Replicator 1 Feed Rate and Print Quality versus Build Time

[Matthew Marlowe]

All,

Since getting my replicator 1, one of the most difficult to understand
print settings has simply been flow rate.
Everyone seems to be using something different, and even makerbot
includes two by default - 50 standard, 80 accelerated.

Well, I first tried 80 accelerated and the printer just shaked too
much or zapped too much around corners for me to feel comfortable. I
want my printer to last as long as possible - thank you.
I applied the firmware reduced acceleration settings for the x & y
axis and these helped tremendously in limiting the worst effects so
they were barely noticeable.
Still, as I started down the path of valuing higher quality prints, I
found that a feed rate of 60 seemed to be the best trade off of
controlled extruder motion versus fast prints. And this seems to
match the other references to speeds of 50-60 being a good balanced
value in other threads.

To be honest, I'm not sure how much benefit there would be to going to
a lower feedrate with the reduced acceleration firmware settings in
place? As it is with a 60 feedrate, most of my recent prints are
5-9hrs long which is about as long as I can have any confidence that
warping will not get out of hand in the HBP (even when it is heated to
115).

And, yet, even this week -- there have been references to feed rate
settings between 30 and 100 on this list!?! Are others really finding
so much benefit moving between so slow and so fast numbers?

I have looked back through prior threads...but I haven't really seen
this issue covered in any depth.

Thanks in advance,
Matt
--
https://www.twitter.com/deploylinux

[Shawn]

It all depends on what you are trying to do.

For instance, early this week I found out I was showing off the
Replicator at a local event this weekend. I had to print up some
pertinent parts, and time was short. So, I bumped the print speed to
120mm, and dropped my typical fill rate to 10% (from 20%). In this
case, speed and quantity of prints is what was important.

However, when I'm trying to do something for detail, I'll slow it down
to as low as 20mm/second. These lower speeds do not have the same
issues as the higher speeds because the speed differences are so much
less and simple inertia becomes almost non-existent. So, when I'm after
high quality I drop my print speed so the surfaces are in better shape
and the details are more noticeable. In addition, I may drop my layer
height (usually from .2mm to .1mm) so the vertical resolution is also
finer (but then the print takes twice as long).

So, in essence, it is about speed versus quality, for the situation you
find yourself in. If you are good/lucky, you find the sweet spot for
each model where you get reasonable quality, at a decent speed. If you
are like me (sometimes lazy), you just bite the bullet and print at a
much lower speed to get the quality.

HTH.

[Zip Zap]

  You need to look into upgrading to Jetty firmware in order to print faster properly. For example,  Jetty firmware accelerates your print head to a top velocity and not a top speed.  So your always accelerating and decelerating around curves and corners instead of making abrupt stops and starts.  There are numerous Youtube examples on this with the Ultimaker, ThingOMatic, etc.  The Replicator was added on later.

---

From: Matthew Marlowe <ma...@professionalsysadmin.com>
To: make...@googlegroups.com
Sent: Friday, September 21, 2012 9:40 PM
Subject: [MakerBot] Replicator 1 Feed Rate and Print Quality versus Build Time

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[Joseph Chiu]

I think Jetty said it best when he said (something to the effect of) accelerated printing is like turning on draft mode.

I have cranked up acceleration up to 120 mm/sec, and set fairly high accel/decel values to print larger parts for mechanical use -- the ringing on those parts were sometimes pretty awful -- but the parts suited the purpose.

I've found 90 mm/sec with a lower jerk (20 mm/sec) and moderate accel/decel (400 mm/sec/sec, iirc?) actually resulted in better quality than non-accelerated printing at 30 mm/sec.

It is a process, though, to get your printer dialed in.  And more methodical you are, the better.  I get a little sloppy sometimes and accidentally overwrite my settings.  (I really should get git installed on my Windows box...)

[Joseph Chiu]

p.s. Replicator firmware is not the same as ToM firmware, but the general principals behind using acceleration would be the same...

[Jetty]

> > I think Jetty said it best when he said (something to the effect of)
> > accelerated printing is like turning on draft mode.

I think it depends on what acceleration you're using. Some
implementations produce better
results than others.

That said, I'm now routinely printing at 100-120mm/s with results as
good (and often
better) than non-accelerated printing at slow rates. So I don't
consider acceleration to
be draft anymore.

For example:
http://www.thingiverse.com/derivative:38852

Part of the issue is that the nozzle contains plastic under pressure.
This pressure is
constantly varying throughout each line segment, so it has to be
managed ahead of
the acceleration and deceleration if you don't want blobbing.
Acceleration firmwares
generally don't handle this or not well, and the quality suffers.

Jerk and acceleration rate also effect ringing. So essentially it
becomes a trade off of speed / mechanics.
Push the mechanics too far with the acceleration settings and you'll
get poor quality.

Also extruder pressure and grip is an issue. Part of the reason I'm
looking
forward to the Kickstarter extruders. If they work, then hopefully we
can get
past the 150mm/s barrier, where the pressure is so large on the MK7/
MK8 that
it starts to slip.

[Dan Newman]

On 23 Sep 2012 , at 5:30 PM, Jetty wrote:

>>> I think Jetty said it best when he said (something to the effect of)
>>> accelerated printing is like turning on draft mode.
>
> I think it depends on what acceleration you're using. Some
> implementations produce better
> results than others.
>
> That said, I'm now routinely printing at 100-120mm/s with results as
> good (and often
> better) than non-accelerated printing at slow rates. So I don't
> consider acceleration to
> be draft anymore.
>
> For example:
> http://www.thingiverse.com/derivative:38852
>
> Part of the issue is that the nozzle contains plastic under pressure.
> This pressure is
> constantly varying throughout each line segment, so it has to be
> managed ahead of
> the acceleration and deceleration if you don't want blobbing.
> Acceleration firmwares
> generally don't handle this or not well, and the quality suffers.

Asymmetric advance algorithms rock. Even better when you can cast them
such that they are linear functions of the motion/kinematics.

Dan

[RocketSled]

I haven't been a Replicator owner for long.  But I do have a lot of experience in CNC and mechanics and electronics.

IMO, the limit on quality is the degree of excitation induced in the structure from the printhead's motion.  Sudden changes in speed and direction cause the entire frame to flex and that motion couples into the build platform (which is unfortunately designed like a diving board).  Acceleration spreads changes in velocity out over a longer period of time, which reduces the magnitude of the impulses that get generated, it 'bangs' on the mechanics less.  But Kinetic Energy cannot be denied and the slower you go, the less of it there is to excite the structure in to motion.  

For any given object, there's a speed below which printing becomes impractical.  But that speed depends on the object and your individual level of patience.  So IMO, if you want the highest quality prints you can get, going as slow as you can stand to go is your best bet.