Makerbot Dual - Heater Block issues

[Lisa M]

Hi folks,

I learned about 3D printing a couple of years ago and started with a Tantilllus build and have been a lurker in this group since then.  I'm not a 3D printer builder/hobbyist but I've been using a MakerBot Replicator Dual at the school I teach at with my students and have been doing all the required maintenance and repairs thus far.

Unfortunately I've had some tough issues this year with a burned out motor cable and some worn nozzles and a broken fan.  I figured since I was going to have to replace a motor cable and fan I might as well do the nozzles too.  The other repairs went well but when I swapped out the nozzles I stripped the aluminum heating blocks.

I ordered more aluminum heating blocks and waited... apparently they aren't easy to find.

Unfortunately when I went to insert the heating elements into the aluminum blocks last night, they wouldn't fit.  I filed out the holes as best I could and put the heating elements in but they were tight (much more tight than the old ones) and I still used the set screw, but really it wasn't necessary.  I had also pre-wrapped the blocks with ceramic tape and then kapton tape.  

Today I tried to print.  It started printing before the temperature reached it's goal of 230.  The temperature never got to 230, there was a bad smell (which I thought might be the new tape), and then about 10 minutes into the print the printer displayed an error stating that it was unable to maintain the temperature and it stopped printing.  Nice to know the failsafe is working :)

Unfortunately I don't really know what to look for at this point.  

Any advice would be appreciated.

Thanks,

Lisa Mulzet

Centennial School

[Nick Wimpney]

You might want to make sure that your temperature sensor is securely attached and contacting the block.  If it isn't in good contact with the block, it'll actually try running the block a lot hotter to try and get the temperature sensor to 230.  Unfortunately, it's actually pretty hard to fail-safe a loose, but still close-enough-to-get-warm sensor, so this definitely can be a fire hazard.  It's nice to see that they do have a timeout on it, but it would probably be better if it were shorter (maybe 2-3x the normal warm-up time)

-Nick

[Lisa M]

Thank you.  I was thinking that might be it.  It will be nice if it's that simple.  I'll have a look later today.

[Lisa M]

Hi folks,

I redid the thermocouples but I’m still getting the message “I timed out while trying to heat my extruders” for both extruders and a bad smell off the left extruder. 

The directions I followed said to bare the wires and then cover them with one layer of capton tape, bend the capton tape covered wire to 90 degrees and place against the aluminum heating block pressing it in place with the washer under the bolt.  I got what looks like really good contact between the washer and the aluminum plate.  Did I do something wrong?

Prior to starting all of this messing around with nozzles and aluminum heating blocks, the thermocouples were working.  I’m not sure how to proceed now.

Thanks,

[Nick Wimpney]

What temperature was it reporting?  Was it _close_ to 230, or was it way lower?

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[Lisa M]

Close to 230.  It was at 229 on the right nozzle on the last print.

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[Dan Steele]

Did you ever manage to get this working?  If it were getting over 230 there would be smoke and the plastic would be trip out like water...(I've had mine go up over 250 before)..It probably isn't the thermocouple if that isn't what is happening...Did you tighten the little alan screw the holds the heater core in too tight and pierce it maybe?  Or just a bad connection in the wire?

Dan. 

 

[Lisa M]

No didn't manage to fix it.  The hole in the heater block was too tight.  I filed it out and then forced in the heater core.  Possibly I damaged the heater core.  I haven't had the time or enthusiasm to investigate further. 

[Lisa M]

too many problems:
Left nozzle won't get warm... Heating core/element is jammed in aluminum block
Right nozzle gets warm but thermocouple isn't working because it gets two warm
Right nozzle is leaking via the threaded end because I couldn't get the 3rd party aluminum blocks to thread to co planar height

I gave up and thought I'd try to order an entire hot end assembly for the makerbot dual. The printer was new in 2012. Now only 2.5 years later, Makerbot does not carry the necessary replacement parts. My school is now the proud owners of an $1800 wooden box.

Makerbot said I should try a third part builder. I'm not impressed with Makerbot's lack of support for its own product.

Anyone know of a good source for the hot end assembly for a makerbot dual?

I would like a fully assembled one with the aluminum crossbar, 2 aluminum heater blocks, nozzles, thermocouple and heating core ready to mount on the printer.

[John Biehler]

Try Greg @ makerbot.ca - he may be able to help. He's always been great when Makerbot hasn't.

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[Lisa M]

I did. That's where I got the aluminum heater blocks that weren't quite right. They only had one in stock and had to wait on a second one to come in.

I haven't enquired about an entire hot end assembly. Kind of figured that if it was tough for them to get the aluminum blocks it would be unlikely that they'd have an entire assembly.

[Lisa M]

...also got two extruder mods (supposedly left and right) from makerbot.ca that didn't fit the carriage. Had to go back to my old printed one from thingiverse. I kinda gave up on makerbot.ca

...not that their service wasn't good ...but they can't seem to get the proper parts either

[Lisa M]

It's a long shot ...but I'm desperate and don't know wherelse to go.  Trying Greg again ....maybe if he doesn't have the parts he has some advice.

