Two things Hello & what size stepper do I need?

[1stcnc]

I first want to say hi to everyone and introduce myself name is Larry.
My question is what size driver and steppers do I need to get 30-40 ipm. I'm wanting to convert an x2 and use the stock screws 16 tpi and using the same for z with the help of LMS's air cylinder conversion. I have been looking at Keling's with the 282oz/in motors for x&y and a 425 oz/in motor for z. Will the 4030 driver handle this or do I need drivers with higher amp./v. like maybe 6 amp and about 36 to 48 v. ? My thoughts are to get it converted and as the screws were out replace with ball screws. Also is one easier or better when it comes to unipolor or bipolor. From what I'm reding it seems Bipolor seems to have a little more power and control?
1stcnc

[The Blight]

I'm using bipolar motors, and these motors are the most common type. You can connect 8 wire unipolar motors as bipolar to get more power out of them. They are also cheaper (as far as I know anyway). 282oz/in should be fine for both y&x. 425 should also be fine for the z if you convert it to use a leadscrew or ball screw. You have to check how much current the motors draw, and how much voltage they can take (voltage should be between 10 to 25 times more then the one listed). So 36-48V sounds about right. I don't know anything about the driver you mentioned, but if it can deliver the amount of power you need, then it should be just fine.

[1stcnc]

the Keling 4030 drivers are 3A. 24 to 40 v. Is a driver in this range strong enough to get the 30 to 40 ipm that I'm wanting?

[hoss2006]

Hey 1stcnc,
I run the KL 4030's with 282 oz/in motors on the X and Y at 40V.
I get 130 IPM on the X and 65 IPM on the Y for rapids.
That's with ballscrews though but the finer pitch of the stock screws should
allow for more torque to be applied to move the table an equal distance.
Top IPM will probably be a little less as the steppers hit their max rpm
but I'd imagine it should get you the 30-40 you want.
Hoss

[project5k]

yea, be carefull here, in my experience your trying to compare apples to bulldozers... getting IPM is a function of your lead screws/ballscrews, motor rpm, and usable torque at a given RPM of the motor... as motor rpm goes up, usable torque goes down... its not JUST about how many amps at what voltage...

also, just a note, and please understand that i'm not bashing your plan, just noting a point, 30IPM is really slow, thats 1/2 an inch a min movement.. If it were me, i would aim for something more like 60IPM for your rapids, you woundnt cut this fast, but it will definately improve your overall experience cause it will move from point to point faster between cuts...

if you figure a 16tpi screw, then you will need to turn that screw 480 rpm to get 30IPM...
this is well within the motors ability rpm wise, but not knowing that particular motor's torque curve, and not having done the torque math, i would think that you should be ok.

i'm assuming that your planning to drive the screw directly with the motor with lovejoy connectors or something of the sort.. if your planning to gear it down using a belt or something then you'll need to take that into consideration... also, at 30IPM you wont be in any danger of running out of available pulses on your parallel port, but just for example, on my setup, i'm using the 45Khz setting in mach, so the math looks like this... (5 tpi screw*2000 step/rev(10x ustep)*270IPM) / 60sec/min = 45khz, so my max speed is limited by mach's output freq... i'm running 52v drive voltage, 4A/phase to the motors, and 500oz/in motors directly tied to the screws... and theres power left there, i could go faster and still have available torque....i dont know why i would ever want to go faster, i certanly cant cut that fast, but if mach came out with a faster port output, my hardware could do it...

another thing to take into consideration is the drive V, as was said above 10 times to 25 times the "motor" voltage is a good place to be.. so if you motor sais 2V then a drive voltage of 40V is 20 times, this should give pretty good performance.. but you also need to remember that as drive V goes up, so does motor heating... i still think that you will be fine, but its part of the over all equasion..

just wanted to give you my input, may help, may not, but i fugure the more information that you have, the better decision you can make...

[1stcnc]

Thank you all for your input. Going to have to do some calculating.
I'm a bit confused though I thought 30 ipm was 30 inches of actual movement per minute?
Thanks again, Larry

[hoss2006]

Originally Posted by 1stcnc Thank you all for your input. Going to have to do some calculating. I'm a bit confused though I thought 30 ipm was 30 inches of actual movement per minute? Thanks again, Larry

You were right, 30IPM would be 30 actual inches of movement if you have that much travel.
5 inches in 10 seconds. 15 inches in 30 secs etc.
Hoss

[The Blight]

also, just a note, and please understand that i'm not bashing your plan, just noting a point, 30IPM is really slow, thats 1/2 an inch a min movement

Probably a typo. Should be 1/2" per sec.