plastruder motor stopped working

[Mike Broome]

I'm just starting to understand why this device will be powered by tears
of geeks. I'm on vacation at the beach this week. I brought my 'bot
with me to show my family, especially my 11-year-old-nephew. I got
things setup, and have tried two prints ...

The first one was a fairly wide object, and the ABS started to cool and
warp and eventually released and the started sliding around. (Yeah, I'm
just printing on taped acrylic. Definitely need to upgrade to a heated
platform or the ABP that came with the kit.)

I started a second print that was a lot smaller to avoid the warping,
and part-way through printing the raft, the plastic stopped extruding.
Ends up that the DC gear motor of the MK5 plastruder has stopped
working. :( I've reset the 'bot, reloaded the firmware on the extruder
board and motherboard, and tried to run it manually through the RepG
control panel both with and without filament. No joy. I took the motor
off of the plastruder, and I can't turn the spindle by hand. (Which I
think I should be able to do.) I don't have tools with me to debug it
any further, and I probably won't really have a chance at home for a few
weeks due to some upcoming travel.

These were only my 5th and 6th prints overall with the 'bot, and I'm
guessing that the DC motor or the gearbox is bad. I'll probably contact
Makerbot about it, unless y'all have a better idea. This may also push
up the timetable on my upgrading to a stepper extruder.

At least my nephew is having fun with the first partially printed object
that's still stuck to the raft. Because it warped, it spins fairly
well. And it can be used as a coaster. Kids are pretty inventive, and
unlike me, he doesn't see it as a failure. :)

M.

[Bill Culverhouse]

I'm not sure that you can turn the gearmotor by hand. Maybe.

 

You could just take it loose and stick the motor leads into the

12v on a harddrive connector on the power supply. To see if

it'll turn.

 

Also make sure the power supply shows signs of life, yadda yadda

A stepper extruder wouldn't be expensive. $25 for a stepper and $40

for the driver board and print a wade's or something.

 

These things do tend to crap out whenever you try to show them off.

Just like that damn dancing frog on the old Looney Tunes cartoons.

 

-b

[Mike Broome]

I'm still working on naming my 'bot. Dancing Frog is now in the
running. ;)

The rest of the Makerbot is working just fine, with all three axes
moving and responding correctly. I don't have a multimeter or any spare
wire or jumpers with me. However, I was just able to connect the motor
directly to 12V on the power supply ... and it turned! And when I
reversed the polarity, it turned the other way! So the motor itself is
working.

And I just pulled up RepG and tried it from there ... and it's also
working. *sigh*

Why the sigh? Because I don't know what I did to get it working. I
took the motor off the plastruder and poked at it. I actually took the
knurled drive gear off and removed the top cover from the gearbox and
looked in there. Only poked it a little bit. (The gears are all
covered in grease, and I didn't want to poke them too hard and have them
all come apart because I didn't know what I was doing.) Maybe something
was stuck w.r.t. the gearbox? Don't know.

S'pose it's time for another test print ... Wish me luck!

M.

[Bill Culverhouse]

Seems like I had an issue or two with the gearmotor getting sort of

stuck. I think part of the problem is that the motor isn't up to the forces

demanded of it. It is also known that the motor can stall at less than 255

pwm.

 

I had issues with EM noise from the motor causing my extruder controller to

reset itself mid print.

 

There are plenty of gremlins that appear when you start messing with the arcane

science of 3d printing.

-b

[Jeff Crews]

Weirdness. I just got all of these (I'm at the Brevard library today).

For the next failure: You can't turn the spindle by hand- the gear ratio is too high. I'd tin the motor leads and make sure they're screwed down in the terminal blocks really well. the next time it craps out check the chip next to the motor connectors and see if it's getting hot. You could heat sink it. Beyond that I have no clue besides contacting MB for an exchange if it happens again and you can't find the reason.

