Question on power supply

[trimsol]

Hello
I have a clone mill 9x49 table / 5tpi ball screws / vari head / 3hp motor / #30 taper.
It had an old centroid built controller that is dead and uses steppers which are dead
-timing pulleys and belts on all 3 axis

I want to scrap the old system and go to mach 3

I plan on using 3 850oz motors for home shop cnc

encoders from digikey amt103

break out board caned cnc or Campbell

and gecko 320x drivers

I just don't know where to get a power supply or do each drive needs it own supply

I have thought about getting PS-6N80 from antec but not sure

Any help would be grateful

[tommylight]

Hi,
First you say it uses steppers and afterwards you mention encoders and gecko 320.
Steppers do not necessarily need encoders and G320 is a servo driver AFAIK.

Anyway here are some basics: STEPPERS you mentioned based on the torque need anything from 24 to 70V and at least 20A to move properly, SERVO motors would need anything from 40 to 200 V and 10 to 30 A.
This is just a rough estimate and do not use this info before narrowing down what you really need. Check again what type of motors you have and what drivers you are planing on using, and let us know.

Regards.

[Jesse B]

Some ratings on the motors you are looking at would be helpful.

Generally for voltage, you find the inductance (in mH), and use this formula: sqrt(Inductance) * 32. This is the highest voltage you should use; the higher the better, but don't exceed it.

For amperage, add up the 3 ratings, and multiply it by 0.67. That's the minimum you'll want, and additional amperage wouldn't hurt.

[trimsol]

My mistake
IT DID have steppers on the machine but when i bought it they made a grinding noise and loud and very slow

what i am looking at is 3 of the following - if that is good i keep seeing 29lb servos but dont know the difference other than the price i just want a good machine that will cut anything that the knee mill was designed for

machine has no backlash in the ball screws
the motors i want to use

850oz from home shop cnc
* skewed rotor design
* continuous torque: 170 oz/in
* peak torque: 850 oz/in
* terminal voltage: 72 VDC
* continuous current: 8.5A
* peak current: 38A
* inertia: 3.39 kg.cm^
* maximum operating speed: 4200 rpm
* torque constant (KT): .1757 N. m/am
* voltage constant (KE): 15.71 volts/100 rpm
* resistance: 85 ohm
* inductance: 2.35 mH
* weight: 8.8 lbs
* 7 inches

and 3 of these
http://www.amtencoder.com/Product/AM...rs/AMT103.aspx

and 3 gecko 320x
which Marcus Freimanis recommended from gecko

I also want to add a rogersmachine encoder board so i can turn off the drives and indicate something in or use machine in manual mode

I use to have a smaller bridgeort mill very small m head i believe 9x36 table with a centroid on it and loved the turn drives off button - but lost the mill in a property battle.

I just thought that higher amps would be enough but not sure
or just 3 independent power supplies
I have heard of building one but i am more likely to win the lottery than figure that out

Thanks for the help

[trimsol]

I had thought about using viper200 and there is a local sale for them but the guy selling them says he could never get them tuned bad instructions poor tech support if any


3 drivers never been passed the tuning phase for 300.00 total

any thoughts??

[Jesse B]

I have heard of building one but i am more likely to win the lottery than figure that out

As daunting of a task as it may seem, power supplies are surprisingly easy to make. All you really need is a transformer, bridge rectifier, switch, fuse/fuse holder, and capacitor(s).

There's an example here: http://buildyourcnc.com/supply1.aspx

Note there's a Part 2 as well.


- Jesse