What causes his "Pock Marked" finish ??

just a guess, chips impacting on the cut surface, either just friction or being crowded by following chips.
 
Low RPMs and it looks like you're not using any coolant or lube.

Turn at 800-1000 RPM. Feed rate is OK. Cuts are very light so you'll see the tracking of any/all imperfections in the cutting edge.

Also, tell us how the piece is supported and how the tool is positioned.

Ray
 
Ahh, more RPM's, interesting.
I need lube cutting aluminum ??
The piece is supported in the chuck and with a live center.
The tool is at 90*, I was getting cut lines so I rounded the bit to get a better finish,
Rounding the bit helped, now the cut lines are very light.
 
Using inserts, make sure they are sharp inserts. Speed up as suggested. Use kerosene or WD40 as lubricant. Use a deeper cut.

For that job I would prefer a very sharp HSS cutter with plenty of rake and clearance, still higher speeds, but not as much as for the carbide. The cut should be about as deep as the nose radius.

It appears to me that the metal is tearing instead of cutting.

Think sharp, plenty of relief, and lubricant.
 
Gregg what brand and model of lathe? Also, what flavor of aluminum
I second Bob K above- try HSS tool
Mark
I've never had that issue and I just have a cheezy little Atlas
 
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GreggC said:
Ahh, more RPM's, interesting.
I need lube cutting aluminum ??
The piece is supported in the chuck and with a live center.
The tool is at 90*, I was getting cut lines so I rounded the bit to get a better finish,
Rounding the bit helped, now the cut lines are very light.
Click to expand...

Yes, coolant or lube for AL. Without coolant or lube, it can/will weld to the tip of the insert.
SFM for aluminum is anywhere between 100 and 150 so, with 1.2" dia and carbide inserts, you need 800-1000 RPM. RPM for carbide = 8 x SFM/dia.

If you have OK ventilation, one quick light spray of WD-40 will work. You will get some fumes though. Be mindful of how much smoke you generate in the shop. Long term, it catches-up with you.


Ray
 
I have zero experience with HSS cutting tools,
Can anyone make a suggestion what to buy ??
Maybe hand hold me and post a link ??
 
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