If you look at the wiki (and listen to Bill) you'll find that there are many complaints about those damn motors. My first one was some kind of prodigy- it never crapped out- still hasn't.

jc

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From: Bill Culverhouse <bill.cul...@gmail.com>
To: techshop-durham-...@googlegroups.com
Sent: Wednesday, August 17, 2011 1:52 PM
Subject: Re: plastruder motor stopped working

[Mike Broome]

On Wed, Aug 17, 2011 at 01:52:50PM -0400, Bill Culverhouse wrote:
> Seems like I had an issue or two with the gearmotor getting sort of
> stuck. I think part of the problem is that the motor isn't up to the forces
> demanded of it. It is also known that the motor can stall at less than 255
> pwm.

I had heard that the DC gearmotor really didn't work at lower PWM
settings so I've only used 255.

> I had issues with EM noise from the motor causing my extruder controller to
> reset itself mid print.

I don't think EM noise is what's happening here. When the extruder motor stops
running, the heater relays that are controlled by the extruder board
still cycle on and off.

I did some more debugging yesterday, and it looks like something going
on or going wrong with the extruder controller board more than the motor
itself. When I tried another print, the extruder stopped working just
as the raft was finishing printing. I stopped the build, and without
changing anything else, I tried connecting the motor directly to 12V,
and it worked.

On Wed, Aug 17, 2011 at 12:00:09PM -0700, Jeff Crews wrote:
> For the next failure: You can't turn the spindle by hand- the gear
> ratio is too high. I'd tin the motor leads and make sure they're
> screwed down in the terminal blocks really well. the next time it
> craps out check the chip next to the motor connectors and see if it's
> getting hot. You could heat sink it. Beyond that I have no clue
> besides contacting MB for an exchange if it happens again and you
> can't find the reason.

Chip on the extruder board overheating is an interesting theory that I
should be able to test pretty easily. I haven't tracked when it has
worked and when it hasn't and how much time has passed between the two.
(To give the chip time to cool down.) Although, I think I let it sit
overnight at one point this week so that might not be it.

Another test I'll do when I get back home is to measure the voltage to
the motor leads at the terminal block on the extruder controller and see
what it is when the motor is working and what it is when it stops. (And
in the future, I'll always bring my 'meter when I travel.)

Mike

[Bill Culverhouse]

I've got heat sinks stuck to my h-bridges and mosfets.

Too many stories of people freeing the black smoke from their chips.

Also when I started running a stepper off the EC chips get really hot.

 

The issue I had I could replicate pretty reliably from the control panel,

by switching the motor on forward 255, and then flip reverse and forward

about 1 sec each back and forth eventually the motor would stop and not

respond until I did a hard reset. The rapid forward-reverse is what oozebane

does to reduce strings. If I went in and search-replaced the extruder off codes

m103 (I think) to remove them I could print any print for hours, with crazy strings

of course. Essentially turning on the extruder at the start and only turning it off

at the end.

 

This went away with the stepper extruder.

 

-b

[Mike Broome]

Very interesting. I scanned the beginning of the GCode yesterday, and I
did see M101 (extruder on) and M103 (extruder off) commands bracketing
each section to print. I had considered trying to "manually" print by
hooking to motor directly to 12V but wondered how messy it would be to
not have the M103 commands in there. Sounds like it would probably
work, but the better option would be to just remove the M103s from the
GCode (or not run oozebane in SF).

And I'll definitely add heat sinks to my electronics odds-and-ends
shopping list.

M.

--
Mike Broome
mbroome(at)employees.org

[Bill Culverhouse]

Not sure but I think even without oozebane SF still turns off the extruder

fairly often. You could do a search and replace with ;M103 to comment

out the m103 codes and just uncomment the last one. Or temporarily add

another line to your replace.csv something like:

M103[tabchar];M103

 

and before you run it remove the ; from the last m103.

 

Also, pick a model that doesn't really have peaks where

it would string, You can still print some good stuff, I printed

a nice darth vader with no m103 codes.

