I was asked by a customer of mine to reproduce this plastic motor coupler in aluminum. To give an idea of size its 3 inches in diameter and about 1 inch high. Its a stepper motor coupler for an operating theater bed.
This part is very special to me as it was the first machining job I charged a price for. I took pride that all other "professional" machine shops that the customer went to could not make this part in one piece, they all wanted to do it in five pieces and bolt them or weld them together.
On my little Taig this part tool about 8 hours to machine because of the share amout of material that had to be removed.
The four outer holes in the coupler are just left over from the plastic molding process and has no functional value. However the center hole is supposed to fit the motor shaft shown below. As you can see it has been rounded out causing the motor shaft to just spin freely inside it.
I carefully took precise measurements of all features in the original part being a bit liberal with a thousandth here and there since the plastic part was a bit warped and had flashing as well as a few digs on the underside.
After couple hours in CAD and few hours in CAM, then a few more hours preparing fixtures for the job I was ready to make some chips. The end result is shown below.
The part was cut out of a 5"x4"x1" piece of 6061-T6511 Aluminum and is within .001" of all desired dimensions.
The motor key hole shown below was made to be a very precise press fit so there is no slop/backlash between the motor and the coupler. You heat up the coupler a bit with a hair dryer and press it on the motor shaft. It should also prevent wearing of the keyhole overtime.
Because of the precise fit its a bit difficult to remove the coupler from the motor shaft after installation. To remedy this I designed the center boss with a hole tapped for 10-32 threads. To remove the coupler from the motor simply screw in a 10-32 bolt into this hole and it would gently lift the coupler of the motor shaft. Protecting the part as well as your knuckles.
Below shows the completed order ready for delivery to the customer. Hope you guys enjoyed with pics.
Chevy
This part is very special to me as it was the first machining job I charged a price for. I took pride that all other "professional" machine shops that the customer went to could not make this part in one piece, they all wanted to do it in five pieces and bolt them or weld them together.
On my little Taig this part tool about 8 hours to machine because of the share amout of material that had to be removed.
The four outer holes in the coupler are just left over from the plastic molding process and has no functional value. However the center hole is supposed to fit the motor shaft shown below. As you can see it has been rounded out causing the motor shaft to just spin freely inside it.
I carefully took precise measurements of all features in the original part being a bit liberal with a thousandth here and there since the plastic part was a bit warped and had flashing as well as a few digs on the underside.
After couple hours in CAD and few hours in CAM, then a few more hours preparing fixtures for the job I was ready to make some chips. The end result is shown below.
The part was cut out of a 5"x4"x1" piece of 6061-T6511 Aluminum and is within .001" of all desired dimensions.
The motor key hole shown below was made to be a very precise press fit so there is no slop/backlash between the motor and the coupler. You heat up the coupler a bit with a hair dryer and press it on the motor shaft. It should also prevent wearing of the keyhole overtime.
Because of the precise fit its a bit difficult to remove the coupler from the motor shaft after installation. To remedy this I designed the center boss with a hole tapped for 10-32 threads. To remove the coupler from the motor simply screw in a 10-32 bolt into this hole and it would gently lift the coupler of the motor shaft. Protecting the part as well as your knuckles.
Below shows the completed order ready for delivery to the customer. Hope you guys enjoyed with pics.
Chevy
