Any non-stick sleeves that can be slid over the hotend wires?  

RE: Any non-stick sleeves that can be slid over the hotend wires?

The silicone socks cover the entire block, including the wires. They're inexpensive and quite effective.

Slice Engineering is selling non-stick PTFE (Teflon) "paint" that could be applied, but I'm not fond of PTFE at high temps.

RE: Any non-stick sleeves that can be slid over the hotend wires?

Posted by: @bobstro

The silicone socks cover the entire block, including the wires. They're inexpensive and quite effective.

 

Which silicone socks do that?  For reference, let's have a look at the genuine e3d pro socks:

There are cutouts that allow the heater cartridge and temperature probe to enter the heater block, so I don't see that the sock offers any shielding to them, and especially not their wiring against an all-engulfing Blob of Doom.

RE: Any non-stick sleeves that can be slid over the hotend wires?

Posted by: @dimprov

Which silicone socks do that?  For reference, let's have a look at the genuine e3d pro socks:

Hmm. I thought I'd had some V6 socks that covered the wiring, but I must be thinking of the Volcano socks. Just had a look and am not finding any for the V6 that do... though I'm not sure why. Nevermind then. Perhaps one of the guys doing their own socks can give it a go? I vaguely recall somebody wrapping everything up in Kapton tape. There's an interesting discussion on the old ways here.

RE: Any non-stick sleeves that can be slid over the hotend wires?

I have found the best method of preventing the blob of doom is not to perform the print and leave technique.  If you stay long enough to ensure that there is good first several layers, you almost never get the blob of doom.  

I do use socks on some printers.   I am not sure if that plays a part.  

RE: Any non-stick sleeves that can be slid over the hotend wires?

Kapton tape was my first thought, the same as @bobstro indicated.  I wonder if a silicon straw would work?  They are pretty cheap and they make them for outdoor drinking glasses.  You could fix it in place with Kapton tape perhaps.

My method is the same as @cwbullet.  I don't leave my printer unattended for the beginning of prints.  Additionally, if I am going to be unattended during the print, I use The Spaghetti Detective to monitor my print and hopefully stop it or alert me before we get to a severe problem.

 -Matt

RE: Any non-stick sleeves that can be slid over the hotend wires?

I know some folks are offended when I stress the importance of properly cleaning the bed and calibrating Live-Z before making other "fixes" for adhesion, but this is the main reason why. My current (Mk3 original) fan duct provides good cooling, but increases the flat area under the fan, leaving only a few mm between the bottom of the fan duct and print. If I didn't have absolute confidence in my bed adhesion, I wouldn't even try to run in this configuration.

So yes, I agree that maintenance and monitoring are essential. I do run a sock though. It does help against "BoD", but also insulates the heater block against thermal shock when the fan kicks on. I'm all for belts-and-suspenders protection!  If I'm not very confident a print is going to succeed, I don't leave it alone.

RE: Any non-stick sleeves that can be slid over the hotend wires?

Posted by: @matto

Kapton tape was my first thought, the same as @bobstro indicated.  I wonder if a silicon straw would work?  They are pretty cheap and they make them for outdoor drinking glasses.  You could fix it in place with Kapton tape perhaps.

 

I like this idea.  If only there were some way to fuse the silicone straw to the silicone sock, then I imagine you'd have pretty robust protection against BoD.  I'd rather throw away a silicone sock and a couple silicone straws than have to replace other parts.

RE: Any non-stick sleeves that can be slid over the hotend wires?

On the other hand, BoD can sometimes/often work its way underneath the silicone sock, so maybe belt and suspenders is wrapping everything in Kapton and then putting a silicone sheath on top of that.  

I'm just spitballing here.  It's not all going to be gold.

RE: Any non-stick sleeves that can be slid over the hotend wires?

@dimprov

Interesting idea.  I am not sure how to feed it through the straw.  

RE: Any non-stick sleeves that can be slid over the hotend wires?

Posted by: @cwbullet

@dimprov

Interesting idea.  I am not sure how to feed it through the straw.  

Good point.  It might work better on a wam bam monster, where you could disconnect the wires at the screw terminal, than on the stock prusa design.

As for sealing off the end of the straw connected to the heat block, maybe some kind of high temperature resistant zip tie would do it?  If such a thing exists that is.  Not a perfect solution, but maybe it gets you close enough.

As it happens, I'm fixing my automated soap dispenser right now.  It uses a zip tie to secure a silicone tube against the nipple of the pump output.  After more than 5 years of uninterrupted service, it is that connection which  finally broke, presumably from material stress fatigue.

Inspiration sometimes comes from unexpected places.

RE: Any non-stick sleeves that can be slid over the hotend wires?

Rather than try to wrap everything in stick-resistant material, how about a simple barrier? A 2-3 inch disc with a hole just large enough for the nozzle to protrude, oriented flat horizontally so that filament can't readily work its way up into the hotend. This would have the added benefit of keeping heat off the print for detailed prints. You'd have to add openings for cooling ducts. 

The only question is where the filament will go if not up into the hotend.

RE: Any non-stick sleeves that can be slid over the hotend wires?

Posted by: @bobstro

Rather than try to wrap everything in stick-resistant material, how about a simple barrier? A 2-3 inch disc with a hole just large enough for the nozzle to protrude, oriented flat horizontally so that filament can't readily work its way up into the hotend. This would have the added benefit of keeping heat off the print for detailed prints. You'd have to add openings for cooling ducts. 

The only question is where the filament will go if not up into the hotend.

Interesting approach.  I'm just not at all sure how to execute that one.

I still think the best of all worlds would be early BoD detection which pauses the print.  Previously I thought a simple electric eye might do it ( https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-user-mods-octoprint-enclosures-nozzles-.../best-easiest-blob-of-doom-detector/), but direct line-of-sight clearances are just too hard for that, and it would more than likely snag something.  

When Tom Sanlanderer reviewed Spaghetti Detective, it seemed rather hit or miss.  On the other hand, Tom did use a raspberry pi, which the author of Spaghetti Detective says isn't powerful enough, so maybe Tom's review was invalid.

RE: Any non-stick sleeves that can be slid over the hotend wires?

Posted by: @bobstro

Rather than try to wrap everything in stick-resistant material, how about a simple barrier?

Thinking about it more, I bet some kind of PCB material like FR4 could be used.  Maybe solder mask would resist a BoD sticking to it?

Or, maybe a hole in a sheet of pure PTFE?  You can buy virgin PTFE in various shapes and thicknesses.  If you want a disc you could just slice through a rod of the stuff (I did this recently for creating ultra high insulation turrets on a sensitive electronics project).  PTFE has  toxic off-gassing potential if it gets too hot that it sounds like you're already aware of, but if the nozzle temperature is kept below that?  Not sure it's worth the risk, but the advantage is: there'd be little if any BoD sticking to it.

RE: Any non-stick sleeves that can be slid over the hotend wires?

I sure am glad you guys are active contributors on this forum, because it would be almost totally dead without you!

RE: Any non-stick sleeves that can be slid over the hotend wires?

Posted by: @dimprov

I sure am glad you guys are active contributors on this forum, because it would be almost totally dead without you!

We're lucky to have had a very active community over the years. You'll see new faces coming in, and occasionally longtime regulars fade away, but overall it's a very active, engaged, and helpful group. 

RE: Any non-stick sleeves that can be slid over the hotend wires?

@bobstro

Isn't that the truth?  I learn so much on this forum.