My overly engineered printer needs help

[Feisty]

Hey guys
Ive been to post about this for ages but never got round to it.
I started this printer when i was 18 (im 19 now) and its been complete for quite some time but ive been messing around with a massive issue for the past 10 months that ive never been able to get past. But first here are the pics

[img]http://i741.photobucket.com/albums/xx51 ... 000853.jpg[/img]
[img]http://i741.photobucket.com/albums/xx51 ... 000848.jpg[/img]
[img]http://i741.photobucket.com/albums/xx51 ... 000845.jpg[/img]
[img]http://i741.photobucket.com/albums/xx51 ... 000828.jpg[/img]
[img]http://i741.photobucket.com/albums/xx51 ... 000827.jpg[/img]

Now comes the problem, Ive been having isues with the extruder blocking due to the filament forming a plug after a while. this results in many partial prints, most of which are around 5mm when they fail
[img]http://i741.photobucket.com/albums/xx51 ... 000832.jpg[/img]
[img]http://i741.photobucket.com/albums/xx51 ... 000836.jpg[/img]

The extruder its self is designed around/ copied from the makerbot mk7 so it should work but no mater what i do i still end up with the same issue. Im currently running Slic3r and mach3 with linistepper controllers

One thing that im wondering about is that im printing with cheap chinese PLA so this could be the problem but i dont have any high quality plastic to compare to.

Feel free to ask any questions on the settup etc but i would really appreciate and help as ive spent soooo long working on this thing that failure is not an option

Cheers
Jonathan Feist

[adman234]

I know that feel bro.

I'm also using PLA plastic, and I was having some jamming issues.

I fixed them by:

-dialing in the temperature, mine was too high so the plastic melted early
-installing a fan to direct air-flow directly to the PEEK tubing to cool the filament so it does not melt too early
-Inner teflon tube was too short, and not flush with the nozzle. I extended the teflon tube by about 1/4" and that helped remove the area for the plastic to pool in.

Your pics don't work for me, so if you already have a PLA fan my apologies. I just used a 50mm computer fan tacked on with zip ties.

Let me know if this fixes the issue.

[WookieeGunner]

What is your retraction? It might be that you are getting some build up from that.

[Feisty]

I know that feel bro.

I'm also using PLA plastic, and I was having some jamming issues.

I fixed them by:

-dialing in the temperature, mine was too high so the plastic melted early
-installing a fan to direct air-flow directly to the PEEK tubing to cool the filament so it does not melt too early
-Inner teflon tube was too short, and not flush with the nozzle. I extended the teflon tube by about 1/4" and that helped remove the area for the plastic to pool in.

Your pics don't work for me, so if you already have a PLA fan my apologies. I just used a 50mm computer fan tacked on with zip ties.

Let me know if this fixes the issue.

thry these links for a pic, in the second one you can just make out the fan on the extruder
http://i741.photobucket.com/albums/xx51 ... 000848.jpg
http://i741.photobucket.com/albums/xx51 ... 000845.jpg

What temperature did you settle on? ive tried temperatures from 170 to 220 but ive been having the same problem. also im not using any teflon or PEEK as im using stainless as a thermal barrier

[Feisty]

What is your retraction? It might be that you are getting some build up from that.

id thought of that but unfortunately didn't help much, it did help a little but i still end up with the same issue just after a couple more layers

[adman234]

I'm no pro, but with PLA stainless is not going to work as a thermal barrier. It conducts heat too well.

My guess is that the stainless heats up so much it is causing the PLA to go soft before it gets to the hotend, then jam up and cool, causing your issue. Again, I had a similar issue because I didn't have a fan blowing on my PEEK rod. My first guess would be to replace that stainless with threaded PEEK.

Pics work now. That is a freaking sweet printer! Looks solid as a rock!

[Polygonhell]

Since you mention it;s a Mk7 copy I assume it has a stainless barrel with no liner.
There are hotends that successfully print PLA using a stainless as a thermal break, but if you look at nopheads experiments, it isn't simple. Both the recent Arcol hotends and the hotend from the prusa I3 do this.
There are two potential issue, the first is that the inside of the barrel has to be very smooth, PTFE is used as a liner because nothing sticks to it, the second is that the wall of the thermal break has to be very thin.
PLA goes soft before it melts and if the heat creeps up the thermal break too far, the plastic mushrooms inside the break and jams, the usual fix is a fan on the thermal break.
You might want to try an additional fan blowing the the thermal break, to see if there is any improvement, to test you could probably get away with a house fan just blowing across the bed.

[Feisty]

Since you mention it;s a Mk7 copy I assume it has a stainless barrel with no liner.
There are hotends that successfully print PLA using a stainless as a thermal break, but if you look at nopheads experiments, it isn't simple. Both the recent Arcol hotends and the hotend from the prusa I3 do this.
There are two potential issue, the first is that the inside of the barrel has to be very smooth, PTFE is used as a liner because nothing sticks to it, the second is that the wall of the thermal break has to be very thin.
PLA goes soft before it melts and if the heat creeps up the thermal break too far, the plastic mushrooms inside the break and jams, the usual fix is a fan on the thermal break.
You might want to try an additional fan blowing the the thermal break, to see if there is any improvement, to test you could probably get away with a house fan just blowing across the bed.

ive got no idea where i could get PEEK or PTFE. I think im going to try shortening the thermal break to try and create a sharper temperature transition. Im hoping that since the thermal break is clamped to a bit of ally with a heatsink and fan it should keep cool?? I dont know but its the easyest thing for me to try atm

[adman234]

Here's a sweet deal on some peek pieces perfect for a hotend making:

http://shop.seemecnc.com/PEEK-Grab-Bag- ... SCRAP4.htm

[Feisty]

Its working!!! All i had to do was shorten the thermal barrier so that almost all of the cold side was in contact with the heat sink. It still needs alot of fine tuning but im happy it will now make it through a print quite reliably. The biggest issue that ive found now is that Slic3r produces very jerky/rough movement around curves. has anyone had any issues with this??

[tom10122]

Lower you acceleration settings in Mach 3 maybe?

[Vallick]

http://www.makerbot.com/support/guides/pla/
try using MK8 nozzle .4mm

https://www.google.com/search?q=MK8+noz ... e&ie=UTF-8