So I installed a brand new J Head which I have bought recently (I wanted to try 0.35mm nozzle - the one I had was 0.5mm).

I fed the filament, heat up the hot end, and extruded about 5mm without any problem. Re-generated g code for a test piece (with configurations for 0.35 mm nozzle), load the g code to Pronterface, and hit Print.

It started jamming in the middle of first layer! Wow.. just incredible.

I tried may more times.. with various temperature, roller spring tension, and feed speed, but none of that mattered. By the way I've learned ABS is a lot softer than PLA, the hobbed bolt can very easily dig into it.

I once said jamming is like a disc or ACL injury which keeps coming back once you have one, but now I think jamming may be more like a virus. It's contagious and my brand new J Head got infected even before I ever used it!


I'm still waiting for a new fan with higher CFM rating. Checked the delivery tracking and it's supposed to get here later today. Once I get it and have it installed on the extruder, I will switch to PLA and try again. However, I am keeping my hope low... after so many unsuccessful attempts of resolving this jamming issue, I am tired of dealing with disappointment.

I'd look into your filament possibly being contaminated.

i would be contacting the vendor you bought your jhead from and seek support from them,
typically with jheads or any hotend it best to get them from the original producer (in this case www.hotends.com) as you are guaranteed to the get a genuine hotend, there's also quite a few clones out there which don't perform anywhere near as well as the original but are advertised as genuine

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sheck626 Wrote:
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> I'd look into your filament possibly being
> contaminated.

Yes.. I think that's a high possibility. I mentioned in another posting, but the very reason I bought this particular ABS filament from this eBay seller was the price (and free shipping!).

Well, I have been pretty much suspecting every possible thing in my printer and blamed it for the jamming so far, and some of them turned out to be innocent (?). So, I won't jump into any concrete conclusion that this is a bad batch of filament... but it still is a possibility.

I am actually thinking about buying the same white color ABS from another, more reputable, vendor and try that out. Yes! Another purchase to make in my never ending quest of resolving this darn jamming issue! LOL.

Also, the next time I buy filaments from a new/unknown vendor, I think I should be translucent/clear color, so that I can visually inspect if there are any impurities in them. Oh well, it will be actually better if I just stick with known/reputable sellers.

I got the new fan I ordered this afternoon.

I installed it on the extruder (this is to cool PEET part of the J Head), loaded up the black PLA, started printing a test piece, and guess what - no more jamming!!!!!

Well, there are some bold spots caused by no extrusion here and there, which is a new issue I am trying to figure out, but at least as far as I can tell, I no longer have the jamming issue. No more chewed up filament!

So, even if it wasn't the bad ABS filament, at least this has something to do with the filament/material. Now I really really want to buy a new batch of ABS filament from a different vendor so that I would know it for sure if my ABS filament really is a bad batch or not.

I'm on my second j-head here and I can tell you that no fan should be needed when printing with ABS. I've had really bad results when trying to print ABS with a fan.

I see the J-Head hotend mentioned more than any other make on these forums. And it seems there are just as many people reporting them jamming.
Why are people buying them?

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Waitaki 3D Printer

waitaki Wrote:
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> I see the J-Head hotend mentioned more than any
> other make on these forums. And it seems there are
> just as many people reporting them jamming.
> Why are people buying them?

In my case, because I didn't know any better. I bought a kit to build my printer, and it just came with a J Head.

What other types of hot end are out there? Which ones are popular? Are there ones which are know for their never-getting-jammed property by any chance? I want that!!

A home built one I reckon!

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Waitaki 3D Printer

waitaki Wrote:
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> I see the J-Head hotend mentioned more than any
> other make on these forums. And it seems there are
> just as many people reporting them jamming.
> Why are people buying them?

They have a good reputation if you buy them from the original designer (hotends.com). There are lots of clones out there though that are crap, and those are usually the ones that people are on here complaining about.

I have two J head mkV brilliant results, the only time it jammed was when I tightened the nut in the peek too much crushed the inner tube. One other issue I had that made it appear like a jam, was the hobbed bolt wasn't catching the filament properly.

I am using an original J-Head from hotends.com. Its been fantastic printing for several months, 3 others reprap printed parts and some other prints. And just yesterday had this jamming when printing the last 2 parts of reprap mendel. I only printing PLA so far, the hotend has a small fan blowing the cold end part. I tried to clear the jam using the filament. Extruding it manually and using pronterface seem fine. but then jamming back when do the print.

I would like to know, how do you clear the jam? Thanks.

I think you would do better starting a new thread rather than re-starting one that's months dead.