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Prusa i3 Rework question: extruder and hotend connection??

Posted by jdmech 
Prusa i3 Rework question: extruder and hotend connection??
June 13, 2014 12:02PM
Hi folks -
Newbie question here: building a Prusa i3 Rework machine.
Am I missing something here? The connection method from the E3d style hot end to the Wade extruder body appears to be nothing more than 2 holes for 3mm screws that slide through the body on either side of the aluminum hub. There doesn't seem to be any other method for clamping it down. It seems quite wobbly and loose when its put together. Any advice folks? Thanks! JD


Prusa I3 - Rework (home built)
w/ heated print bed. Borosilicate glass plate.
Ramps 1.4 board, Arduino 2650
Thermaltake 750watt power supply
Ulti-panel lcd controller
Marlin firmware
Cura - slicer/print software
Re: Prusa i3 Rework question: extruder and hotend connection??
June 13, 2014 12:04PM
Here's what I am looking at:
Attachments:
open | download - IMG_20140613_115444.jpg (339.9 KB)
Re: Prusa i3 Rework question: extruder and hotend connection??
June 13, 2014 01:32PM
It does look inadequate. Is it a kit or?
Re: Prusa i3 Rework question: extruder and hotend connection??
June 13, 2014 01:51PM
Hi Ralph -
No, It's from the whole parts kit from an ebay purchase.
It is the latest model 'Prusa i3 Rework' featured here on reprap.org
http://reprap.org/wiki/Prusa_i3_Rework_Extruder_assembly

Not sure what version this extruder is.

thanks - JD


Prusa I3 - Rework (home built)
w/ heated print bed. Borosilicate glass plate.
Ramps 1.4 board, Arduino 2650
Thermaltake 750watt power supply
Ulti-panel lcd controller
Marlin firmware
Cura - slicer/print software
Re: Prusa i3 Rework question: extruder and hotend connection??
June 13, 2014 04:44PM
There have been others that have modified the extruder but the STL from the original emotion tech files remains unchanged. IIRC the E3D heatsink is different than the Magma. The pics on the Wiki show a Magma. I've been using JHeads on the Rework kits as it's more forgiving and flexible with regards to printing PLA for a beginner. They fit no problem with the two through holes. I haven't used my E3D in a couple of months now and haven't tried to mount it on a Rework. It may take one of the slotted mounts that mount to the bottom of the extruder like on the Gregs. Here's a pic of an older J Head mount. [jheadnozzle.blogspot.com] It would basically be a spacer plate that would tighten up the slop in the hotend to extruder connection. I had to use one when I installed the E3D on a first gen i3 single plate with a Gregs from an i2.

When I get a chance I'll see what the deal is with the extruder and the E3D (IIRC my E3D is a v5) and see if there is an easy fix. The hot end needs to be tight to the extruder and not spin, regardless of the hot end or extruder. Other than changing a part it could be something as easy as shimming it with foil though that's not an optimum solution. Another solution could be an ABS spacer plug to take up that slack, depending on how loose it is. A bummer with the Rework STLs is that there is no source so it makes it harder to do things like move the through holes or change the depth of the counterbore the hot end uses to mount to the extruder.
Re: Prusa i3 Rework question: extruder and hotend connection??
June 13, 2014 04:52PM
Thanks for the detailed info! I just drilled and tapped 4 - 8-32 holes and put some 3/8" setscrews in. Totally fixed! This is my beginner learning machine so everything is new to me. Cheers!


Prusa I3 - Rework (home built)
w/ heated print bed. Borosilicate glass plate.
Ramps 1.4 board, Arduino 2650
Thermaltake 750watt power supply
Ulti-panel lcd controller
Marlin firmware
Cura - slicer/print software
Attachments:
open | download - 1402702778987.jpg (249.6 KB)
Re: Prusa i3 Rework question: extruder and hotend connection??
June 14, 2014 12:50AM
That was a handy solution. Mine had wobble in a stock Rework extruder as well. The difference in the top most flange on the J Head is about 1 mm taller on the J Head with the slot below that flange to the next flange about 1 mm taller on the E3D. The result is the movement in the hot end. On a brand new J Head from Brian a couple of days ago and an Aluhotend I use the mounting is snug and as expected. My concern with the set screws is how the tapped holes will stand up to the heat. That part of the hot end on an E3D is pretty cool but if the part is PLA longer exposure to heat may be an issue. I think giving it a try is the best option.
Re: Prusa i3 Rework question: extruder and hotend connection??
June 14, 2014 08:15AM
I have a pla block with an E3D and have no problems. The top of the heatsink isn't even warm.
Re: Prusa i3 Rework question: extruder and hotend connection??
June 14, 2014 11:39AM
What extruder do you have, Ralph? Is it a Rework and if so how did you mount it?

My current project is a herringbone gear set for the Rework that doesn't require another X carriage. There is a fully modified extruder with herringbones on Thingiverse but it's basically an entire redesign and he does have Sketchup files. [www.thingiverse.com] I've got one printing right now. I'd like to be able to change just the stock Rework gears to herringbones and the ability to mount an E3D without the other mods though while keeping the rest of the design as is. Triffid Hunter has a good herringbone caluclator/generator in OpenSCAD and I found another for Solidworks. As noted above the extruder mounting counter bore in the body will need to be about 1 mm shallower to allow the E3d to mount tightly. I'll try an ABS spacer disc in the meantime.
Re: Prusa i3 Rework question: extruder and hotend connection??
June 15, 2014 05:58AM
I had the same issue, what i did was use an M10 washer (I think its M10 - whatever fits inside the hole), and that made it perfect.
Re: Prusa i3 Rework question: extruder and hotend connection??
August 22, 2015 04:39PM
Quote
add1ct3dd
I had the same issue, what i did was use an M10 washer (I think its M10 - whatever fits inside the hole), and that made it perfect.

Embarrassed I didn't think of this (was gonna sand down with my dremel a bit... great tip! worked for me too!
Thanks add1
Re: Prusa i3 Rework question: extruder and hotend connection??
August 22, 2015 04:40PM
Quote
add1ct3dd
I had the same issue, what i did was use an M10 washer (I think its M10 - whatever fits inside the hole), and that made it perfect.

Embarrassed I didn't think of this (was gonna sand down with my dremel a bit)... great tip! worked for me too!
Thanks add1
Re: Prusa i3 Rework question: extruder and hotend connection??
January 25, 2017 10:24AM
Thank you so much for this! I ended up printing all of my parts -- not from a buyer. And I am having the same issue. Hopefully that works! smiling smiley
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