The pieces where then glued together and sprayed with several coats of automotive filler surfacer .
Later on , after it was cast luckily , I dropped the pattern and the glued parts became unglued again .
Apparantly pla isn't easy to glue .
Oh well , I only need one sand rammer anyway .


DSCN0101.JPG
 

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
While I was at it , I made some ingot moulds . Cut out of 3mm steel with a plasma cutter and tig welded together .
Angles are 10° , witch is more then the usual 3 or 5° .


DSCN0106.JPG




Casting ingots is really a waste of fuel , unless you have a way of controlling and refining the alloy . The reason I did this is that I had several boxes and buckets with all kinds of scrapped materials . This way it does take up far less space . I'v weighed them and put them on a shelf for future use .
DSCN0112.JPG



I wasn't quite finished , there are still a couple of buckets of scrap left to be processed . But unfortiunatly my "crucible" failed .
It was made from a fire extinguisher . I think it lasted 15 melts or so .
A bit dissapointing because it was quite thick walled steel . Maybe I should use a scrapped argon cylinder for the next one .
That should be 5 or 7mm thick .
DSCN0111.JPG

DSCN0110.JPG
 

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
A future project is making modular flasks .
Once again a myforboy design .

The idea is to be able to make different sizes of flask by combining various panels .
With three sizes it's possible to make several different flasks like a small square , a medium square and a large square and a couple of rectangulars in between . If the panels are also made in two different heights the nr of combinations is very high .
I really like this idea as I only have 4 buckets of sand and I want to keep the flasks as small as possible .
Downside is that it takes eight panels to make a single one size flask .
So a full set will take a lot of castings and offcourse I would like to have two or even three sets .
I can only do a couple of panels each time , so this might take forever .

This is the smallest panel of full height . Eight panels are needed to make a single flask of one size .
DSCN0102.JPG



I tried to do a couple more , but this is what happend . I think the metal wasn't hot enough when poured and it froze up before it could fill the mould cavity . That was the last of my sand , so now I need to recondition it before I can do some more . And I need a new crucible as well , so the end for now .
DSCN0108.JPG


DSCN0109.JPG
 
Last edited:

Ken Brunskill

Well-Known Member
Joined
Feb 16, 2019
Messages
156
Reaction score
22
Location
Fremont, CA
It's been quite a while since I fired up the furnace . This weekend I finally had the time
to melt som ali , make a few moulds etc .

Here's the first . This beautifull flywheel was designed by ken brunskill . He mailed it to me , and I just scaled it a little
and put on some pattern draft .
3D printers are the perfect tool to make patterns . No matter how complex the shape is , as long as "rules" for a pattern are
observed it'll turn out ok .
Just imagine how much work it would have taken to make a wooden pattern .

The pattern printed in pla , no surface treatment was done apart from dusting it with parting powder .
View attachment 125794


The casting , actually this is the second casting , I did two of them .
The second casting turned out better then the first one . The feeder is in the middle , and four risers on each "corner "
This one has almost no pitting , but still quite some flashing at the parting line .
I guess I'm still a bit clumsy when pulling the pattern from the sand . Or my homemade sand isn't the best quality .
Flywheel will be used on an atkinson differential engine .... someday :)
View attachment 125796

Couldn't resist . I cleaned up and machined the first casting . Turned out quite OK altough there is some pitting and a few little blow holes .
I'll make a poly v-belt pulley out of this one to power a gear pump I'm building .
View attachment 125797
Very nice indeed! Doing you own casting, is something I contemplated, however now have sold off all the gear and am too close to retiring my shop to restart now.
 

abby

Well-Known Member
Joined
Apr 13, 2009
Messages
515
Reaction score
173
Now you realise that steel dissolves rapidly in molten aluminium !
 
Joined
Jan 7, 2013
Messages
32
Reaction score
24
Location
spokane wa
I process automotive engines for the hobby caster, I use fire extinguisher based crucibles for a couple reason. one is that I pour 150 to 200 lbs per session in about 2 hours. The weight of the full crucible is about 13 lbs and "when" not "if" failure happens its a pin hole, I don't need to worry about major failure or handling the extra weight of a normal crucible. What I do to make the steel crucibles last is to Coat the inside and outside of the extinguisher with ceramic slip that I get from the local ceramics shop, The coated crucible will last through about 500 to 750 lbs ,without the ceramic coating it is lucky to last through 100 lbs.

