Home made cast iron parts?

[neksmerj]

I'm sure this subject had been touched on before, but not in any detail.

I've done a quick search on this Forum, and have come up with everything, but not foundry casting.

Have any members cast their own parts in say grey cast iron, of had parts cast by a local foundry?

I presume the starting place, in either event, would be to make a model of the part. From there make a sand mould, melt some old cast iron, and pour.

I've simplified things a bit, and therefore, would like to know what's really involved.

The part I would like to make is the same size and shape as a thread chasing dial body, fairly complex with lots of curves, flats and radii.

Ken

[malb]

Ken, melting cast iron is not very easy, remember a full on oxy acet is working hard to heat small areas of it to red hot.

Once you decide exactly what you need cast, you need to make your pattern suitable oversized, and with 'runners' (molten metal reservoirs) incorporated to ensure an adequate ongoing flow of of metal to keep the casting solid as the surface cools and contracts. If the casting is to have any hollows, you also need core patterns for the hollow ares.

Then you go to the sandbox and make up all the mould for the casting, ancluding any core moulds. This involves the moulding boxes, green sand, and grapite powder as a release agent.

Then you estimate the mass of metal required to pour the casting, add maybe 40% for loss, dross and spillage, and source the metal and the crucible to heat it in, and the hardware to handle the crucible, hold it place in the furnace, and pour from it into the mould.

Finally you locate a suitable furnace, and all of the attendant safety gear, and attempt to melt and pour the metal. More than likely, either there is not quite enough, or the crucible heated unevenly in the furnace and the bum fell out of it when you went to lift it to pour.

Reasisticly, you can design the part in consultation with a patternmaker who will ensure that he can pattern it so that it can be case during the design phase. Then you could make the patterns yourself, again in consultation with the patternmaker, or you pay them to take the design and give you back an expensive raw casting that they have had cast for you.

Best reference I can suggest is Foundry Work For The Amateur by Terry Aspin. I used to have a copy but it was loaned a number of years ago and never found its way back home.

[Fossil]

Hi Ken,

I recently made inquiries in to casting, and decided that for iron, it was out of my league.
I want to get a new cross slide cast up, similar to the myford, so I can mount a rear toolpost. I have found a guy in Sydney that will pour the iron for me, for a carton of beer, however I am to make up the pattern for the job, and the timing has to suit his timing of other jobs, which is all ok by me. If you really want to go that route, I could slot your job in at the same time, though Hercus, being a south bend clone, should mean you could get the dial fairly easily from the states. I saw one go on ebay.au last week for twenty dollars or so.

[joe greiner]

Everything malb said. Although you may find aluminium works just as well, and melts at a lower temperature. Lindsay Books ( http://www.lindsaybks.com/ ) carries the late Dave Gingery's Home Metal Shop series, and I'm halfway certain they're available from book sellers in Oz. Probably in libraries too.

Joe

[Bodgy]

Ken

Like the others say, casting iron is a non trivial matter. Sure the method is the same as casting ally brass bronze etc., but the temperature involved is much higher. This means better furnace, better crucibles and far more expertise.

I'm getting on top of ally and brass casting, and although my furnace can melt iron it'll be a long time before I try to make anything sensible. Oh, and even when cast the part will need to be expertly machined from the rough cast.

Go with Fossil or just buy it. A single graphite crucible will cost much more than the part on EPay.

[neksmerj]

Hi Fossil,

Have sent you an email.

The South Bend thread dial gauges are slightly different in shape to the Hercus ones, and have the fixing screw underneath instead of in front. The casual passer by would not know the difference, but I would.

It definately seems by everyone's comments, that to attempt home casting would be foolish. Best left up to the experts, eh?

Ken

[snowyskiesau]

Metal casting is something I would love to try one day.
Most of the websites I've looked at cover aluminium or other non ferrous metal casting but there are a few that do cast iron as well.
The effort involved may be too much for just a few parts but as an ongoing hobby ...

Here's (http://home.iprimus.com.au/cmckeown/foundry.htm) one home foundry site from Cameron McKeown, and here's (http://members.optushome.com.au/terrybrown/) another from Terry Brown.

[Beerbotboffin]

Hi Neksmerj & Snowyskies,

Metal casting is not only useful & rewarding, it's damn good fun!

