I installed Direct Extruder for the Mini, ask me anything
 
Notifications
Clear all

I installed Direct Extruder for the Mini, ask me anything  

  RSS
ryandam
(@ryandam)
Active Member
I installed Direct Extruder for the Mini, ask me anything

The story

I see lack of direct extruder discusion for the Mini so I created one.

I have no doubt about the printing quality of the Mini, it amazing! But now I want to print more TPU/FLEX and it's where the problems appeared. Yes you can print TPU with stock extruder/Bondtech dual gear extruder (bowden extruder for short) but you have to slow down the speed and it's a pain to wait. Not to mention sometime you have filament stucked in the extruder gears or sometime you have under extrution.

So I decided to give Direct extruder a go. I have looked in to @MAMSIH design for awhile and I love how compact and elegent it is, but I have some problem with it (one of the biggest is the mount for PINDA is very weak and easy to broke) so I make some improments:

Prusa Mini Direct Hextruder Retro

 

You can find more instruction in my post, so give it a try.

How the result?

Currently I am quite happy with my upgrade, I can print TPU at least 2x faster with better quality now.

 

For PLA, I currently not see any different in the quality, will do more print to see.

Ask me anything

This is the first time I try using Direct extruder so I really exited. Please ask me any thing or give me some suggestions so you and me can learn something new.

This topic was modified 2 weeks ago by ryandam
Posted : 11/09/2021 3:54 am
BogdanH
(@bogdanh)
Reputable Member

Very interesting!

First of, I really like part cooling shroud design as I was looking for similar for stock Mini printhead.

In general, I think that's the cheapest (about 60€ +filament) upgrade to direct drive for Mini and if I get more interested on TPU, I will sure consider this solution. Btw. would be interesting to know how total weight compares to stock print head.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 11/09/2021 10:11 am
ryandam
(@ryandam)
Active Member
Topic starter answered:

 

Posted by: @bogdanh

Very interesting!

First of, I really like part cooling shroud design as I was looking for similar for stock Mini printhead.

In general, I think that's the cheapest (about 60€ +filament) upgrade to direct drive for Mini and if I get more interested on TPU, I will sure consider this solution. Btw. would be interesting to know how total weight compares to stock print head.

This setup will add ~125g more to the existing print head.

Beside TPU printing capacity, I notice slightly better PLA quality in some corner of the print. I still testing it out and will post here for more comparation.

Posted : 11/09/2021 10:49 am
BogdanH
(@bogdanh)
Reputable Member

Beside TPU printing capacity, I notice slightly better PLA quality in some corner of the print.

Yes, I would expect that to be the case in certain situations (depending on printed object). If nothing else, then because of better part cooling, which is important when we print small objects -at least so my thoughts.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 11/09/2021 11:11 am
ryandam liked
Crawlerin
(@crawlerin)
Prominent Member
Motion

Ha, I was thinking that with rise of smaller pancake steppers it may not be out of place to have direct feed on MINI. There are few small toolheads which could potentially be utilized, this one looks more compact in width than something like Mini-Afterburner I had in mind initially.

Did you have to do firmware changes? I would not worry about e-steps, but for example filament loading and unloading routines may be out of whack a bit if feeding tube is few dozens of millimeters instead of 28 or so centimeters 😀 

Did you have to slower print speed? Also, what about motion, and vibrations of cantilever? Does it affect it too much, especially when Z-hopping and toolhead is near the unsupported end with cantilever? Would be interesting to slap an accelerometer at the end of X axis and compare outputs vs stock toolhead. If it affects prints, it may be a good case for input shaping (requiring alternative firmware of course).

Good job BTW! It could only be good if it turns out MINI can handle direct feed without much issues, open up possibilities to print flexibles a bit better.

Posted : 14/09/2021 11:14 pm
ryandam
(@ryandam)
Active Member
Topic starter answered:
RE: Motion

Ha, I was thinking that with rise of smaller pancake steppers it may not be out of place to have direct feed on MINI. There are few small toolheads which could potentially be utilized, this one looks more compact in width than something like Mini-Afterburner I had in mind initially.

For the Mini I think due to the frame (only 1 side for Z compared to MK3) so to minimize vibrations, Pursa have to reduce the X axis length. The compact width of the Mini's heat sink design I think is very clever to reduce X length. I really love the design of the Mini Afterburner but you will loose some X axis size. The other direct extruder setup is Sherpa Extruder but I think the design is not as sexy as this design.

Did you have to do firmware changes? I would not worry about e-steps, but for example filament loading and unloading routines may be out of whack a bit if feeding tube is few dozens of millimeters instead of 28 or so centimeters 😀 

for the filament changing process, I had described in the description of the model (HERE), basically firmware change is not required but you have to manually load/unload filament. But for the sake of convenience I modified the firmware to change estep, motor current, filament changing process, now I don't need to insert g-code to anywhere and the filament changing process is as easy as the default extruder setup.

Did you have to slower print speed? Also, what about motion, and vibrations of cantilever? Does it affect it too much, especially when Z-hopping and toolhead is near the unsupported end with cantilever? Would be interesting to slap an accelerometer at the end of X axis and compare outputs vs stock toolhead. If it affects prints, it may be a good case for input shaping (requiring alternative firmware of course).

Currently I'm using default profiles (with some modify of retraction and linear advance), so the print speed is the same. For the quality I have some observations:

- With the default bowden setup the print will have under-extrude in some edge corners. Now with direct extruder its gone.
- Less stringing.
- A little bit ringing pattern with speed profile.

Righ now I dont have any accelerometer to measure vibration but I think the effect is acceptable for the default slicing profile.

Posted : 15/09/2021 3:10 am
Share: