20 mm cube calibration question?

[James Adams]

I'm printing calibration 20mm cubes. specifically calibrating for .2mm
layer height on my cupcake.

The problem is my cube isn't square, more rectangular. on the y axis
side I'm getting 19.98 (good enough), but on the x axis it's 19.03
basically a millimeter short. I'm wondering In skeinforge where should
I start to troubleshoot? I'm using version 35 of skeinforge.

The bot itself has pololu electronics for steppers, 16th step; and I
upgraded to twotime's x y inspired mendel. So x and y resolution is
pretty good mechanically.

[Nick Ames]

I don't think this is a problem with skeinforge, but a problem with your
hardware. I think the most likely possibilities are a mismatch between
your 'bot and replicatorg's steps per mm setting or missed steps on your
x stepper motor.

Make sure your belts are at medium tension, and increase the current to
the motor with the potentiometer on the stepper driver. Print another
cube, and try a few other objects to see if they have the same problem.

If all your objects are off in the x direction proportionally to their
size, then edit the definition for your driver in machines.xml. Edit the
machines.xml in your home folder; on linux, this is
/home/yourusername/.replicatorg/machines.xml.

[Rob Giseburt]

Check your machines.xml and make sure X and Y have the same steps/mm
set. Also check the jumpers or resistors on the Pololu boards to make
sure they're set right.

-Rob

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[Z LeHericy]

WOW, those settings are PERFECT! switching to these has given me the best prints i've ever gotten on my Makerbot!

I was hesitant to try due to the low PWM, but it works just fine so long as I keep the filament loose...

still getting some wobble, but it's less than half a mm, so i don't really care...

Have you posted these settings on the MB wiki? if not, please do!!!

-Z

On Sat, Jan 8, 2011 at 11:11 PM, coasterman-1674 <coast...@live.com> wrote:

Tighten the belt and turn up current to stepper motors.

And .2mm is quite a goal. Most cupcakes use between .32 and .4.
I suggest these values as a starting point assuming you have a MK5
extruder:
.2mm layer thickness
2.5 width/thickness
34mm/s
197PWM

.2mm layer height makes prints about 2x longer. However, they turn out
like you have a $50,000 machine next to your desk, except instead it
is a $900 cupcake CNC.

Allow +- 0.1mm deviation from ideal, due to backlash and other
factors.

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[AARON DOUBLE]

Is the wobble a Z thing or a backlash thing?

[Z LeHericy]

i'm thinking it's due to a bent z-rod, but all my rods are a bit bent, so when I put the z rods in, I positioned the bends in such a way that the platform would rotate back and forth about it's center instead of wobbling... it solved most of the problem, but it only works because all the rods are a bit bent... Eventually, I plan to upgrade to a smooth rod and bearing system, instead of the threaded rods, similar to the Z-rider, but my own design...

-Z

[AARON DOUBLE]

I need to finish the Z-rider instructions, It sucks, they are going to take forever and I haven't had a chance to do them.

[Z LeHericy]

I can definitely attest to the quality being at or above that of a more expensive printer... when holding the part I just printed next to a part I printed a couple years ago on a Dimension DST machine, the ONLY differences are that my layers are thinner, and that there's a slight wobble in my z axis...

i am using a MK5, but I plan to upgrade it to a stepper mk5...

-Z

On Sun, Jan 9, 2011 at 8:55 PM, coasterman-1674 <coast...@live.com> wrote:

I'm happy those settings work good for you! I assume you have a MK5,
since most of them produce near identical prints. It does in fact
appear that those setting create prints equivalent to that of an
expensive 3d printer.

On Jan 9, 10:51 pm, Z LeHericy <zeno...@gmail.com> wrote:
> WOW, those settings are PERFECT! switching to these has given me the best
> prints i've ever gotten on my Makerbot!
>
> I was hesitant to try due to the low PWM, but it works just fine so long as
> I keep the filament loose...
>
> still getting some wobble, but it's less than half a mm, so i don't really
> care...
>
> Have you posted these settings on the MB wiki? if not, please do!!!
>
> -Z
>

> > makerbot+u...@googlegroups.com<makerbot%2Bunsubscribe@googlegroups.c om>

> > .
> > For more options, visit this group at
> >http://groups.google.com/group/makerbot?hl=en.
>
> --
> -Zeno LeHericy
>
> //((=:Z:=))\\
> INVENTIONS
> Technologies
> zinventions.com

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[Z LeHericy]

I've wanted to make the switch for quite some time, but have no programming experience (other than web) so it's a bit out of my league...

I also think it would probably be better to at least partially gear down the stepper, to even out the steps, otherwise, you'll get the issue that is my largest complaint with the DST machine I worked with before, which was that the infill lines it drew had little ridges from the steps of the stepper...

-Zeno LeHericy

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On Sun, Jan 9, 2011 at 9:09 PM, coasterman-1674 <coast...@live.com> wrote:

I've noticed that the Mk5 has mounting screws located correctly with
support for a stepper motor. All you have to do is find a high torque
motor.

> > <makerbot%2Bunsubscr...@googlegroups.c om>

[The Ruttmeister]

On Jan 22, 10:42 pm, Z LeHericy <zeno...@gmail.com> wrote:
> I've wanted to make the switch for quite some time, but have no programming
> experience (other than web) so it's a bit out of my league...

You don't really need to do any programing other than to add tools to
SF, and that's just a 30 second text editing job. There is firmware
already out there. The hardest thing for me was cobbling together the
connections from the EC to the stepper driver.

>
> I also think it would probably be better to at least partially gear down the
> stepper, to even out the steps, otherwise, you'll get the issue that is my

There's also the issue of torque, I'm running my printed gears for
steppers and with a 5:1 reduction I'm running the driver very high.
I'd go for an even higher ratio but I might have trouble fitting the
big gear on the build platform!

I've not really gone too much into the motor reversal side of it yet.
But maybe I should try looking at editing the firmware... Need to
change it so the stepper stays energized when stopped as the
compression in the molten pla is causing backlash!
Or just add a rapid advance in the reverseify thing. Hmmmm