Blew up my Hot End.

Well the PTFE finally failed on my first hot end. The threaded MIG welding tip blew out. I almost finished a whole set of plastics with it...

So after what seemed like many wasted hours trying to make a new design this is what I finally came up with. Its a collaboration of ideas I've seen on other working units. It was the best I could come up with for what I had available. So far its working good... I'll keep my fingers crossed. Pics attached.

i like the design, but is the copper welding tip end threaded into the stainless steel?

[en.wikipedia.org]

you would be better off using a copper nut to hold the welding tip in place with the stainless steel as a guide, with a larger hole to allow the tip to rest into the stainless steel plate, held in place by the copper nut threaded into the copper welding tip.


imho.

Yea the copper is threaded into the stainless and ptfe. Im gonna have to tear back into it. It just started seeping around the ptfe.

I can't be sure if you have looked at my hot end in the past, but since you use the MIG tip, I think you may find it helpful to review.

[reprap.org]

The page needs to be updated with all of the improvements that I have made, but the most important change that I have made is in how I drill the PTFE for use on my hot end.

Begin with a 40mm-45mm length of PTFE Rod, Diameter for me is 13mm (1/2 inch)

When I drill the barrel out, I now use three (3) bit sizes: 3mm through all, 3.5mm through (length - 1mm), and 4mm through (length - 3mm). This drastically delays/reduces the heat transfer between the PTFE and the filament until it enters the melt pot (MIG TIP), preventing jamming, and also reducing the amount of drag that must be overcome.

Note that in my design, I use the PTFE as the structural support for the hot end. Some ppl will say that this is not a reliable method, and they may be right (maybe all PTFE is not the same), but in my case, I have put at least 30 pounds of filament through my current hot end, and it shows no signs of wear.

Thanks, I will have to try your method for the ptfe. My first hotend I just threaded the mig tip into the ptfe with no other support. Worked fine for almost a complete set of plastics. Then I got greedy and turned the flow rate up another 10mm/s and it blew shortly after.

I made a 16mm PTFE insulator with an M10 thread on it and screwed it into brass. I didn't last long enough to do the first layer!

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[www.hydraraptor.blogspot.com]

ptfe tubing works also as long as there is support wood, metal, larger ptfe ,or other high temp support material. around it and no gaps between cold end and hot end.