J Head Extrusion problem
November 27, 2012 04:05AM
Hi I have some issues with my new wade extruder.

After ensuring that my extruder is working properly, I made a calibration test print on my new Wade Extruder. It was fine for a while (may be for 5mns). Just paused as the first layer of my test print didnt stick properly. When I tried to reprint, the extruder didnt seem to work. tried pushing manually but it appeared that something got choked. Opened the extruder and the hotend to find that my PTFE got choked with a bit of PLA. Please see the photo attahced. It appears that PTFE got cooked with heat and when it cooled for a moment it freezed. When I pulled the PTFE out the other side (i.e. towards the hot end) is hollow. The size of the PTFE from this end is now shorter than filament dia.

I heated up to 200-210

What could be the problem. Is it heating up too much that PTFE is expanding and contracting?
Attachments:
open | download - PTFE choked.JPG (12 KB)
open | download - PTFE choked from front.JPG (23.7 KB)
open | download - Wade Extruder.jpg (61.6 KB)
Re: J Head Extrusion problem
November 27, 2012 05:00AM
Did you buy a genuine J-head or a knock off? Because it looks like a clone
Re: J Head Extrusion problem
November 27, 2012 06:54AM
Asger, I bought it from a supplier in Australia - Melbourne extrude3d.com got some good feedback from people who bought from him.
Re: J Head Extrusion problem
November 27, 2012 07:57AM
I don't think that even qualifies as a j-head hot end - it's completely missing the milled vents and the brass block is completely different.
Re: J Head Extrusion problem
November 27, 2012 08:43AM
Fwiw I don't think it was sold as a jhead, tom may attribute the jhead as his starting point, but its his own design.

Looking at the pictures I think your ptfe liner was too short, I had similar issues at one point and I wasn't initially pushing the liner far enough into the peek block before marking and cutting to length as per toms instructions, since fixing that I haven't had an issue, what diameter is the filament you are running?

Gaz
Re: J Head Extrusion problem
November 27, 2012 01:16PM
[forums.reprap.org]

probably the same issue you are both suffering from, you purchased a knock-off (nothing wrong with that when it's open source, but when it's not done RIGHT!! theres a fucking issue)

best thing you can do, and this will probably save you TONS of agony and sleepless nights, buy the real deal.

www.hotends.com 59,99 plus 3.75$ for international shipping, get the best fucking hotend ever made! MUERICA!
Re: J Head Extrusion problem
November 27, 2012 05:04PM
the ptfe tubing was not in far enough. it looks like it needs to be in about 8mm deeper next time. hand drill out the excess feedstock and try, try, again!
Re: J Head Extrusion problem
November 27, 2012 05:46PM
@ Gaz, I should have mentioned it clearly. 'It is a Jhead inspired design'. didnt intentd to complain - the quiality of the hot end build is great and without any doubt I am very impressed about Tom and his product quality. I am using 3mm filament


Thank you all for the input.

After reading your input and a post by jamesdaielv explanation on PTFE on another post, I figured out the issue.

Also recollected one thing when I was assembling it. After putting the hotend, PTFE and peek togather I tried to manually push PLA. Felt a click as the PLA entered the peek. I thought it could be due to PTFE settling in the right place. After first two or three pushes, it disappeared. I thought it would have lined up and just continue the assembly.

I will give it a go tonight with a slightly larger length of PTFE after testing the length in the peek.
Re: J Head Extrusion problem
November 27, 2012 09:33PM
when i asked for filament diameter, i was asking for the precise measured diameter and roundness. If the filament is over 3mm in diameter at any point of its cross section it will grip the ptfe. Some manufacturers sell as 3mm +- .1mm and up to .1 ovalling as their standard tolerances, this could mean the filament is up 3.2mm across in one direction, trying to push this through a constrained ptfe tube with a 3mm ID will always be problematic.

GaZ
Re: J Head Extrusion problem
December 14, 2012 10:30AM
Sorry I didn't find this sooner!

To everyone that doesn't know, I'm the maker of these hot ends. I don't claim for them to be J-heads, and I do attribute my inspiration from them. One of the reasons I set up a webstore was to pull them away from the stigma of being called J-head clones. sad smiley

The hot ends are of my own design and dimensions and drawings are all available on my blog. I also do dev work on new stuff too, but till i have working protos I tend not to blog about them.
such as my 5 in 1 multi extruder proto here...
5 in 1 multi extruder proto

To answer the question, if i'm not too late

I do have assembly instructions on my blog, so please check them out smiling smiley. It does look like the PTFE tube isn't long enough. The length of the ptfe is set by placing the tube into the Peek and trimming 2mm above the exit.

If that PLA is the sample I provided you when we met, its much much too hot, it should be flowing easily around 175. Please check your firmware and make sure you have the correct thermistor setting.

The purple PLA is from Vik, its dimensions, to answer Gaz, are around ~2.85mm.

Any issues with assembly, or extruding issues, you have my email. (and 3eality you have my phone number too so feel free to call!)


[kininarutom.blogspot.com.au]
[extrude3d.com]
Aussie made hot-ends
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