Turning servo motor shafts

[wcarrothers1]

I have gotten some Yaskawa SGMG-30A2ABS motors and SGDB-30ADG drives

Hoping I can score some of their smaller motors (as I'll admit the 30 is quite big at 18lbs but would make a nice long axis motor)

Anyway the issue with the 30 motor is it's output shaft is 35mm. Need it down to around 22 or 24 mm to interface with my next biggest gear reducer. Wondering if anyone has any experience in altering the diamerter of servo motor shafts or if it's even really possiable.

I'll probably end up just leaving these for when perhaps I retro fit my bridgeport but who knows they might end up on my current 10x5' project..

b.

[RCaffin]

Step 1: machine up very carefully an extension tube to go over the 35 mm shaft. It needs to be a very close fit. Or use a very large parallel-shaft collet chuck.

Step 2: mount motor on bed of lathe at headstock end, align carefully with bed. Use dial gauge for both horizontal and vertical deflections with extension piece made in step 1. You do not have to be on the headstock axis.

Step 3: power up servo motor and turn shaft down. Gently and carefully.

Cheers

[MikeZee]

The way you turn down servo shafts or any motor shaft for that matter is to take the motor apart, ( after all is was in pieces before assembly at the factory ), Put "keepers" in the stator to prevent magnet losing power, setup rotor true in lathe and perform desired machining. Reassemble. I have done many, many, motor shaft modifications and never with the motor assembled.
You'll never get it true or even rigid enough to machine.

[holbieone]

mount the motor on a lathe

spin the motor under power and use a tool post grinder(keep the rpms down)

[RCaffin]

Originally Posted by MikeZee The way you turn down servo shafts or any motor shaft for that matter is to take the motor apart, ( after all is was in pieces before assembly at the factory ), Put "keepers" in the stator to prevent magnet losing power, setup rotor true in lathe and perform desired machining. Reassemble. I have done many, many, motor shaft modifications and never with the motor assembled. You'll never get it true or even rigid enough to machine.

Yeah, we have disassembled motors too, but many prefer to not risk losing the magnetisation. Depends on the motor of course. AC motors ... hack away!

In some cases it may even be possible to chuck one end of the motor shaft and hold the other end with a live centre. Have to stop the motor from spinning!!!! But this can work very well.

Using a tool-post grinder is possible of course, but many people worry about getting grit into the bearings and ways. It all depends, as usual.

Skinning cats ...

Cheers

[mactec54]

wcarrothers1

Thats a big motor, would be more suited for your 10'X5' machine build, I would try not to change the shaft, you could make a coupling for the motor with a flange on it, you can then bolt any size timing pulley to the flange, turn a step on the flange to locate the timing pulley

[RCaffin]

Originally Posted by mactec54 Thats a big motor, would be more suited for your 10'X5' machine build, I would try not to change the shaft,

Actually, that's a very good point. The motor manufacturer chose that shaft size for a good reason. Reducing from 35 mm to 22 mm may weaken the shaft too much. Buy the necessary fittings or couplings and use the existing shaft. Why risk it?

Cheers

[MikeZee]

Servo motors have permanent magnets in them, you take out the rotor and put "keepers" in the stator to prevent loss of magnetism. He's going from 35 mm down to 22 or 24 mm - how long do you think it's gonna take him to grind off 11 to 13 mm, all morning maybe? c'mon people let's think a little.

[holbieone]

Originally Posted by MikeZee Servo motors have permanent magnets in them, you take out the rotor and put "keepers" in the stator to prevent loss of magnetism. He's going from 35 mm down to 22 or 24 mm - how long do you think it's gonna take him to grind off 11 to 13 mm, all morning maybe? c'mon people let's think a little.

he would be grinding off 6.5 mm ,"c'mon let's think a little" will you !!!!!!

[gridley51]

Originally Posted by holbieone he would be grinding off 6.5 mm ,"c'mon let's think a little" will you !!!!!!

And,only an idiot would consider grinding any amount over a few thou.

[holbieone]

Originally Posted by gridley51 And,only an idiot would consider grinding any amount over a few thou.

thanks for correcting me , i won't grind over a few "thou" any more sorry

maybe you should let the world know about this ,there's whole company's out there braking your rules ,
getting work done , making money grinding all types of parts removing a s@&t load of material by grinding

[gridley51]

Originally Posted by holbieone thanks for correcting me , i won't grind over a few "thou" any more sorry maybe you should let the world know about this ,there's whole company's out there braking your rules , getting work done , making money grinding all types of parts removing a s@&t load of material by grinding

There are a few companies out there removing large amounts of materials by grinding,but it`s not common.
You might also consider the guy is asking how to reduce a motor shaft for a retrofit,hardly a company with a grinder capable of doing it in a reasonable time at a reasonable cost,so,only an idiot is going to suggest grinding.