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Working with cast iron castings.

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kellswaterri

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#1
Hello All,
I build model steam engines from casting kits, the castings are un machined, and I work to drawings. Some kit suppliers cut their tolerances pretty fine making a bit of an adventure, now I do not know much about the different types of cast iron but this stuff leaves me looking like a coal miner. If you put in a search for ''corncrake'' my Photobucket album should appear, the large 10'' cast iron flywheel had a skin on it that had to be under cut with an angle grinder, very hard to get through, but turned fine otherwise. I used a combination of Glanze insert tool and tipped tools...how would you guys approach machining castings like these.
All the best for now,
John.
 

Shade

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Hello All,
I build model steam engines from casting kits, the castings are un machined, and I work to drawings. Some kit suppliers cut their tolerances pretty fine making a bit of an adventure, now I do not know much about the different types of cast iron but this stuff leaves me looking like a coal miner. If you put in a search for ''corncrake'' my Photobucket album should appear, the large 10'' cast iron flywheel had a skin on it that had to be under cut with an angle grinder, very hard to get through, but turned fine otherwise. I used a combination of Glanze insert tool and tipped tools...how would you guys approach machining castings like these.
All the best for now,
John.
Cast iron is dirty and mill scale can be very hard, sound like you have normal CI, I hate the stuff and avoid it as much as possible.
 

kellswaterri

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Hi Shade,
I could use aluminum or plain steel but the models just would not authentic, as you say it is dirty stuff to work with. I always use a good full face filter mask with cartridge and even then it manages to get up my nose. The cold spots and scale can be a real nuicance,
All the best for now,
John.
 

Chester

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Need advices on removing old rust on cast iron parts, old lathe stand. Equipment I have is a 4 in hand grinder, general motor buffer and bench grinder. From reading on this site, it seem some people use WD 40 and a wirer wheel. Is this good way to go? Chester
 

nivlek

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I worked for several years in an iron casting repair facility (continuous oven preheat, fusion welding, and machine shop) and in my experience, it is always good to use a shop vac and hold the hose nozzle right down to the area that is being machined.

Also, with cast iron, cover the ways when you can, use a shop vac with the finest cage filter you can get, an old sock or two over the hose bib inside the canister can help catch the big stuff and pre-filter the powdered stuff before it gets to the cage filter.

If you're using a big diameter facing mill or a large fly cutter, (> 5 inches) stay out of the way and put your fan on it to blow the dust in the desired direction while wearing a dust mask. Just dont breathe any more than you have to, and protect the ways as well as you can.

For 12-13 years I went home every day with some iron dust in my clothes... When you work around iron, you can taste it when you lick your lips at any given time. After awhile, you wont even notice, sorta like when you live by the train tracks, you dont notice the train after a couple years!

Summary: Dust management.

Regards.
 

ScrapMetal

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#6
Need advices on removing old rust on cast iron parts, old lathe stand. Equipment I have is a 4 in hand grinder, general motor buffer and bench grinder. From reading on this site, it seem some people use WD 40 and a wirer wheel. Is this good way to go? Chester
I would just dump the part(s) in a bucket of Evaporust and let it sit for a few hours. The stuff isn't exactly cheap as I paid about $23 for a gallon of it the other night at an auto parts store but I think it's worth every penny.

It's non-caustic and non-toxic. I've been known to de-rust smaller items on our kitchen counter (the wife isn't exactly happy about this though).

Hope that helps,

-Ron
 

Flammable_Solid

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#7
Need advices on removing old rust on cast iron parts, old lathe stand. Equipment I have is a 4 in hand grinder, general motor buffer and bench grinder. From reading on this site, it seem some people use WD 40 and a wirer wheel. Is this good way to go? Chester

I would go for sand blasting it. Using a wire wheel will stick small piece of steel into the exterior of the casting, possibly causing you additional corrosion problems down the line.
 

