[Feist92]

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







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



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. Note a couple of the pics have the previous extruder that i swaped out for the mk7 style one. 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

BTW sorry if the pics are massive, they look ok on my computer so fingers crossed
Cheers
Jonathan Feist

[neilw20]

Is it because seek times are excessive, either due to poor plotting sequences or motion not being fast enough?

[BAMCNC.COM]

Your temp isn't hot enough and as the cool plastic gets to the nozzle its cooling it. Turn up temp and insulate nozzle.

[Fastest1]

Insulating the heated chamber as BAM suggested will help a lot. It will stabilize the temps better.

[Feist92]

Is it because seek times are excessive, either due to poor plotting sequences or motion not being fast enough?

could be but theres not really anything i can do about how the part is sliced. the rapids are set at 120mm/s i could go faster but i figured that was probably fast enough, any recommendations on what speeds to try?

[Feist92]

Your temp isn't hot enough and as the cool plastic gets to the nozzle its cooling it. Turn up temp and insulate nozzle.

Good point on the insulation, ive been trying to work out what to insulate it with but havnt had many ideas.

What temps would you sujest? Ive tried everything between 180 (too cold to stick to the bed) and 220 which should be rather excessive from what ive heard. the temperature dosnt seem to have much effect on the plug forming as ive had the same problem no mater what temp i try.
i should really try some better plastic but the only source in new zealand is about 4 times the cost of makerbots filiment before shipping

[Fastest1]

They make a product for wrapping headers on cars, it is woven cloth tape. It is used to hold heat within the headers and keep under hood temperatures down. Thermotec IIRC is the brand name. Otherwise the white sheet of fibrous material (that is generally included in the extruder kit) and Kapton tape will do a great job.

[Feist92]

They make a product for wrapping headers on cars, it is woven cloth tape. It is used to hold heat within the headers and keep under hood temperatures down. Thermotec IIRC is the brand name. Otherwise the white sheet of fibrous material (that is generally included in the extruder kit) and Kapton tape will do a great job.

thanks for the suggestions ill see what i can find. Im going to try shortening the thermal barrier to hopefuly make a sharper heat transition zone

[BAMCNC.COM]

I did just the opposite, so I could preheat my plastic, I used ABS though.

[hoss2006]

Get yourself a J-head and your trouble will go away.
http://reprap.org/wiki/J_Head_Nozzle
Also cut your printing feedrate way down, 30mm/sec, when you start making good parts then increase a little more.
I've been using the chinese filament from reprap walmart for months no problem with a j-head M4.
Hoss

[Feist92]

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. Im wondering if cv mode in mach3 could get around this??

[neilw20]

CV mode. Most definitely

[Feist92]

im getting this problem despite having cv mode on, are there any settings i can change to make it have more of an effect?

[neilw20]

IS the acceleration/deceleration set OK? Is it just plan jerking at a change of direction?
Are all rapid moves with the cursor (and shift key) smooth an start and stop nicely?
Do you getting any jerking while traveling fast along an axis? (PC / Windows problem)
Does it ever lose position?

[joeybagga]

Feist92,

Your machine looks very sturdy.
Did you design it yourself or is it open source?
Please tell us more about it.

JoeyB

[BAMCNC.COM]

Is your curve a lot of small moves or an actual arc?