[Dan Steele]

Hey Lisa,

If you're really stuck you could probably get someone in town to make the aluminum blocks for pretty cheap (They are just a cube with a hole or two drilled and then tapped into them..The holes don't even really need to be in precise places.  My plate is pretty full (overfull) right now or I'd offer to do it myself  but there has to be someone in the community who has the equipment to make a few blocks.  Thermocouples and heater cores are pretty generally available as well.  I know it's a pain in the butt to rebuild it like that, but don't call the machine dead yet!

Dan.

[Trent Shumay]

We can CNC aluminum here if you can get your hands on the design for the block. I don't have it offhand, but I think the MB Dual was still open source, so if that design exists somewhere, it's not a big deal to cut some blocks.

T

[Lisa M]

Good to know about the CNC aluminum blocks.

We sent it off to Thorstad and they did a bunch of work on it.

They did replace the thermocouples.  The printer was working well for a few days.

Unfortunately after removing the fan and motor on one side to fix a clog, it has stopped reading temperatures again (on both sides).  It gets to 214 but won't read up to 220 and clearly the nozzle is way hotter than 220. 

I think this time I've done something wrong with the path of the thermocouple. 

I noticed at MakerFaire that none of the 3D604 folks who were at the show were even still using a replicator 1 ;)

Not sure if any of you can help ...but does anyone have a picture of how the thermocouple wire should pass through the area where the extruder motor, heatsink and fan are?

[Nick Wimpney]

If the thermocouple wires are shorted together you'll end up with an average of the temperature between the junction at the end (which is what you want to measure) and the temperature at the shorted point.

I don't know anything about the replicator specifically, but I wonder if that might be what's causing the bad values.  It might be as simple as folding some kapton tape over each wire so they can't touch each other, or anything else metal at more than one point.

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[Lisa M]

Hi Nick,  I don't know if they are touching and shorted together.  There is kapton tape around them.  Here is a picture:

 

I'm not sure how the thermocouple wires were originally running.  This is how they are now (after I had to remove the motor and fan to clear a clog), but the printer is still failing to read the temperature of the nozzles correctly. 

 

I know it looks like they are criss-crossed but I have not detached them from the aluminum heater blocks so they are still connected to the correct sides (L and R)

 

[Lisa M]

I thought about it, reread your post, and uncross-crossed the wires ...separated by clamping bolt. 

Tried starting and loading filament.  Got an error message (first one today) "Heating Failure #1! Software Temp Limit Reached!  Please shutdown or restart"

...argh.  I go home now and rethink my life decisions. 

[Dan Steele]

I had mine there..It's getting a bit long in the tooth though, I've rebuilt the print head I don't know how many times, and the mean time between failures is creeping up to the point where I spend almost as much time fixing it as printing with it :P...

It sounds like the issue you are having is definitely thermocouple related..I'd pull check to make sure the wires are getting a good connection on the screwdown posts on the board  and then make sure the thermocouple connection on the extruder end are good.  I run mine from the back of the bar and up between the two steppers and use a couple of zap straps to hold everything firmly together...

The thermocouple wires are so small I can barely see them...When I put in new ones I'll pull the wires a bit apart and then fold Kapton tape over top of them..Then the trick is tightening the screw that hold them to the heater block just enough that it holds firmly but isn't crushed...

With the cost of printers coming down as fast as they are, and the amount of time I've spent lately fixing mine I'm really starting to side with taking the buy a new printer route sooner rather than later...Just not sure which one I'll go with yet.

Dan.

[Lisa M]

Thanks Dan,

I ordered new thermocouples ...gave those a go.  Unfortunately I'm getting error message "“Heating Failure #1! Software Temp Limit Reached! Please Shutdown or Restart" now.  ...with new thermocouples (the expensive ones from Bilby).

I can't get past this error message.  I thought maybe resetting firmware would work but I can't get the makerbot software and my pc to see the printer before it gives it's error message.  

I'm not sure at this point what else to do ...if it were just my printer (not my schools) I'd say trash compactor ...but I need it running for my classes.

Wish we had more money. ...as it is I'm out of pocket now approximately $200.00 this year on repairs ...and my school budget is out another $500 approx.  It would be great if the repairs actually worked but it seems I'm wasting both time and money here. 

[Dan Steele]

I've had that error before and it turned out for me to be caused by the Thermocouples shorting, once I fixed the short the problem went away...The thermocouples not working right is a scary thing because the heater core will get hot enough to start a fire if you're not careful.

The extruder assembly is fairly simple in principle the problem is the constant heating and cooling tends to make wiring brittle, and wear away solder when you take it apart it can jostle the loose connection and cause more problems.  The feed tube and nozzle also get build up over time, which can be torched out but they also get abrasions over time which causes build up to happen faster.  I'm sure you've encountered all of the above.  It can be super frustrating and time consuming to take it all apart and put it back together half a dozen times to get it right.  I'd be happy to take a look at it if you want some help next time I'm in town, I know you've been fighting with it for some time..I probably won't be back in Vancouver until the beginning of August though..

Dan.