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- Dec 25, 2011
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- 10,477
The reasons that cutter height is important or even critical are many.
But the most important two are that if the cutter is much too low the cutter will tend to dig into the work piece or be pulled. Given that even with all brand new parts there is some backlash in the cross feed screw to nut (the threads must have some running clearance or they will bind). This allows the cross slide to move a few thousandths toward the work. And can sometimes can cause chatter which will result in poor to very poor finish.
If the cutter is too high, the front of the cutter will rub against the work because the cutting edge won't be touching the work. So the cutting edge should almost always be dead "on center". There are relatively inexpensive gauges available that make putting the cutter dead on center easy. The most common style is a plastic block with a bubble level vial in it. The front of the gauge is a 90 deg. "V" with the legs of the "V" in the vertical plane. The "V" touches the work above and below center. The bottom of the rear of the gauge bisects the "V" and rests on top of the cutter. To use, you hold the "V" against the work and the bottom of the rear down against the top of the cutter, and raise or lower the cutter to center the bubble.
370592279135 on eBay is a cheap example. 25276252479 is a better one (I have one of these). 252762525452 is a different way of doing it. This might be used with a collet setup if the work was for example too short to use the front "V" type on. I have one of these, too.
Anyway, however you do it, the BXA is just too large for your lathe. You should as soon as you can switch to an AXA. If you are a little lucky, you might find someone with a 14" who has an AXA set that he would swap for your BXA set.
But the most important two are that if the cutter is much too low the cutter will tend to dig into the work piece or be pulled. Given that even with all brand new parts there is some backlash in the cross feed screw to nut (the threads must have some running clearance or they will bind). This allows the cross slide to move a few thousandths toward the work. And can sometimes can cause chatter which will result in poor to very poor finish.
If the cutter is too high, the front of the cutter will rub against the work because the cutting edge won't be touching the work. So the cutting edge should almost always be dead "on center". There are relatively inexpensive gauges available that make putting the cutter dead on center easy. The most common style is a plastic block with a bubble level vial in it. The front of the gauge is a 90 deg. "V" with the legs of the "V" in the vertical plane. The "V" touches the work above and below center. The bottom of the rear of the gauge bisects the "V" and rests on top of the cutter. To use, you hold the "V" against the work and the bottom of the rear down against the top of the cutter, and raise or lower the cutter to center the bubble.
370592279135 on eBay is a cheap example. 25276252479 is a better one (I have one of these). 252762525452 is a different way of doing it. This might be used with a collet setup if the work was for example too short to use the front "V" type on. I have one of these, too.
Anyway, however you do it, the BXA is just too large for your lathe. You should as soon as you can switch to an AXA. If you are a little lucky, you might find someone with a 14" who has an AXA set that he would swap for your BXA set.