Dimension Shaft to support

Let's Make Robots Project Ideas
1

Hello,

I am new in this forum but not in Robotshop.
I have a problem choosing motors and fixation, because it’s very hard to find their specifications. It miss a lot of dimensions.
So, the products are :

  • Pololu 37D mm Metal Gearmotor Bracket (Pair) Product code : RB-Pol-03
  • Pololu 12VDC, 350rpm 29:1 Metal Gearmotor Product code : RB-Pol-81

In the picture of the Bracket, we can see the motor shaft in low position. I’d like to put it in high position by rotating it 180°. I thing it can run like this but i don’t know the dimension between the shaft and its base.

Faithfully,

Aurélien

2

Thank you for reply.

I need the specification (on the support) of the center of the six holes which maintain the motor on the support. Whithout this, i can’t make properly my CAO. I know the diametre of the cercle where are the six holes (31 mm) but I don’t know where is the center of theses 6 holes from the base.

3

The circle diameter of the holes are the same on the motor and on the support. But if i don’t know the center of the holes on the support, i can’t draw my support in solidworks and i can’t determine the exact position of the motor shaft after positionning it.

4

It’s important to check the “useful links” tab in the product description. There, you will see the Mechanical Drawing for RB-Pol-03. In the additional images for RB-Pol-81 you will see a dimensional drawing. Based on these two sheets, you can figure out the overall dimensions if you flip the motor.

5

You need to use both drawings to get the center of the holes as it would be on the bracket. The motor’s mounting holes are located on a 31mm diameter circle and they are spaced at 120 degrees apart.

6

The hole pattern is on a circle whose diameter is 31mm. Use geometry to determine the length of one side ‘H’ of an equilateral triangle placed inside this circle. Once you know that value, you can calculate the length of the opposite line ‘d’ which connects the hole to the centre of the shaft (equilateral triangle, so each angle is 60 degrees). The motor’s shaft lies almost perfectly between these two holes.