Re: Cincinnati Arrow 750 VMC Retrofit
Posted: Mon Mar 27, 2023 1:47 am
Hey everyone, I know it's been a while since my last post. Life can get in the way, but since then, there have been several updates.
First off I resolved my issue about the Y axis servo placement. I was doing the final measurements and design changes for my Y axis extension tube when I thought about making sure that the X axis servo would fit without modification, because regardless I knew it would require an adapter plate made to bolt on the motor to the original mount. Well I am glad I check prior to ordering the material and fabricating the plates and extension tube because it wouldn't fit!! I mocked it up to the X axis servo mount to make sure the servo shaft and ball screw shaft were concentric, and they I moved the table in the X axis to check for clearance but it would hit the side of the motor... so now I had to make a call, would I make an extension tube for the Y axis AND make something to offset the X axis motor to the side so it would clear the table (something like a timing belt and pulley setup)?
So after lots of thinking, I decided to scrap the whole idea and just buy new servos. The servo motors I originally wanted to use are Yaskawa SGMGV-30A3A61 servos, but I decided to buy 2 Yaskawa SGMGV-20A3A61 so its a smaller motor with less power but I am confident it will be more than adequate for my machine. The new motors actually have the exact same mounting pattern as the old servos so it actually bolts right up in place of the old servos. However, the motor shaft sticks out too much and is way too close to the ball screw shaft to have enough clearance to fit the shaft coupler. To resolve this, I will machine a spacer plate to fit in front of the servo to give the proper clearance between the shafts. I 3d printed a mockup adapter and it fits perfect so I will machine the spacers in the next couple weeks.
First off I resolved my issue about the Y axis servo placement. I was doing the final measurements and design changes for my Y axis extension tube when I thought about making sure that the X axis servo would fit without modification, because regardless I knew it would require an adapter plate made to bolt on the motor to the original mount. Well I am glad I check prior to ordering the material and fabricating the plates and extension tube because it wouldn't fit!! I mocked it up to the X axis servo mount to make sure the servo shaft and ball screw shaft were concentric, and they I moved the table in the X axis to check for clearance but it would hit the side of the motor... so now I had to make a call, would I make an extension tube for the Y axis AND make something to offset the X axis motor to the side so it would clear the table (something like a timing belt and pulley setup)?
So after lots of thinking, I decided to scrap the whole idea and just buy new servos. The servo motors I originally wanted to use are Yaskawa SGMGV-30A3A61 servos, but I decided to buy 2 Yaskawa SGMGV-20A3A61 so its a smaller motor with less power but I am confident it will be more than adequate for my machine. The new motors actually have the exact same mounting pattern as the old servos so it actually bolts right up in place of the old servos. However, the motor shaft sticks out too much and is way too close to the ball screw shaft to have enough clearance to fit the shaft coupler. To resolve this, I will machine a spacer plate to fit in front of the servo to give the proper clearance between the shafts. I 3d printed a mockup adapter and it fits perfect so I will machine the spacers in the next couple weeks.