Acceleration Marlin / GRBL

For my self-built machine I have used stronger steppers (Nema 23 / 2.8 A / Toshiba drivers). Initial tests with GRBL have produced high speeds with slow start and deceleration before stop.
After the change to Marlin I get only slow speeds without any acceleration.

Of course I have tried different values in the Config.h of Marlin.

I'm currently testing only the Y axis (the second values in the definitions). The values are:
 
#define CONFIG_STEPPERS_TOSHIBA
#define DEFAULT_AXIS_STEPS_PER_UNIT {800, 640, 800, 500}
#define DEFAULT_MAX_FEEDRATE { 300, 300, 5, 25 }
#define DEFAULT_MAX_ACCELERATION { 3000, 9000, 100, 10000 }
#define DEFAULT_ACCELERATION 3000
#define DEFAULT_RETRACT_ACCELERATION 3000
#define DEFAULT_TRAVEL_ACCELERATION 3000

With DEFAULT_TRAVEL_ACCELERATION I have entered higher values up to 10,000 and do not recognize any increase in speed. And absolutely no acceleration at longer distances.

Is Marlin not capable of acceleration?

Of course its capable.
You might be hitting the upper limit so you wont notice a difference.
Try a small value so you can see. something like 40. It should noticeably ramp up and down with it set that low.

With the settings given in my first post I got 100 mm movement in about 6 seconds.

Now I changed the max feed rate für Y to 30:
#define DEFAULT_MAX_FEEDRATE { 300, 30, 5, 25 }
Result: No change in speed, no acceleration.

Then in Pronterface I set the max speed from 3.000 down to 300 mm/min.
Result: Now I got 100 mm in 20 seconds. Much slower, but also no acceleration.

Then in Pronterface I set the max speed to 8.000 mm/min.
Result: 100 mm again in 6 seconds, no acceleration.

Now I know that Pronterface affects the settings. I can not use Universal G code transmitter because version 1.0.9 does not support Marlin. New experiment with
#define DEFAULT_MAX_FEEDRATE { 300, 300, 5, 25 }
and Pronterface max speed = 6.000.
Result: 100 mm in 6 seconds, unusual noise at start and stop - but no steps lost. Maybe a sign of slow start and stop

Pronterface max speed = 10.000.
The noise at the start now takes longer. I hear and see a very slow start, which goes directly into the higher speed without a ramp.

Higher than 10,000 I need not to go in Pronterface, because that is the limit for Toshiba drivers. Nevertheless I tried it with 30,000 and there is a change. The start and stop phase now takes more than 2 seconds and is extremely slow.

Good to hear that there is no ramp. From the extremely slow speed it switches very quickly to the (still slow) higher speed.

For comparison: with GRBL I reach the maximum Y-distance of 346 mm in only 8 seconds on the same machine. And this with a nice even ramp.

Do I have to live with this Marlin behavior or are there other settings?

Update your eeprom... Is probably ignoring firmware settings

I read the values from the EEPROM with M501. They are identical to the set values:

SENDING:M501
echo:V39 stored settings retrieved (465 bytes; crc 4546)
echo: G21 ; Units in mm
echo: M149 C ; Units in Celsius
echo:Filament settings: Disabled
echo: M200 D1.75
echo: M200 D0
echo: Steps per unit:
echo: M92 X800.00 Y640.00 Z800.00 E500.00
echo:Maximum feedrates (units/s):
echo: M203 X300.00 Y300.00 Z5.00 E25.00
echo:Maximum Acceleration (units/s2):
echo: M201 X3000 Y3000 Z100 E10000
echo:Acceleration (units/s2): P R T
echo: M204 P3000.00 R3000.00 T3000.00
echo:Advanced: S T B X Z E
echo: M205 S0.00 T0.00 B20000 X20.00 Y10.00 Z0.40 E5.00
echo:Home offset:
echo: M206 X0.00 Y0.00 Z0.00

No change in behavior.

Edited 1 time(s). Last edit at 08/28/2017 11:27PM by thpitsch.