Broken extruder, likely machining issue

[stienman]

I was just finishing my machine when the top metal part of the extruder broke at the bottom of the threads. It appears that either the bottom up internal machining was too deep, or the external threads from the top down went too far down. Either way, the two operations left such a thin sliver of metal connecting the two halves that it snapped apart before I was able to extrude anything.

[img]http://i288.photobucket.com/albums/ll16 ... hotend.jpg[/img]

I have a picture here of the whole hot end with the broken pieces:

http://www.flickr.com/photos/adavis/778 ... 1075329876

I'll call the SeeMeCNC crew tomorrow, but wanted to post this as a form of documentation in case it happens to anyone else.

One can probably use a caliper to measure the internal depth of the larger diameter hole and the length of the threads from the top to see if that area is weak on a given extruder part.

[johnoly99]

Sorry about that steinman, John here. That's a first for us to see? (We usually break stuff first lol). Send us your address in an email to seemecnc at gmail dot com and we'll send you out a new part.

[tom10122]

Wow looks like a mistake , my hot end is pretty sturdy and it is thick around the threads

[Phoenix]

the same thing happened to me in the exact same spot

[hsb727]

That just happened to me as well and I guess I do not have to
include a picture as the original is exactly the same.
I found the web to be only about .4 mm. A drill depth change of
1 or 2 mm less would correct that issue.
Cest la vie
or
poop occurs
LOL

[steveeverson]

Hi John, the same thing happened to me with the one I bought a couple of weeks back. (had it delivered to Dallas as I was working there, but back in the UK now) There seemed to be very little metal between the threads.
Hope you can help me out.
Cheers
Steve

[johnoly99]

Ok guys. Sorry for the late reply on this one. If you have already emailed us about a broken hotend, you have replacements on the way.

Here's what it was. Yes, the drill depth was correct, the problem was actually, ME. Haha, if you can't make fun of yourself right? So, when I set up the lathe to run those parts last time, I touched off the threading tool on the SIDE of the insert, and didn't comp to the centerline. Basically, the threaded area then became ~.080 longer, which put the threads root right where the drill taper was, which made the parts weak and break. I went thru the parts, found the ones that were done that way, and tossed them out. I ran 100 GOOD parts the last couple days, so now I know what and how, I shouldn't goof again. My bad, and I seriously apologize for you guys that got one and it broke. Sucks, I know.

If you have any part failures, non electrical at least, remember to email us, and we'll get you going. If it's a defect, like this one was, we replace it.

[stienman]

Thanks for checking into it further!

Is there an easy way for me to determine if the one I have now is affected? I'm currently being very gentle with it just in case, but I don't want to be caught out in a few months if it was a weakened one.

Also very keen to see the Bowden setup it sounds like you guys are developing for Steve's extruder for the Rostock max.

[johnoly99]

stienman, just take a pair of wire cutters, and pinch it hard in the groove of the last thread towards the mounting flange. If it pops right off, it's a dud, and I'll send you a new one ASAP. If it doesn't feel like it's gonna crack, let it go.

[Eric]

Me too. I was able to snap mine just with my unaided hands. Sending email now.