calculating turns ratio for a rack and pinion
Moderator: cnckeith
-
- Posts: 12
- Joined: Fri Feb 16, 2018 9:31 am
- Acorn CNC Controller: Yes
- Allin1DC CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: none
- DC3IOB: No
- CNC11: Yes
- CPU10 or CPU7: No
calculating turns ratio for a rack and pinion
Hello,
hello.
I am still new to centroid. Am using it to make my CNC and the axes are moved by a rack and pinion.
my pinion pitch diameter is 30mm. it is coupled to the motor directly (no gear ratio)
my steps/revolution is (800). I have set this both in the driver and the wizard.
I want to set my turns ratio from the wizard as advised from the threads of almost similar problem. it is currently set at 5 mm/turn. I have tried using this document I got from a different thread http://www.centroidcnc.com/dealersuppor ... ds/036.pdf to calculate but I am facing a difficulty.
From the document, my turns ratio is currently at (5), I instruct my axis to move 10mm and it moves 190mm. this gives me a multiplier of 19. I multiply and get (19*5=95)
I however cannot input this value to the wizard since the maximum allowed value is 39.4. I have tried and tested with other values but still get the same value. (95)
calculating the distance my pinion moves per revolution is 94.26 (which is close to 95) and makes sense as to what I am supposed to be putting in this dialog box from the centroid manual.
someone please help me point out what I am missing.
thank you
MPU PLC: acorn_mill_plc.src
MPU PLC TYPE: ACORN (11)
SYSTEM ID C8FD19D3CCE3-1121170269
hello.
I am still new to centroid. Am using it to make my CNC and the axes are moved by a rack and pinion.
my pinion pitch diameter is 30mm. it is coupled to the motor directly (no gear ratio)
my steps/revolution is (800). I have set this both in the driver and the wizard.
I want to set my turns ratio from the wizard as advised from the threads of almost similar problem. it is currently set at 5 mm/turn. I have tried using this document I got from a different thread http://www.centroidcnc.com/dealersuppor ... ds/036.pdf to calculate but I am facing a difficulty.
From the document, my turns ratio is currently at (5), I instruct my axis to move 10mm and it moves 190mm. this gives me a multiplier of 19. I multiply and get (19*5=95)
I however cannot input this value to the wizard since the maximum allowed value is 39.4. I have tried and tested with other values but still get the same value. (95)
calculating the distance my pinion moves per revolution is 94.26 (which is close to 95) and makes sense as to what I am supposed to be putting in this dialog box from the centroid manual.
someone please help me point out what I am missing.
thank you
MPU PLC: acorn_mill_plc.src
MPU PLC TYPE: ACORN (11)
SYSTEM ID C8FD19D3CCE3-1121170269
-
- Posts: 2187
- Joined: Sat Nov 18, 2017 2:32 pm
- Acorn CNC Controller: Yes
- Plasma CNC Controller: No
- AcornSix CNC Controller: Yes
- Allin1DC CNC Controller: No
- Hickory CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: Acorn 238
- DC3IOB: No
- CNC12: Yes
- CNC11: No
- CPU10 or CPU7: No
- Location: Bergland, MI, USA
- Contact:
Re: calculating turns ratio for a rack and pinion
IF pitch diameter is 30 then circumference is 30 * pi or 94.24778mm
1 / 94.24778 = 0.01061 revolutions per mm
I would recommend both adding mechanical reduction and increased microstepping to at least 1/8 or 1600 steps/rev
1 / 94.24778 = 0.01061 revolutions per mm
I would recommend both adding mechanical reduction and increased microstepping to at least 1/8 or 1600 steps/rev
-
- Posts: 12
- Joined: Fri Feb 16, 2018 9:31 am
- Acorn CNC Controller: Yes
- Allin1DC CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: none
- DC3IOB: No
- CNC11: Yes
- CPU10 or CPU7: No
Re: calculating turns ratio for a rack and pinion
thanks for the reply Gary.Gary Campbell wrote: ↑Mon Feb 19, 2018 10:00 am IF pitch diameter is 30 then circumference is 30 * pi or 94.24778mm
1 / 94.24778 = 0.01061 revolutions per mm
I would recommend both adding mechanical reduction and increased microstepping to at least 1/8 or 1600 steps/rev
however, the wizard is asking for mm/revolution and not revolution/mm. using 0.01061 runs my driver to an error.
Re: calculating turns ratio for a rack and pinion
Metric threads are stated in mm/rev unlike imperial threads which are stated as rev/inch. Consult your drive and motor docs to first get your motor steps/rev squared away before worrying about mm's/rev. Steps/rev is a fixed value that doesn't change with ball screw pitch, rack and pinion ratios, pulley ratios etc..
