Perplexing Plastruder MK5 - Not getting over 200C, suddenly

[j_siegel]

Hi all,

I'm hoping to get a bit of guidance on how to troubleshoot my newly
problematic MK5 extruder.

Previously, I had problems with the teflon wire desoldering at around
205C and letting the temperature drop when the wire pops out. I fixed
that and have printed for 20 or 30 hours at 220C, but the extruder
will no longer reach operating temperature and seems to heat up more
slowly than before, maxing out around 195 or 200C if I really wait
around awhile. The problem "happened" sometime between starting a
print and cancelling it early (because I had to leave the house, not
because there was any indication that things were going wrong).

I've taken the usual steps:
*Checked thermistor calibration
*Upgraded, downgraded, upgraded firmware again - testing each time
*Checked the MOSFET - LED is working fine, so I believe that means
it's working alright
*Checked the relays/tried a different relay
*Replaced the Teflon wire (crimp method this time)

This was all after checking the resistance, which I can't seem to get
a solid read on. In parallel, the resistors measure 5 or infinite ohms
(instead of the 2.5 I should be getting). I have rewired the
connection multiple times and still get this value, though I have not
checked the value of the individual resistors (it slipped my mind).

Is it possible that one of the resistors "cooked"? If it makes any
difference, my two resistors were different when they arrived - one
KAL105JB and one 810F5R0E - I'm thinking maybe one of them handles
heat worse than the other.

I'd welcome any and all suggestions. I'm going through widthdrawl now!

Thanks,
Josh

[Aaron Double]

Did you update your firmware?

I would check your PID settings.

Best,

Aaron Double

[j_siegel]

Thanks Aaron, I forgot to say - I tried the default PID (something
like 5 .03 and 35 IIRC) and the "tweaked" ones (D was 105?!). Still no
luck. I'll wait for a few more suggestions, otherwise I'll tear it
down tomorrow and measure each resistor individually.

[j_siegel]

Also, just got out the IR thermometer and started heating it. One
resistor got hot, the other didn't. I really doubt it's the wiring, so
my bet is that the resistor fried and is offering infinite resistance.
All the current is going through the other resistor, but the increased
resistance (5 ohm instead of 2.5) is causing it to not reach operating
temperature.

Has anyone else had a problem with the KAL10 variety resistor? This is
rather disappointing that it failed so early (if indeed it did), but
it should be a rather easy fix..

[DLPlanes]

Alright so that just happened to me! I finally got me thermostat working, right! And
now when I go and try to heat it up in only reaches to certain temperature, and goes down!
And its not the wiring because I check with a multimeter and it was working fine.
I think its a bug in the firmware, try downgrading the firmware one by one till one work.

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[Zip Zap]

Make sure all your power supply wires to your relay is tight.  The de-soldering or melting usually happens when you have a blob excess amount of solder at the connections.  You should wind or crimp your wire to the connections and dab it with a small amount of solder.  When you see solder droop from the connections then scrap off the excess droop with some tweezers.  Over time, you will just have a small sliver of solder over the connections that will sit still.  I've used high temp 300C solder and it still melted at 200C when I used too much.

As for the power or heating up issues, use a separate relay for the extruder and one for the HBP.  Also, connect each to their own power plug or have the HBP relay downstream from the extruder relay.  The extruder should have priority over the HBP.

---

From: j_siegel <sie...@gmail.com>
To: MakerBot Operators <make...@googlegroups.com>
Sent: Mon, October 25, 2010 3:29:46 PM
Subject: [MakerBot] Perplexing Plastruder MK5 - Not getting over 200C, suddenly

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[j_siegel]

The wires are good and tight - I've resoldered twice already, using
new wire.

I really feel like at this point it's either software (which is weird,
since it worked fine on R20 and new firmware before the incident) or a
bad resistor. Tomorrow I should be able to pull it apart once more and
check everything, unless anyone else has last minute ideas. I'd really
rather not have to resolder those wires again, and if I bend the
crimps at this point they're likely to break of metal fatigue.

It shouldn't make any difference that the resistor in one of the
packages is slipping out of the heatsink, right? Or would that be
indicative of possible damage? Maybe it's not conducting well anymore?

I just can't think of a situation where the plastruder was generating
over 10W of heat, and these are (supposedly) rated to 12.5W...

On Oct 26, 4:03 am, Zip Zap <zzap...@yahoo.com> wrote:
> Make sure all your power supply wires to your relay is tight.  The de-soldering
> or melting usually happens when you have a blob excess amount of solder at the
> connections.  You should wind or crimp your wire to the connections and dab it
> with a small amount of solder.  When you see solder droop from the connections
> then scrap off the excess droop with some tweezers.  Over time, you will just
> have a small sliver of solder over the connections that will sit still.  I've
> used high temp 300C solder and it still melted at 200C when I used too much.
>
> As for the power or heating up issues, use a separate relay for the extruder and
> one for the HBP.  Also, connect each to their own power plug or have the HBP
> relay downstream from the extruder relay.  The extruder should have priority
> over the HBP.
>
> ________________________________

> From: j_siegel <sieg...@gmail.com>

> makerbot+u...@googlegroups.com.

[j_siegel]

All: FWIW, it was my resistor that was in fact bad. I removed the
heaters and while one measured 5 ohms, the read infinite. I replaced
the resistors (ordered from DigiKey) and it's back to working fine.
Hopefully this isn't a larger issue than just my printer.

[j_siegel]

So, I just drove my 'bot on a 1200 mile trip. No overnights, took the
printer in for the night, and when I got home the printer wouldn't get
over 180. Did the usual debug, and once again a resistor had fried. Am
I seriously the only one having this problem?

At least I'll get a chance to use high temperature solder this time..

[Theron Trowbridge]

I've got a bot that after a trip is having trouble getting above about 190 C.  I've been assuming it was the power supply, but now I'm thinking I'll check the resistors.


-Theron
^