 

-b

[Jeff Crews]

I pulled plenty of heat sinks off of the various ancient mobos and video cards at the Space. Dremel them to size and glue them on. that double-sided heat sink tape would be good for attaching them too.

jsc

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From: Mike Broome <mbr...@employees.org>
To: techshop-durham-...@googlegroups.com
Sent: Thursday, August 18, 2011 10:06 AM

Subject: Re: plastruder motor stopped working

[Bill Culverhouse]

If you guys are interested in upgrading to pololus this looks like a good option:

 

https://groups.google.com/d/topic/makerbot/lOi-VhmoLws/discussion

 

Rob Giseburt is trying to get together orders for a 3 axis pololu carrier board he's

designed. $45 you will still need to buy the 3 pololus which are about $13 each.

The makergear carrier is $29 and you need 3 of them plus 3 pololus.

 

Just FYI.

 

-b

[Tom Billman]

FYI,

I've got one of these. http://www.buildlog.net/blog/2011/08/open-source-4-axis-stepper-driver/

A 4 Axis moderately power controller with replaceable driver boards @ < $100 99% assembled looked good to me.

I'll be using this for my laser and possibly a slow pick-n-place.

Best regards,

Tom

--
Tom Billman
Giant Shoulder, Inc.

[Bill Culverhouse]

That looks good, 4th axis driver would be handy for the extruder as well.

 

-b

[Mike Broome]

I had some time at the end of last week to do a bit more debugging on
this including testing output voltages with my multimeter. Here's what
I found with both v2.6 and v2.5 of the extruder firmware:

- sometimes when I started up the 'bot from a cold start, the extruder
DC motor would work for a short time, other times it wouldn't work at
all

- was able to see with a multimeter that when it was working, it was
outputting 12V. was able to watch on the 'meter when it stopped
working, and the voltage fell from 12V -> 0V (on the 1A/1B outputs) or
from 12V -> about 90mV (on the 2A/2B outputs). one of the times I saw
the voltage to the motor drop, it dropped to about 7V for 20-30
seconds before dropping on down to 0V

- once it gets into this state, I haven't found any way to get it back
out other than turning it off an waiting, and even that isn't
consistent or reliable

- throughout all this, the H-bridge chips (Allegro A3949) on the extruder
controller board are not getting hot to the touch

My current working theory is that the extruder controller board is bad.
I started looking at the schematics of the Allegro A3949 chips to see if
I could probe the input pins to find out if the chip is being told to
stop the motor or not. Haven't gotten anywhere with that.

The only other thought I have is maybe the motherboard is telling the
extruder controller to stop. Can't think of any reason it would do
that, and I'm not sure how to debug the command and control path at that
level.

Won't have time to do anything more with this for the next couple weeks
as we're heading out to Burning Man. When I get back, I'll probably try
to swap the extruder controller board. Anybody have a spare lying
around? If not, looks like the latest generation from Makerbot is about
$90. (My first upgrade!)

Mike

[Jeff Crews]

I do have a spare, although it is my crusty, handmade one. It functions, though. I will put it in the Space (usual place, at the rear next to my Jacob's Ladder and other crap.) Might be good to try it for a while and see what happens.

JSC

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From: Mike Broome <mbr...@employees.org>
To: techshop-durham-...@googlegroups.com

Sent: Wednesday, August 24, 2011 7:57 AM

[Bill Culverhouse]

It's still sounds exactly like my problem though. A new EC might fix it, but I tend

to think the EC is good if you were using a stepper intead of the DC gear.

 

Mine had the exat same issues, we swapped in jeff's DC motor and the issue

went away. So I upgraded to a stepper and haven't had issue with the EC since.

 

Have fun and Burning Man. Carry sunblock. :-)

 

-b

[Jeff Crews]

Mike:

Considering what Bill said, if you have time you could drop off your EC at teh Splat and I could sub it in for my EC on Big Red and see how it behaves with a stepper motor.

JSC

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From: Mike Broome <mbr...@employees.org>
To: techshop-durham-...@googlegroups.com

Sent: Wednesday, August 24, 2011 7:57 AM