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Lathe Threading
开云体育Quick question.? Both MACH2/3 use a 1 PPR index for threading.? Don't know about MACH4.? LinuxCNC requires both 1 PPR for the start of the G-Code and after that requires the multiple pulses for speed/position tracking. ? My understanding with LinuxCNC is that if the spindle speed changes it's detected very quickly and the Z axis velocity is changed to maintain the position relative to the spindle position.? Thinking of a thread as really just a really long hypotenuse of a triangle.? In other words it's tracking the spindle 'position' from the encoder pulses (in addition to velocity) and makes sure the Z follows that position. ? Since a 1 PPR can change speed between revolutions I would expect that MACH also just tracks speed of the spindle?? What would happen if the spindle speed was changed between passes?? Like you did a feed hold at the end of a pass with the tool retracted.? Changed the spindle speed.? Then start again.? ? Since the acceleration is fixed does MACH calculate a new acceleration ramp to enter the existing thread at the same spot? ? John Dammeyer ? ? ? "ELS! Nothing else works as well for your Lathe" Automation Artisans Inc. www dot autoartisans dot com ? |
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I am using LinuxCNC for threading because of the issue you have mentioned. With Mach3 I was getting incorrect pitch on the first 2 turns because of the load slowing down the motor. LinuxCNC does a beautiful job. you can hold the chuck to slow the lathe and it keeps cutting perfectly. I have a 70mm disc with 60 slots, one deeper with two slotted photo interrupter to pick up the two pulses
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开云体育Thanks. ? Yes, like my ELS, a fundamental rule for 1 PPR threading is that the spindle must not change under threading load. ?Normally that's not a lot anyway with a few thou per pass.? And my ELS does do minor compensation for Z axis motion if the spindle changes speed but of course nothing is detected for a full turn. ? More wondering if there is a difference if feed hold is hit and if then the spindle speed is changed. ? LinuxCNC with the index and quadrature does much better. John ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Rob Carr via groups.io
Sent: January-18-21 3:29 AM To: [email protected] Subject: Re: [MachCNC] Lathe Threading ? I am using LinuxCNC for threading because of the issue you have mentioned. With Mach3 I was getting incorrect pitch on the first 2 turns because of the load slowing down the motor. LinuxCNC does a beautiful job. you can hold the chuck to slow the lathe and it keeps cutting perfectly. I have a 70mm disc with 60 slots, one deeper with two slotted photo interrupter to pick up the two pulses |
开云体育Does MACH4 not thread with a 1PPR sensor? John ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Dan Mauch
Sent: January-31-21 11:03 AM To: [email protected] Subject: Re: [MachCNC] Lathe Threading ? I have succefully used mach4 several times to encoder cut various thread on my lathe. It works fine. Here is a video? |
开云体育Yes, Mach4 does thread with a 1ppr sensor. ? From: [email protected] <[email protected]> On Behalf Of John Dammeyer
Sent: Sunday, January 31, 2021 2:36 PM To: [email protected] Subject: Re: [MachCNC] Lathe Threading ? Does MACH4 not thread with a 1PPR sensor? John ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Dan Mauch ? I have succefully used mach4 several times to encoder cut various thread on my lathe. It works fine. Here is a video? |
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Mike Blake
开云体育
On 1/02/2021 3:02 am, Dan Mauch wrote:
I have succefully used mach4 several times to encoder cut various thread on my lathe. It works fine. Here is a video?Nice work, although maybe you might want to think about a tripod or stabilizer for the video's :-)
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