Chester

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I would go for sand blasting it. Using a wire wheel will stick small piece of steel into the exterior of the casting, possibly causing you additional corrosion problems down the line.
Will those cheap harbor freight guns work good, or should I take it somewhere to have it done? Thanks for your reply, Chester
 

swatson144

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#10
I often buy cheap import indexable tool holders that come with inserts. I just use the inserts that came with them for busting rust and mill scale. 5 tools with inserts for 20$. They actually work pretty good on a small lathe with good inserts.

Steve
 

kellswaterri

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#12
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.
 

Flammable_Solid

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#13
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.

What type of cast iron are the sprue from? Grey? Ductile? White? It sounds like most of the issues people here are running into is they are trying to machine cheap cast iron that wasn't innoculated properly, so it is carbidic on the surface and required grinding to start machining.

Sprue (or the runner system) is going to have some slag, sand, and shrinkage in it as well, regardless of the material cast.

If you'd like a full tutorial on cast iron, let me know.
 

kellswaterri

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#14
I have not a clue as to breed of castings, only too glad to get it...getting material where I live is a nightmare...bronze and cast iron has to be imported from england and is very costly, thank you Flamm for the heads up on the material,
John.
 

Chester

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I often buy cheap import indexable tool holders that come with inserts. I just use the inserts that came with them for busting rust and mill scale. 5 tools with inserts for 20$. They actually work pretty good on a small lathe with good inserts.

Steve
I order a gravity feed gun and soda blast media, anything else I should know or advice from anyone, please send it. I will give update when I get it, and when i get started. Never did this before and I am little uneasy.

- - - Updated - - -

I would just dump the part(s) in a bucket of Evaporust and let it sit for a few hours. The stuff isn't exactly cheap as I paid about $23 for a gallon of it the other night at an auto parts store but I think it's worth every penny.

It's non-caustic and non-toxic. I've been known to de-rust smaller items on our kitchen counter (the wife isn't exactly happy about this though).

Hope that helps,

-Ron
Thanks Ron, but I would need 5 to 10 gallons to set it in, so I am going to try a cheap HF sand blaster gun. I will keep evaporust in my mind for a smaller project, thanks for your advice, Chester
 
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ScrapMetal

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#16
I order a gravity feed gun and soda blast media, anything else I should know or advice from anyone, please send it. I will give update when I get it, and when i get started. Never did this before and I am little uneasy.

- - - Updated - - -


Thanks Ron, but I would need 5 to 10 gallons to set it in, so I am going to try a cheap HF sand blaster gun. I will keep evaporust in my mind for a smaller project, thanks for your advice, Chester
Understood. I just hate using my sand/soda blaster as it is MESSY like nothing else on this planet. Oh, also found out that blasting soda will kill your grass in a big way. Don't ask me how I know...

-Ron
 

Chester

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Understood. I just hate using my sand/soda blaster as it is MESSY like nothing else on this planet. Oh, also found out that blasting soda will kill your grass in a big way. Don't ask me how I know...

-Ron
Ron, good to know this about the grass, I was planning to use my backyard. I do like my grass and my garden very much, is there something else I could do, or sand blasted with? Thanks, Chester
 
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Chester

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Please tell me your feeling on using soda to sand blast with, or what do you like to use? Chester
 

ScrapMetal

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#19
Sorry Chester, I've been kind of preoccupied the last couple of days. I'm far from an expert on blasting and blasting media but to my knowledge the answer is, "it depends...". :biggrin:

Straight soda blasting is great for cleaning things like carbon, soft paint and grime off soft materials like aluminum without damaging it. I don't think that's what you want to try for removing rust from cast iron, for that I think you will need something a bit more aggressive. Here is a little bit on the differences on Eastwood's site.

Depending on just how rough your cast is you may also have issues leaving behind some media on the iron so you'll have to be extra careful to clean it up or suffer very short tool life. I'm sure there are others here with far more experience on cast than I have.

Hopefully that helps a bit,

-Ron
 

Chester

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#20
J
Sorry Chester, I've been kind of preoccupied the last couple of days. I'm far from an expert on blasting and blasting media but to my knowledge the answer is, "it depends...". :biggrin:

Straight soda blasting is great for cleaning things like carbon, soft paint and grime off soft materials like aluminum without damaging it. I don't think that's what you want to try for removing rust from cast iron, for that I think you will need something a bit more aggressive. Here is a little bit on the differences on Eastwood's site.

