Cast iron

[mitch_prest]

has anyone tried cutting cast iron with their bot.. I have a piece of cast that I would like to take a couple thou skim off.. is it possible or will I just be breaking more bits...

mitch

[dlcw]

By accident I drove a 1/4" Super O through one of my clamps that was cast iron. Clamp won, bit lost....

Don

[mitch_prest]

score one for the no side....

[navigator7]

Has the cast already been machined or would you be machining through the casting skin or outer surface?
The outer surface is very hard.

I'm not a bot owner yet but as a former machinist, I don't think you can reduce the cutter head speed enough nor do you have the machine rigidity.
Machine rigidity was always a problem even with mills and shapers designed for the task.... Especially on a light first pass. The goal being to cut through the hardface on the first pass.

My experience with cutters was limited to HSS and some carbide.

BUT?????

If you could mount a suitable grinder to your Z ...
....or mount the part to the Z and the grinder to the table????

I've never seen a grinder used in a climb cut.

If I was to try something like that I'd want to locate the part as close as I could to either end of the gantry.

HTH
Good luck!

[mitch_prest]

the surface was previously machined.. it has some corrosion that I wanted to get rid of.. I had thought of the grinder idea.. mounting it rigidly to the bot may be an issue.. I have a magnetic table so the mounting the part is not a problem.. I have a 3/4 inch bit with a single cutter I was going to sacrifice.. how slow would I need to get the spindle ..

mitch

[navigator7]

I'm guessing as slow as your spindle turns.
Your feed rate is a guess on my part. Slow.
I went by ear and chips.
Your chips should look like graphite.
I'm guessing you may see sparks.

Removing rust?

Coke, Naval Jelly, Iron-Out, vinegar, Hammerite Gel, Ospho, a wire wheel, or a soft grinder pad?

[mitch_prest]

its more than rust.. slight pitting... more that a wire wheel can fix..

I am not sure how slow the HSD spindle can go and still have enough to keep turning.. maybe someone else has some experience there..

[navigator7]

What is the application and the need for a machined surface??
Rust is really hard too...but brittle.
I don't see the risk/reward going well for you....especially if your tool slips, your part moves or you goof with the machine.
If it's already machined, there are file techniques that can produce superior finishes and no risk.
Cast files very nice.
(Except for the surface.)

[bcondon]

Hey Mitch,
I would recommend getting a decent belt sander 3x21" with paper $40 (Sears) and take your time...

I love my machine WAY too much to take the chance you are talking about!

Chuck... I have a full metal machine shop from my Dad which is just sitting there...I wished I listened to my Dad and worked more with him in the shop... He did metal, I did wood, now I have BOTH shops and need to get some education on the metal side. I am not sure if the local technical schools still teach metal working with lathes and millers...

[shoeshine]

LOL Bob, What a delightful problem to have

[navigator7]

@ Bob,

There is a 1935-ish book by South Bend. It's called How to Run A Lathe.
Lindsey Publications is making reprints.
This book covers all the basics with the exception of carbides.
That's a start.

For me...the toughest part of the learning curve was to plan all my work so as to leave the part in the chuck or in the mill until completion of the machining.

I'm assuming you have one off machines and no CNC stuff.
CNC has caused the price of one-off machines to plummet.
It used to be a cnc machine couldn't do a one off part and make money with all the programing involved but I think that has really changed.

The other side of machine work is welding, brazing and silver soldering.
Finding your niche with metal is tough. You have to be good fast and cheap and know what jobs to turn down.
All fun stuff...unless you are upside down in the rain and snow shocking your self senseless trying to get a project done by zero hour.

[clueless]

What size cutter are you planning on using? If we know that, we can get you the speeds and feeds. I've cut a lot of cast iron, not on a bot, but with manual and CNC machines. Shouldn't be a problem at all if you can get the RPM down. Just need to know your endmill size and what the piece is. There's a big difference in cast iron used for making various things and cast iron that's been exposed to high heat. It can get very hard. Not too hard to cut, but hard. If it wasn't exposed to high heat, like on an exhaust manifold, it'll cut fine.

[mitch_prest]

i would probably use a 4 flute 3/8 end mill .. the piece is a small cast head..

and bob... I have a number of the south bend publications in pdf...

[mitch_prest]

here is a url with the south bend books..
http://www.wewilliams.net/SBLibrary.htm

[clueless]

A safe place to start would be 3,000 RPM with .3 inches per minute if I calculated that right. It's been a long time since I did that calculation so I hope my memory serves me correctly. Let us know if it works out.

