/diy/ - Do It Yourself

[That guy No.410440]

Aluminum Gear Attempt No.3
planning on casting this thing in the morning (about 5 hours from now) and hoping my new furnace doesnt fall apart.
will keep posting pics of progress and ill see if i can video the cast
>pic is my first attempt, didnt dry out the plaster mould enough and needed to melt more aluminum. using sand casting this round

[That guy No.410443]

>>395388
second attempt
>used plaster mould
>didnt melt enough

[That guy No.410446]

will be carving the gear out of wax this time aswell

[That guy No.410448]

the wax dried and the same template from before

[That guy No.410450]

A rough scratch of the outlines before we begin

[That guy No.410451]

the inside carved out, or in other words the easy part

[Anonymous No.410453]

Lurking. Also, will you post pics of the furnace?

[Anonymous No.410454]

Wax will probably crack when you're pounding on the sand mould. I usually see wooden positives on you tube. Got a band saw or a scroll saw?

wax might still work. Maybe... Leave the wax in the sand and give it an extra dose of release agent and just put extra fube sand around it wland don't worry about packing it too tight?

[That guy No.410456]

i heat the white knife and cut the basic outline before making the final shape with the stanley
half way there...

[That guy No.410458]

>>410454
only got a jigsaw and no vice. tried cutting out of wood before but it ended up too messy.

[That guy No.410461]

after over an hour of carving this is the last part you want to ruin. wax has broken on me before when i got too impatient and tried to rush the final teeth

[That guy No.410463]

last pic for tonight
the finished model

[That guy No.410465]

>>410453
i spent less time making the furnace then carving the bloody gear hahaha

[Anonymous No.410480]

Don't get me wrong, I think it is really cool what you are doing. But please tell me it is just decorative, because there is no way the resulting product would be good enough for a machine.

I would be more likely to use this for decorative art, maybe make a few busts, some aluminum letters like you see on old colleges, Hood ornaments etc. Polish it to a mirror finish. Before they used chrome on cars, they used mirror polished aluminum.

[Anonymous No.410649]

>>410440
I saw your previous thread, or at least this picture in a 'show your current project'-thread I believe. I don't quite remember, but I'm very interested. I'll be lurking and wish you good luck concerning your experiment. Let us know how it turned out.

Also; what did you use as a source for the aluminium ?

[Anonymous No.410653]

>>410480
he could make a good deal of money making figurines...

[That guy No.410866]

>>410480
oh dont worry, im only trying to cast a shape more comlicated than a circle (and i also have an absurd love for gears). once ive passed this barrier then ill look at casting some useful

[That guy No.410869]

>>410480
oh dont worry, im only trying to cast a shape more comlicated than a circle (and i also have an absurd love for gears). once ive passed this barrier then ill look at casting something useful.
my main goal is to cast brass
>>410649
alumium cooking pots and a large roll of left over flashing

sorry guys wont be melting today, got a call from work and wont have the time. however tomorrow is my day off so ill definately be casting. in the meantime ill get my sand ready

[Anonymous No.410885]

>>410869
Hey, I'm about to make a foundry oven on my backyard to cast some aluminium too...

Any tips? Are you using butane for fuel?

[Anonymous No.410892]

>>410885
Also, have you ever tried melting beer cans?

[Anonymous No.410909]

>>410440
wow, nice work! Never saw an aluminum gear; I don't think.

I'm pretty sure the only one's I've seen were tin or some pot metal amalgamation.

This would be great for those folding bikes and aliminum naturally protects against rust by forming a layer of alumina.

[Anonymous No.410919]

Did you read Dave Gingery's books?

[Anonymous No.410924]

>>410919
Example page

[That guy No.410933]

>>410892
never tried melting cans before but ive read that you do get a lot of slag from them. i use charcoal briquettes from the supermarket to power mine. as for tips, be patient; the amount of times i ruined a pefectly well cast or burnt myself because i tried to hurry things up is stupid. better waiting another 10 minutes then repeating hours of preperations. other than that just trial and error.
>>410919
havent read it but will definately add it to the list, thanks

a quick update before i head off to work. managed to pack the gear in there nicely but when i went to melt the mould out i dropped the whole thing. luckily i made a spare so the plan on casting tomorrow is still on, just need to carve it tonight after work

[Anonymous No.411447]

>>410933
Well that rules lost wax casting out for when casting alumium. will be having another go tonight using a hollow mold instead

[Anonymous No.411449]

>>411447
might also need to make adjustments to my "crucible" so it doesnt pour so quickly

[Anonymous No.411457]

What kind of forge (or smelter) would I need to cast mild steel?

