What head should I be looking at to solve my jamming problems?

I have been working on getting this built for quite some time now. The latest hang up is my ability to extrude properly. The motor seems to work properly and grips the material well but the extruder barely works. I can push material through it problem free but it consistently jams up. I have yet to be able to print anything. Needless to say this is frustrating as I think I am so close but yet the most important part is holding me back.

I have read much and suspect heat break problems and as you can tell this is a bottom of the line extruder but I thought I would at least be able to do something with it. I have ordered a cheap (20.00) J-head to play with to see if that will help. My Z - Axis just goes up and down but I figured I could adapt it somehow to try it. Here's what I purchased - [www.ebay.com]

What do you recommend for a reliable head? What are you using and would you recommend it? I just have PLA to work with right now but would like to do ABS. Any nozzle recommendations?

Of course I would like to do it cheaply but since I have little invested at this point, I am willing to spend to get a good unit, just don't know what a good unit is.

I ditched the clone that came with my printer for an E3Dv6, which seems to be highly recommended. However the v6Lite wasn't available at the time. Definitely would have gone that route instead for $35 had it been an option. E3D has a great reputation, so I don't think they would release a dud.

As for your current issues, are you using the all metal hot end you linked now or is that the "j-head" you just bought? I always thought j-heads had peek bodies. If you are using an all-metal hot end now, I can't tell what the fan in the photo is cooling, but I would assume that the fins on the body are getting to hot as heat creeps up the hot end. This causes the PLA in the PTFE tube to expand, creating a jam. It is also possible that their is a gap inside the hot end between the PTFE tube and the melting chamber (?). Depending on your settings, it is also possible for melted plastic to pool in this area and create jams.

I would try making sure the PTFE tube is as far down in the chamber as it will go. Try to point a fan at the extruder cooling fins, keeping it running at full speed whenever the hot end is above 50 degrees. Then apply a few drops of sesame seed oil to a freshly cut end of the filament before reloading it in the hot end.

Also, what temperature are you extruding at?

Edited 1 time(s). Last edit at 06/10/2015 04:51PM by Kurzaa.

Thanks for the reply - I was looking at the E3Dv6 and was thinking of picking it up but decided to wait and see what was said here. It looked like for 80-90 bucks I could pick one up. I think that is high but if it works well then I am in. I just purchased the J-head and will give it a try when I get it. If it works then I could see myself buying a spare or two for easy swaps as it is pretty cheap. As far as the one I am using now in the picture I think you are correct with it getting hot up inside. In the picture I have the fan moved to the side. It's the only way to load the filament and verify motor movement. I have played with the extruding temps up to 220 but I have yet to get it to properly extrude. If I push on the filament the nozzle will extrude but it seems as if I cannot provide enough pressure consistently to have it work. I might be barking up the wrong tree and need a different extruder but it seems to work fine but that is without a load. Just want this fixed if I can find out what others are using it will be a big help.

Thanks again!

Give the jhead a chance! IMHO the E3d is over hyped and over priced.

Here is a tip for the jheads. The nozzle that comes with them can seriously vary in specs. I solved all my worries by this super secret trick that I'm sharing here for the first time.

I observed that my filament would not extrude smoothly or properly, and noticed that the nozzle entry way (the top hole, not the output hole) seemed quite small. So I took a chance. I located a 2.25mm or so drill bit and i increased the hole diameter (where the filament feeds in! not the nozzle hole). I carefully drilled the hole down to close to the end of hte nozzle where it starts to make its \/ nozzle shape.

After I accomplished this (then let out a deep breath because the first time I tried it i went right through the nozzle....), I reassembled it and have been printing smoothly ever since.

I have printed ABS, PLA, HIPS @ 245, Nylon @ 250 and PET+ at 260 degrees with no problems at all. I have permanently and cheaply solved my jamming and clogging issues.

Ok so here is my unscientific theory on why this worked.

As the filament feeds into the nozzle, it needs a "transition period" to go from "Solid" to "Liquid". The technical term is "Glass Transition." I surmised that because of the heat sink and the fan and the stainless steel tube, this transition happens suddenly at the nozzle, and there is not enough of a "buffer" to help the plastic melt and to give the nozzle a ready supply of molten plastic. This buffer accommodates the filament's expansion. Without it, it causes back pressure and jamming.

It may not seem like much, but it helped a ton. I have also thought that maybe just using a .3mm nozzle with a 1.75 filament would afford the same benefit. I have no issues with retraction either.

Edited 1 time(s). Last edit at 06/11/2015 03:31PM by thetazzbot.

Thanks tazzbot, I will certainly see what my knock off does and if it does not make the cut try your trick. I broke 2 drill bits today attempting to make nozzles, need to order more drill bits! I was hoping I could find something that worked cheaply and then order a few so I have spares on hand when I do need to clean / work on them. I am thrilled to hear what you did and about how well it worked for you. I have to agree with your comment about not enough buffer or as I have read else where a bigger "heat break" area to insure that things don't get clogged. It would seem to make sense that having a larger area around the filament would give it a little bit more play and some area for heat to escape if it did get above the heat break area but I have never heard it mentioned. The answers I have found are bigger heatsinks and more fans. I am also interested in knowing more about the PTFE filament liner and how best to work with it. It seems like all of the new heads have it down the entire cold region but it also sound like this is not a must have.

This is all new to me, at first glance it all seems so simple, until it doesn't work. I guess part of the fun is in finding out why, but I could do without that part.

I really appreciate your input.

Thanks again!