I built my furnace a few years ago, and it is still giving great service. Aluminium is no worries at all. I am in the process however of converting from gas fired to Waste Oil as the price of LP is just getting rediculous.

With Waste Oil, will be able to melt cast iron no probs (though the much higher heat destroys the refractory much faster). Also, I will have to get a new crucible as I don't want to cross-contaminate aluminium / iron.

It really is satisfying to have a need for a part, make a pattern for it and have it cast the same day (usually anyway). It's also quicker than trying to chase some obscure part that no one is interested in helping you find.

If you don't believe how easy it is, have a look at youtube - there are people on there from the subcontinent casting in dirt, wearing thongs! It's that easy. Though wear boots!!!!!

Beerbotboffin

[damian]

I have a ladyfriend in Sidinee who is a sculptor. Quite sucessful apparently. Anyway she gets lots of stuff cast at a local foundry. She does a lot of bronze and shrinkage is less of a problem with that, so you can use a sample as a pattern and it'll probably be near enough.

From a purely economic perspective it's not really worth it, but from an adventure perspective you might find it really rewarding. Just because I don't find casting attractive, nor would I do a 100 point restoration on a lathe, doesn't mean you shouldn't :)

Have fun.

[matthew_g]

If you are serious about metal casting go to this link and have a good look around.
http://www.backyardmetalcasting.com/ (http://www.backyardmetalcasting.com/)
The blokes name is Lionel and if you need to ask him a question or two he is most helpful.Matt

[Dano48]

Fossil, I recently finished machining my cross slide for an American Atlas 12x36, I got it sent from the USA for AUD$109.00 including shipping, if you're interested Ican look up the address for you,
Cheers,

[Fossil]

Hi Dano,

That cross slide looks fantastic! Nice work. :)
That is exactly the cross slide that I want on my lathe.

Thanks for the offer. I have been "going to" AKA GUNNA do the new cross slide for ages now. The casting of the item isn't an issue, as I already have a deal in place. The machining however is what is preventing me from getting in to it. I don't have a shaper or mill. :(

My Brother has all the gear, but he is too busy making millions of dollars to pay me back any favours.
I think I'll let it go until I get a mill. Hopefully before I die. :)

[Dano48]

Thanks Fossil, it took a while to get it there, I machined it in my micro mill, it wasn't easy I had to do it in stages, if you change your mind , here is the address check it out it has other things including castings for a back tool post!,
Cheers,
http://www.statecollegecentral.com/metallathe/index.html

[Buncha]

I think these guys would be willing to do a one off casting job.

A.W.Bell foundry
Work: 9799 9555
Work Address:
145 Abbots Rd.
Dandenong
www.awbell.com.au (http://www.woodworkforums.ubeaut.com.au/listingLink.do?url=www.awbell.com.au&logData=)

Cheers,
Buncha

[nine fingers]

Hi Ken, I have a mate in Geelong who set up a foundry, just to cast parts for a steam traction engine. The main castings were (cast iron) for the differential , he also machined and cut the gears him self.
With assistance from an Alcoa employee they cast aluminiun , bronze etc,in small quantities ,a weekend money maker.
He is not on the internet ,so if you wish to speak to him ,send me a PM.
regards nine fingers.

[jomac6]

Ken, melting cast iron is not very easy, remember a full on oxy acet is working hard to heat small areas of it to red hot.

Once you decide exactly what you need cast, you need to make your pattern suitable oversized, and with 'runners' (molten metal reservoirs) incorporated to ensure an adequate ongoing flow of of metal to keep the casting solid as the surface cools and contracts. If the casting is to have any hollows, you also need core patterns for the hollow ares.

Then you go to the sandbox and make up all the mould for the casting, ancluding any core moulds. This involves the moulding boxes, green sand, and grapite powder as a release agent.

Then you estimate the mass of metal required to pour the casting, add maybe 40% for loss, dross and spillage, and source the metal and the crucible to heat it in, and the hardware to handle the crucible, hold it place in the furnace, and pour from it into the mould.

Finally you locate a suitable furnace, and all of the attendant safety gear, and attempt to melt and pour the metal. More than likely, either there is not quite enough, or the crucible heated unevenly in the furnace and the bum fell out of it when you went to lift it to pour.

