[ihavenofish]

so ive got me a new raptor thats almost assembled (blue one, pics have been posted). im working on adjustemnts and mods to make it a bit more "turnkey friendly"

had been trying to figure out what servo power and ball screws would yield a good result. im used to steppers, which provide tend to provide alot of torque at 0, and little to none at speed.

yaskawa has some new servos, called the junma series. they are 100-750w, take step and direction, and autotune themselves within a reasonable inertia ratio. they have an app that will tell you what motor is needed based on the machine spec and performance desired. these motors and drives are specifically made to be replacements for steppers, so they are simple to set up, if slightly more limited in function than a full featured industrial kit.

it was really quite surprising seeing the results and recomendations.

a 24x48 raptor (18"x40" safe travel) with a 1hp er20 spindle is the basic example. the performance requirements were set very high, and included cutting feed forces agressive enough to stall the spindle. weight was exaggerated slightly to account for variables and acessories.

25mm x 20 pitch ball screw on the x, 15mm x 20mm pitch on the y and z.
all axes have a 2:1 belt drive and as such, a 1181 ipm rapid speed with a 3000rpm motor. acelleration was set to 0.5G.

this is fully 3x faster acceleration and top speed than a typical raptor with chinese steppers and gecko drives.

for the X axis, the recomended motor is 400w.
for the y and z axis, the recomended motor is 200w.

if you reduce the top speed to 590ipm by using a 10 pitch screw, and use a 20mm X screw, the acceleration to 0.25G, on a shorter machine (say 18x18" travel) you can comfortably use a 200w motor on the x, and 100w on the y and z.

so if youve got a raptor, phantom, or viper, you should be looking at smaller motors, nothing bigger than nema23/60mm seems to be needed to achieve dramatically improved performance over steppers.

[BanduraMaker]

What kind of performance could you get with 10mm pitch screws on all axes?

[ihavenofish]

What kind of performance could you get with 10mm pitch screws on all axes?

direct drive as in a stock raptor, 25mm x screw with a relatively light spindle?

you are limited in rpm unfortunately on the x axis. motors go 3000+rpm, the screw likley wont handle much more than 2000 because of length and alignment.

with that in mind, you should get 590-800 ipm with 0.25G acceleration on a 400w servo. the junma models however dont like the inertia in that setup - 10:1. (edit: direct drive will work, just read and found you have a 36" raptor, not 48")

if you create a 2:1 belt drive, youll get the same speed and accel, but be able to use even 200w motors with no issue on the X at 590ipm. you could then increase the acceleration on 400w motors to 0.3G

0.25G is "100" in the mach3 acceleration settings when set to inch. your stock steppers are like set somewhere between 25 and 60.

on the Y, direct drive 200w as fast as you can get the screw to spin at 0.25 - 0.3G. (at least 600-800, likely as much as 1200ipm.)


Z is more complex. 400w direct drive is safe, 200w in belt drive is safe for speeds up to 600ipm. faster speeds might cause issues with regenerative power since since gravity is helping force the spinlde down.

[xsnrg]

running with direct drive verses a 2:1 belt....what would the advantages be other than being able to use a lower watt motors, which would be a cost saving measure.

[gio666]

the 400w and 750w motors are so close in price its better to get 750w

[ihavenofish]

yeah, youll end up paying more for the belts and pulleys and such.
200w and 400w tend to cost exactly the same. 750w is often only $50-$100 more.

you want a belt drive only on setups like a 2525 screw thats long, because its rpm limit is low. the belt lets you use more power from the motor.

[beachcnc]

Have been trying to find pricing on the Yaskaw Junma 750 w servo/drive...any idea of. The cost??

[ihavenofish]

expensive as it turns out. $800-$900 at the best.
delta is probably a better option at $700 or so - with more features.