Broken Heatbreak in heat radiator  

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HowardHo
(@howardho)
Active Member

When trying to remove the nozzle from the heater block, the heatbreak rotated and broke off right at the heatsink radiator.  It didn't take much force to twist off.  I can't remove the stub since it the threads are too tight, probably due to the thermal paste drying locking in the threads.  Seems to me the "newly designed" heat break tube wall is too thin between between the M6 and M4 threads, that is, the narrow part.  You can see by the picture it's very thin.

Has anyone else seen this problem?  How did you unscrew the heatbreak out of the heatsink?  I tried a screw extractor, digging a screw driver into the center but it's too hard, even tried boring the center with a smaller bit but the drill wouldn't go all the way in. 

Thanks in advance. 

Posted : 10/12/2020 7:32 pm
vintagepc
(@vintagepc)
Noble Member

It's supposed to be thin... else it won't function very well as a heatbreak. As you've learned, that does mean they can be fragile. This is why nozzle changing guides recommend that you prevent the heatblock from turning by holding it with a wrench. 

 

You could try chucking it in the freezer overnight to see if the thermal characteristics of the different metals cause it to break free. 

 

Posted : 10/12/2020 9:20 pm
jwvaughn
(@jwvaughn)
Estimable Member

You might try a tool like this https://www.amazon.com/Hengory-Damaged-Extractor-Stripped-Remover/dp/B07SY78C4P/ref=sr_1_125?dchild=1&keywords=broken+bolt+extractor&qid=1607666456&sr=8-125

I'm not recommending the brand but just using it as an example.

I would guess that heat might work better than cold if it is old filament make it stick rather than thermal paste. 

Posted : 11/12/2020 6:05 am
HowardHo
(@howardho)
Active Member

Oh, that is how it is suppose to work.  I just assumed the heatsink radiator dispersed all the heat, thus the name.  I did use a wrench but the heat block turned before I  realized the wrench had slipped a little.  Believe me, it didn't take much. 

Putting it in the refrigerator didn't work.  Turns out the coefficient of expansion of aluminum is 24x10(-6), and steel is 12x10(-6) which means the aluminum will contract around the steel at low temp making it tighter.   I'm assuming the heatblock is steel, but may be wrong.  I tried higher temp with a heat gun and that still didn't work since there wasn't enough of the heatblock to grab onto.

Seems to me even if the whole module was out with the heat block was removed I still couldn't get the heatblock out of the radiator since the m4 threads, the thinner end, would be screwed all the way in the radiator and it would still be stuck inside it.  Twisting the heatblock to loosen it would have just broken it anyway.  I'm beginning to think thermal paste is a bad idea and the heatblock should just be screwed into the radiator hand tight.

update: I finally did get the stub of the heatblock out of the radiator.  I did it by milling a slot through the radiator and through the stub.  This created a slot that I was able to grab onto with a flathead screwdriver.  It took a lot of torque but I was able to get it out.  Unfortunately, the radiator now has a slot in it and I don't know if it will affect performance.

I'm going to get a new radiator and heatblock.  I was hoping someone would have a better solution. 

 

Posted : 11/12/2020 6:10 am
HowardHo
(@howardho)
Active Member

@jwvaughn

Thanks, good idea. I did look for an extractor but couldn't find one small enough to fit in the 1.4mm slot of the heatbreak.  I tried drilling the hole bigger to fit a larger extractor but was afraid of using too big a drill and damaging the threads in the radiator.

Appreciate the suggestion.

Posted : 11/12/2020 6:15 am
cwbullet
(@cwbullet)
Illustrious Member

That will be tough to remove.  I am having the same issue with a grub screw.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 12/12/2020 3:00 am
jwvaughn
(@jwvaughn)
Estimable Member

Glad you got it out.

I was wondering if extractors went small enough and I agree that even if the drilling went well, the extractor could still go in to deep and ruin something.

My guess it that the heat break is brass. Also, I'm not convinced the problem was caused by thermal paste and would still bet on a bit of filament being the culprit.

Posted : 12/12/2020 5:22 am
cwbullet
(@cwbullet)
Illustrious Member

@jwvaughn

Extractors come down to less than 3mm.

--------------------
Chuck H
3D Printer Review Blog...
Posted : 12/12/2020 10:48 pm
jwvaughn
(@jwvaughn)
Estimable Member

I didn't look very hard for small ones.  The set I purchased many years ago are neither metric nor small going up from 1/4".  I should probably get a small metric set because you never know when you will need them.

Thanks for the info - jwv

Posted : 12/12/2020 11:15 pm
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