How to tune Ramps + a4988 + Stepper motors

Well, I've loaded Marlin. In Repetier I can move my motors. They dont feel very torquey to my fingers. The a4988 are set as they came. What needs to be done to be sure ther a4988s are outputting the optimal power to the motors?

My motors are :42BYGHW811 76oz/in

1.8° Step Angle
•4800 g-cm holding torque @ 2.5A
•4240 g-cm low speed torque
•NEMA-17 Bipolar 4-wire

Recommended Voltage 12 V DC
Rated Current 2.5 A
Coil Resistance 1.3 Ω

It could depend on the Pololu boards you have. Some will need around 0.45v measured on the pololu board while some others (which you may have) will require around 0.8v

Edited 1 time(s). Last edit at 10/04/2013 09:02PM by waitaki.

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Waitaki 3D Printer

First, I'd run the machine through some prints and see if you're skipping steps or going into thermal shutdown on the A4988's. Just be prepared to actively cool the stepper drivers with a fan or two.

If you max out the 1A that the pololu's are delivering and are skipping steps, then it may be time to reconsider some things.

Those Wantai's need an awful lot of current, a lot more than the 1 ~ 1.2A that the A4988's can supply.
[www.pololu.com]
[www.pololu.com]
[www.wantmotor.com]

Maybe try a DRV8825-based driver. Even those can't really supply a full 2.5A, but at least it'll get you close ~ 2.2A.
[files.panucatt.com] << Best-in-class driver for the $$$, price break @ Qty=5
[www.pololu.com]

Perhaps a THB6064AH solution?
[www.youtube.com]
[www.massmind.org]
But for 4 axes that is an expensive route ~$160!

Or just get different motors that the A4988's can easily drive.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]