calculating turns ratio for a rack and pinion

[Orukoh Jaramogi]

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

[Gary Campbell]

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

[Orukoh Jaramogi]

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

thanks for the reply Gary.

however, the wizard is asking for mm/revolution and not revolution/mm. using 0.01061 runs my driver to an error.

[diycncscott]

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..

[Orukoh Jaramogi]

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..

Okay. I have my pulses/rev set.


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.

[Gary Campbell]

Do you have a part number for the pinion? How about the pitch module and number of teeth?

[Orukoh Jaramogi]

Do you have a part number for the pinion? How about the pitch module and number of teeth?

Module = 1. Pitch diameter = 30. Number of teeth = 30

[frijoli]

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..

Okay. I have my pulses/rev set.


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.

What is the pulse per rev?

[Orukoh Jaramogi]

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..

Okay. I have my pulses/rev set.


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.

What is the pulse per rev?

800 pulse/rev

[diycncscott]

As ALWAYS, please post a report when requesting support. Without it, we simply don't have enough information to help you.