making ali castings

[bigegg]

Time wise I would have thought it would be way faster to do it on a lathe. So it really comes down to is your time cost free? The solid aluminium wouldn't cost that much but if you compare it to scrap ali yes it costs a lot more.

I suppose I'm looking at it with my business head on which may not really apply here.

How long would it take to turn down a 6"x1" aluminium cylinder to a 2" diameter? Genuinely, I have no idea.

On a £200 hobby lathe (since that's about the cost of an "ongoing hobby" foundry + drill press), rather than a 2.5K Holbrook (or whatever)

 

[bigegg]

Making the styrene form , coating it with a melted, shaped & scraped wax & then doing the plaster shell can make a much cleaner cast . Especially if you pour some petrol inside the styrene form after the plaster has set dried off ..it will melt the styrene into the petrol which can then be poured off . there will only be a thin innse wax shell which will melt /burn out as in lost wax casting & thus allow a much quicker mould filling so allow for plenty of decent sized sprues & vents .

Leave it for a few days to lose the explosiveness of the petrol , put it in the sand box copes /drags etc .then cast away , the finish will be as smooth as the outer shell of the wax was . You can also be artistic in the wax if it is thick enough & put your details , dates or " Stolen from .... etc etc. on it so it is cast in the cast item .

Leaving the mould inverted over the foundry will burn out most of the styrene. (or in the oven on gas MK9 for a 5 or 6 hours, if you like sleeping in the shed - DAMHIKT!)
I've also burned out small molds with a propane weedeater.

I don't like petrol as anything other than a car fuel - it bites!

 

[Maker]

Acetone will dissolve polystyrene & blue/pink modelling foam, I never knew petrol did though (it smells like it should).

Can't remember what salt

Sodium carbonate.

 

[DAPPH]

I discovered the white polystyrene dissolving qualities of petrol when I did a self build five portal all steel barn from a precision manufactured kit.
The stanchion base anchor bolts were covered in blocks of styrene whilst teh floor was cast in situ , they were wired in position to stop them floating up out the concrete .
Rather than spend hours trying top pick the stuff out when it had dried my " rough diamond " mate said , " Watch this f****r and poured some petrol over it ..in a few seconds it had all dissolved leaving a nice clean setting up point to play with .

 

[Kent]

Time wise I would have thought it would be way faster to do it on a lathe. So it really comes down to is your time cost free? The solid aluminium wouldn't cost that much but if you compare it to scrap ali yes it costs a lot more.

I suppose I'm looking at it with my business head on which may not really apply here.

I have to agree and it don't cost nothing to melt energy wise either

 

[Rocketman]

How long would it take to turn down a 6"x1" aluminium cylinder to a 2" diameter? Genuinely, I have no idea.

On a £200 hobby lathe (since that's about the cost of an "ongoing hobby" foundry + drill press), rather than a 2.5K Holbrook (or whatever)

Wouldn't take long. You can take massive cuts in ali compared with steel. Just sounds like you could finish the job in a couple of hours by machining it and have a better pulley strength wise.

 

[Maker]

****** said in his first post that he wants the biggest pulley to be 10", Where on earth do you get 10" aluminium round (On a hobbyist type budget)? Casting is the ideal option.

 

[Rocketman]

http://www.blackburnsmetals.com/products-aluminium-bar-sections.html

Low grade 6 series won't cost much either

Edit - Quite likely they will have a off cut no one wants they will let you have cheap.

 

[Maker]

I cant seem to find a price on there, do they sell it in short (less than a foot long) sections?

 

[Rocketman]

I cant seem to find a price on there, do they sell it in short (less than a foot long) sections?

You can buy what ever length you want.

Cheaper ali grades work out £3-KG but like I say they have bins of off cuts so you might get a real bargain.

Edit - there of loads of non-ferrous metals suppliers TBH it was just one of the ones I have used for tooling ali.

 

[Maker]

@****** , How wide does each step of the pulley need to be (How wide is the belt?)? How many steps will be on it?

 

[Maker]

You can buy what ever length you want.

Cheaper ali grades work out £3-KG but like I say they have bins of off cuts so you might get a real bargain.

Offcuts might get you a bargain. Also, depending on how wide they need to be, it might be possible to get a drop of heavy aluminium plate, roughly cut out some circles, turn them perfectly round and bolt them together into a stepped pulley. I think your more likely to find a bit of thick alu plate than a section of 10" round.

 

[taycat]

noggin ends sell 16" dia alli by the inch.
but its £40 per inch.
it's a 1/2" belt and one pulley containing 3 steps starting 10" then 6.5" and last one 3".
then another of 10,8,6,and 4".
want to make one as it's a new skill to learn and along with swarf can get loads of small ali punch outs for scrap price.

 

[Maker]

Flat or vee belt?

 

[taycat]

v

 

[Rocketman]

noggin ends sell 16" dia alli by the inch.
but its £40 per inch.
it's a 1/2" belt and one pulley containing 3 steps starting 10" then 6.5" and last one 3".
then another of 10,8,6,and 4".
want to make one as it's a new skill to learn and along with swarf can get loads of small ali punch outs for scrap price.

That's not a horrendous price as it works out £4.40 a KG. I would hazard a guess (I have bought a shed load of ali over the years) on smaller diameter like 10" bar they will reduce the price per KG so you might be more like on a 10" bar £10 per inch.

But if it's new skills you are after it is irrelevant. Have fun casting

 

[taycat]

sorry looked at 10" 16" is actually £100 per inch.

 

[Maker]

3 meters of 9&½" aluminium bar from Parker steel is £1400, that's £3.50 per Kg. You should get a length, make loads of pulleys and sell them on eBay for a profitMaybe not.

 

[Rocketman]

sorry looked at 10" 16" is actually £100 per inch.

The most expensive ali in the world

 

[bigegg]

Acetone will dissolve polystyrene & blue/pink modelling foam, I never knew petrol did though (it smells like it should).

"molotov cocktail" and "napalm"


both real world applications of polystyrene dissolved in petrol.