Working with cast iron, what is different?

projectnut said:
Years ago, I made the MLA-21 5C collet chuck from a kit offered by Andrew Lofquist. The casting was good quality and cut easily with HSS. More recently I ordered a semi-finished 10" chuck backplate on eBay. There was a world of difference between the castings. The backplate was nearly impossible to cut with HSS and was full of hard spots. I switched to an old, cemented C2 carbide tool purchased many moons ago from Enco. It cut the casting like butter. If you know the material is from a good source, I wouldn't hesitate to use HSS tooling. However, if you suspect the material was from an offshore source, I wouldn't attempt HSS, but rather go straight to C2 carbide.
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Bought the cast iron from Speedy Metals. They seem to be the least expensive source buying by the inch. No idea of the quality.
 
I've only done one large turning project with cast iron. I needed to modify a backing plate for a Pratt Burnerd chuck. I was very strongly advised beforehand to cover up every possible nook and cranny the dust could get into. Here's how I approached the project:

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Glad I took the precaution. That stuff got everywhere. A word of (obvious) caution: Turning was at very slow RPM's with particular attention to keeping spinning parts away from cloth.

Regards

P.S.: What's the paintbrush trick?
 
tjb said:
I've only done one large turning project with cast iron. I needed to modify a backing plate for a Pratt Burnerd chuck. I was very strongly advised beforehand to cover up every possible nook and cranny the dust could get into. Here's how I approached the project:

View attachment 393930View attachment 393931View attachment 393933View attachment 393934View attachment 393935View attachment 393936View attachment 393937View attachment 393938

Glad I took the precaution. That stuff got everywhere. A word of (obvious) caution: Turning was at very slow RPM's with particular attention to keeping spinning parts away from cloth.

Regards

P.S.: What's the paintbrush trick?
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Photo courtesy of @wachuko
View attachment 393939
From what I understand it reduces some of the problem.
 
projectnut said:
Years ago, I made the MLA-21 5C collet chuck from a kit offered by Andrew Lofquist. The casting was good quality and cut easily with HSS. More recently I ordered a semi-finished 10" chuck backplate on eBay. There was a world of difference between the castings. The backplate was nearly impossible to cut with HSS and was full of hard spots. I switched to an old, cemented C2 carbide tool purchased many moons ago from Enco. It cut the casting like butter. If you know the material is from a good source, I wouldn't hesitate to use HSS tooling. However, if you suspect the material was from an offshore source, I wouldn't attempt HSS, but rather go straight to C2 carbide.
Click to expand...
My first project on my lathe was a cast iron backplate. I ordered from CDCO cdcotools.com it had no inclusions. It was not hard.

C2 is not the grade to use on CI. I believe C6 is, or if using inserts, check the manufacturers charts.
 
All the photos:

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IMG_2464.jpeg

This kept all the cast iron dust from my face and surroundings.... one of the best advices that I have received in this forum...
 
When I've machined cast iron, I cover the ways near the chuck with aluminum foil: it conforms easily to the areas you want to
cover and if by any chance it gets caught in the moving parts it will just shred. I also set up the hose from my shop vac
adjacent to the work so that the majority of chips are sucked up rather than going everywhere else.
 
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Guess the fun will begin. Two pieces of cast iron arrived. Both oversized. The 2 x 2 x 3 is coming out as 2.3 x 2.3 x 3.1 or so. The 5" piece is around 1/8" diameter oversized and about 1/8" longer than promised. Should be fine. Skin doesn't seem too bad from my inexperienced eyes. They look nicer than I expected. Will start on the rectangular block first. Thanks for the tips!
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Good thing Speedy Metals packs well. The box was quadruple wrapped in filament tape, was a bugger to open up.

UPS dropped the small heavy box crushing one of the box corners. In my experience, if a box is mangled, UPS delivers it stealthily to avoid human contact. All other times, you can see them coming and going. I'll look at the material under some magnification for cracks. Not expecting any, but might as well look before starting machining!
 
woodchucker said:
My first project on my lathe was a cast iron backplate. I ordered from CDCO cdcotools.com it had no inclusions. It was not hard.

C2 is not the grade to use on CI. I believe C6 is, or if using inserts, check the manufacturers charts.
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Things may have changed over time, but when i was looking for tooling to turn cast iron C2 was preferred. According to the 2008 Enco catalog "C2 is for Cast Iron and nonferrous materials". "C5 or C6 is for steel and steel alloys"

I saved a copy of the catalog for the "Primer" section at the beginning of each tooling section. It gives the preferred material type, profile, coating and other pertinent information to take into consideration when ordering tooling for specific materials. I'm sure that in 14 years some information has changed, but the old recommendations still work.

To John's point no cutting fluid was used.
 
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