Depending on just how rough your cast is you may also have issues leaving behind some media on the iron so you'll have to be extra careful to clean it up or suffer very short tool life. I'm sure there are others here with far more experience on cast than I have.

Hopefully that helps a bit,

-Ron
Ron, what do you think of aluminum oxide for rust, and do you have any concern with this media? Will it work in a gravity feed gun? I want to thank you for your help. I am lost here, and that means I spend a lot of money on wrong things. Like to get the right materal and equipment at least the second time around, I usually get in right on sixth or seventh time. Chester
 

Flammable_Solid

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#21
J
Ron, what do you think of aluminum oxide for rust, and do you have any concern with this media? Will it work in a gravity feed gun? I want to thank you for your help. I am lost here, and that means I spend a lot of money on wrong things. Like to get the right materal and equipment at least the second time around, I usually get in right on sixth or seventh time. Chester

Aluminum oxide will be OK, other than it's more expensive than sand.
 

ScrapMetal

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What he said. :+1: The aluminum oxide is fairly aggressive so "in theory" you would need less of it than you would some other material that is not as aggressive like sand.

I'd go with the aluminum oxide.

-Ron
 

Chester

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What he said. :+1: The aluminum oxide is fairly aggressive so "in theory" you would need less of it than you would some other material that is not as aggressive like sand.

I'd go with the aluminum oxide.

-Ron
If I do this outside and clean up and wash everything down, could there be a residue that could harm my dog? Chester
 

ScrapMetal

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#24
Not unless your dog has a taste for sandpaper (aluminum oxide). ;) Basically, you'll end up with your blasting media (be it aluminum oxide or a silica based "sand"), iron oxide, iron, paint, crud, and anything else that might be on the piece you're blasting. Nothing that could really be much of a hazard. Soda blasting, on the other hand, leaves all that soda on everything. Probably not good for anything's health in high quantities.

Oh, another little "warning" - If you're not using a cabinet this crap goes everywhere! Do not do it anywhere near your (or especially your wife's) car/truck. Covering your vehicle in abrasive material is not a good idea. Make sure the wind is blowing it away from anything you have an attachment to, preferably towards that neighbor's place (whom you don't like too much). :biggrin:

-Ron
 

Railway Bob

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#25
Unlike steel, aluminum, brass, or bronze which create nice curls of swarf, machining cast iron is like machining a block of sand - grains of dark coal-like cast iron fall off of the work like sand falling off of a sand core. The only way to machine cast iron is with a bit of elbow grease and lots of perserverance. Keep the vac handy so that it doesn't get all over your machines. Some people lay a cloth on the ways of their lathe as the cast iron filings are like putting a bucket of sand on the machined surfaces.
 

4gsr

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#26
Take the cast iron shavings (dust) mix it in with your fertilizer and spread it over your yard. Your grass will thank you for it!
 

Chester

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Not unless your dog has a taste for sandpaper (aluminum oxide). ;) Basically, you'll end up with your blasting media (be it aluminum oxide or a silica based "sand"), iron oxide, iron, paint, crud, and anything else that might be on the piece you're blasting. Nothing that could really be much of a hazard. Soda blasting, on the other hand, leaves all that soda on everything. Probably not good for anything's health in high quantities.

Oh, another little "warning" - If you're not using a cabinet this crap goes everywhere! Do not do it anywhere near your (or especially your wife's) car/truck. Covering your vehicle in abrasive material is not a good idea. Make sure the wind is blowing it away from anything you have an attachment to, preferably towards that neighbor's place (whom you don't like too much). :biggrin:

-Ron
Ron, I have a small green house, 5' height 3' witlh and 2' depth. I think I could make this into a cabinet, it is covered in heavy clear plastic over plastic rods. I may have to replace plastic rods with 1/2 in. copper pipe. Bought this at a hardware store for maybe 30 dollars, was going to used it to grow my own tomatoe plants from seeds. Thanks, Chester
 

Ray C

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#28
CI that's not been de-glazed is tough to work on and eats carbide like popcorn. Most folks will "pickle" the CI in muriatic (hydrochloric) acid which pretty-much dissolves the glaze. I've never done this but it's a known common practice. I don't know the concentration that's used but I do believe that George Wilson and/or others know the answer. It's commonly available at many places and pretty cheap.

