Author Topic: Cast iron ''SPRUES'' can they be of use to the model machinist?  (Read 15230 times)

Offline kellswaterri

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Hi all,
visited our local Railway Museum Engineering workshops today...after a wander around and a bit of a chat I left with a fairly large and heavy bag of bits of bronze and cast iron...the cast iron was the cut off ''SPRUES'' from castings done in the workshop foundry...I intend to give them a try after first giving them a good going over with an angle grinder...what do you guys think?
John.

Offline chucketn

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #1 on: August 12, 2013, 07:14:59 PM »
They could be a grat source of cast iron for pistons and the like for small engines...
Are they good quality under the skin? How big are they?

Chuck

Offline kellswaterri

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #2 on: August 12, 2013, 07:40:26 PM »

Hi Chuck, some about the size of a large orange, some of apple size, they all have an attached leg of 3/4'' diam.I will be giving them a going over with the angle grinder before I try to cut them...heres hoping :noidea:

Offline spuddevans

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #3 on: August 12, 2013, 09:30:01 PM »
what do you guys think?

I think that they will be absolutely useless, you should immediately package them up and send them to me for safe disposal  :Lol: :Lol: :Lol:


Tim
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Offline tangler

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #4 on: August 12, 2013, 09:36:42 PM »
Sprues, being the connection of the casting to the outside world, will be the first bits to solidify so there is a chance that they have chilled and will be hard but otherwise they should be the same quality as the rest of the casting except perhaps for some dross on the surface exposed to the air.  What a nice gift. 
Cheers
Rod

Offline ths

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #5 on: August 12, 2013, 11:52:01 PM »
I'd expect chilling at the 'outside' end of the spruce. Begin machining from the 'inner' end, you'll soon find out how much is usable.

Hugh.

Offline b.lindsey

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #6 on: August 12, 2013, 11:55:04 PM »
John...given their size and shape, what are tiy hoping to machine from them? Just curious.

Bill

Offline Maryak

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #7 on: August 13, 2013, 01:22:49 AM »
Hi John,

I built a mill engine using sprues and cast offs for the main parts, (cylinder, base, valve chest, piston). One thing they are not good for is piston rings.

If you want the best result machine off the hard skin and then let them rust away in a corner for a while to age them.

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline b.lindsey

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #8 on: August 13, 2013, 01:50:40 AM »
Bob, I know we joke some about castings "aging" under the workbench, etc., and I understand what you mean about machining the hard outer skin off...but what exactly is the science behind letting a cast piece of iron age?  What does it actually do to the metal by allowing it to oxidize?

Bill

Online Dan Rowe

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #9 on: August 13, 2013, 02:35:00 AM »
They take a skim cut on the Sulzer diesel cylinder liners for the same reason and set them in the back field for a year or so. This normalizes the the stress in the casting before machining the liner to finish dimensions.

Dan
« Last Edit: August 13, 2013, 02:41:24 AM by Dan Rowe »
ShaylocoDan

Offline Maryak

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #10 on: August 13, 2013, 02:45:22 AM »
Hi Bill,

It's my understanding that aging cast iron castings is for stress relief of the metal brought about by the casting process. Heat treatment is another option to achieve the same thing but requires equipment not normally found in a home workshop. i.e. something to bring it to 600C and hold it there for a while to ensure all of it is at that temperature and most importantly allow it to cool down evenly. Usually done by allowing it to cool inside the furnace as the furnace cools down.

For the hobby machinist chucking it under the bench for a year or so is a much cheaper and easier process.

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline derekwarner

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #11 on: August 13, 2013, 06:10:13 AM »
From an OZ trained old school point of view.....

1. A sprue riser tube diameter irrespective of ?? length is calculated relative to the mass of the casting in question
2. The cooling rate in the sprue will have been greater that the mass of the casting
3. Irrespective of the quality of the iron blend.........the differential [chilled] cooling effect will have altered the structure of the iron in the sprue riser
4. One would suspect skin effect hardness as others have noted, you may also find greater carbon under the skin

Burying them in the back yard [as messes Rolls & Royce did with cast iron engine blocks] :naughty: will not change the metallurgical composition of the iron....again it will simply dull [normalise]  the in cast stresses created at the initial cooling post casting.............Derek
« Last Edit: August 13, 2013, 06:38:55 AM by derekwarner_decoy »
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Offline Jo

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #12 on: August 13, 2013, 08:00:42 AM »
Heat treatment is another option to achieve the same thing but requires equipment not normally found in a home workshop. i.e. something to bring it to 600C and hold it there for a while to ensure all of it is at that temperature and most importantly allow it to cool down evenly. Usually done by allowing it to cool inside the furnace as the furnace cools down.

Sticking it in the centre of a bonfire can work, and provides a long cooling time. ;)

Jo
Usus est optimum magister

Offline Maryak

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #13 on: August 13, 2013, 08:36:26 AM »

Sticking it in the centre of a bonfire can work, and provides a long cooling time. ;)

Jo

As Mr Fawkes would say all of us Guys bow to the feminine touch.  :ThumbsUp:

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline kellswaterri

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #14 on: August 13, 2013, 12:02:22 PM »

Hi folks,
            thank you all for your comments, as Tel would say...thats a gnarly one or two or... now I know why there was a large heap of them lying outside the shop...I will try and clean up some of the shanks first, they could be used for piston material...the larger bits,I will have to Glare at them while I have a cup of coffee, the glare might be enough to make them behave.