Cutting Copper on a Lathe.... need input.

[MychesterCNC]

I have a little Taig lathe, I've just been using it for fun, cutting different pieces and so on- now all of a sudden I can't get a smooth cut no matter what- the only thing I changed is I went from cutting aluminum and brass to cutting copper- I've tried (brand) new cutters (same as before, but sharp) different speeds, and I've researched every "chatter" and "cutter" (types, hardness, cutting angles) related video and article I could find online. Here's the Youtube video (sorry about the poor quality, but I figured an "eyes-on" look by someone who knows their stuff is the best way...) and you can see first hand what a horrible pass I'm getting.

After I posted this in the Taig section a few days ago, and someone told me about a "hook" shaped bit, I tried that and I'm now at about 90% the way to a smooth quiet cut, are there any other tips for cutting copper that I could do/try to get a cleaner, smoother cut as I got with aluminum and brass?

Any input would be greatly appreciated! (Below is the original video I posted to show the severe gouging and rough surface (with a LOT of noise) that I was getting).

YouTube - REDNIKON TAIG PROBLEM.MOV

[packrat]

It looks like you have no clearances on your tool bit. Here is a basic primer in tool grinding; http://www.sherline.com/grinding.htm

Also you normally cut toward the head stock/chuck not away from it.

Copper is "stickier" than brass and aluminum and tends to weld/gall the chip back on to the part. There should be both more top clearance and a nose radius on the tool bit.

If you don't have anyone to help you learn about running a lathe here are some books on basic lathe operation; http://www.lindsaybks.com/bks/lathebk/index.html
Even though not for your brand of lathe, the basics haven't changed no mater who built the lathe.

[sasf]

Have you used a coolant and the slowest speed possible, coolant can really help the finsih. Go watch the videos at Smithy.com, they has some good examples and videos that really help the beginner. Smithy also has a very good latheing and Milling coolant that improves the finish and tool life tremendously.

Steve
SASF

[Shane123]

feed towards the spindle, use a tool with a relief on it, and turn your tool post to only use a corner to do the turning instead of dragging the flat on it.

[jeffrey001]

Look at this video, not for copper but the will work with any material.

TOOL BIT GRINDING #1 South Bend Atlas Lathe tubalcain - YouTube

TOOL BIT GRINDING #1 South Bend Atlas Lathe tubalcain - YouTube

Jeff

[sasf]

Shane123, is your cutting bit exactly aligned with your tailstock?

[Shane123]

i have never checked if it is aligned with the tail stock. I have only checked the tail stock to the spindle and the spindle to the ways.. I have a 2 piece aluminum tool setter with level in it, so i can set my center and edge. I can spec if out and take photos tomorrow at work if you like......

[sasf]

to cut copper-you must have a bigger radius on your tool bit and it must be exactly on centerline of the work-piece. coolant helps.-art

[Shane123]

i use insertable tooling whenever possible, mainly sandvik. .015 radius works good for me...
but my tooling is all centered off the 2 piece gauge.

[H.A.S.]

For what you are cutting, I'd use High Speed Steel blanks. The video posted above pretty much explains clearance angles, relief, radii. I've threaded copper pieces 3" dia., threaded portion was 16" long, and RPMs of over 600, all day long. Takes practice.