Of course, CI is loaded with carbon and pickled or not, it's going to make a mess. I'm not fond of machining it but have done it many times. It's really sexy looking stuff once it's been surface ground though... Have a look.

Back 1.JPG

Ray

Back 1.JPG
 

4gsr

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#29
One of my first jobs as a engineer/designer, after I left the machine shop and school, was to design (copy) a cast iron bridge plug that we use in the oilfield for plugging oil wells with. The entire plug is made of class 40 gray iron. I thought I knew every thing about cast iron, that was an under statement. Thirty years later, I'm still learning! Anyways, one of the things I was involved with was machining of cast iron by turning and drill/milling. The newer generation of machinists have no clue how to machine cast iron as their grandpa's and great grandpa's did 60 plus years ago.

We talk about how abrasive cast iron is and how it tears up cutting tools. The biggest reason for this is not applying the proper speeds and feeds. Cast iron cuts best when you hog it with high feeds and slower surface feet than that of mild steel. It likes broad nose tools, taking shallow depths of cuts, with coarse feed for finishing. It likes sharper pointed tools with good nose radius taking deep cuts with coarse feeds. Fine feeds is what kills the edge on cutting tools cutting cast iron. When you use this approach the "skin" that everyone talks about is not an issue.

In our world of today, it's unheard of to use the old method of tooling that was used in the old days. Today, we use super coated carbides and PDC tipped tooling to cut cast iron. If done correctly, you can still hog it, in fact, you want to hog it with high feed rate with as deep of cut as you can take. Finish cut need to be done with coarse feed too with large nose radius tools. But the HSM usually doesn't have the luxury of doing all of this. A lot of excellent advice has been given and I wont repeat any of it. But hog it every chance you can within reason and you'll be surprised how much more your cutting tools will last.

One last suggestion, I prefer to cut it dry, but if you insist on cutting it wet, use flood coolant.
 

scwhite

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#30
One of my first jobs as a engineer/designer, after I left the machine shop and school, was to design (copy) a cast iron bridge plug that we use in the oilfield for plugging oil wells with. The entire plug is made of class 40 gray iron. I thought I knew every thing about cast iron, that was an under statement. Thirty years later, I'm still learning! Anyways, one of the things I was involved with was machining of cast iron by turning and drill/milling. The newer generation of machinists have no clue how to machine cast iron as their grandpa's and great grandpa's did 60 plus years ago.

We talk about how abrasive cast iron is and how it tears up cutting tools. The biggest reason for this is not applying the proper speeds and feeds. Cast iron cuts best when you hog it with high feeds and slower surface feet than that of mild steel. It likes broad nose tools, taking shallow depths of cuts, with coarse feed for finishing. It likes sharper pointed tools with good nose radius taking deep cuts with coarse feeds. Fine feeds is what kills the edge on cutting tools cutting cast iron. When you use this approach the "skin" that everyone talks about is not an issue.

In our world of today, it's unheard of to use the old method of tooling that was used in the old days. Today, we use super coated carbides and PDC tipped tooling to cut cast iron. If done correctly, you can still hog it, in fact, you want to hog it with high feed rate with as deep of cut as you can take. Finish cut need to be done with coarse feed too with large nose radius tools. But the HSM usually doesn't have the luxury of doing all of this. A lot of excellent advice has been given and I wont repeat any of it. But hog it every chance you can within reason and you'll be surprised how much more your cutting tools will last.

One last suggestion, I prefer to cut it dry, but if you insist on cutting it wet, use flood coolant.
 
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