Prusa i3 Extruder?

Hi everyone,
I want to build a prusa i3 with a single aluminum plate but I am confused with the extruder design. The compact extruder does not have an idler and it doesn't seem obvious to me how you would even mount one.
[github.com]
There is only two screw holes for example instead of 4. I came across this nice design:
[imgur.com]

I am curious if anyone knows where I can find the plans to that and if there is a single analog. I would prefer a direct drive compact extruder to a wades because I want the flexibility to dual extrude in the future. Any suggestions for the best motor and hardware to buy is also greatly appreciated because I only have experience with wade's extruder.

Thanks so much!

Just as an update, this fork of the prusa repository has the altered double extruder that matches the photos:

[github.com]

Thanks Einstein!

How are you mounting the idler bearing in your extruder idler? I don't see a shaft or anything in the rendering.

I just built my I3 last week from lazer cut frame. I used Qu-BD extruder but replaced the gear with mk8 and replaced the feed parts. It works really nice now. I had to make a new mount from a piece of angle channel because using the universal mount for the I3 puts the extruder in the middle and the hot end on the QU-BD is very short so I had to fix it to hang below the bottom slide rail. I just about have it calibrated perfect the only issue I am working on now is on larger prints the abs is warping.
Here are some pics of my build

Prusa I3 Pic 1
Prusa I3 Pic 2

Edited 2 time(s). Last edit at 01/21/2013 02:58PM by skew.

I am building a prusa i3 as well, I got the kit from twelvepro, I like to use the qu-bd extruder as well, could you use the makerbot mount on the x-carriage? I see two holes on the makerbot adapter, would they match the holes on the x-carriage, my kit also has only two holes.


Thanks.

You will still have to make some kinda bracket so the nozzle will be lower than the x carriage that's the issue I ran into. I built the twelve pro frame also I am really happy with everything. I would like a better extruder mount mine looks rigged up but it is work fine.

I have posted a few issues (and the solutions I have used to make it work) with the compact extruder in the i3 github.

Please note this extruder is intended for a geared motor like the one from 2engineers.com and not for the PG35L that was used before.

Hey Misan,
I was looking on github for your fork but I don't see it, where am I looking for that extruder?
Thanks!

As there was a major revision of the Prusa3 recently I did not want to misguide people with older parts and I removed. My comment above refers to Josef Prusa's Prusa3 repository, where I uploaded my changes. However, you can get my file from a repo I've just created: [github.com]

Sorry for the mess. (It should be clear that I am still learning about the git thing and how to use it properly).

I'm going to build an i3 soon and purchased a J-Head MK V-BV / 1.75mm / 0.40mm - what would be a good extruder for this hotend?

It depends on the type of frame you use (they use different x-carriage). It depends on the availability of motors too. I can see the one I bought from 2engineers is no longer available and its replacement will require changes on the extruder piece (I guess, as I have not research the topic further). PG35L is ok too, but I am not sure about its availability. A Greg's type is always a sure bet, but depending on your x-carriage some work may be needed on your side to adapt it.

I did some work and now this Greg's Wade extruder can fit Prusa i3 x-carriage: [www.thingiverse.com]

I'm unable to mount this ^ version of Greg's to the current 50mm X carriage. The Idler hinge screw and the hotend (JHead) mounting screws want to run into the X carriage, creating a non-flat interface. Am I doing it wrong?

This part is to be attached to a T-shaped x-carriage from single_plate Prusa3 repository. For Jhead the screws that fix it should be oriented like the ones shown in the picture above, so the back of the extruder should be flat ...

Oh! I didn't realize the X carriage was different between the single plate and box frames. Why's that? I thought the T-shaped carriage had been replaced by this rectangular-ish version with the bottom bearing offset to the side.

And, are there nuts on the other end of your JHead screws? Thank you so much for the response.

I guess box_frame can handler heavier extruders better and for that a beefier carriage is called for.

The holes are slightly smaller than M3 thread, so if you tap them M3 no need for nuts (there is not pulling force on the M3 screws).

If you cannot tap them, just screwing the bolts will do it too.

I'm sorry if this pulls this thread off topic, but I don't understand why there is a single_plate set of files and then in box_frame I can set "i_am_box=0" and generate (what would seem to be) single plate parts. I would love to find an explanation of what's going on there. And thank you again, you've helped me a lot.

mjrice Wrote:
-------------------------------------------------------
> I'm sorry if this pulls this thread off topic, but
> I don't understand why there is a single_plate set
> of files and then in box_frame I can set
> "i_am_box=0" and generate (what would seem to be)
> single plate parts. I would love to find an
> explanation of what's going on there. And thank
> you again, you've helped me a lot.

The box frame branch evolved faster than the single plate or mini with some of the box parts not compatiable with the other builds. I'd assume the box version evolved faster due to the frame being more available at first and easier to source for many people. There was recently a realignment of that repo and another repo called "vanilla" spawned that not only contains the source but also .stl files as well.

The original Prusa i3 uses a direct drive extruder a smaller X carriage than the i2. A Greg's wasn't fitted until others started building them. To use the Greg's people started using the dual extruder X carriage with an extruder with the newer hole mount spacing.