[navigator7]

@ Mitch

OIC!
A cast head.
You need a perfectly flat sealing surface beyond the pitting to interact with the head gasket to hold combustion gases.

I hope this thread doesn't serve to ruin the fun. My naysaying peers are my best motivators.

If the Bot was adept at machining cast I'm sure it would be advertised. There is nothing like the right tool for the job.
Even SB's own specs on it's machine are out of the tolerances one would expect to find after paying money to surfacing a head.
I had know idea you wanted results! ;-)

If your SB does make chips, more than likely a dome shape of around .002 will be created.

That is a job for a surface grinder or a ridged machine design for the purpose.

Now that I know what your goal is.....and if you still are intent upon this....i'd consider a grinder versus and end mill.

You'll need a fixture and a diamond tool to true the wheel.

On the other hand, Like Dirty Harry said: A Man has Got To Know His Limitations!

Who are we to limit you? :-)

I saved this steam engine from the jaws of death, hanging lifeless from a rusty rotten choker hooked onto the teeth of a loader bucket....waiting for the scrap steel bin to clear.

7058
Instead they dropped it in my pickup truck. Score!!!

With a Jet mill and a Southbend 9: lathe, I rebuilt the machine and ran steam through it.
Damn was it beautiful! The castings were a work of art.

7059
I rebuilt the fly ball governor by making new parts, machined the D-Valve, honed the steam cylinder made new piston rings, and poured new babbitt bearings.
Steam is so much fun! Particularly rebuilding old stuff.
My hobby was buying old time stuff and repairing it and selling it.
The steam engine netted me 4K for a two weeks worth of work that occurred over a four month time frame.

7060

[myxpykalix]

I like the before and after pictures. You have to have a good bit of knowledge and commitment to ressurect something from the dead. Most people would look at that thing for the scrap metal.I like the bottom picture as it looks like a good impression of rube goldberg and one of his contraptions.Good job.

[mitch_prest]

glad to see I am not the only crazy one... anyone can take a head down to the machine shop and get it ground... my goal is to test the limitations of what I can do with what I have available... the grinder attached to the Z axis might be the way I end up going...

I really like that band saw ...

[bcammack]

What are the dimensions of the piece? I used to true up the head/block mating surfaces on "tiller motors" for our racing karts years back. I aspired to a granite surface plate, but settled for a heavy piece of flat glass, sitting on my workbench.

I taped a sheet of 3M wet-or-dry sandpaper on it, shot some light oil on the paper, and slid the piece 'round and 'round until I was satisfied with the result. Just be certain to put the piece down on the paper _gently_!

[clueless]

Without question, a surface grinder would be the correct tool. But I've never seen not having the right tool for the job stop a botter yet


Cool project Chuck, well done.

[navigator7]

@ Jack,
You are spot on!
That's exactly what the loader operator said: "What do you want this POS for?"

@ Mitch,

I've been thinking about your goal. You have quite a few options with the mag table but you might need some fixtures. One might be a 90º plate slotted on both surfaces. There is a name for this thingy but I forget. Most machine shops build their own. A surface grinder mounted to the Z takes the load off your machine. However, a quality grinder is very pricey. The used market for things like that was best from people who didn't know what they had. Like I said, the availability of cnc machines trashed the one-off market. Forget trying to mount a hand grinder. What is needed is like a spindle mount and a 90º attachment for the grinder....securely attached with minimal cantilever.

The bandsaw hubs were wallered out. I built up with nickel brazing rod and machined bearing pockets; Built a tensioner; the mechanism that adjusts the table was gone and there was no height adjuster or blade guides. It too was a POS. I built the boiler in the background. It was rated at 10HP and ran on diesel or kerosene. What you probably can't see was a kit model steam engine somebody gave me. A 1/4 steam hose is hooked up to it. You could blow on the inlet and the engine would turn. Just think of the steam engine our politicians could power?? ;-)

I was just goofin' around in the pic. I went to the leather store and asked for 4" leather belting 14' long. The lady looked at me and in a dead pan voice said: "Sir, they don't make cows that long!"

I'm still laughing.

@ Brett,
A lapping table?
Figure 8's isn't it?
One of my precious toys was a granite tombstone and scribe used for scribing lines into plates to be machined. I had a Loupe that magnified where the scribe lies crossed. The loupe had cross hairs like a rifle scope. It was amazing how far off you'd be eyeballing and by feel with a regular punch. You removed the magnifying glass and inserted a punch and tapped it lightly with a small ball peen. You picked up the dent later with a quility punch and a proper blow.
I can't believe I sold it all to get into 3D CAD and buy Macs. ;-(