Gecko G540 - local source

[irving2008]

You can run steppers below their rated phase current, you just derate the torque by the ratio of the currents. So a 4.2Abipolar stepper rated at 1.8Nm will, on a 3.5A drive, give 1.05Nm RMS instead of 1.27Nm RMS

[compfranon]

You can run steppers below their rated phase current, you just derate the torque by the ratio of the currents. So a 4.2Abipolar stepper rated at 1.8Nm will, on a 3.5A drive, give 1.05Nm RMS instead of 1.27Nm RMS

Whoa ... way over my head, although I am led to believe that matching drive/stepper is far better rather than adjusting to suit .... Remember MESSENGER

[Buba b]

Im replacing my Hobby CNC board with the Gecko mainly because the Zaxis on my mini mill needs more torque. Ive got SY60STH86-3008 Nema 23 stepper motors from Zap on my machine and with the 3.5amp in parallel with 3.3k 5% resistors i should have 2.5nm (or 83% of there ) holding torque ( once i figure how to wire them up lol ). Not much of an increase over the Hobby board at 2.15nm but im hopeing just enough to stop it from stalling. If not then il replace the Z axis motor once i find one that matches the amps , which as you say Compfanon finding motors to match to get the most torque in the Uk is not proving easy. If i dont pay tax then i still think it will be a good buy .... but ive got the feeling il be getting a bill soon , the goverment needs more of my cash.

[compfranon]

Im replacing my Hobby CNC board with the Gecko mainly because the Zaxis on my mini mill needs more torque. Ive got SY60STH86-3008 Nema 23 stepper motors from Zap on my machine and with the 3.5amp in parallel with 3.3k 5% resistors i should have 2.5nm (or 83% of there ) holding torque ( once i figure how to wire them up lol ). Not much of an increase over the Hobby board at 2.15nm but im hopeing just enough to stop it from stalling. If not then il replace the Z axis motor once i find one that matches the amps , which as you say Compfanon finding motors to match to get the most torque in the Uk is not proving easy. If i dont pay tax then i still think it will be a good buy .... but ive got the feeling il be getting a bill soon , the goverment needs more of my cash.

Heres hoping the bill gets lost in the system somewhere. The thought of "additional" charges put me off. My plan is to get (3) of the same motors from Zapp and drive with PM752's, all housed in a nice tower case perhaps along with the control pc.

My guru is helping me sort out appropriate power supply.

Good luck with your project.

[crustybugger]

Im replacing my Hobby CNC board with the Gecko mainly because the Zaxis on my mini mill needs more torque. Ive got SY60STH86-3008 Nema 23 stepper motors from Zap on my machine and with the 3.5amp in parallel with 3.3k 5% resistors i should have 2.5nm (or 83% of there ) holding torque ( once i figure how to wire them up lol ). Not much of an increase over the Hobby board at 2.15nm but im hopeing just enough to stop it from stalling. If not then il replace the Z axis motor once i find one that matches the amps , which as you say Compfanon finding motors to match to get the most torque in the Uk is not proving easy. If i dont pay tax then i still think it will be a good buy .... but ive got the feeling il be getting a bill soon , the goverment needs more of my cash.

Hi
I am using a Powerpac 34 frame series wound stepper and it only draws 3.3 amps for 845oz-in on a z axis and it runs plenty fast enough.
Terry

[Gary]

one thing you need to remember is it is not the holding torque you need but the torque at a given speed.
In most cases the holding torque is totally irrelevant.
Also if you under rate the current this will only really effect the torque at the lower speed range, and will have little effect at the higher speeds as this will be lower than the torque you would get at lower current.

Dont forget the lower the current means the higher the inductance and that means you need more volts to force the current through the copper. So spending more money for a 3.5A motor will in most cases give you less performance than using a 4.2A motor and running at 3.5A.
Without the volts you are choking the driver and you will not get a good performance.
People always forget about volts, and with a stepper system it is very important.

[crustybugger]

The one particular stepper I'm using is Pacsci rated at 845 oz in at the rated current of 3.3 amps which is what I set my drive at. It is a 4 wire series wound and has a phase inductance of 8.3 mh.
Experts seem to all agree that low inductance is required for the best performance and I have found that this is not the case.
Unipolar drives are also said to be inferior, I have been using such a drive on a small lathe set up for a production contract and had no problems at all.
Also, I have never been able to get the type of rpms from a stepper that are discussed on forums either using high or low inductance motors, unipolar or bipolar, series, parallel. I'm talking rpms that that are actually useful to drive anything.
I have purchased high end drives and quality new steppers over the years and never been able to get they speeds I read about, then again i'm a microstepping fan.
Regards