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22nd March 2012, 10:03 PM #1SENIOR MEMBER
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Casting about for cast iron casting ideas
Now say that title again, only quickly ... I'm thinking of trying some cast iron in the not too distant future and would like any ideas for things to make in iron.
About all I can think of at the moment would be two sets of arbor supports for a certain Eastern European milling machine (yes RC, I haven't forgotten you either ) and maybe a 60cm I beam style straight edge as they are supposed to perform better than camelbacks. My local casting guru tells me he has a sack of zirconium flour for coating the moulds to prevent any nasty hard silicon carbide forming on the surface. Apart from that it should be on a par with casting bronze in that iron melts a bit higher in temperature.
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22nd March 2012, 10:28 PM #2
How bout a new compound slide for Blondie?
But seriously, I have cast brass and al before but to cast iron is sort of the holy grail for me. I'd be making a good range of vises, maybe some Kingway tool parts, a grinder rest or two....the list goes on.
Ewan
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22nd March 2012, 10:48 PM #3
Are you thinking cast iron or cast steel?
Out of interest how will you get the metal to pouring temperature?
and what will you use as the casting medium?regards from Alberta, Canada
ian
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22nd March 2012, 10:59 PM #4SENIOR MEMBER
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Ueee, there's a few aluminium alloys a lot stronger than cast iron, don't know how they age though. It'd be nice to make an aluminium vise with steel on all the wear surfaces
I'll be using iron, steel will ignite into a foamy mess in a gas fired furnace with lots of sparks, smoke and a visit from the fire brigade so it's ruled out unless I get a nice secondhand induction furnace with an inert gas cover.
The furnace is a gas fired one and the moulds will be made of resin bonded silica sand.
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22nd March 2012, 11:15 PM #5
Hi Graziano,
How about a few shaper vises, I can do smallish pours of cast iron, but nothing near enough for a decent shaper vise.
I'd be thinking of making a cupola...
Regards
Ray
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22nd March 2012, 11:53 PM #6SENIOR MEMBER
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23rd March 2012, 12:01 AM #7
Hi Graziano,
Shaper vises come in all sizes, 10 or 12" would be a pretty fair size. I'd guess all up weight might be in the 80 - 100 kg range, an A20 crucible, would be 20 pounds or is it 20 kg of bronze, I can never remember.
Anyway, it's not relevant, it would need to be a fair bit bigger for what I was thinking.
You mentioned cast steel throwing sparks and fumes? I've never tried casting steel, but with the cast iron, I mix in layers of charcoal and soda ash with the cast iron, when loading the crucible, to form a layer that stops oxygen from stripping the carbon out of the cast. Would that same approach work with steel?
Regards
Ray
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23rd March 2012, 12:39 AM #8SENIOR MEMBER
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The A20 would be 20Kg of bronze, it really needs two people to pour it easily.
I understand steel casting is even more specialised than stainless steel, if molten steel doesn't have some kind of gas blanket it can react with air and actually ignite with oxygen, foaming up and overflowing the crucible. In the old days of crucible steel they used green glass chips to melt and form a covering a bit like a flux layer but I don't know if they were pouring it out of the crucible after making the steel. Charcoal might react with the steel and form cast iron instead of steel.
The guy who's teaching me definitely doesn't want to revisit the experiment after the last time and rates it as worse than the time they had accidentally fed a piece of scrap magnesium from an old Victa mower base into the furnace.
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23rd March 2012, 12:56 AM #9
Hi Graziano,
I can imagine magnesium would be a bit of excitement, I actually bought some magnesium ribbon with the idea of adding it to a cast iron pour, they do this in foundries when producing SG cast iron, the magnesium acts as a nodularizer, but what they do is have a special capsule of some kind that they submerge into the molten cast iron, luckily common sense came to the rescue before I tried throwing magnesium ribbon into the crucible...
You can buy nodularizers from foundry suppliers, but I can't recall any brand names, I haven't yet got around to trying it.
Ask your mate if he knows of some product names or suppliers of nodularizers.
Regards
Ray
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23rd March 2012, 10:18 AM #10SENIOR MEMBER
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Ray, if you sealed the magnesium in a bit of steel tube, it should make it into the molten iron without igniting, there are some bronze additives that are sealed in copper tubes for that purpose like phosphorous.
I've been looking at Budget Casting Supply in the States as they seem to supply small quantities that I'd need. Getting various additives in pre Internet days was a major hassle, even now the local foundry suppliers want to know how many pallets of a particular additive/inoculant you want to buy off them. I was looking for calcium silicide to add to the cast iron which should be a grain refining agent such as they use for making mehanite iron.
Anyway the plan is to use a good source of machinable cast iron such as diesel engine parts and see how it casts without any additives: when it was originally cast it would have had grain refining agents added and should still retain those original properties. If I was melting old barbecue parts and manhole covers I'd be inclined to start adding calcium silicide to try and get something machinable.
Another item I was thinking of making would be a cast iron surface plate around 40x40 cm in size.
Cheers,
Mark
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23rd March 2012, 05:52 PM #11
Hi Graziano,
The straight edge idea, is a good one, Suburban make a beam type straight edge.
Are you thinking of this style..
CAST IRON STRAIGHT EDGES by Suburban Tool, Inc.
Do you think you could do 36"?
Regards
Ray
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23rd March 2012, 07:28 PM #12SENIOR MEMBER
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That's kind of like what I had in mind, maybe with a taller web for increased rigidity and a wider base so that dovetails could be machined into the sides of the base. I was thinking of maybe 60cm maximum as I can then use a local surface grinder to grind the bases flat. 36" would be do-able, just not machinable by me.
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23rd March 2012, 07:51 PM #13SENIOR MEMBER
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I made a rough pattern for a 750mm one to get some pricing on a casting. Didn't look too bad so making the proper pattern is almost at the top of the project list, as soon as I finish painting the boat interior. I have to dig out the small table saw anyway so I can cut the tapered timber I need to get a pattern that comes out of the sand cleanly. The big saw doesn't do tapers (rise & fall only) and I hate resetting the big band saw when I've other alternatives.
When I get back at the end of next week I'll revisit this, see if I can get the patterns done. My thinking was to make some with flat edges and some with a bottom wide enough to mill for spotting dovetails.
900mm would be possible but 750mm is the biggest I could mill. Once I get my new surface plate though, in theory 1m should be possible on the table diagonal - I think.
PDW
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23rd March 2012, 08:21 PM #14Distracted Member
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23rd March 2012, 08:54 PM #15.
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I just looked at the prices. I understand the desire to make your own. Does a parallel straight edge have any great advantage over the more attractive camelback design such as this one by Deming?
◥◣36" DEMING CAMEL BACK 45° DOVETAIL STRAIGHT EDGE◢◤ | eBay
BT who has not been to the scape fest and knows nothing.
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