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Melted Colllet On Mk3s No Copper Ring  

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Acorn
(@acorn)
Active Member
Melted Colllet On Mk3s No Copper Ring

So for some reason the collet on my Mk3s decided to melt during a Nozzle Change.

It was then that I found out that Prusa do not use the small copper ring that usually sits in the top that the collet goes into.

Does anybody know why? Also why is the small clip that holds the collet in the locked position also not used?

They are sending me a new one but they did not know why the metal ring was not used on their machines.

Just seems strange that it comes with the replacement collet you can buy from e3dv.

https://e3d-online.com/embedded-bowden-coupling-for-metal

This topic was modified 2 years ago by Acorn
Posted : 26/08/2019 9:46 pm
JoanTabb
(@joantabb)
Moderator
RE: Melted Colllet On Mk3s No Copper Ring

to the best of my knowledge the e3d ring is Brass
Prusa may have decided to CNC turn the heatsinks with the correct profile in the aluminium in preference to using E3d partss... I have never seen one without the Brass ring... 

Having said that I didn't look at my new Mk3 Hotend assembly that closely, so I may well have one myself, and not be aware... 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 26/08/2019 11:54 pm
JoanTabb
(@joantabb)
Moderator
RE: Melted Colllet On Mk3s No Copper Ring

the Circlip that some folk use under the collet, should not be necessary if the hot end is assembled in line with Prusa recommendations, however the circlip does help to make assembly easier for some people.

My first Prusa, was a Mk1, with an E3dV6Lite hot end, and in those days, circlips were unheard of... so I learned to assemble the hot ends without them...   and these days I only use them because I got some with a new heatsink, and thought, 

a, I wonder if they will actually fit in a prusa extruder housing...   Yes they did

b, now that I know they fit, is there any point dissassembling the hot end to remove them, and No there wasn't...

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 27/08/2019 12:03 am
Martin L. liked
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(@)
Illustrious Member
RE: Melted Colllet On Mk3s No Copper Ring

I honestly can't recall what the top of my heat sink looked like: brass or aluminum.  It's possible you received a defective (incomplete) heat sink.

As an fyi, my last tear down I added the clip. Seems like a no brainer to help retain the PTFE.

Posted : 27/08/2019 6:35 pm
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(@)
Illustrious Member
RE: Melted Colllet On Mk3s No Copper Ring

Seems without the brass insert the collet won't even stay in place: 

Unless of course Prusa is now having E3D make "Prusa spec" heat sinks along with their custom heat breaks.  Though, it seems like a misdirected effort to save costs, if that really is what they are doing.

 

Posted : 27/08/2019 6:43 pm
Acorn
(@acorn)
Active Member
Topic starter answered:
RE: Melted Colllet On Mk3s No Copper Ring

Well I have had fun and game with Customer Services.

First I was told that they DO NOT use the Brass Coupler as they call it in their Heatsinks.

I was not sure about this so the next day I asked again and was told that they DO use the Brass Coupler in their Heatsinks and mine was missing.

It was agreed that a new Hotend would be sent just in case of any damage, but before the order was placed that rep's shift ended and I was transferred to another rep to finish up.

This new Rep disagreed with what the Rep I was just talking to said and refused to send a new Hotend even though it had already been agreed with the previous Rep. His reason they DO NOT use a Brass Coupler in their Heatsink.

About an hour a go I re contacted Customer Services again as it did not end on good terms with the last Rep I spoke too (they were very rude). After asking the Quality Assurance Department they confirmed they USED to use the Brass Coupler but not any more.

Apparently its whatever stock they get sent from e3dv. Some Heatsinks have it some don't. He did suggest that I apply thermal paste to the Heatbreak. When I took mine apart it did not have any on it. When I asked why he said that they only just started to apply thermal paste to the Heatbreak in July 19 and my machine that was shipped in July must have been one of the last that was sent out without the thermal paste.

So the end result is I have no real answer of if the brass Coupler is needed. The different Reps disagree with each other. If you order the parts from e3dv it comes with a Brass Coupler and the guides show the Heatsink with a Brass Coupler but apparently some have them, some do not so take your pick.

