Techzone kit - Extruding problems

Haven't had any luck extruding while running prints, so I'm starting to think it may be the hotend. I can manually extrude, but it seems very slow. I've been stuck using repsnapper so far, so not sure if another program might work better.
I pulled the filament back out of the hotend after my last printing attempt and towards the bottom 2" it was almost twice as thick as original. Not sure if this is normal or not, figured it might explain why not much is coming out.
I'll see what I can do with it for now though.

The very first advice coming to my mind is : change to another hotend. You'll need to do it sooner or later, so better save your time.

The original one is the major flaw in that kit :
- It's trying to keep the metal barrel secured inside ptfe, which will only work for a little time : the ptfe will creep and let go the barrel (and the fact you have such a big expansion at the end of the filament may be a sign the ptfe already started to expand).
- The way the ptfe thermal barrier is clamped into the x carriage is also prone to failure, as ptfe is very slippery.

I personally mounted a simple mendel-parts hotend v5 which works fine, and I think people reported other kind of hotends working on their techzone huxley. But you'll have to print some modified parts and / or add holes in your x carriage for attachment.

I'd be happy to help you with that if you need assistance - although IMO this should be done by techzone as their kit is flawed.

Edit : picture of the replacement for techzone hotend clamp that let me attach the threaded rods that retain the peek block of a mendel parts hotend V5 (http://www.mendel-parts.com/index.php/catalog/extruder/hot-end-v5-for-3mm-filament-complete-pre-assembled.html).

Edited 1 time(s). Last edit at 10/26/2011 04:08PM by DeuxVis.

Second advice, in the mean time you can still use tricks to make your original hotend usable for some time :

- Constrain the ptfe thermal barrier with a hose clamp - it will slow down the creeping.
- Drill 2 holes in the ptfe and slightly scratch the barrel so that 2 little screws / bolts can block the barrel from unscrewing itself out - see [reprap.org].

I did this myself while waiting for the new hotend. It worked for a while then started to leak melted plastic between the ptfe and barrel, but it was enough to allow me to print the parts I needed to mount the new hotend. I'll post pictures later on.


Edit : pictures of my attempts to have the original hotend work; It did, but not for long (step 1) and then for long but leaking some plastic (step 2).

Edited 1 time(s). Last edit at 10/26/2011 04:05PM by DeuxVis.

Thanks for the information. I've decided to try a new hotend. Hopefully it will be in within the week so I can try to get things working.
I'll post an update once I get working on it again.

Got my hotend in now, all installed at least. Seems to be fairly hard to push plastic through, not sure if mine is a bit too large or not yet. Looks like I'll need to work something out to secure my bowden cable since it keeps coming loose.

Verify that your filament is not too large (and check in 2 directions, it could be oval) regarding the inner diameter of your bowden. The cable slipping out its clamps is often a symptom of that for me.

If the filament is not oversized, you can use various tricks to secure the bowden cable :

- Insert thin material (cut out of a soda can, etc) between the bowden tube and its clamp, and secure with hose clamps. Do not over-tighten that, you don't want to reduce the cable inner diameter. Punching holes in the thin material can help it grip the ptfe tube.

- Some people had success by screwing a nut on the bowden cable.

- Print another pair of bowden clamps with tighter inner diameter. I'm currently designing STL for those, as techzone only provide the hot end side model and the extruder side is different. Will let you know when I've got something usable.