rep2 broken heater wire, repairable?
Jason Preuss
I can slide the wire back in and it does heat up but it doesn't extrude, the plastic doesn't want to melt. I don't know how this thing works but it looks like maybe there are two wires and I have only one going in. I updated my ticket yesterday with Makerbot and am waiting for a reply but was wondering if there was something I could do myself as a short term fix. I really want to have this working for the holiday break.
Z LeHericy
That looks to me a lot like a thermocouple wire and not a heater wire, in which case it should be fine to wrap it in kapton tape and put it back in.
Jetguy
HINT, HINT, moderator TAKE NOTE OF THIS and post some documentation or
some kind of answer.
MBI disabled the safety cutoff system on our bots (Replicator 1).
There was a second temperature switch that would shut off in case we
had a heater get stuck and raise the temperature of the extruder to
unsafe levels that can start a fire. They disabled and removed that on
production Replicators. IF the thermocouple (temperature sensor) ever
came loose away from the metal block (it's only held under a screw/
washer combo), then we have no sensing of the real head temperature.
Since this is a thermstat setup where we try to maintain a temp, if
that thermocouple cannot sense the true head temp, the heater will be
stuck on. It's a 40 watt heater. Think about it, a 30 watt soldering
iron melts metal. 40 watts unchecked will get hot enough to melt the
aluminum block and catch any plastic on fire.
IF you even suspect for a second you have a non-functioning
thermocouple, DO NOT turn the bot on until fixed. Since we have no
open source diagrams or anything of a Replicator 2, none of us can
tell you if there is a secondary safety system so it's best to assume
there isn't one. I know there is a basic firmware test at boot to see
if the thermocouple is connected electrically to the motherboard, but
this specific circumstance of it not being attached to the heater
block is not covered by that safety test and could happen. I know the
stupid giant sticker on the cable bundle to the extruder head is so
people don't pull on the wires but that's not a catch all. Plus, who
left that eyesore on their bot? Simply put, the attachment isn't
foolproof.
On Dec 22, 6:16 am, Z LeHericy <zeno...@gmail.com> wrote:
> That looks to me a lot like a thermocouple wire and not a heater wire, in
> which case it should be fine to wrap it in kapton tape and put it back in.
Jason Preuss
I guess I will just have to wait out MB support and have a printless holidays. Thanks for the info, it may have saved me yet another disaster.
Lucas Saugen
Lets assume the thermocouple comes lose. Temp will start to read close to room temp. Heater will turn on but temp won't rise. So maybe the bot looks for this state and shuts down.
If Temp <= 30c & HeaterOn = 2 min
Then display warning and shutdown.
For that matter it should abort a print if the temp drops 20c below printing temp or if the heater has been on full for too long a time.
Dictated but not read...
>
>
Dan Newman
On 22 Dec 2012 , at 7:52 AM, Lucas Saugen wrote:
> Wouldn't it be possible to add a safety cutoff to the firmware?
>
> Lets assume the thermocouple comes lose. Temp will start to read close to room temp.
the correct temp but still to be roughly tracking the rise and fall of the
blocks temp. I.e., it might be held a few millimeters away from the block,
even as the extruder travels around.
> Heater will turn on but temp won't rise. So maybe the bot looks for this state and shuts down.
>
> If Temp <= 30c & HeaterOn = 2 min
> Then display warning and shutdown.
being on continuously for too long. The more critical case is one
where the uProcessor fails while the heater switch is in the on state and
power flows continuously to the heater core. Since the uProcessor is
in some failed state (hung, dead, software bug, etc.), the switch remains
on and the temp keeps on climbing with nothing to check it. As such, a
(sane) hardware defeat seems called for.
BTW, MBI has stated that they tested a run away heater core and found that
it couldn't heat the extruder to above 260C. Personally, I'm a little
skeptical of that: what happens when the bot was in an enclosure, for
instance? However, since I've never tried such a test, I have no real
data.
I write "sane" since the safety cutoff on the ToM wasn't the best design:
to activate the cutoff, a relay has to be triggered. A more sound design
which recognizes a common problem with relays would always activate the
relay for normal operation and in the event of a failure, deactivate the
relay. That way, the bot only operates when the relay is functioning.
As it stands now, a ToM can operate normally when the relay is not functioning
and in that case the safety cutoff won't work should it attempt to activate.
Dan
BilbyCNC
Yes this is the thermocoupler/cable, which tells your machine when the heater block is hot enough to extrude.
There should be 2 raw wire ends picking out of a short length if heat shrink that normally wedges into the hex nut on the heater block.
A) make sure you still have 2 raw ends on the same length
B) undo the hex nut at the back of heater block - heads up here this is at the back if extruder block and hard to get to do of you undo the 2 cap screws on the long aluminium extruder mounting block - accessed from under extruder, you can lift the block up and out for easier access - you will have had to undo the front fan right through to the extruder motor also.
