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| Thread cutting on a Stanko 1A616 |
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| ksor:
--- Quote from: Ned Ludd on November 30, 2013, 06:47:38 PM ---Hi Ksor, If the formula does not produce a deep enough thread,could it be that you need to go twice the dial reading. The reason is that the convention on a metric lathe is that the cross slide dial reads in diameter reduction not actual movement, so to get a specific depth you have to double the dial figure. Ned --- End quote --- Yeah, I have thought about that as you can see on my web site (only if you can read Danish OR you did the translation AND the Google translation is good enough :palm: ) but this doesn't Work either - the 'best' result is somewhere between ! But IS this formula OK: Cutting Depth = Pitch * 0,8660 - maybe this formula is wrong - I just found it on the internet :scratch: :scratch: I wonder why the diameter is NOT a part of the formula as a sort of min and max limits - obviously you can't do a thread with a Pitch=2mm on a diameter less than 4mm - it has to be much larger. :loco: - right ? |
| Ned Ludd:
Hi Keld, Are you going straight in or off set top slide cutting? If going straight in, 0.866 X pitch would be about right, but if going in at an angle the top slide movement would be close to the pitch as it is an equilateral triangle. Figures are only close to theoretical as the thread is not a perfect triangle because of the flats at crest and root (for Metric and US threads), but should give a good starting point. Ned PS with the cutting insert you appear to be using, going straight in would not cause any problems because of the chip breaker design, but cutting close to a shoulder might be problematical. |
| ksor:
--- Quote from: Ned Ludd on December 01, 2013, 11:39:04 AM ---Hi Keld, Are you going straight in or off set top slide cutting? If going straight in, 0.866 X pitch would be about right, but if going in at an angle the top slide movement would be close to the pitch as it is an equilateral triangle. Figures are only close to theoretical as the thread is not a perfect triangle because of the flats at crest and root (for Metric and US threads), but should give a good starting point. Ned PS with the cutting insert you appear to be using, going straight in would not cause any problems because of the chip breaker design, but cutting close to a shoulder might be problematical. --- End quote --- At this one I was going "strait in" - in next sample I'll try to set the compound slide to 28-29.5° and the try to match a factory made nut :med: :med: |
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