Makerbot Replicator Bowden Tube experiment - MakerBot Operators

The old Google Groups will be going away soon, but your browser is incompatible with the new version.
Message from discussion Makerbot Replicator Bowden Tube experiment
Received-SPF: neutral (google.com: 64.30.218.170 is neither permitted nor denied by best guess record for domain of dan.new...@mtbaldy.us) client-ip=64.30.218.170;
MIME-version: 1.0
Content-transfer-encoding: 7BIT
Content-type: text/plain; CHARSET=US-ASCII
Subject: Re: [MakerBot] Makerbot Replicator Bowden Tube experiment
From: Dan Newman <dan.new...@mtbaldy.us>
In-reply-to: <5321ea87-98e2-418b-8f1a-64f99f136f45@googlegroups.com>
Date: Thu, 04 Oct 2012 11:51:36 -0700
Message-id: <67AFC7BA-BC15-4F01-9558-93BEE47CF64D@mtbaldy.us>
References: <5321ea87-98e2-418b-8f1a-64f99f136f45@googlegroups.com>
To: makerbot@googlegroups.com

The other direction we need to take extruders is *faster* feed rates.
Right now with the Jetty Firmware, we can run the bot's quite fast
(> 300 mm/s), but the 1.75mm filament extruders cannot handle those
speeds.  A 3mm filament extruder likely could as you only need to
ingest filament at one third the rate (1 / 2.93).

Sure momentum is an issue at those rates and thus having a less
massive extruder is very helpful.  But you can compensate for a massive
extruder by have small max accel/decels and tighter jerk control.
Doing that slows down the print and for small prints may mean never
hitting the top/target feed rates.  For large prints, there's
plenty of "take-off" room in which to hit top speeds.

Dan


On 4 Oct 2012 , at 11:09 AM, delsydsoftware wrote:

> 
> 
> <http://farm9.staticflickr.com/8182/8054156782_5c25417a6a_b.jpg>
> 
> <http://farm9.staticflickr.com/8310/8054155728_7cd5b65a09_b.jpg>
> 
> <http://farm9.staticflickr.com/8178/8054151859_bfd10d2a5d_b.jpg>
> 
> 
> Since the 3-point adjustment mod I did worked so well, I figured I'd do 
> something a little crazier. I decided to convert the Replicator to a Bowden 
> tube setup.
> 
> I made a custom bracket to mount the extruder stepper motors to the back 
> of the Replicator, and attached some Teflon tubing. I'm still designing 
> parts to hold the tubing in place on the print head, so for now the tube is 
> just wedged in place with a tiny screwdriver. That works surprisingly well, 
> actually. I also added a Lin Engineering stepper motor damper to the 
> extruder, which seems to really clean up blobbing caused by backlash. I'm 
> using the Minimalistic MK8 mod to feed the filament directly into the 
> teflon bowden tube, which leads straight into the print head.
> 
> The guardian squirrel was printed at 50 microns layer height, with 
> print-o-matic set for 60mm/s and 70mm/s extrusion speed. With no motors 
> attached, the print head is really fast. I was able to do some test prints 
> at 150 mm/s at about the same quality as an 80mm/s print with the original 
> setup. Echoing is greatly reduced as well. The machine is also amazingly 
> quiet now. You can occasionally hear the damper knock when the stepper 
> motor makes a drastic direction change, but that's really not a big deal. 
> The y axis on my machine has always been the loudest, and it quieted right 
> down. I'm planning on adding a damper to it as well, to see if I can reduce 
> the noise a bit further.
> 
> The only catch right now is that I need to design a bracket for the right 
> extruder that hits the X limit switch. I've been tapping the switch by hand 
> when the print head resets. I had overlooked that little detail, because I 
> assumed that Makerbot wouldn't have used the side of the stepper to tap the 
> limit switch. Bad assumption! There is nothing like hitting the print 
> button and hearing your belts grinding.  :(
> 
> I'm also thinking about using a different set of heatsinks for the print 
> head. Only a small portion of the heat sink is making contact, so the rest 
> is basically wasted surface area. I doubt that the top of the heatsink is 
> really doing much work. I was thinking of using some passive ram heatsinks 
> instead, the type you see on Corsair Dominators. 
> 
> Here's a vid of the extruder/damper in action. I'm going to work on the 
> rest of the bracket designs when I get home:
> 
> http://www.flickr.com/photos/delsydsoftware/8054221343/in/photostream
> 
> Total cost so far is $13 for tubing and $25 per damper. I used spare screws 
> from the MK8 build to attach the bracket to the motor, so those expenses 
> were already covered. So, basically $63 total for a great increase in speed 
> and high-res print quality.
> 
> -- 
> You received this message because you are subscribed to the Google Groups "MakerBot Operators" group.
> To view this discussion on the web visit https://groups.google.com/d/msg/makerbot/-/vuCY4hzHVmsJ.
> To post to this group, send email to makerbot@googlegroups.com.
> To unsubscribe from this group, send email to makerbot+unsubscribe@googlegroups.com.
> For more options, visit this group at http://groups.google.com/group/makerbot?hl=en.
>
Create a group - Google Groups - Google Home - Terms of Service - Privacy Policy
Account Options