If I were to buy a Brass Coupler and install it do you think it would damage the Hotend or affect print quality if it was not originally shipped with one?

 

This post was modified 2 years ago 2 times by Acorn
Posted : 27/08/2019 7:27 pm
JoanTabb
(@joantabb)
Moderator
RE: Melted Colllet On Mk3s No Copper Ring

if you buy a black collet and a brass insert, try the black collet in the heatsink on it's own first, if it is incredibly loose and falls out under gravity, then you are probably missing the brass ring... time to fit the one that you will have,

if the black ring clicks into position and does not fall out under gravity, try re assembling your hot end without the brass ring... 

 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 27/08/2019 7:59 pm
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(@)
Illustrious Member
RE: Melted Colllet On Mk3s No Copper Ring

July 2019 they started using thermal paste ?!??    Interesting; my OLD MK3 had thermal grease when I bought it.  Now I'll need to check my spare set I purchased a while back when I bought the MK3S upgrade kit (I was going to have both versions on hand).

 

This post was modified 2 years ago by --
Posted : 27/08/2019 9:26 pm
Acorn
(@acorn)
Active Member
Topic starter answered:
RE: Melted Colllet On Mk3s No Copper Ring

Sorry made a little mistake it was the end of June 2019 not July they started applying thermal paste to the Heatbreak.

 
Me: Well there was none in the first place. It was completely clean when I removed it.

 
CS: Did you mean that there was not thermal compound?
       I understand it
      We started applying fairly recently, when was your printer shipped?
      I suggest in this case applying a good amount of it on the heatbreak it will definitely help!

 

Me: It was shipped at the end of june

 

CS: We started applying it more or less on that period you might have had one of the last printers without it

 

 

This post was modified 2 years ago by Acorn
Posted : 27/08/2019 9:43 pm
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(@)
Illustrious Member
RE: Melted Colllet On Mk3s No Copper Ring

Two years ago they were shipping with grease ... but then they may have been buying assembled E3D-V6 assemblies; and changed to assembling the parts themselves back when they release the MK3S - then readded grease in June after customers were having print problems.

So checked my "new" hot end: No brass.  And heat sink is so tight to the heat break I can't loosen it by hand, which means it was assembled wrong and most likely has no grease. Also means the idiot doing the assembly could have bent the heat break, too.

E3D-V6 Assembly:

Screw the HeatSink onto the HeatBreak by gripping the heatsink in one hand and the heater block in the other. It only needs to be tightened up hand-tight. Do not overtighten.​

 

This post was modified 2 years ago by --
Posted : 27/08/2019 11:40 pm
Martin L.
(@martinl)
RE: Melted Colllet On Mk3s No Copper Ring

Hello @acorn,

I understand your frustration; we are sorry for this bad experience you had!

Ad heatsink: I confirm both versions (with and without brass insert) exist, the version without the insert is newer and is now used as a default version. There is absolutely no difference in the functionality of the heat sink and the whole hotend, the version with and the version without the brass insert work the same. See this hotend assembly manual from E3D showing both versions interchangeably.

Ad thermal paste: There must always be some thermal paste on the heatbreak threads that go into the heatsink. We were always applying it, and as a reaction to the feedback from the community, we have recently started applying more of it.

The thermal paste seems to kind of wear down over time, so it is a good practice to apply more of it during your maintenance session after every couple of hundreds of print hours.

If there was no trace of any thermal paste (white or grey viscous stuff) on the threads of your heatbreak, it must have been an honest mistake of one of our guys who assemble and test the hotends, and it may be the reason why your collet melted down. We are terribly sorry for this, as I can see, my colleagues have already arranged a replacement including the heat paste for you. If it's not expedited yet, it should happen anytime soon.

I will make sure to let the Manufacturing department know about this to prevent this from happening again.

This post was modified 2 years ago by Martin L.
Martin L.
Official Prusa Research CS...
Posted : 27/08/2019 11:50 pm
rmm200 liked
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