In the pictures of the mold castings it appears that you are pouring from both sides. I would only pour from one side it allows easier fill , I would also place the sprews on the opposite side corners rather then the middle of the sides.
 

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
You're quite right about he mould castings .
I poured one side , and noticed the riser didn't fill up . So in an attempt to save the casting I poured from the opposite side .
No avail , the other side also froze up .

150 to 200 lbs , that is quite something . How big a crucible do you use then ?
 
Joined
Jan 7, 2013
Messages
32
Reaction score
24
Location
spokane wa
My crucible holds 12 lbs. The furnace is based on a 200 gallon oil tank and tilts on a set of elec actuators It fires with 2 waste oil burners at about 6 to 7 gallons per hour on high fire. The burners are controlled using servo motors on needle valves and the temperature of the melt pool in the furnace, I pour at 1425 to 1475F. I have 3 sets of 8 molds that i rotate pouring and dumping into quench tanks. Each set of molds is filled with one crucible..

I would think that you are pouring a little to cold, The largest casting I have done was a Jet boat intake casting, used about 50 lbs and I poured it at 1400F. any colder then that and it wouldn't fill all the way.
 
Joined
Jan 7, 2013
Messages
32
Reaction score
24
Location
spokane wa
I had another thought on the casting problem, if you were using aluminum without enough silicon -about 8%- the surface tension is high enough that it doesn't flow well through a thin casting. I only process automotive castings or wheels so that the aluminum that i sell is consistent at about 9 to 11% or very close to 356.Alloy. Non casting scrap like wire, extrusions,-ladders etc- or metal from machine shops normally does not have the necessary silicon for good casting. and it will have problems in larger thin castings like the long sides of your cope and drag.

Art b
 

timo_gross

Well-Known Member
Joined
Feb 26, 2020
Messages
272
Reaction score
140
I wasn't quite finished , there are still a couple of buckets of scrap left to be processed . But unfortiunatly my "crucible" failed .
It was made from a fire extinguisher . I think it lasted 15 melts or so .
A bit dissapointing because it was quite thick walled steel . Maybe I should use a scrapped argon cylinder for the next one .
That should be 5 or 7mm thick .
View attachment 125802
View attachment 125805

Master Yoda should be able to pull himself together and melt the scrap without any crucible :) Just a little concentration when beeing at it.

My suggestion for normal people, order a crucible from China or buy one at the local foundry supply. I paid about 12 USD for a small 2kg pot. Did not use it a lot, but few heatings and it is still O.K. specially the inside looks still clean and unharmed.
They are not as delicate as you might think, and at the moderate 600° to 800° C for Al melting they last quite a bit.
For sure more hours than steel.

Read the thread small casting (alluminium) aty home. It contains quite a crucible discussion and I could not help to quote your failed vessel. ( sorry for that)
Clay graphite is what you can search for. Another advantage will be that you do not oxidize and damage it from the outside as rapidly. The clay can take quite a beating from a gas torch.

When melting aluminium beware of iron, if the scrap includes screws etc or if you use an unlined steel melting pot, the iron can leech into the metal causing it to go very sluggish an impossible to work with.
A good source of metal scrap is old car engine pistons they are pretty iron free and actually are a special alloy to resist heat in service.

Now you realise that steel dissolves rapidly in molten aluminium !

Kitchen metallury: It is like making coffee pots out of sugar, it works for some time. The coffee will be sweet and eventually it creates a mess. :) That is why most people do not use sugar for making coffee mugs.

Greetings Timo
 
Last edited:

timo_gross

Well-Known Member
Joined
Feb 26, 2020
Messages
272
Reaction score
140
I had another thought on the casting problem, if you were using aluminum without enough silicon -about 8%- the surface tension is high enough that it doesn't flow well through a thin casting. I only process automotive castings or wheels so that the aluminum that i sell is consistent at about 9 to 11% or very close to 356.Alloy. Non casting scrap like wire, extrusions,-ladders etc- or metal from machine shops normally does not have the necessary silicon for good casting. and it will have problems in larger thin castings like the long sides of your cope and drag.

Art b

That is what I was also told by several experts (real ones with foundry work background), my friends advised me, if you have extrusions, -ladders etc. Just go to a local metal recycler try to trade a kilo for a kilo. You get your casting grade and the scrap dealer usually should be O.K. with a swap deal, as long as your stuff is clean, free of Iron and copper scrap and not painted.

