My Replicator ..... It Arrived!!!!

[kevin quinn]

Ordered my Replicator around 10am Saturday morning ( august 4th ) and just signed for it!! 7 day lead time my ass !!! I wasnt expecting it till the week of the 20th. 

Ordered a Prusa mendel 2 weeks ago but its been a nightmare. Missing pieces and acrylic extruder base plate. Solder stuff crimp wires. Blah. So said F'it and ordered the replicator which I should have done in the first place. I only got the single extrudered for the time being though. Basically cause the prototypes I designed for a project are single color as is the final project. So saved the 250 difference between the single and double extruder since I already 'wasted' money on the prusa, and spent more then I wanted. My buddy is going to take over the build for me, so Ill have to 3D printers in the course of 3 weeks before I even printed one part/piece. lol

The bad part is I've been up for almost 20 hours. So I'm not even going to unbox it just yet. Have work at 11pm tonight, and because I work an off shift thursday is actually my friday so I may end up calling out of work and making it a 3 day weekend to 'play' with the new toy. :)

[PropellerScience]

I got the Replicator for the exact same reason you did, I didn't want
to spend the rest of the year building and tuning it. I got the dual
extruder knowing full well the second extruder would probably end up
as a spare. I just keep natural ABS in the "spare", and that's pretty
handy when you think of it. At the moment I think it's easier and
cleaner to just print separate colored parts, and stick them together
later, like the Higgs-Boson by Todd Blatt from Makerbot I just
finished up. Have fun, it just works!
http://www.thingiverse.com/derivative:35504

[Doogiekr]

As a semi-new replicator owner as well... I can make a couple of
suggestions to get you started.

Level your platform... then level it again... and when you think its
good... level it some more. If you can use a dial indicator to do it,
then even better. This cured sooooo many of my print issues.

Enclose your bot... keeping the heat in the build area for printing
ABS is a huge help for taller prints that dont get as much of a
benefit from the heated build platform.

Measure your plastic... often... and use the measurement in the print-
o-matic settings.

Those 3 things could have saved me a ton of hours and wasted ABS. Not
that I mind, it was part of the learning process, but if you get those
things right then you can spend your time fine tuning or just having
fun printing.

Good luck and enjoy =)

[CarryTheWhat]

YES leveling, leveling, leveling... and then ambient temperature (which can be held in check by enclosing). I have lousy climate control (mostly just windows), so whenever the temp drops below 65 or 70, failure rate skyrockets especially for large prints.

Would you mind explaining what you mean about measuring the plastic?

Measure your plastic... often... and use the measurement in the print-
o-matic settings.

 Do you refer to the filament diameter? What problems does this cause? The only obvious problem I have seen is when the diameter thins out too much, and the extruder gear slips.

Thanks!

[Doogiekr]

Yes, the filament diameter... If it is very different than what is in
print o matic then it can really screw things up as that plays a large
role in how much the machine lays down each layer. Pretty sure the
default is like 1.82 but the filament i am currently printing with is
actually 1.73... If I dont change it, the my prints are terrible.

[CarryTheWhat]

What exactly is the effect of having this out of sync? For example, without good leveling, I see a lot of lifting; and without managing ambient temperature, I see a lot of cracking. What problem does this alleviate?

[Dan Newman]

On 9 Aug 2012 , at 2:02 PM, CarryTheWhat wrote:

> What exactly is the effect of having this out of sync?

If the slicer thinks that the diameter is D when it's really s*D
then it will compute the incorrect volume of plastic output per
extruder step. The error will be (1 - s^2)/s^2 = (1/s^2 - 1). So,
in the supplied example, the s = 1.73/1.82 = 0.95 and so the error
is around 0.1 or 10%. Well, that means that 10% too little plastic
will be output when printing the model and it will thus be a bit anemic.

> What problem does this alleviate?

Poor print quality owing to too much or too little plastic output by
the extruder.

Dan

[Lee Nelson]

What if the spring loaded pinch wheel was used as a measurement for filament diameter? That could be used to calculate material volume on the fly.

Or maybe an optical measurement..

[Shawn]

This has been discussed but introduces other problems.

The current method has the slicer program (SF in our case) taking an
estimated average of the filament diameter, then using that to calculate
how much to turn the feeder motor to produce a required volume of plastic.

The suggested method requires the slicer to NOT do this, but instead
somehow specify how much plastic is needed at each location, then the
onboard electronics can measure the filament dynamically and do the
calculation to decide how to get the the required volume.

This is a bit of a radical change from the current method, though I and
others agree this would probably be better in the long run. Basically
the onboard electronics has to get smarter, which means more expense.
Still, I have a couple of spare single board computers that have enough
oomph to run a full Linux distro. I'm hoping that one day when things
calm down I can try putting one of these into the printer and see if I
can "make it work" - including filament measurements. I'm sure someone
will beat me to it though.

Shawn

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[Hugh Johnson]

On Aug 9, 2012, at 2:39 PM, Shawn <sgr...@open2space.com> wrote:

I'm hoping that one day when things calm down I can try putting one of these into the printer and see if I can "make it work" - including filament measurements.  I'm sure someone will beat me to it though.

I happen to have just seen this the other day https://github.com/modmaker/BeBoPr

I haven't tried it or anything but it looks promising.

Hugh Johnson

[Lee Nelson]

What if a pressure sensor was placed in the hot end. I imagine there is an industrial component that could take the heat or the chamber could be redesigned. The advantage would be either a supplement to the calculations or possibly make them unnecessary. The software would try to keep a constant pressure in the hot end chamber regardless of fluxuations in filament diameter.

[Shawn]

I'm not an engineer, but that sound promising!

[Sean Tu]

You're basically talking about having some sort of accumulator to ensure a constant and consistent feed. If you take a look at the Filabot the tube where the auger lives is serving the same purpose. 

The problem that comes up is the extruder has an open nozzle so precisely turning off the pressure, and extrusion, will be a problem. We already see this with the little dangling pieces from the extruder because of the excess pressure even when the stepper isn't feeding it anymore. Having a accumulator will just make this problem worse as there will be more volume under pressure. 

For making filament this isn't a big deal, you just throw out a few inches. For a printing it would probably be a problem.

On Thu, Aug 9, 2012 at 5:57 PM, Shawn <sgr...@open2space.com> wrote:

I'm not an engineer, but that sound promising!

On 12-08-09 04:25 PM, Lee Nelson wrote:

What if a pressure sensor was placed in the hot end. I imagine there is
an industrial component that could take the heat or the chamber could be
redesigned. The advantage would be either a supplement to the
calculations or possibly make them unnecessary. The software would try
to keep a constant pressure in the hot end chamber regardless of
fluxuations in filament diameter.

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[Lee Nelson]

Thanks for the feedback. Would it be possible to have a nozzle that closes?