Ok now you can see what is going on. The thermo cable was wired so it popped out through the front of the aluminum mounting block, then under it to the back of Heater block, they are changing this now so it goes straight out the back and thus can not get caught on misprints like yours did
Push the thermocable back through the hex nut and sit deep into the hole. you do not have to tighten it yet, but you will have to sit the block back in place and connect the motor back
Turn on the machine and run pre-heat and watch the monitor display , even better compare with a digital thermometer ....9 out of 10 it's all good. Those cables are surprisingly strong
If it is put it all back together and print. If not, you need a new cable.
IMPORTANT : the heat shrink stops and air getting in there and giving a false reading so even when testing it is important to get a seal!
Hope that helped
Lee
BilbyCNC
Jason Preuss
Jason Preuss
Andrew Russell
So after some back and forth (and a delay because of their annual shipping department closure?!?) I finally got a replacement thermocouple. Problem is I was given no instructions on how to replace it and it looks like I have to tear half of the bot apart to replace it, something I am hesitant to do without documentation. Anyone have any info to point me to for thermocouple replacement on the rep2 (I didn't see any on the website)? I have sent yet another message to tech support but tomorrow will make 4 weeks my machine has been out of commission and I don't want to have to wait another week to get information if someone here already has it.
--
Jason Preuss
Before you begin, do the following:
• Unload any filament.
• Turn of the Replicator 2.
• Remove the filament guide tube and spool holder.
• Unplug power and USB cables.
1. Detach the active cooling duct.
Gently pull the active cooling duct away from the nozzle. Allow the duct to hang.
2. Remove the extruder from the gantry.
Use the 2.5 mm hex wrench that came with your Replicator 2 to unscrew the two bolts holding the extruder to the extruder carriage. One bolt is at the left side of the extruder carriage and the other is at the right.
3. Free the extruder cable from the clips on the back of The Replicator.
The clips can be difficult to open. Press down on a clip and slide the interlocking hooks apart to open it. Set the extruder down next to your bot.
4. Snip the zip tie securing the end of the extruder cable.
Be careful not to cut any of the wires inside.
5. Remove the black wire wrapping from the extruder cable.
Find the seam in the black cable and unroll the wrapping. The wrapping will easily pull of of the entire cable.
6. Flip The Replicator so that it rests on its left side and the bottom of the machine faces you.
7. Remove the electronics bay cover.
Use the 2.5 mm hex wrench to remove the eight M3x6 bolts holding it on. Set the bolts aside.
8. Detach the thermocouple from the Mightyboard.
The thermocouple attaches to a set of terminals at the bottom right corner of the Mightyboard. If these terminals are secured by buttons, push the bottons on the terminals to release the red and yellow leads. If the terminals are secured by screws, use a small flathead screwdriver to loosen the screws until you can remove the leads.
9. Attach the new thermocouple.
Slide the red and yellow leads on the new thermocouple into the same set of terminals. Remember to attach them to the "A" side rather than the "B" side. The terminals are labeled "Red" and "Yellow" and it's very important that each lead goes into the correct one. For terminals with buttons, press the buttons on the terminals, slide the leads all the way in, and release the buttons. For terminals with screws, slide the leads in and tighten te screws. Tug on the leads to make sure they're secure. You may find that it's easier to reconnect one lead at a time.
10. Exchange the old thermocouple for the new one in the extruder cable.
The extruder cable is a bundle of wires taped together at intervals. At each place where the bundle is taped, carefully cut the tape, remove the old thermocouple from the bundle, add the new thermocouple to the bundle, and re-tape the bundle.
11. Cut the broken thermocouple from the extruder.
The thermocouple is attached to the back of the thermal core, the block that holds the nozzle, with a small nut. Snip the wire just above the nut and insulation material.
12. Unscrew the nut.
It's important that the thermal core stay in place. Use an adjustable wrench or pliers to prevent it from rotating as you unscrew the nut.
13. Attach the new thermocouple.
Screw the nut at the end of the new thermocouple into the thermal core. Again, be careful not to allow the thermal core to rotate. The new thermocouple should now be attached to the Mightyboard, the extruder cable, and the extruder.
14. Add the wire wrapping back to the extruder cable.
15. Bolt the extruder back onto the extruder carriage.
16. Push the active cooling duct back into place.
17. Zip-tie the wrapped extruder cable to the extruder.
Position the zip tie as close as possible to the extruder cap and tie it as tightly as you can.
18. Return the electronics cover to the bottom of your Replicator 2.
The thermocouple replacement is now complete. Plug in your Replicator 2, reload your filament and go back to printing.