USing Makergear stepper extruder with Pololu driver

[Owen M Collins]

I am moving my MG Stepper extruder over from the Gen3 stepper driver to a PSMD board. I have the 3G5D shield added and can jog all the axis like with th cable hack. But Maybe I need to adjust the trim pot. Right now when I hit jog on this Fancy new RepG 34 the Extruder stepper doesn't move. I hear it trying. Any thoughts?

Thanks all,
O.

[Whosawhatsis]

If you hear it trying to step, you probably just need to adjust the pot on the stepper driver.

Are you sure that it's not moving? The pololu driver will move the stepper 8x slower, so if you didn't account for that in your machines.xml file, it may look like it's not moving when it is just moving very slowly.

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[Owen M Collins]

I thought I put in the right step number for 1/1/6 stepping. Here is the Machine profile I made:

<machine>

<name>3G 5D Cupcake (Pololu XYZA, MakerGear Stepper Extruder)</name>

<geometry type="cartesian">

<!-- different pulleys on X and Y axii -->

<axis id="x" length="100" maxfeedrate="10000" stepspermm="94.1397046"/>  <!-- sixteenth-step driver -->

<axis id="y" length="100" maxfeedrate="10000" stepspermm="94.1397046"/>  <!-- sixteenth-step driver -->

<axis id="z" length="100" maxfeedrate="170" stepspermm="2320"/> <!-- sixteenth-step driver -->

<axis id="a" length="100000" maxfeedrate="3000" stepspermm="1487"/><!-- was: 100.470957613814818 -->

</geometry>

<tools>

<tool name="Makergear Stepper Extruder" model="Batch 1" diameter="0.35" stepper_axis="a" index="0" type="extruder" motor="true" fan="true" heatedplatform="true" motor_steps="3200" default_rpm="3" heater="true"/>

</tools>

<clamps></clamps>

<driver name="makerbot4g">

<!-- optional, defaults to first serial port found.    <portname>COM1</portname> -->

<!-- required: we need 8 bit and 38400 baud. -->

<rate>38400</rate>

<parity>8</parity>

<!-- optional, defaults to 1.                          <databits>1</databits> -->

<!-- optional, defaults to N.                          <stopbits>N</stopbits> -->

<!--<debuglevel>5</debuglevel>-->

</driver>

<warmup>

</warmup>

<cooldown>

(Turn off steppers after a build.)

M18

</cooldown>

</machine>

O.

[notstarman]

I just went through a similar problem in another post(http://
groups.google.com/group/makerbot/browse_thread/thread/
17fe4c9b1d3bdae4/49d35c7c3a2e56ab?show_docid=49d35c7c3a2e56ab) and
convinced my self that RepG wants steps/mm.

First it looks like you have your A axis defined in two places. Under
tool and under the axis info. These number disagree. Since the RPM
number is very very slow I think that it is dominating you axis number
giving you a slow extruder. Try removing this reference.

Also 1487 is too many steps per mm.
Here are the calculations that I used when I did a similar update
using the 51:7 Big gear extruder. (https://www.dropbox.com/s/
uljkn2n5f04jyne/cal%20for%20A%20axis.jpg)

200 Steps/Motor Rev * 16 uSteps/Step * Motor Rev/6 Teeth (small Gear)
* 13 Teeth (big Gear)/ Rev Drive Gear * Rev Drive Gear/(Drive Gear
Diameter*pi)=

200*16*13 u steps
---------------------------------
6*(Drive Gear Diameter in mm)*pi

If we assume that you have an 8mm Drive bolt then you should have a
number closer to 275.86856802595191533273185651236 usteps/mm

> >> For more options, visit this group athttp://groups.google.com/group/makerbot?hl=en.

[neoteric]

here is my machines.xml entry. Working great. Sorry it took so long
to get to you, traveling.
<machine>
<name>aa 3G 5D Cupcake with makergear (3g polulu, Makerger+Pololu

Extruder)</name>
<geometry type="cartesian">
<!-- different pulleys on X and Y axii -->

<axis id="x" length="100" maxfeedrate="5000" scale="94.1397046"/>
<!-- sixteenth-step driver -->
<axis id="y" length="100" maxfeedrate="5000" scale="94.1397046"/>
<!-- sixteenth-step driver -->
<axis id="z" length="100" maxfeedrate="150" scale="2560"/> <!--
sixteenth-step driver -->
<axis id="a" length="100000" maxfeedrate="5000" stepspermm="1487"/
>
</geometry>
<tools>
<tool name="Makegear" type="extruder" material="pla"
floodcoolant="false" mistcoolant="false" fan="false" valve="false"
collet="false" heater="true" heatedplatform="false" stepper_axis="a"/