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J head clone issues

Posted by thefuzzbl 
J head clone issues
February 08, 2014 09:12PM
I just wanted to share my experience with a J head clone that I recently purchased. I wouldn't have purchased this normally but hotends.com was out of stock when I was gathering parts.

First I tried to use the Jhead clone as it came. This failed miserably. It would build up a lot of pressure and then spurt out PLA. For reference I am using 1.75MM PLA. This clearly didn't work very well.

Next, I disassembled the hot end. I found that inside it looked pretty close to the hotends.com product but it was made pretty poorly. The vent holes were not actually holes, the gaps were all wrong. I bored out the liner tube to be just 1.95MM so the PLA would pass through without binding up. I bored out and chamfered the brass nut. I opened up all the cooling holes into cooling holes. I also reduced the overall length by 1MM on my lathe. When reassembling the unit I made sure to add PTFR tape to the threads and I double checked the gap and made sure that everything was as good as i could be.

Still no dice. If I push filament through by hand it does come out but it all curls around the tip. When trying to extrude with my airtripper V3 it just sits and strips the filament. It passes through the airtripper V3 with mo problems when not hooked into the hotend.


I have placed an order with hotends.com to get a real hotend. Any suggestions to get this thing working in the mean time? I hate to sit with just one detail left.
Re: J head clone issues
February 09, 2014 08:34PM
I feel your pain. Hot-end reliability is the #1 problem with FDM printing. I don't think that anyone designing them really knows what they are doing. I don't think anyone really understands why they jam so often- is it poor filament quality, foreign objects, poor temperature regulation, retractions pulling molten filament up into cold part of hot-end, or ?

I have found that most of the time when my hot-end jams I can get it printing again by manually pushing on the filament. That tells me that brute force from the extruder should be able to keep a jam-prone hot-end working.
Re: J head clone issues
February 16, 2014 10:12PM
sadly have been using a clone for the last one year... prints abs without problems but needs a lot more pressure to extrude than a standard j-head...
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