Pretty sure my heater block is cracked and needs to be replaced?  

RE: Pretty sure my heater block is cracked and needs to be replaced?

It's always a bit difficult to tell the specific details from a photo, but yes, it looks like there's a definite fracture in the heatblock.

Yes, that is the correct part.  However, if you're Stateside, you can also get them from Amazon quicker and cheaper, as the shipping is domestic as opposed to from the Czech Republic.

From the photo, it looks like the wiring is intact.  However, there may be a challenge getting the heater element and/or the thermistor out of the damaged heatblock.  It might be a good idea to just order the complete E3D hot end.  Again, if you're stateside, Amazon will have these.

My hunch is that it will probably be usable as is for noncritical printing.  There may be some alignment or calibration error due to the damaged heatblock.  I would first repeat the Z calibration before doing any serious prints.

As to what caused it, metal fatigue and thermal stress is my only guess.  The impact of the nozzle slamming in to anything, whether it's the heatbed, or a printed part, or anything, should not be severe enough to fracture the heatblock.

RE: Pretty sure my heater block is cracked and needs to be replaced?

Posted by: @mjdth

Anyway, I noticed in OctoPrint that the nozzle temp was fluctuating +/-5° very regularly lately when that didn't happen before. Looked around for about 5 seconds and saw this very obvious crack on the heater block(?):

Couple of questions:

1. Does that just need to be replaced with this part?
2. Is the red wire also damage-looking there?
3. Is it unsafe to print PLA with this currently?
4. What would cause this? I'm assuming somehow improper bed leveling or having the nozzle/etc run into parts as they are printed/etc? 

Thanks!

Anyway, I noticed in OctoPrint that the nozzle temp was fluctuating +/-5° very regularly lately when that didn't happen before. Looked around for about 5 seconds and saw this very obvious crack on the heater block(?):  Yes, this is possible.  I have noticed this on one of my printers.  

Questions:

1. Does that just need to be replaced with this part?
2. Is the red wire also damage-looking there?
3. Is it unsafe to print PLA with this currently?
4. What would cause this? I'm assuming somehow improper bed leveling or having the nozzle/etc run into parts as they are printed/etc? 

Answers:

1. That is the correct part, but I would be prepared to replace the whole hotend.  You never know if you can readily use any of the parts.  The nozzle can be worn, and part may break during the disassembly.  
2. Hard to tell, but if it heats, it is probably ok, but the wires are fragile after extended use and tend to break during disassembly.  
3. I would replace it as quickly as possible.  
4. It is hard to tell.  I would hazard to guess.  I have never had one break.  

RE: Pretty sure my heater block is cracked and needs to be replaced?

I've never had a heater block crack so if your printer is only a month old I would get on the chat with Prusa Support. Maybe they'll send you a free replacement, or they claim it's wear and tear not covered under warranty. But it's worth a try. The hardest part of the replacement is usually to get the heater and thermistor out of the block. Make sure you preheat it to 280 or so. 

RE: Pretty sure my heater block is cracked and needs to be replaced?

Thank you all for your responses, much appreciated. I was about to go order the hot-end and decided to start a chat w Prusa support just to see what they'd say. 

First thought they had: maybe it just really looks like a crack but is actually burned filament. They suggested I heat the tool to 280 and try scraping it off with a toothpick. Which worked. So I have no crack in my heater block, but I do have some damage to my ego for not even thinking of that. 😣 

Now I just need to keep working on the temperature fluctuations...

RE:

Relax. If this in fact a crack (shit happens, even to the best product) and not just filament residue (which should not be that hard to determine when the block is cold) then it should be fully sufficient to remove the heater block which should take less time than reading through repeated fullquotes . If you want to waste money, buy a full E3D hotend right away or just buy a new printer; if you don´t have money to burn, remove the hotend assembly from the extruder carriage (this is not rocket science and the instructions on the Prusa website are excellent step-by-step), get yourself a quality, well-fitting hex key from your local hardware store (the one contained in the Prusa kit should fit well, but a key with a nice grip will do even better), BEFORE you attempt to remove the screws with an inferior product, then remove the screws of the thermistor and the heater cartrige (the ends of the two cable sets entering the heater block), remove both from the heater block and then re-build. I never had to heat up the block to remove these parts and I would not know why this would help. Your printer is not old enough that I would expect the thermistor and cartridge to be about welded into the heater block, as may be happening with long-used systems.

If this fails, then you will need to replace the heater block as well as the heater cartridge and the thermistor, but still I fail to understand why you would need a full hotend.

In any case - and yes I understand that apparently in the U.S. there is no such thing as warranty on anything - get on the chat with Prusa support (log into the shop and then open the chat window) and tell them what´s happening, they might be happy to send you the required parts.

Cheers

Chris

RE: Pretty sure my heater block is cracked and needs to be replaced?

LOL, that's why it's extremely difficult to diagnose via a photo on the board.  It sure looked like a cracked heatblock to me.