The advise for the ordinary non experts, that I was given. "Out of old castings, new castings you must cast" Soda cans are probably the worst choice, they should be left to the professionals with the fluxes, alloying materials, dust and gas filters and rotating drum furnaces.

Greetings Timo
 
Last edited:

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
I'm quite sure the alloy isn't the issue here . All my raw materials are either alloy wheels or recycled castings from medical equipement like centrifuge buckets and rotors . No ectrusions , and certainly no soda cans . That is a complete waste of time and fuel . Besides , the first one came out just right , and it was thesame alloy only a different pour . It's definitly the temperature .

The reason I started with the fire extinguisher is that I needed to pour close to 10Kg ( 22Lbs) in a single pour . Only thing I could find big enough was a fire extinguisher to hold that amount . Later on I continued using it , but only filled to 50% or even less . Wich is still 5Kg (10Lbs ) .

Round here there are no foundry supply stores that I know of .
I have to make my own greensand , and my furnace was made from a perlite and fire cement mixture . If I cant' diy it , I'm basicly stuck .
And even if I could find a real crucible , wich obiously I don't , it should be a very big one to hold at least 5kg ( 11lbs) of metal .
Chinesium would certainly be an option if only belgian customs didn't add 200% to the ticket . I bought a cnc spindle once for 100$ give or take and ended up paying over 300$ when the package was opened by the customs .

In a previous life at my previous employer we had a foundry amongst our customers . They made wood stoves and things like that .
To bad I no longer have any contacts there . Otherwise I would have had a couple of flower pots made in cast Iron and some ingot moulds to .
Cast Iron seems to be a far superior material then steel for this kind of work . Oh wel , dream on I guess .

Art , can you elaborate on the coating you use on the crucibles . What material , how do you apply it etc .
Any pictures maybe ? I've never even heard of the proces .

Pat
 

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
Here's my furnace btw just in case someone is wondering .
A propane tank and a mix of perlite and fire cement .
Bolted to an old lawn mower chassis makes it easy to transport and store .
Propane powered for now , wast oil burner in the near future .


Furnace.jpg
 

stragenmitsuko

Well-Known Member
Joined
Jan 19, 2016
Messages
323
Reaction score
139
Give or take 15 minutes when started from cold . For abt 5Kg ( 11 Lbs ) of metal .

Once molten , I add sodium carbonate to degass . It is pushed to the bottom of the crucible with a plunjer and it causes gas bubbles .
These gas bubbles drive out hydrogen dissolved in the molten metal . Hydrogen causes porosities in the cast , the degassing reduces
those porosities . It's not perfect but it's better then nothing
Myfordboy has a few good videos showing this process .

I also used to add some lo-salt ( kitchen salt with low natrium content ) as a drossing flux .
Lately I don't do that anymore . It doens't seem to make much difference anyway .
 

darwenguy

Well-Known Member
HMEM Supporting Member
Joined
Oct 26, 2013
Messages
216
Reaction score
287
Location
United Kingdom
Give or take 15 minutes when started from cold . For abt 5Kg ( 11 Lbs ) of metal .

Once molten , I add sodium carbonate to degass . It is pushed to the bottom of the crucible with a plunjer and it causes gas bubbles .
These gas bubbles drive out hydrogen dissolved in the molten metal . Hydrogen causes porosities in the cast , the degassing reduces
those porosities . It's not perfect but it's better then nothing
Myfordboy has a few good videos showing this process .

I also used to add some lo-salt ( kitchen salt with low natrium content ) as a drossing flux .
Lately I don't do that anymore . It doens't seem to make much difference anyway .
Nice looking furnace, thats the same style as my first furnace, i did the oil thing too, but i did have problems with the perlite mix melting when i used it for brass.
I honestly dont see a problem with a steel crucible, they oxidise and flake evenentualy but there for nothing to the handy type. like you say same here in the uk ceramic crucibles in a good size cost lots and often end up already cracked when orded from china. Im no expert Ive only been casting for around 6 years and made maybe 5000 castings. ive had around 20 ceramic crucibles, they realy are pot luck some dont last long at all especially in the cold and damp here. I now just save them for my brass and bronze alloy pours.
Best regards.
Luke
 
Top