Reasisticly, you can design the part in consultation with a patternmaker who will ensure that he can pattern it so that it can be case during the design phase. Then you could make the patterns yourself, again in consultation with the patternmaker, or you pay them to take the design and give you back an expensive raw casting that they have had cast for you.

Best reference I can suggest is Foundry Work For The Amateur by Terry Aspin. I used to have a copy but it was loaned a number of years ago and never found its way back home.

Ive got a spare copy of Terry Aspins book "Foundrywork for the amateur"
If you need it send me an email [email protected]

[neksmerj]

Hi jomac6,

Have sent you an email.

Ken

[Fossil]

Hi again Ken.

There is one on ebay now. He has started bidding at $100.00 which seems a bit excessive IMO, but here is the link anyway.

http://cgi.ebay.com.au/Hercus-thread-chasing-dial_W0QQitemZ320264889242QQihZ011QQcategoryZ92083QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[neksmerj]

Hi Fossil,

Yeh, spotted that one myself, but at a starting price of $100, a tad over my budget!

All I can say is, it is a genuine Hercus unit, and they are scarce.

South Bend reproductions sell around the USD $50 to $60 mark, plus shipping.

No harm in asking, any member out there have a thread chasing dial they no longer use?

If maybe, please send me a PM.

Ken

[neksmerj]

Just supposing I had a sample of the part I wanted to make, in my hand.

I see two paths I could follow,

1. Make a drawing of the part, and then attempt to make a pattern, or have a pattern maker make one for me. Not the preferred option.

2. Use the actual part to make a mould, then cast a pattern from that.

I realise that shrinkage would have to be taken into consideration, but having said that, if a mould is the best way to go, what would I use as a moulding medium?

Plaster of Paris, pourable rubber, sand? Your comments are welcome.

Ken

[neksmerj]

There must be many members, who would love to be able to cast their own parts, in cast iron, or have it cast at a professional foundry.

I've had no response to my last question. Surely one of our members, will have the answer. After the Sunday night roast has begun to settle, please wack your gogs on, turn the computer on, and respond.

Beats having to talk to the missus, who's nodded off in front of the tellie, and should be doing the dishes, surely?

Ken

[joe greiner]

For cast iron, and similar melting-point metals, the final mould will have to be sand, I think. At an FSU Fine Arts demo several months ago, the sand medium was more robust, i.e. it had some cementitious properties that enabled more complex shapes of mould parts - several components of piece molds. I don't know the formula. I might be able to get more info from the professor.

I've used ordinary silicone sealant for a flexible mould for lead, but it didn't smell very good. Later, I used a similar material with higher temperature resistance for some production castings. That material is intended for sealing chimney pipes, but cost about US$10 per tube as of a few years ago. Note that lead has a much lower melting point than aluminium or cast iron.

To make an expanded pattern directly from the original, it might be possible to make several cycles of match castings in plaster of Paris. Plaster of Paris expands upon hardening, and each cycle of negative-positive etc. would be slightly larger than its predecessor. To some extent, the expansion ratio can be predicted or controlled. This is a somewhat clumsy, and probably obsolete technique. Most industrial tooling plasters have an objective of minimising expansion, so the proper product might be hard to find.

For a reasonably simple part, the simplest current technique is likely to make a 3D CAD model from your measurements of the original. The 3D model is then enlarged by the required expansion ratio, and "printed" via CNC Rapid Prototyping; there are service bureaus doing this in various materials and methods, and some of the CNC gang on WWF might provide more info.

Your best bet is to Google [patternmaker] within WWF. One of the members (Barry White, I think) is a patternmaker, and a few others too. A PM to him/them would provide more authoritative advice than any of my blatherings.

Joe

[malb]

The Aspin book has a good outline of the proceess and mix for the sand casting side of it. The sand has to be very very dry,and has a small percentage of a binding agent mixed into it. From my dicky memory, I am thinking Linseed Oil but could be way off the mark.

Fossil's post just after mention of the book got me going for a second or two, Aspin's book on ebay starting at $100. But then my pulse slowed as I realised that he meant a complete or near complete product, not the book. I had spotted it and sent Ken a PM earlier.

Ken, even if you had a casting as a pattern, I think you would need to consult a patternmaker for the actual pattern piece. The casting would be good reference for the patternmaker, but the issues of sizing, and whether to cast as a solid and risk chilling when you have to machine the bore, or coring the centre would need to be considered.

