Tips Of Lathe Tool Bits Rolling Up.

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BarnyardEngineering

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After owning my Logan 815 lathe for almost a year I finally got to the steel yard for some 6061 aluminum round stock. Got a nice 3' long piece of 2-1/2" round.

My first project was a simple 3/8" thick "donut" to use as a motor mount spacer on the front of a model airplane.

Now I don't have much for tooling, mostly some Harbor Freight carbide bits and what little came with the lathe. I did purchase an Aloris-clone QCTP.

Far as I could tell the tool was dead nuts on center on the work, but I kept rolling up the tips. Ruined half a dozen tools the same way.

So what am I doing wrong? I watch many of the youtube makers religiously, and thought I understood the basics.
 
BarnyardEngineering said:
After owning my Logan 815 lathe for almost a year I finally got to the steel yard for some 6061 aluminum round stock. Got a nice 3' long piece of 2-1/2" round.

My first project was a simple 3/8" thick "donut" to use as a motor mount spacer on the front of a model airplane.

Now I don't have much for tooling, mostly some Harbor Freight carbide bits and what little came with the lathe. I did purchase an Aloris-clone QCTP.

Far as I could tell the tool was dead nuts on center on the work, but I kept rolling up the tips. Ruined half a dozen tools the same way.

So what am I doing wrong? I watch many of the youtube makers religiously, and thought I understood the basics.
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What do you mean by "rolling up the tips?" An easy way to see if you are on center for outside turning is to pinch your 6" scale gently and vertically between the cutting edge and the work. If the scale is standing vertical, you are on center, if the top is tilted toward you, the tool is too low, if tilted away, the tool is too high. If you are speaking of aluminum getting welded to the cutting edge and building it up with aluminum, WD-40 or kerosene used as a cutting fluid will help with that. Some of the Chinese brazed carbide tools are ground with poor geometry and the side of the tool will rub on the work. Check for that as well. If the steel below the carbide is rubbing it can be ground off on a normal bench grinder. You need diamond or silicon carbide wheels to grind the carbide. You say it is 6061. Is it factory stamped as 6061, and what is the temper (6061-T6, 6061-T651, 6061-T0, or whatever)?
 
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Im not sure what rolling up means. The above post covers some potential issues.I dont think your going to ruin a brazed carbide cutter on aluminum.I wonder if what your experiencing is the workpiece is not properly supported and its moving. If the work shifts it can cause tool chipping or breaking
 
seasicksteve said:
Im not sure what rolling up means. The above post covers some potential issues.I dont think your going to ruin a brazed carbide cutter on aluminum.I wonder if what your experiencing is the workpiece is not properly supported and its moving. If the work shifts it can cause tool chipping or breaking
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Try running the spindle in the wrong direction for the tool being used, this never works well.
Two weeks ago I set up a CNC lathe job to be run by an operator, not a machinist. 1000 parts with simple OD's on one end only, 3/8" crs turned to .220 diameter X .350 length.

Four easy steps.
Place part in chuck firmly against stop
Close door, turn on spindle and push start button
When cycle ends stop spindle, remove part
Chuck next part, if you encounter problems ask me for help.

I ran maybe 10 parts with him watching so that he had it down, after about 25 parts he tells me that the insert broke, a 55° screw down.
Sure enough it was broken in half at the hole, he had run the spindle in reverse.
 
By chance are you using the tool bit to cut the inside of the hole? If so then you need to raise the bit above the center so the it doesn't rub on the bottom. Can you post some photos?
 
If "rolled up" is material on the tool tip, that can be common with aluminum. Need to use some sort or cutting fluid. WD-40 as suggested above is one. Those HF carbide tools leave a bit to be desired, especially right out of the box, and you do need a 'green' (silicon carbide is what it is called) wheel to grind them on.
 
By "rolled up" I mean the sharp tip of the bit is bent upwards.

I just don't understand how it can bend UP when the force of the cut is DOWN.

This happened while facing and while boring. Spindle is turning in the correct direction. It does not even have reverse.
 
I am still gonna bet it is material build up. Take a scale, or small piece of metal or aluminum and carefully put it against the end of the tool, and or side matching the angle of the cutter. Then "roll" it on the cutting edge with a little pressure and the lip should pop off. At least that works for me when that happens. YMMV.
 
BarnyardEngineering said:
By "rolled up" I mean the sharp tip of the bit is bent upwards.

I just don't understand how it can bend UP when the force of the cut is DOWN.

This happened while facing and while boring. Spindle is turning in the correct direction. It does not even have reverse.
Click to expand...

Is it possible your tool is set too high? Maybe try lowering it a bit?
 
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