DIY Thread - Let's see your "Inventions".

[MeepBeep]

Oooh nice what kind of motor is it a servo?      Or Stepper?    Does the motor have a keyed shaft or round....

It's a generic geared down 110V egg turner replacement motor found on Ebay (about $15) they are 1/240 RPM, so one revolution every four hours...

It has a 6mm D-Shaft, I had to remove the little nylon arm in had pressed on the shaft when it came...

The arm you made is awesome...  How are you controlling the speed on the motor with a Rheostat or with a digital controller...

Thanks the arm was the only hold up, on the project, I looked all around and could not find anything over the counter that was reasonable...

Aluminum is interesting stuff never worked with casting it...  what kind of casting medium did you use?

Don't laugh, but the rough arm shape was cast in the worst grade play sand (the kind that almost has pea gravel sized chunks) you can get at the hardware store using the lost foam method... It's what I had laying around and convenient at my house for a quickie... My brother has all the nice casting sand but I didn't want to take a trip over there,for this project... The rough casting was cleaned up on a table saw, yes you can SLOWLY cut aluminum with a carbide blade on a table saw if you are careful and take your time... Then hand filed and cleaned up with sand paper... Aluminum cans are 6140 aluminum so not really a casting grade but it still cast OK for small stuff...

Here are some of the rough lost foam test castings (and one cleaned up) that I poured before I roughed out the shape of the arm and cast that... Sorry no pictures of the arm casting in raw form...

a similar technique would be to use a disk of aluminum fastened to a drive collar affixed to the shaft of the motor and a hole drilled in the disk to provide attach point.  But that would require buying either scrap materials or new and cutting a disk.

Yep, most people do the cam setup, but I wanted to try something different as the arm fits better into the grand plan of bigger incubator I'm working on...

i looked again and can see the set screw affixing the arm to the shaft...  awesome.

Yeah two set screws actually, one into the flat of the D-Shaft one opposite just for good measure... I find it easier to simply drill a hole through the entire shaft and tap through both sides creating two set screw holes opposite each other...

 

[perchie.girl]

When I used to design tools for Aerospace I used 6160 T6 good stuff for holding pressed in pins and Bushings. But a cast plate of it the thickness you used for your little arm would be $$$....

I am not a machinist only a designer. I always consulted with the Machine shop before finalizing a design and releasing it for prototyping. But I do know about aluminum and its odd needs.... and the peculiar way it absorbs the contents of the atmosphere when melted..... so I never thought of using sand casting for even prototypes.

So I take it you melted it down using an acetylene torch and you already had a crucible... My dad was the machinist in the family he worked his way up to tool maker then tool designer.... and was always making things from scratch. This would be something right up his alley....

deb

 

[bruceha2000]

Thanks the arm was the only hold up, on the project, I looked all around and could not find anything over the counter that was reasonable...
Don't laugh, but the rough arm shape was cast in the worst grade play sand (the kind that almost has pea gravel sized chunks) you can get at the hardware store using the lost foam method... It's what I had laying around and convenient at my house for a quickie... My brother has all the nice casting sand but I didn't want to take a trip over there,for this project... The rough casting was cleaned up on a table saw, yes you can SLOWLY cut aluminum with a carbide blade on a table saw if you are careful and take your time... Then hand filed and cleaned up with sand paper... Aluminum cans are 6140 aluminum so not really a casting grade but it still cast OK for small stuff...

Here are some of the rough lost foam test castings (and one cleaned up) that I poured before I roughed out the shape of the arm and cast that... Sorry no pictures of the arm casting in raw form...


Yep, most people do the cam setup, but I wanted to try something different as the arm fits better into the grand plan of bigger incubator I'm working on...
Yeah two set screws actually, one into the flat of the D-Shaft one opposite just for good measure... I find it easier to simply drill a hole through the entire shaft and tap through both sides creating two set screw holes opposite each other...

Wouldn't it have been easier to make from wood? Or are you a "melt and mold" guy to the core

Certainly much more professional looking in cast and finished aluminum than it would be in wood. Of course I've never worked in metal so like the carpenter to whom the solution to every problem is a hammer, my solution to most things is wood. Like metal work, you just need the right tools.

 

[perchie.girl]

Quote:
LOL then there are those of us where wood is mystifying.... I am a plastics person myself and sheet metal.... Casting is what I have done for jewelry so I understand the process... but could never attempt it.

So In my case I would make the arm out of a piece of delrin.... or polycarbonate...

deb

 

[MeepBeep]

So I take it you melted it down using an acetylene torch  and you already had a crucible... 

My brother has all the good casting stuff, he does a lot more metal casting than I do so I just go over there generally... For this though since it was a small quick and dirty job, I did it at home with stuff I had laying around... The 'crucible' I used was a small stainless steel mixing bowl, and I have a small DIY charcoal foundry I made a while back for quick metls like this...

A few handfuls of Kingsford charcoal, hookup up the cheap air mattress inflator to give it lots of oxygen and in about 3 minutes I can melt about 3 dozen soda cans and do a quick pour before the charcoal needs replenishing... I have the stuff to convert my little foundry to propane but have not got around to doing it...

