random notes

[Jeff Crews]

(Now that I can actually print I'll be a pain and try to keep the sense of the local "printing community" going.)

Various odd things and notes for new printers like Mike (and soon Otto!)

My ABS prints had a hella ugly bottom layer with too much plastic. then the top layers were fine. When I went into change my SF settings to print raftless, I discovered that for some reason the default was to print the bottom layer with 65% speed, but 100% plastic flow rate. I have no clue where that came from.

My first raftless print was still a little ugly because I didn't realize that I couldn't put the nozzle at truly "zero:" I needed a  (~0.3mm?) gap above the build surface because the raft settings usually took care of that for me.

My PLA test cube is almost 1 mm larger in X and Y than the ABS one. I think that's an effect of oozy PLA due to the temp being too high (default 200, so I'll bump it down bit by bit.)

For some reason the default PLA profile has so many different temp settings,  plus heat up/cool down times for each one, that the test cube took over an HOUR to print. After I realized what was happening I just let it roll but I'm going to change all the temps to the same value. On the good side, the RepG time estimator works really well- it said that was how long it'd take.

JSC

[Mike Broome]

Thanks for the info and for keeping the pot stirred in the local
printer community, Jeff!

So I'm a n00b at this stuff. I've now successfully printed 3 (yes,
three!) things on my printer. A calibration cube, a heart, and a crank
handle for the Z-axis. I've done no tweaking of any settings. I
just picked basic Cupcake or maybe Cupcake with HBP (even though I don't
have a heated build platform and am printing on kapton-tape-over-acrylic
at this point) and told it to go. And go it did! Not perfectly, but it
definitely printed.

I'm ready to start what sounds like an arcane process or trying to get
settings tweaked and dialed in. I'm just not sure where to start.

You talk about SF settings. I'm printing from ReplicatorG which has SF
build-in (or in a subdirectory, and it's invoking it under the covers).
I don't see any way to tweak SF settings from RepG, and in the brief
poking around the SF directory structure, it wasn't obvious where
changes would be made. I probably need to spend some quality time with
the SF manual or try to make sense of the web pages a bit more. Maybe
next week when I'm at the beach. But if you or anyone else has some
hints or pointers for where to start, I'd appreciate it.

Looking over the Makerbot wiki, I see some calibration and tweaking of
settings for the Thing-o-matic (like stepper REF settings), but not much
listed for the Cupcake. I'm guessing there's little that can be done
with the MK5 plastruder since it's a PWM controlled gear motor. Any
interesting tuning for the X,Y,Z steppers with v2.3 stepper driver
boards? (Other than upgrade the boards to Pololus? ;)

Mike

--
Mike Broome
mbroome(at)employees.org

[Jeff Crews]

Bill knows a lot more than I, but I'll give it a shot.

First of all, look at the Makerbot blog and find um... someone's Skeinforge tutorials- it's a 5 parter or so in which he covers the big variables that you can control.

With a gearmotor extruder, you are pretty much stuck at 255, full speed. So you control how much plastic gets put where with feed rate- how fast the platform moves, and the various "width over thickness" and other variables.

To tweak them you load your model, click "Generate Gcode," and pick your profile. Probably "Cupcake Basic." Then click "Edit" and the entire Skeinforge world of confusion and pain will show up. You should really read those tutorials first to know where to find what variables and how to adhust them. But if you're getting something recognizable already, then you're very close.

And definitely put some tape or something on that platform. I printed directly to acrylic and it took a jackhammer to get it off.

JSC

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From: Mike Broome <mbr...@employees.org>
To: techshop-durham-...@googlegroups.com
Sent: Monday, August 8, 2011 6:01 PM
Subject: Re: random notes

[Jeff Crews]

Whup, here is the series on SF variables:

http://davedurant.wordpress.com/2010/11/04/configuring-skeinforge-index-to-articles/

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From: Mike Broome <mbr...@employees.org>
To: techshop-durham-...@googlegroups.com
Sent: Monday, August 8, 2011 6:01 PM
Subject: Re: random notes

[Mike Broome]

Thanks, Jeff! I'd missed the "Edit" option along the way. I'll go take
a look at that later ... *maybe* after reading the info at the link you
sent. (Or more likely, I'll go take a look, be very confused, than go
read up to try to make sense of it all.)

My first print (calibration cube) was on naked acrylic. I added a layer
of kapton tape for the two prints last night, and they came off much
easier. Still a PIA to get all the bits of the raft off the thing,
though.

Assuming your offer is still open, I'll probably pick up your ABP at
Splat tomorrow and give that a whirl (since I probably won't have a
chance to build mine for a few weeks) to see what difference a heated
build platform makes. I haven't noticed any curling or lifting, but all
of the prints I've done have been fairly small so far.

M.