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Fan for Jhead-Lite?

Posted by botbuilder 
Fan for Jhead-Lite?
November 21, 2014 01:01PM
Is a fan necessary when running a Jhead lite?

Currently building latest version smartrap from github and my 40mm fan almost matches the extra holes on the head attachment bracket, but not quite.

Deciding if I should rig something or go without a fan.

What's everyone else doing?
Re: Fan for Jhead-Lite?
November 23, 2014 01:08AM
I asked the same question to a buddy of mine. He says that if you are using PLA you will not have a problem with it. It doesn't seem like a hotend that will get too hot near the top as it is made out of plastic. He has used his for many many hours and never had a problem with it overheating any of the plastic.
Re: Fan for Jhead-Lite?
November 25, 2014 12:19PM
I just ran mine without a fan and wish I didn't.

Now need to reprint the mount and attachment since they are now warped.

I like the simplicity of the new mounting system with servo-less auto-leveling, but I think it introduces too much movement in both z and x axis.

I also have the previous smartrap design with the servo. It did take a little more time to build and configure, but really haven't had any issues since.
Re: Fan for Jhead-Lite?
November 29, 2014 09:18AM
Use a hairdryer to straighten the parts. And DO NOT use the j-head light without a fan cooling the mount. It will destroy the mounting parts. Happened to me too.
Re: Fan for Jhead-Lite?
November 30, 2014 01:06AM
I concur. The j-head lite is passively cooled, but that means it radiates a ton of heat upward. Not for use with a pla carriage, without a fan.
Re: Fan for Jhead-Lite?
December 03, 2014 01:04PM
If you use a fan with the Jhead lite don't let any air blow on the heater block. The thing is under powered and can't maintain temperature if there is any airflow on the nozzle / heater block.
I had jamming issues with this hot end on PLA, I am now using an ALUhotend which I recommend highly!
Re: Fan for Jhead-Lite?
December 05, 2014 02:27PM
This is why I stopped selling kits. I can't account for a hot end that I didn't assemble. As for "under powered," your average 40watt heater cartridge is made in a Chinese gulag. They're ridiculously over powered and unsafe. I make it a point to source my components responsibly. As for the fan, all you need to do is cycle down the speed, depending on your setup. I don't think shrouds are a good fit for the design.
Re: Fan for Jhead-Lite?
December 05, 2014 02:52PM
Actually once I put a fan duct on my PLA cooler aimed at the bed the problem went away. I still think a small 25-30mm fan directed at the upper part of the J-Head lite would be a good idea, or maybe even encasing it in a small piece of Cu tubing to act as a heat sink for the cold end. I was getting some clogging with PLA. I think you sourced a 6.8 ohm resistor, a 5.6 ohm might have been more optimal. Of course I may have had my PID settings a bit off too. Mine was a kit, but I think I followed your directions very closely.

I did get quite a few good prints out of the J-Head lite before it started to clog. I don't think it was bad filament because I never had any issues with the same filament with the ALUhot end that replaced it. To be fair I'm now using a 0.4mm nozzle instead of the 0.35 I ordered on the Jhead lite. I know that the J-head lite is one of the two hot ends currently being used on the smartrap, with PLA so it does work. I'm very happy with my ALUhotend (at twice the price, but also half the cost of an E3Dv6).

BTW, those Chinese Jhead clones are crap. They only have 4 vents instead of the 5 that the real ones do, and often leave out the Teflon liner. Most come with a resistor not the heater cartridge. Those heaters are made in both 30w and 40w, the 30w ones are reasonable, the 40w are overkill. The ALUhotend ships with the 30w kind.

Edited 1 time(s). Last edit at 12/05/2014 02:58PM by kscharf.
Re: Fan for Jhead-Lite?
December 05, 2014 05:36PM
I think I've successfully mitigated any PLA issues with the V2. I like the alu, but comparing the 2 is like comparing apples and oranges. One's actively cooled and one's designed to be passively cooled. If I had known people would repurpose it to be actively cooled on a plastic carriage, I might have gone with a 5.6 ohm resistor. That's not it's intended use. I could design something made for a fan, but I have no need for it.
Re: Fan for Jhead-Lite?
December 05, 2014 06:37PM
Have you ever tried switching back and forth between PLA and ABS? Some hot ends will jam doing this. That may have also been a problem I had with my jhead lite.
BTW I haven't seen you on ebay for a while. Right now I'm building a Wilson (got an aluhot end for that), but I also am thinking of building a smartrap. Might want to try the jhead lite on that one (would buy an assembled one with a .4mm nozzle) but would print the plastic bits in ABS to avoid the heat. That printer would be for PLA only. The smartrap has a hotend mount designed for the jhead-lite with a built in z probe.
Re: Fan for Jhead-Lite?
December 05, 2014 06:57PM
Haven't had much problems switching back and forth. I think you just have to give it a good purge and baby it up or down to the right temp while feeding it a couple mm's every few seconds. I'm working a good 50-60 hours a week on 2 jobs. I just don't have the time for Ebay right now. Maybe next year.
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