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can linux cnc can cut a thread using only breakout board without using mesa card
- Dinuka_Shehan
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11 Jul 2019 15:57 #139113
by Dinuka_Shehan
Replied by Dinuka_Shehan on topic can linux cnc can cut a thread using only breakout board without using mesa card
I think you have the code for the PP for threading .
What is PP?
What is PP?
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11 Jul 2019 16:23 #139114
by Clive S
Replied by Clive S on topic can linux cnc can cut a thread using only breakout board without using mesa card
PP = parallel port. I think you said you using one with a simple bob
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15 Jul 2019 11:51 #139417
by andypugh
Replied by andypugh on topic can linux cnc can cut a thread using only breakout board without using mesa card
You probably can use the 2000 count encoder for threading with the parport + BoB but only at low speed.
At high speed you will lose counts.
This might be acceptable, threading is often done at low speed.
But, if you are going to fit an encoder, it is probably best to have one that works at all speeds.
But most lathes make it difficult to fit an off-the-shelf encoder, as the spindle is so large, and a home-made slotted disc is an easier solution.
There is a class of encoder called an "elevator encoder" that can have a very large through-bore suitable for a lathe spindle, if you can find one cheap.
At high speed you will lose counts.
This might be acceptable, threading is often done at low speed.
But, if you are going to fit an encoder, it is probably best to have one that works at all speeds.
But most lathes make it difficult to fit an off-the-shelf encoder, as the spindle is so large, and a home-made slotted disc is an easier solution.
There is a class of encoder called an "elevator encoder" that can have a very large through-bore suitable for a lathe spindle, if you can find one cheap.
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15 Jul 2019 17:34 - 15 Jul 2019 17:40 #139472
by Dinuka_Shehan
Replied by Dinuka_Shehan on topic can linux cnc can cut a thread using only breakout board without using mesa card
Hi,
Thank you for help and your valuable information.
I am going to make a slotted disc for myself and it will be cut on a 2mm thickness piece of acrylic or 5mm thick ebonite disc.
I planned to fix it on my spindle thread which used to tighten the taper roller bearings of spindle.
It is 33.5mm of major thread diameter.slotted disc will placed between two locknuts.
Slotted disc will have 60 slots and only one tooth cut too deeper for index pulse.
slot size wiil be 3mm wide and depth of 4mm and only one tooth depth for 6mm to index.
PCD(pitch circle diameter) of (3x3)60/3.1416=114.59mm.
diameter of disc will be 114.59+3=117.59mm.
I am using two optocoupler speed sensors to detect the index pulse and phase A.
its slot wide 6mm and height of 7mm.
is this well enough for my setup?
Thank you for help and your valuable information.
I am going to make a slotted disc for myself and it will be cut on a 2mm thickness piece of acrylic or 5mm thick ebonite disc.
I planned to fix it on my spindle thread which used to tighten the taper roller bearings of spindle.
It is 33.5mm of major thread diameter.slotted disc will placed between two locknuts.
Slotted disc will have 60 slots and only one tooth cut too deeper for index pulse.
slot size wiil be 3mm wide and depth of 4mm and only one tooth depth for 6mm to index.
PCD(pitch circle diameter) of (3x3)60/3.1416=114.59mm.
diameter of disc will be 114.59+3=117.59mm.
I am using two optocoupler speed sensors to detect the index pulse and phase A.
its slot wide 6mm and height of 7mm.
is this well enough for my setup?
Last edit: 15 Jul 2019 17:40 by Dinuka_Shehan.
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15 Jul 2019 17:41 #139474
by Dinuka_Shehan
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15 Jul 2019 18:11 #139486
by tommylight
Replied by tommylight on topic can linux cnc can cut a thread using only breakout board without using mesa card
You can find a lot of those sensors on old photocopiers or printers, although they should be fairly cheap.
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16 Jul 2019 12:19 #139557
by andypugh
Yes, that will work well. I ran with exactly such a system for years.
You could consider adding a phase B, it will give you the ability to rigid tap.
Or use a two-sensor detector for A and B.
Replied by andypugh on topic can linux cnc can cut a thread using only breakout board without using mesa card
is this well enough for my setup?
Yes, that will work well. I ran with exactly such a system for years.
You could consider adding a phase B, it will give you the ability to rigid tap.
Or use a two-sensor detector for A and B.
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16 Jul 2019 16:16 #139569
by Dinuka_Shehan
Replied by Dinuka_Shehan on topic can linux cnc can cut a thread using only breakout board without using mesa card
but I cannot use Phase B on my bob.
It just 20khz.
so I searching for a new bob for cheap price for my purpose.
It just 20khz.
so I searching for a new bob for cheap price for my purpose.
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16 Jul 2019 16:18 #139571
by Dinuka_Shehan
Replied by Dinuka_Shehan on topic can linux cnc can cut a thread using only breakout board without using mesa card
I have already got some old photocopiers optocoupler switches but the problem is I can not figure out the pins of those switches.
any ideas?
any ideas?
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16 Jul 2019 16:21 #139572
by andypugh
20kHz is an (approximate) parallel port limitation rather than a limitation of the BoB.
What is your base period set to in the HAL / INI files?
60 slots / 4x quadrature / 20kHz is 5000 rpm....
Replied by andypugh on topic can linux cnc can cut a thread using only breakout board without using mesa card
but I cannot use Phase B on my bob.
It just 20khz.
so I searching for a new bob for cheap price for my purpose.
20kHz is an (approximate) parallel port limitation rather than a limitation of the BoB.
What is your base period set to in the HAL / INI files?
60 slots / 4x quadrature / 20kHz is 5000 rpm....
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