john.w18
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Flexion Extruder Prusa Mk2S

Jul 17, 2017 2:29 am

I am a big fan of the Flexion Extruder that I had on my Wanhao i3. It has very good performance, particularly with flexible filaments. The E3d will be repurposed for a 400x400mm Hypercube build I am working on. The problem is that I couldnt find anyone who had modded the Mk2s to accept the extruder.

I decided to start playing with a solution. My goal was to use all existing hardware except for the thermistor. I used Josef's mk2s files as the base in order to keep the probe and mounts in the same location as a stock mk2s. The only thing that is not 3d printed is a 2inch L bracket (http://www.homedepot.com/p/Everbilt-2-i ... /202033914).

Performance is outstanding (once I callibrated the extrusion steps per mm).

I am willing to publish the files on thingiverse but the only thing I cannot confirm is whether Josef's files allow derivatives to be published. I tried contacting Josef but didnt get an answer (he is probably a very busy guy). Can anyone answer the licensing question for me?
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john.w18
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Re: Flexion Extruder Prusa Mk2S

Jul 22, 2017 3:03 am

Ok so I have everything working. Still fine tuning the extrusion settings but it prints. I have uploaded the files to Thingiverse.

https://www.thingiverse.com/thing:2446630

Instructions
1.) Get hold of 2 inch L bracket https://www.homedepot.ca/en/home/p.2-in ... 73650.html
2.) Use dremel/metal tool to create hole for extruder barrel and drill extra hole to bolt extruder block to bracket
3.) Bolt corner brace to 3d printed extruder cover. The 3d printed parts include holes so you can line up the L bracket and get the right height. I used whatever screws I had sitting around
4.) Remove the extruder cover from stock e3d hotend and dissassemble
5.) Mount the 3d printed extruder cover using the two stock m3 bolts.
6.) Assemble the flexion extruder, you can use the stock extruder heater.
7.) Replace thermistor with NTC 3950 100K type thermistor. Soldering is required here. I just cut the existing thermistor wire and soldered the new one in.
8.) Mount the heater block and extruder with the stepper motor (similar to instructions for the Duplicator i3 plus https://flexionextruder.com/support/i3-style-printer/)
9.) Attach the 30mm extruder fan using m3 bolts and install the Pinda probe in the same manner as stock.
10.) Attach parts cooling fan using 3d printed part on thingiverse (same link as above)
11.) Insert following gcode to reset home Y position
G1 Y25 F1500; move to Y=25
G92 Y0; set this position as new Y0
12.)You will also need to recalibrate the steps per mm for the extruder.
I used the following and assume it will be similar for other systems.
M92 E96.98

What is outstanding is calibrating the extrusion multiplier and width.
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daniel.k26
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Re: Flexion Extruder Prusa Mk2S

Jul 26, 2017 11:57 am

This looks promising to me great work!!

Did you try TPU and when yes what is the Print speed?

john.w18
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Re: Flexion Extruder Prusa Mk2S

Jul 27, 2017 12:08 am

Currently I just put TPE and it worked great. I have not pushed the speed to fast but comfortably printing TPE test cubes at 2000mm/min. I only have the HT version connected so far which has issues TPU. I will switch to the regular version and give it a go soon.

john.w18
Posts: 38
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Re: Flexion Extruder Prusa Mk2S

Jul 30, 2017 1:54 am

Ok an update on my experience with the Flexion. It prints really well.
I had some major quality issues at first.
For Simplify3D you need to turn off "coast at end" and "wipe nozzle". I am not sure why this makes a difference, maybe it is because the flexion has much better filament control than stock E3D. I also set retraction to about 2-3mm as the flexion can easily handle it. For most filaments you will need to drop down the extrusion multiplier. Stock settings for the Prusa are 1.0 but with the Flexion I am hitting 0.95.

stephen.a2
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Re: Flexion Extruder Prusa Mk2S

Aug 03, 2017 12:05 pm

Hey John,

Thanks for posting these instructions. I purchased a Flexion Extruder a few days ago and I'm trying to fit it to my Prusa i3 Mk2. I've very new to 3d printing so I'm way out of my comfort zone! Anyway, I believe I have completed most of the steps but I have a few questions:

1. Would it be possible to get a few more photos of the assembled extruder from a few different angles just to make sure I've got it right?
2. I'm struggling a bit with step 10... Does the printed part slide onto the end of the L bracket? I live in Australia so I wasn't able to go to Home Depot to get the exact L bracket that you suggested and unfortunately it doesn't quite fit into the groove in the printed part. A photo of how this goes on would be great if you don't mind.
3. Do the gcode values (step 11) go into Slic3r somewhere?
4. How do I do step 12 and where does this code go?

Thanks for your help!

Stephen

john.w18
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Re: Flexion Extruder Prusa Mk2S

Aug 04, 2017 1:52 am

Hi Stephen,

Being an Aussie expat I can understand getting the homedepot part is an issue.
Whatever L-bracket you use, you will need to use a dremel or similar tool to get the barrel to fit. I did toy with 3D printed versions but the problem is that even using carbon fiber PETG it lacks the rigidity of steel. I attached some more photos so it is clearer. You will be able to reuse at least one hole from the L-bracket for mounting the heater block. The other hole you will likely need to drill.

The fan bracket does slide onto the slot. I have attached a photo of how the fan bracket slides onto the L-bracket. If you can give me the measurements for the end of your L-bracket I can make you a bracket and then upload to thingiverse. The only thing I ask is that if you can add details in thingiverse comments of where you got the L-bracket from so that it can help people who do not have access to the home depot version.

Will continue with gcode in next post.
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john.w18
Posts: 38
Joined: Feb 10, 2017 2:18 am
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Re: Flexion Extruder Prusa Mk2S

Aug 04, 2017 1:58 am

For the gcode I am assuming that you are using Slic3r.

I use Simplify3d and give you more detailed settings for that slicer.

I did take a look at Slic3r and attach a screen shot of where to go in order to add the gcode. I inserted the gcode where it should go based on my Simplify 3D profile.
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stephen.a2
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Re: Flexion Extruder Prusa Mk2S

Aug 04, 2017 8:59 am

Hi John,

Thanks for your message. I have everything in place now and I'm just waiting for my thermistor to arrive (I wish I'd read your instructions more carefully the first time and ordered it with the flexion!).

I ended up doing a bit of filing on the printed part so it would slot into the L bracket. Just in case anyone else want to know I purchased the following bracket from Bunnings:
https://www.bunnings.com.au/zenith-50mm ... k_p2760232
The end of this bracket is 16mm in width and about 1.5mm thick.

Thanks for the gcode information. Yes, I am using Slic3r. Will my settings be the same as yours? I believe my hot end is sticking out an extra mm or two from the L bracket (judging from your photos).

I have a couple more questions:
1. I've notice that the flexion nozzle sits in a completely different spot to the original one. It means the nozzle can't reach the back of the heat bed. Does that mean I've reduced the size of my print area a bit?
2. When you say "calibrating the extrusion multiplier and width"... This is done in Slic3r too?

Thanks again!

john.w18
Posts: 38
Joined: Feb 10, 2017 2:18 am
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Re: Flexion Extruder Prusa Mk2S

Aug 04, 2017 8:24 pm

Yes you do lose a little bit of build area.

If you find your nozzle is offset differently to mine then you can adjust the gcode. If you can change the value of Y25 to another value (eg Y30). Do not worry if you get it wrong. The worst that can happen is that the purge strip at the beginning prints into air.

G1 Y25 F1500; move to Y=25
G92 Y0; set this position as new Y0

For Slic3r, I have attached screenshots of where the relevant settings are.

I would recommend finding something small to print and test your settings.
https://www.thingiverse.com/thing:1363023 is a good test.

With the Slic3r settings it is generally pretty hard to screw things up too badly . I learnt what most of the settings do by changing the setting and looking at how the print turns out. Takes time to get the hang of it but once you do you can diagnose print defects pretty easily.

https://www.simplify3d.com/support/prin ... eshooting/
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