[Woodlee]

Just supposing I had a sample of the part I wanted to make, in my hand.

I see two paths I could follow,

1. Make a drawing of the part, and then attempt to make a pattern, or have a pattern maker make one for me. Not the preferred option.

2. Use the actual part to make a mould, then cast a pattern from that.

I realise that shrinkage would have to be taken into consideration, but having said that, if a mould is the best way to go, what would I use as a moulding medium?

Plaster of Paris, pourable rubber, sand? Your comments are welcome.

Ken

Ken,

If you have the original part have you thought about having it machined out of a solid lump of steel or aluminium billet on a CNC machining centre ?
Probably cheaper to grab that one off Ebay though.

Kev.

[Fossil]

Ken, have you seen the dials that this guy is selling?

http://cgi.ebay.com.au/Chasing-Dial-To-Suit-Hercus_W0QQitemZ260255787639QQihZ016QQcategoryZ92083QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[neksmerj]

Hi Fossil,

Yes, have sighted the unit in question, my concern is the exposed gear at the bottom.
Will hang out for something closer to the original.

Have nearly completed drawings taken from an original, with the intention of making up a pattern, and taking it from there.

Ken

[Beerbotboffin]

Hi Ken,

If you're not concerned about original parts, why not just cast in aluminium. It will be painted anyway (I assume), so you wouldn't know the difference. Structurally, I see no reason why aluminium wouldn't have sufficient properties.

One technique that has been used for years is to (allow for shrinkage / machining) is to 'enlarge' the relevant portion of the pattern (assuming you are using the original as a pattern). The problem with using the original part is the two part mould. Normally with a pattern, it would be in two halves (generally along a line of symmetry). With an existing part you obviously can't do this unless you're prepared to cut it in half.

I personally feel that drawing up the dimensions and making a new part would be the way to go. I'd also cast in aluminium (and that's precisely what I intend doing when i get a spare 5 minutes!)

The other options that would be valid are: Lost wax / investment casting (you can use your original part as a mould) or lost foam.

Hope this helps and I havn't forgotten anything, but the drugs are playing with my mind..........

[neksmerj]

Hi Beerbotboffin,

I'm not against using aluminium, provided it was fitted with some sort of bush.

I presume you recommended aluminium for ease of home casting. I've drifted away from home casting in preference to having a professional foundry do the dirty work.

Am exploring having a pattern made using the rapid protoyping method, and am waiting on quotes.

Good suggestion,

PM sent.

Ken

[Barry_White]

This is a reply I made to neksmerj (Ken) from a Private Message he sent me. I thought a few others might be interested in my response.

Hi Ken

I was indeed a Pattermaker many years ago but still have a lot of the knowledge. Cast iron is probably one of the hardest metals to cast apart from cast steel.

There are a couple of things you must consider first that are critical to getting it right.

I was not only a Patternmaker I also spent several years as an Inspector in a Cast Iron Foundry.

When making a pattern they are made from some timbers that the average person would never come across and amongst these are Yellow Pine, Sugar Pine, Jelutong and Beech.

When you make a pattern you have to allow for contraction of the casting as it is cooling and this is done by making the pattern using a contraction rule. The most difficult part about this is trying to source one and also there are a few different ones because different metals contract a different rates. I have done a Google search for Contraction rule and cannot find one reference but I am sure someone would still manufacture them and mine disappeared along time ago and I can no longer remember the contraction rate for cast iron although I remember the contraction rate for cast steel which is 1/4" to the foot which means all your measurements of the pattern would be that much bigger by that ratio.

The other problem with cast iron is when you cast it it is actually called white iron and is very brittle and it has to be annealed to take the brittleness out of it and that is a whole new can of worms and a technical process.

When making the pattern you need to allow a taper on it so that is can be withdrawn fro the sand mould and then you have to make a core box to the reverse of the inside shape of the casting so that you can make a sand mould of the internal shape and this is made from a different composition of casting sand so it can be handled with out damage.

After all this do you still want to attempt it

[kats1719]

Hi this is the one that i have it was made by A and R transmissions Roy Gross. No longer in business he used to make a huge amount of hercus replacement parts hope this 77361

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