-
- Posts: 12
- Joined: Fri Feb 16, 2018 9:31 am
- Acorn CNC Controller: Yes
- Allin1DC CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: none
- DC3IOB: No
- CNC11: Yes
- CPU10 or CPU7: No
Re: calculating turns ratio for a rack and pinion
Okay. I have my pulses/rev set.diycncscott wrote: ↑Mon Feb 19, 2018 11:04 am Metric threads are stated in mm/rev unlike imperial threads which are stated as rev/inch. Consult your drive and motor docs to first get your motor steps/rev squared away before worrying about mm's/rev. Steps/rev is a fixed value that doesn't change with ball screw pitch, rack and pinion ratios, pulley ratios etc..
I am now worrying about the mm/rev I am getting. I don't want to venture into introducing gearing in my mechanism while I can get a solution.
-
- Posts: 2187
- Joined: Sat Nov 18, 2017 2:32 pm
- Acorn CNC Controller: Yes
- Plasma CNC Controller: No
- AcornSix CNC Controller: Yes
- Allin1DC CNC Controller: No
- Hickory CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: Acorn 238
- DC3IOB: No
- CNC12: Yes
- CNC11: No
- CPU10 or CPU7: No
- Location: Bergland, MI, USA
- Contact:
Re: calculating turns ratio for a rack and pinion
Do you have a part number for the pinion? How about the pitch module and number of teeth?
-
- Posts: 12
- Joined: Fri Feb 16, 2018 9:31 am
- Acorn CNC Controller: Yes
- Allin1DC CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: none
- DC3IOB: No
- CNC11: Yes
- CPU10 or CPU7: No
Re: calculating turns ratio for a rack and pinion
Module = 1. Pitch diameter = 30. Number of teeth = 30Gary Campbell wrote: ↑Tue Feb 20, 2018 2:28 am Do you have a part number for the pinion? How about the pitch module and number of teeth?
-
- Posts: 595
- Joined: Tue Sep 12, 2017 10:03 pm
- Acorn CNC Controller: Yes
- Allin1DC CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: 1030090099
- DC3IOB: Yes
- CNC12: Yes
- CNC11: Yes
- CPU10 or CPU7: No
- Location: Outside Winston-Salem, NC
- Contact:
Re: calculating turns ratio for a rack and pinion
What is the pulse per rev?Orukoh Jaramogi wrote: ↑Tue Feb 20, 2018 12:56 amOkay. I have my pulses/rev set.diycncscott wrote: ↑Mon Feb 19, 2018 11:04 am Metric threads are stated in mm/rev unlike imperial threads which are stated as rev/inch. Consult your drive and motor docs to first get your motor steps/rev squared away before worrying about mm's/rev. Steps/rev is a fixed value that doesn't change with ball screw pitch, rack and pinion ratios, pulley ratios etc..
I am now worrying about the mm/rev I am getting. I don't want to venture into introducing gearing in my mechanism while I can get a solution.
Clay
near Winston-Salem, NC
unofficial ACORN fb group https://www.facebook.com/groups/897054597120437/
near Winston-Salem, NC
unofficial ACORN fb group https://www.facebook.com/groups/897054597120437/
-
- Posts: 12
- Joined: Fri Feb 16, 2018 9:31 am
- Acorn CNC Controller: Yes
- Allin1DC CNC Controller: No
- Oak CNC controller: No
- CNC Control System Serial Number: none
- DC3IOB: No
- CNC11: Yes
- CPU10 or CPU7: No
Re: calculating turns ratio for a rack and pinion
frijoli wrote: ↑Tue Feb 20, 2018 7:05 amWhat is the pulse per rev?Orukoh Jaramogi wrote: ↑Tue Feb 20, 2018 12:56 amOkay. I have my pulses/rev set.diycncscott wrote: ↑Mon Feb 19, 2018 11:04 am Metric threads are stated in mm/rev unlike imperial threads which are stated as rev/inch. Consult your drive and motor docs to first get your motor steps/rev squared away before worrying about mm's/rev. Steps/rev is a fixed value that doesn't change with ball screw pitch, rack and pinion ratios, pulley ratios etc..
I am now worrying about the mm/rev I am getting. I don't want to venture into introducing gearing in my mechanism while I can get a solution.
800 pulse/rev
Re: calculating turns ratio for a rack and pinion
As ALWAYS, please post a report when requesting support. Without it, we simply don't have enough information to help you.