# Roller diameter

**URL:** <https://forum.avidcnc.com/t/roller-diameter/1880>\
**Category:** General Chat\
**Created:** [March 20, 2023, 4:18pm UTC](https://forum.avidcnc.com/t/roller-diameter/1880 "2023-03-20T16:18:56Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![Thomas](https://avatars.discourse-cdn.com/v4/letter/t/e36b37/32.png) [@Thomas](https://forum.avidcnc.com/u/Thomas)\
**Post date:** [March 20, 2023, 4:18pm UTC](https://forum.avidcnc.com/t/roller-diameter/1880/1 "2023-03-20T16:18:56Z")

</div>

Can someone tell me the Diameter of PRO NEMA 34 Roller Drive Spindle? please help. Thank you

---

<div class="post-metadata">

**Author:** ![subnoize](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/subnoize/32/2197_2.png) [@subnoize](https://forum.avidcnc.com/u/subnoize)\
**Post date:** [March 20, 2023, 4:28pm UTC](https://forum.avidcnc.com/t/roller-diameter/1880/2 "2023-03-20T16:28:29Z")

</div>

1/2" I think. 12.7mm in metric. But from the website;

> - The R&P system is based on a pinion with a 1" pitch circle. The total linear distance traveled per revolution of the pinion is thus 3.14159". With the 3.2:1 reduction, this means that the distance traveled per motor revolution is 3.14159 / 3.2, or 0.9817". If you have a stepper with 200 steps per revolution, this means you have 200 / 0.9817" = 203.718 steps per inch, or 0.004908" per step. With 10x microstepping , you would have 2037.18 steps per inch, or 0.0004908" per step.

---

<div class="post-metadata">

**Author:** ![djdelorie](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/djdelorie/32/515_2.png) [@djdelorie](https://forum.avidcnc.com/u/djdelorie)\
**Post date:** [March 20, 2023, 4:50pm UTC](https://forum.avidcnc.com/t/roller-diameter/1880/3 "2023-03-20T16:50:09Z")

</div>

I’ll agree with the web site. The drive pinion is PI inches per revolution and 20 teeth; the rack has 20 teeth per PI inches, or about 0.1571 IPT. Just less than 4mm (3.9898mm). Learned this the hard way 😉

---

<div class="post-metadata">

**Author:** ![Thomas](https://avatars.discourse-cdn.com/v4/letter/t/e36b37/32.png) [@Thomas](https://forum.avidcnc.com/u/Thomas)\
**Post date:** [March 22, 2023, 12:41pm UTC](https://forum.avidcnc.com/t/roller-diameter/1880/4 "2023-03-22T12:41:10Z")

</div>

Thank you for your quick response, however, I would like to know the larger diameter of the Aluminum gear not the pinion.  
Best regards  
Tom

---

<div class="post-metadata">

**Author:** ![djdelorie](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/djdelorie/32/515_2.png) [@djdelorie](https://forum.avidcnc.com/u/djdelorie)\
**Post date:** [March 22, 2023, 4:51pm UTC](https://forum.avidcnc.com/t/roller-diameter/1880/5 "2023-03-22T16:51:13Z")

</div>

according to my notes, those are 5GT gears, the one on the motor is 20 tooth and the larger one 64. So 64\*5mm = 320mm circumference, or 101.9mm pitch diameter Actual OD might vary, but a quick check with a ruler says I’m close 😉