Defective Ultimaker Brand Thermocouple

[printerfan 5]

I have ordered 2 thermocouples from Ultimaker this month and both have had major sizing issues. The first was so large it could not fit into the accompanying official block I purchased without getting stuck half-way in. So, I received a replacement that fit, albiet snugly. I installed this replacement and attempted to print ABS, a clog insued, and when I attempted to disassemble the hotend, the new thermocouple is now also lodged in the block and is not able to be removed. So from what I can tell, the already snug thermocouple permenantly expanded when heated and now its stuck.

Is anyone else having issues with new thermocouples coming out from ultimaker?

Any recommendations for fixing this?

[Dim3nsioneer 558]

Maybe it's rather a problem of the aluminium block than of the thermocouple? What does fbrc8 say? (You are located in the U.S., aren't you?)

[printerfan 5]

The reason I do not beleive it is the aluminum block is the old thermocouple that I had fits fine, it slides in and out with almost no resistance in every aluminum block. The first replacement thermocouple I got was so large it couldn't even be installed, then the second replacement was a snug fit, but got lodged once it was heated. The aluminum block is official ultimaker too, I just bought the hotend pack.

I ordered the replacement thermocouple from fbrc8, and they were quick to send the replacement when I told them about how the first was defective. They didn't say much about what they thought the cause was, but they requested that I send the first defective thermocouple back, so that they could determine the cause.

I haven't had a chance to mail it back, I was going to do that today, but after seeing the new replacement is now stuck, I may have to mail it back along with the aluminum block its stuck in.

[gr5 2,228]

You can take it all apart, and put the aluminum block with the temp probe still in it in a vice. Then drill from the other side (opposite the thermocouple) with a small drill bit slightly larger than a paperclip wire.

You will feel the drill suddenly move when it gets to the tiny air gap between aluminum and temp sensor. Pay attention or you will miss it. It's not so hard to notice.

Then stop drilling and push a paper clip in and PUSH the sensor out (instead of pulling it out).

I actually was able to do this on a UM2 block but never had to do this on the UMO block.

[printerfan 5]

You can take it all apart, and put the aluminum block with the temp probe still in it in a vice.  Then drill from the other side (opposite the thermocouple) with a small drill bit slightly larger than a paperclip wire.  

You will feel the drill suddenly move when it gets to the tiny air gap between aluminum and temp sensor.  Pay attention or you will miss it.  It's not so hard to notice.

Then stop drilling and push a paper clip in and PUSH the sensor out (instead of pulling it out).

I actually was able to do this on a UM2 block but never had to do this on the UMO block.

I can fit a bent paper clip into the hole already and have tried to push it out using that as well as a small torx screwdriver. What is the purpose of drilling? Doesn't that risk damaging both the block and the thermocouple?

[gr5 2,228]

I haven't looked at my UMO aluminum block in a long time - I didn't realize the hole went all the way through. For the UM2 it doesn't go through so I had to drill from the back (the olsson block has a small hole already to push probes out with).

Well I guess you should remove the whole assembly, put it in a vice and push much harder.

[printerfan 5]

I can try, but its so tight that I don't think it is going to budge. Even if it does come out after using extreme force coupled with a vice, its just ridiculous that I have to do this to simply disassemble my hotend, I paid "ultimaker prices" for a product that was supposed to properly fit and function, yet it does not.

I have struggled with this printer for a year now and I am getting to a point of frustration where I am almost ready to just sell the printer and move on to a different brand, this community is the ONLY reason I have not jumped ship.

[printerfan 5]

Update 3:

Fbrc8 recommended I use WD-40 to attempt to remove the thermocouple, then soak the parts in acetone to remove any WD-40 residue. They stated its a time consuming process, but they have got it to work in the past. I'm not comfortable attempting this at the moment due to the chemical composition of WD-40, its not something I want on any moving mechanical parts or parts that express high heat. I may try this as a last ditch effort to get it off.

I'm unhappy with the situation. The parts should fit, plain and simple, the amount of money charged for the hotend pack and the thermocouple do not justify a fitting incompatibility. Had I bought these from China off ebay, I would be more forgiving, but I didn't, I paid extra so I would not have to experience something like this. I do not think I will be ordering "official ultimaker" parts in the future, I will save money and order from ebay if this is the quality to be expected.

I was able to disassemble the hotend enough to get to the hotend barrel at the level of the peek. I alternated between heat and no heat on the block to carefully pick out the clog with a thin sculpting tool, it took a long time, but I think I was able to spare the threading from being coated with filament. I was able to get the nozzle to soak in acetone, which works wonderfully, let it soak for 24 hours, agitate, pick out ABS with thin tool, soak for another 24 hours in acetone, agitate and pick out ABS again, and repeat until all ABS is gone (usually took me 2-3 trials of this to completely clean the nozzle).

I have my UMO printing again, for which I am thankful, but I switched back to PLA for now. My conclusion for the origin of the clog is the "preheat ABS" setting on the ulticontroller was the cause of the problem. For ABS, the nozzle heats up to 250C before the bed reaches 100C, meaning the ABS cooks for 5-10 minutes causing it to change properties and harden. Oddly, the "preheat PLA" setting does not do this, the nozzle does not heat up until the bed temperature is reached. So on an UMO, I would avoid the "preheat ABS" setting on the ulticontroller and simply manually set the bed temp first, then once its reached set the nozzle temp.

[gr5 2,228]

I agree - 250C for 10 minutes will definitely turn ABS into a kind of material similar to chewing gum.