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Replacement hotend part

Posted by Desertboy 
Replacement hotend part
March 29, 2017 03:07AM
Hi I need a new one of these mine was blocked solid I tried drilling it out and just destroyed it.

I was wondering would a metal j head from ebay work as a drop in replacement (Short version) I have a mendel with this type of extruder on it

Re: Replacement hotend part
March 29, 2017 06:51AM
I was thinking this

I hope it will drop in so I can do a print job I need to do and then print the parts so I can upgrade the printer to an oversize prusa i3 with a box frame, larger print area & lead screws.
Re: Replacement hotend part
March 29, 2017 08:30AM
Drop in is unlikely, they come in different lengths. at best you would have to adjust your z endstop

What you really need to look at it hows it mounted

Take a look at [reprap.org]
It lists a lot of types and their mount type

It look like you might have a J-Head MK I (1 in top picture)
Re: Replacement hotend part
March 29, 2017 10:21AM
I think that's the one as well, I get the z stop needs adjusting winking smiley just hoping it will fit my mount and not melt it lol. I want to rebuild the printer but need the printer to print the bits so I can rebuild it winking smiley

It mounts via friction a plastic part grasps the end with the ptfe sticking out and nut and bolt and used to tighten.

Edited 2 time(s). Last edit at 03/29/2017 10:32AM by Desertboy.
Re: Replacement hotend part
April 03, 2017 07:40AM
Hi I got the hot end now tried to hook it up and getting a reading of 300C+ from the hotend when off! Does anyone know what thermistor I should set this to?

I bought this one

I've emailed them to ask as well.

I did try a few settings but when I set it to 3950 Ultimaker I got a reading of 900C+

I had to remove the fan for it to fit in the same holder on the mendel but if I change some screws or hacksaw them shorter I should be able to get it to fit.

Edited 3 time(s). Last edit at 04/03/2017 07:54AM by Desertboy.
Re: Replacement hotend part
April 04, 2017 07:58AM
Thats probably short, it goes to max temp in the thermistor tables.

Got a multimeter? unplug the thermistor from your board set your MM to ohms, most read about 100k in a 25c room.
Re: Replacement hotend part
April 04, 2017 09:17PM
Thanks for the replies. I will check with multimeter, I had it extruding but it failed twice will try again later today (It's 2am here at moment lol, can't sleep) and get some photo's this time. I haven't got the fan installed at moment could his cause the blockage? My first hot end had no fan so figured it would be ok. The blocake is happening in the nozzle throat, it starts extruding after 1-2 layers it stops when I take the hot end apart I find the plastic stuck in the nozzle throat I've heated the end up (With throat attached) and then pulled the plastic wire out. When I refeed fresh wire into rebuilt hotend extrudes ok for the first few layers and bloacked again.

Was doing a funny ribbing when extruding, I do have access to a decent snap on infra red thermometer but heard they aren't particularly accurate with hot ends.
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