turning cast iron

This forum is dedicated to those hobbyists with the 3-in-1 metalworking machines. Mill-Drill-Lathes. Tips, techniques, modification and use of these machines is topical.

Moderator: Harold_V

Post Reply
magicman
Posts: 5
Joined: Sun Apr 13, 2008 5:52 am
Location: Waterloo, Ontario

turning cast iron

Post by magicman »

Was going through a DVD on lathe operation other day and came across reference to turning cast iron and it stated that coolent was not needed. anyone able to respond/advise? Have never turned cast. Bought design/plan for copola and hope to try it.
Matt
Posts: 59
Joined: Thu Apr 05, 2007 11:12 am
Location: Chilliwack, BC, Canada

Post by Matt »

I have heard that is the nature of the material. With cast iron there is quite a bit of free carbon (forming graphite?) and it's this that does the lubricating. I have drilled a little bit of it and have never needed a lubricant.

Matt
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Post by Harold_V »

It is not only not required, it is not desirable. The dust from machining gray iron is horrible. You wouldn't want it mixed with anything that would transport it to places that are hard to clean, and would stick it down what is likely to be permanently. Coolant that was subjected to cast iron would quickly become black and coat everything it contacted.

As you alluded, the free graphite in cast iron serves to lubricate the cutting tools quite well.

One of the jobs I held after leaving the missile industry was a shop that produced floatation equipment, along with mining equipment and huge sump pumps. Cast iron was very much a part of their operation. We worked alternate two week shifts, dayshift and swing shift. At the end of the second week of swing shift, the entire shop shut down about a half hour early, so each machine could be washed down with Stoddard solvent to remove the accumulated crud. All cast iron was machined dry. I can't imagine using coolant, in spite of my extensive history of running flood coolant on machines.

Harold
Bill_Gardei
Posts: 611
Joined: Wed Jan 08, 2003 10:03 am
Location: Columbia TN, USA

Post by Bill_Gardei »

...I almost never use coolant/lubricant on any material
including cast iron. But then again I am never in a hurry.
Coolants and lubricants are great for production volumes
and very hard materials. Cast iron is not.

Bill
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Post by Harold_V »

Bill_Gardei wrote:...I almost never use coolant/lubricant on any material
including cast iron. But then again I am never in a hurry.
Coolants and lubricants are great for production volumes
and very hard materials. Cast iron is not.

Bill
There are operations that cry for lubrication in machining, regardless of the nature of your work. It need not be production to benefit by its use. A good example is tapping or reaming a hole. Turning or milling to close tolerance is yet another.

Flood cooling and lubricating is nice, but has its drawbacks as well. For one, it's typically quite messy. You can avoid the bulk of the mess by having a small container of lubricant at the ready, and apply it with an acid brush as required. It won't serve as a coolant, but the lowered friction of a lubricated cut does help keep heat down. That's a common method used by those of us that ran light production on machines where cooling wasn't important, but lubrication was.

There are not many operations that aren't improved with lubrication, especially when surface finish is considered. It also prolongs tool life, and can prevent broken tools. Think of parting when you consider that thought.

Harold
oldbrock
Posts: 142
Joined: Mon Apr 14, 2008 8:36 pm
Location: Castlegar. BC, Canada

cast iron

Post by oldbrock »

Cut it dry, wear a good quality mask and a hat. The carbon gets into everything and you will need to take a shower when you get in the house. Just machining a pair of rotors and I need to clean up. Peter
Jose Rivera
Posts: 3803
Joined: Wed Feb 21, 2007 9:21 pm
Location: Vallejo California

Cast iron

Post by Jose Rivera »

Here you can see pictures of cast iron being cut
http://www.chaski.org/homemachinist/vie ... hp?t=76409
16WhiteColly
Posts: 56
Joined: Thu Jun 04, 2020 2:59 pm

Re: turning cast iron

Post by 16WhiteColly »

Cast iron, machine dry, turn, drill, etc.
40 year retired machinist.
John Hasler
Posts: 1852
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: turning cast iron

Post by John Hasler »

Rig up a vacuum. It won't get everything but it cuts down the mess a lot.
16WhiteColly
Posts: 56
Joined: Thu Jun 04, 2020 2:59 pm

Re: turning cast iron

Post by 16WhiteColly »

I have used WD 40 when tapping, but no difference in the results of the thread finish.
40 year retired machinist.
Post Reply