Re: [CAD_CAM_EDM_DRO] reprap build started

There is absolutely no reason to switch to a Makerbot extruder from a
Wade's, and there are many good arguments against! I have heard of way too
many problems with the MBI extruders to trust them. A PLA extruder body
works just fine, provided you have a suitable insulator on your hot end,
though on a long print at 230c I see how you could begin to run into
problems.

The easiest solution would be to just print a new extruder body out of
ABS... That is the beauty of having a printable 3d printer, if you need a
replacement part, just print one!

If you don't want to do that for some reason, you can add a fan blowing over
your insulator. You want to try to avoid cooling the hot end, but you do
want to cool the insulator, and cooling the part is handy as well. The
simplest solution to that is to insulate the nozzle.

Also, you may well be printing too high... 230C was common wisdom, but in my
experience it is much hotter than is needed. I print 1.75mm ABS at 200c,
though 1.75 melts faster so the extra temp may be necessary to get 3mm
filament to melt. Try dropping them extrusion temp by 5c at a time until you
reach the point where you start having trouble extruding, then go up by 2c
at a time until you get the best results. Another way to tell you are
extruding too hot is the odor. Overheated ABS stinks badly, but if it is
only heated to the right temperature the smell is not exactly pleasant, but
really not bad at all.

DC extruders are completely obsolete, so there is absolutely no reason to
maintain compatibility with them. It is not just that they do not work as
well, it is literally not possible to use them to accurately extrude a known
volume of material. Because of this, none of the newest slicing software
even supports them, since extruding a known volume is absolutely critical to
get decent, consistent print quality. The best advice I can give you is to
run a recent firmware (Sprinter is most popular, but I prefer SJFW), a
modern host program (Pronterface is the only good choice at present), modern
electronics designed for a stepper extruder (RAMPS or Sanguinololu for now,
but other options are probably going to be available soon), and slice with
Skeinforge 40 or above or SFAct, which is a slightly simplified version of
SF40. (fwiw, do resist the urge to write a new firmware, there are already
too many to keep things straight!)

Hope this helps!

On Sat, Oct 8, 2011 at 5:59 AM, Kevin Martin <kpmartin@...> wrote:

> Our printer has a (variant on?) Wade's Extruder which uses a stepper motor
> to feed filament from a coil.
> Some of our problems were due to the fact that we were extruding ABS at
> 220C from an extruder whose plastic parts were printed in PLA which has
> lower softening and melting temperatures than ABS. Heat leaking from the
> nozzle and melt chamber kept finding new paths to the extruder body and
> softening them. Heat from the stepper motor was also causing grief (the
> current adjustment is a near-microscopic unmarked trimpot on the extruder
> driver board). I eventually made a new extruder body out of maple. Now it
> extrudes reliably, and we are trying to get a reliable set of software tools
> (possibly involving replacing the printer or stepper firmware) to make a
> semi-turnkey system for all of us to use.
>
> As things are currently coded, the stepper-based extruders and the DC
> motor-based extruders need different (incompatible) GCode to run them. I am
> resisting the strong urge to rewrite all the firmware and tools so they
> interact in the proper (IMHO) manner, both because of the time it would
> take, and also because it would add yet another (incompatible) branch to the
> current mess of open-source versions.
>
> Every now and then while we were trying to get the extruder to work some
> helpful chap would suggest we replace the existing extruder with (the
> latest-and-greatest new) MakerBot extruder, not realizing how much bigger
> the latter is...
>
> -Kevin Martin
> the Papertrail Handmade Paper & Book Arts
> New Dundee, Ontario
> 518-884-7123
> www.papertrail.ca
>
>
> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:
> CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of wolfgang
>
> to add to the confusicfication...
>
> Are you making the coil extruder head, the syringe based head, the
> powder head, or the pellet head?
>
>
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