Cutoff Large Diameter Stock - How?

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Phil3

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I am using a Southbend 9' lathe and trying to use a cutoff tool in a QCTP to cut off a piece of aluminum 2.9" in diameter that has a .625 hole in the middle. The cutoff tool is .090" wide. This is not going well at all. The chatter is awful, the bit bit in once and stalled the lathe (belt slip), and the squawking is alarming. I have tried speeds from about 240 to 580 or so, with no improvement. Lubes don't help. I can't go any faster with this lathe, but can go slower in back gear. I have not had this problem before with the cutoff tool not so far extended and I expect that it hanging out there pretty far is the cause of the problem. But, if it is, how can I cut it off?

Phil
 
Bite the bullet and at least get one of those little 4" X 6" horiz/vertical bandsaws. I got 1 in 1974,and it was my only saw for years. Couldn't live without it. With a good blade,I have accurately cut iff 6" round steel by rotating it. Have a Roll In saw now,and a vertical contour saw,but for small stuff,I go to my little original saw. It is a Dayton. Not sure if it is USA or not,being that old. It still works just fine.
 
george wilson said:
Bite the bullet and at least get one of those little 4" X 6" horiz/vertical bandsaws. I got 1 in 1974,and it was my only saw for years. Couldn't live without it. With a good blade,I have accurately cut iff 6" round steel by rotating it. Have a Roll In saw now,and a vertical contour saw,but for small stuff,I go to my little original saw. It is a Dayton. Not sure if it is USA or not,being that old. It still works just fine.
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I have such a saw. I would use but don't know how to hold a 3/8" thick, 3" diameter piece in a chuck to face both sides. Would certainly prefer this way, but don't know how.

- Phil
 
Phil3,not sure what you're asking. If it's about holding small,odd shapes in the 4" X 6" bandsaw,I drilled some holes in the cast iron base that the metal rests on,between the vise jaws. Threaded them,and use milling machine hold down clamps to screw down smaller pieces of metal,leaving the part I want to saw sticking out in the downward path of the blade( POOR WORDING!!!!).

It has worked quite well. I can saw the corner off a 1 1/2" cube (for example) of steel at any angle I want. I couldn't have caught that in the vise before this modification. I can't cut off very short lengths of round stock with it,but it works fine for all sorts of odd pieces I need to saw. It is still the only saw I have in the shop that I can just clamp little pieces of metal in,letting the weight of the saw do the cutting,rather than having to stand there and shove metal against the blade. This mod only took a little while. Drill and tap the holes to fit your milling machine clamps.
 
Put a piece of half inch dowel in your tailstock chuck and slide it in the hole to hold the cutoff piece from dropping. Run the lathe as slow as possible and use a good sharp hacksaw with lube. It will cut fast and fairly smooth.
 
try running slow 120-150 rpm and try kerosene?

do you have any side relief and rake ground on the parting tool? you can also grind a very slight angle on the tip of the parting tool to help roll a chip, but it will try to make the parting tool deflect so you have to account for it.

I wouldnt use a hacksaw on a lathe while the lathe is running no matter how slow the lathe was turning, I like my arms and hands attached..
 
If the jaws on your saw are big enough just leave the piece clamped in the chuck and remove it from the lathe and clamp cheuck and all in the saw if the jaws want to twist cut a piece of scrap the same dia as the chuck and and clamp in the back of the jaws so they dont twist.The material still in the chuck and face it off.
 
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