Working with cast iron?

[JackG]

Hi All,

I’m starting a Kerzel hit & miss engine. The cylinder and piston are cast iron; however I’ve never worked with this material before. For those who’ve used cast iron, are there are any ‘tricks of the trade’ or things I need to know or look out for when working with it? I’ll be using a Sherline lather and mill.

Thanks,
Jack

 

[Tin Falcon]

cast iron is not hard to machine
follow published speeds and feeds to start with
recommend machined dry or air cooled.
tends to have small chips powdery shop vac while machining will keep things clean and chips off the ways.
Tin

 

[stevehuckss396]

Clean up your machine after every use. CI will rust fast and leave spots/stains on your machines.

 

[jonesie]

watch when using unknown grades of cast iron some scrap cast iron can be hard,window weights cast cart wheels can be tough to cut on a small lathe. good cat iron cuts good with carbide or high speed toolbits. you will end up with fine dust and try to keep from breathing to much, dust mask helps. it is like cutting carbon. good luck jonesie

 

[moconnor]

Hello:

Before I set-up to turn cast iron on my lathe, I protect the ways and the area near the work with aluminum foil. It can easily be formed into temporary chip shield and really saves on clean-up time afterward. Another tip: wipe down the lathe before hand of any oil film where it is not needed. The fine chips and swarf from cast iron can really fly and they will stick to anything that is oily.

It is absolutely necessary to do a thorough clean-up afterward to remove all traces of the chips, swarf and cast iron dust. There is probably nothing worse for your lathe than to not clean it up after working with cast iron. The carbides in the iron will rapidly wear the sliding contact surfaces and when mixed with oil, you might as well have put lapping compound on your ways.

Hope this helps.

Regards,
Mike

 

[Steve_Withnell]

Cast Iron is a good to machine, but it is very dirty. Concur with all the remarks about dust everywhere and the dust turning into a lapping compound. if the cylinder is cast iron, then I'd personally use a sharp HSS tool and run very slowly. This produces a very nice finish.

Comment on sash window weights is interesting, before about 1930 (+/-10), the weights are an excellent quality source of CI, afterwards, they became horrible, full of hard spots etc.

 

[rake60]

I'm allergic to nickle so every time I cut grey cast iron my eyes get extremely irritated
and sometimes have some minor breathing problems.

It actually had me at the hospital emergency room several times when cutting it on
an industrial scale at work.

A Shop Vac nozzle over the cutting tool sucks up most of the fine dust in my hobby
shop to keep things more comfortable for me.

While coolant isn't necessary for cutting most cast iron alloys, I would saturate it at work.
It didn't hurt the iron and kept the nickle in the dust from becoming air borne and
making be miserable.

Rick

 

[tel]

Personally I find Cast Iron a joy to work. The bit of a mess it leaves behind is a small price to pay. As for sash weights - I have had a very good run with those as well, occasionally get one with a hard skin (chilled) but once you get beyond that .....

 

[Harold Lee]

If you have felt in your apron way wipers, make sure you remove them and give them a good cleaning too. The CI dust can become embedded in there and continue to grind on your ways. I would use a kerosene soak and then a good soak in way oil IMHO. I'm sure there are many methods that others use but whatever they are do not neglect giving them some attention.

Harold

 

[Captain Jerry]

I have been working with cast iron quite a bit lately and I like it so much that I am building two engines with cast iron in place of brass in all locations that would normally think would be brass or bronze. I am using cheap brazed carbide tools, carefully sharpened and diamond honed. They are used dry and at higher than normal HSS speeds. the results are good but I have noticed something strange. It is not necessary to take a second cut to clear tool spring back. On a second pass, no more material is removed. There IS no spring back!

I am beginning to doubt the concept of tool deflection and spring back. When I cut steel I get spring back. When I cut brass, I get spring back. When I cut aluminum, I get a lot of spring back, even on the third and fourth pass. I don't think it is TOOL spring back. I think it is MATERIAL spring back. I think the softer metals deflect away, I don't mean bend, I mean more like depress. I think the harder more crystaline cast iron doesn't deflect,

Am I right...maybe.?? ???

Jerry

 

[Maryak]

I am beginning to doubt the concept of tool deflection and spring back. When I cut steel I get spring back. When I cut brass, I get spring back. When I cut aluminum, I get a lot of spring back, even on the third and fourth pass. I don't think it is TOOL spring back. I think it is MATERIAL spring back. I think the softer metals deflect away, I don't mean bend, I mean more like depress. I think the harder more crystaline cast iron doesn't deflect,

Am I right...maybe.?? ???

Jerry

3 out of 4 maybe : ;D

Best Regards
Bob

 

[Captain Jerry]

Another fact about cast iron. I cuts nicely with a hacksaw. No drag on the blade, no binding in the cut. BEWARE!! There is no warning that the cut is almost through. Most metals start to sound a little different at the end of the cut and the off cut piece starts to bend away from the kerf. Not so with cast iron. The cut ends abruptly and your hand crashes into the vise.

I learned this a few weeks ago. #$%#$@@! I learned it again day before yesterday. %^#%##! I learned it again today. ##$%@@!!
I guess I'm just untrainable!

Jerry

 

[JackG]

Thanks for the thoughts. The main points that I glean from this is:
• Clean up afterward
• Don’t use oil or other cutting fluids

Other than that, it's easy. Anything that I missed?

Jack

 

[arnoldb]

Jack, that's pretty much it.

You'll end up with nice black fingers because of the high graphite content in CI, but as others have said, it's really easy to machine if there are no chilled spots in it. You can machine it fairly quickly as well; just be careful at sharp corners; CI is brittle and will break easily on sharp edges.

One other thing to beware of - if you get cast iron bar stock, the chances are good that the outer skin might have inclusions (sand/slag and so on) - if you need to clean that off, go for a good deep first pass and try to get under that skin. If you use HSS cutters, be prepared to re-sharpen your cutter after that pass. Once through the crud, it is a lovely metal to machine; in fact, I prefer it over all others including brass.

Regards, Arnold

 

[petertha]

Does anyone have experience with cast iron in terms of it being better or worse than leaded/free machining steel like 12L14 when it comes to making relatively thin + deep grooves for cylinder fins? Seems like when you scale down real world engines to model size, the equivalent groove width works out very thin dimensionally & difficult to machine, at least thats the feeling I get. Would Durabar CI be a good material choice in this regard?

 

[GailInNM]

I recently did several small cylinders with fins 0.030 inch wide with 0.040 inch spacing and 0.250 inch deep. I used a P1-N 1mm wide parting tool set up with no back rake and 7 degrees front rake. Tool tip height was set with a dial indicator as was the side to make sure it was parallel to the lathe cross slide travel. Material is standard class 40 cast iron barstock from Enco or Speedy metals.

Photo was to show something else, but it is the bast I have showing the fin detail.