I am just getting started in a new diy 5x3 router, table steel is all cut and waiting for the welder to get it done.
Very stiff build, Hiwin 20mm rails, CNC Router Parts rack and their pinion drives. I have a Chinese 6040 at the moment to make many of the pieces for the new machine. These are OK but no so good doing 3d on Australia's very hard woods, and soooo slow.

I have decided to go servo and have spent a week, long days, researching servos.Putting the numbers of the machine into a couple of the calculators i get 400W for X. This will be dual drive for X so thinking 200w a side. The "Tim the Tool Man" starts coming out so maybe the 300w motors instead as they are only $20 more. I have read not to go more than 1 size over so am happy doing that. Can get second hand big name units fairly cheap, about the same price as the DMM stuff new. Am thinking probably better to go DMM as they would be new and seem to have some good support here on CNC Zone.

Problems

On their website DMM list several motors but downloading the motor spec sheets the numbers don't match and the 300w is not shown at all. The CNC RP NMEA 34 pulley has a 1/2 bore hopefully the 200 and 300w motors match this as i would have to get a bore increase done by a machine shop, more cost. I would like to confirm some other dimensions as well to make sure it will all go together nice. Has anyone got up to date data on their motors, i would ask DMM but don't want to bother them until I am sure i will go that way.

In their info DMM specify an inertia ratio of 10:1 max. I have tried a few calculators but seem to not get the result in a form i can understand. I also haven't really grasped the units of measure very well either so I am shooting in the dark on Inertia ratios. I have picked up that a speed reducer while giving a torque advantage also reduces the apparent inertia of the driven mass by the square of the reduction ratio. Any one have any advice on this topic, maybe i am over thinking it a bit.

Mike