[Anonymous No.411467]

>>411457
not too sure to be honest, with aluminium i only need to get it up to 800, with steel you have to have it atleast 100 degrees above its melting point which is generally around 1500-1600. take a look at some metal casting forums for a good idea of where to start, i used to visit metalcastingzone but the website has changed

[Anonymous No.411470]

>>411457
backyardmetalcasting.com is still my favorite site.

He's able to do it with waste oil and a ducted fan.

The fuel and air is pretty easy. The hard part is getting the crucible and refractory of the foundry good enough to withstand the temps. With most DIY solutions, you're going to replace the foundry every 6 or 10 firings because everything you can DIY will just fucking melt.

Most people just buy a crucible because they're not that expensive and too hard to DIY.

[That Guy No.411474]

>>411457
heres a good recipe for refractory

[Anonymous No.411475]

>>411467
>>411470
>>411474
Thanks guys, I'm still just in the planning stages.

[That guy No.411636]

tonights casting should be a good one, flowed in fairly nicely when i poured it. just waiting for it to cool down at the moment before i dig it out.

pic is the change i did this round. when i tried melting the model out in the oven the sand got wet and started falling apart, this time i went through the middle with a soldering iron

[That guy No.411637]

the casting in all its flaming glory

[That guy No.411642]

So close...
the middle section is fine but i have always had problems getting the edges right. tomorrow ill change the direction i pour the metal in and see if that gets any results. currently im pouring it in from the middle with two vents on the side, ill try from one side to the other next time.

[Anonymous No.411655]

>>411642
Can I get a photo of this from another perspective ?

I see you have a problem with the aluminium filling in the mold correctly. May I suggest making a higher cast ? Vertically elongating the pouring shaft and vents should increase the hydrostatic pressure in the liquid aluminium in the cast, pushing it further into the nooks and crannies of your mold.

Also, how did your new furnace hold up OP ?
I like you for sticking to it and your continued experimentation.

[Anonymous No.411661]

>>411655
thanks will definately try that out tomorrow
this a shot from the side so you can see the vents, the middle vent is where i poured from

fairly surprised by how the furnace is holding up, no chips or cracks yet. bought a bag of 20kg premix all pourpose concrete from bunnings for $5 for the refractory since i couldnt find any fireclay.

[Anonymous No.411722]

Are you planning on machining it into a workable gear, or is this just to practice casting?

[Anonymous No.411733]

Casting an aluminium gear is pretty pointless.

Also note that aluminium is one of the worst materials to use for a gear because it wears very poorly and aluminium against aluminium contact produces a bunch of black gunk.

The only commercial aluminium gears are hard anodized then teflon coated to try to step around the many disadvantages of aluminium.

[Anonymous No.411737]

I think your sand needs more clay and some oil in it. It should hold together when you take the positive out of it.

you seem to be combining two mold methods. Lost wax you get your wax positive and cover it in a hard ceramic and bake the ceramic to harden it and the wax will melt out. With sand casting, you set your positive in the sand, pack it around it, cut a shaft for pouring and venting to either side. Open the mold back up, take out the positive and cut gates in it.

it looks like your sand is collapsing when you take the wax out?

you could also try leaving the wax in place and pouring the metal right into it... Might explode that way though.

[Anonymous No.411739]

>>411722
he said it was decorative/practice in the last thread

[Anonymous No.411749]

>>411733

>one of the worst materials to use for a gear

that's odd, considering that they sell aluminum timing gears (one gear is steel, other one is aluminum) for the ford I6 300 which is one of the most reliable motors ever designed.

[Anonymous No.411751]

>>411749
maybe it's supposed to break
maybe it's a failsafe

[Anonymous No.411761]

>>410440
OP if you want to make a gear, why not use indexing. it would be easier for you and the surface finish would be better. casting should be used for more complex shapes

[Anonymous No.411782]

>>411749
Reliable as it may be, that gear break from time to time apparently, seeing ass they sell them. Sardonics aside, I'd imagine it's the bigger gear that is aluminium, which could stand being that much weaker since the load from the chain will be distributed over more cogs.

I'm also curious, the timing belt/chain has to be changed from time to time. Do they also change the sprocket? I'm studying mechanical engineering at the moment and we're taught that while a steel part can, if properly dimensioned, last forever as far as fatigue is concerned, an aluminium part will fatigue and break given enough load cycles, pretty much no matter how small the load.