The cheap foundry I used for this project, a used freon tank that was given to me, a scrap piece of pipe, the air inflator (99 cents @ Goodwill), scrap of garden hose, and the stainless steel bowl (49 cents @ Goodwill) The insulation in the foundry is a product call Structo-Lite, it's a Plaster of Paris, Perlite and silica sand mix used for old fashion plaster walls, $12 for a 50lb bag at the hardware store...

Just add charcoal or even wood works for aluminum...

Wouldn't it have been easier to make from wood? Or are you a "melt and mold" guy to the core   Certainly much more professional looking in cast and finished aluminum than it would be in wood. Of course I've never worked in metal so like the carpenter to whom the solution to every problem is a hammer, my solution to most things is wood. Like metal work, you just need the right tools.

Sure wood would have been easier, but in this application I felt aluminum was a better long term solution, plus it's fun tow work with and gives me a reason to play with molten metal... I grew up a wood worker from an early age, but about 10 years ago I started to work with metals and I find metal working has it's own charm, I like the 'precision' metal affords... I don't have nearly as many metal working tools, although I do have a small metal lathe and small metal mill, both are in storage right now thus the use of a table saw and hand tools on this job...

This was also the first time my daughters got to see me melt metal and got to see molten metal magically appear from aluminum cans and be made into something else...

So In my case I would make the arm out of a piece of delrin....  or polycarbonate...

Delrin was my first idea, but like a lot of my stuff it is still in storage, and I wanted to avoid paying $10 shipping for a $5 scrap of Delrin

I also considered casting it in polyurethane casting resin, as I have a lot of cold resin casting experience but that again would have required purchasing the resin and silicone to make the molds and cast...

I even considered casting it in 'Wood's Metal' as I have a few pounds of that laying around... If you are not familiar Wood's Metal is a lead alloy that melts as 158°F so you can literally melt it in a double boiler on the stove like chocolate But, figured the lead, and cadmium in the Wood's alloy had no place in my incubator even if exposure risk would be nearly nonexistent...

**Note a typo earlier aluminum cans are 6061, not 6140

 

[perchie.girl]

@MeepBeep

I am Totally in Awe....

Keepiing the simpicity of melting aluminum and casting it in my notes.... One of my neighbors has an old horse shoers forge.... the kind that use acetelyne.... I may try to talk him out of it....


You could use that aluminum for all sorts of things... in my case because it shines up sooo pretty I would be using it for art....

deb

 

[MeepBeep]

One of my neighbors has an old horse shoers forge.... the kind that use acetelyne.... 

Acetylene is really overkill and costly to just melt aluminum, propane works fine, as will natural gas if you can get the gas company to install a 'high pressure' regulator take off at the meter...

Waste oil is another option we have used...

My brothers DIY big propane foundry build will easily melt copper and brass as well (sounds like a jet engine) our end goal is to melt and mold cast iron but you really need to invest in high end costly refractory cement to melt cast iron as regular cement will melt and plaster will crumble at those high temps... And yes I said cement will melt, my brother had a melt down in one foundry trying to get the foundry up to cast iron temps, he noticed the flame wasn't burning right, took off the lid and the crucible was literally floating in a pool of molten cement , homemade lava in the backyard

Honestly though beyond the obvious dangers melting metals like aluminum is a cheap hobby... Lots of DIY videos on Youtube and even a few sites dedicated to it...

If you really want to go cheap, you can dig a hole in the ground and line it with firebricks, as a dead simple foundry and use a soap can crucible for aluminum, and get decent results, but I recommend you invest a few bucks more, the soup can will burn up after a few melts, stainless is much better on a budget...

 

[aart]

Quote: What happens to the paint on the soda cans when you melt them?

 

[MeepBeep]

What happens to the paint on the soda cans when you melt them?

The paint goes *POOF*

Beyond the paint on the can, an aluminum can is nearly all surface area, and once you heat it and remove the paint the entire surface oxidizes instantly, this creates aluminum oxide (aluminum rust) and is an impurity... But the good thing is that this dross (the term for the impurities when melting aluminum) is fluffy and light and instantly floats to the top so it can be scooped off before you pour, the pure aluminum pools below it...

Not absolutely necessary for most DIY backyard casters as most of the aluminum dross comes out fine on itself and floats to the top, but if you want to force it out right before pouring you can take a little bit of Morton 'Lite' salt it's a combination of two salts, wrap up a little bit in a piece of aluminum foil and toss that in the molten aluminum, it will act as a flux and clean the remaining impurities out forcing them to float up...

This is one of the drawbacks to using soda cans as an aluminum source, you get a lot of impurities, about 30% by weight will be waste... You will find most people turn to using old alloy car rims or aluminum engine blocks instead for cheap aluminum due to this, plus those aluminums are generally a casting grade and pour better...

 

[perchie.girl]

Quote:
I run propane for cooking and heating water at the house. But I like the idea of using charcoal.... and the blower.... The blacksmiths forge would have the firebricks too.... they are very teeny only enough to heat up a bar of steel. I took a horse shoeing class forty years ago. and forged my very own horse shoe from bar stock. I learned how to braise in that class as well. Not that I have done anything since with that knowledge... LOL.

all my ground is decomposed granite.... it would be simple to make a fire pit for work like this. I have been considering doing some wood fired pottery as well.... just reading about it...

deb