Modding the Lulzbot Flexystruder for the robo3d

I don't like the stock gregs wade extruder for flexibles, shoving a tube in there kinda works, but I want something better. This is a mod in progress it may turn out to not work wont know till I try.

Lulzbot seems to have a good solution and their source files are freely availible.
https://www.lulzbot.com/store/tool-heads/lulzbot-taz-flexystruder-tool-head-v2
http://download.lulzbot.com/TAZ/accessories/tool_heads/version_2/Flexystruder_v2/
- Old Assembly instructions. The new version doesn't have the adjustment screw anymore the rest of the install should be the same I think. ( drill size will be different once I mod the file for 1.75 )
http://devel.lulzbot.com/TAZ/accessories/flexystruder/flexystruder-1.0/

So i'm working on modifying it to work on the robo3d. The lulzbot uses 3mm filament. So I'm having to tweak around with this to make it work for 1.75

I'm currently on iteration #5 haha.


My last one version 4 almost worked.. i punched the main hole out to 4.2mm so that a 4mm outer, 2mm inner PTFE tube fits snugly.. I also cut out a 7.3mm x 2.5mm hole in the bottom to fit the black portion of the e3D ptfe holder up in there. The problem with version 4 was that the hobb bolt was not perfectly lining up centered with the hole so i I am printing a new version now that lets the bearing sit in a tad further. The other problem with version 4 was that the filament would go through tightly and great with no PTFE tube but it was too tight with the tube in there.

My current and hopefully working version ( fingers crossed ) I moved the main filament hole over 1mm.

I wont be able to test printing until Monday. because i don't have any PTFE tube left other than a tiny peice.


Will need one of these now too, because the new extruder doesn't have mount holes






getting the grove cut in the PTFE is is as easy as running a 8mm drill bit through I didn't have one but 5/16" worked.

If this whole project ends up not working at least i have a cool Jig now to moon cut PTFE tubes lol

 

Well test #5 didn't work. moving the hole over 1mm "duh" made it so the PTFE tube didn't get cut all the way through...so that wont work.

This may not be possible with 1.75 filament... i'm trying test #6 now with .5mm over. If that doesn't work I may have to go with Lulzbots old version that had an adjustment screw on the side.

OR maybe try setting it up so it doesn't need PTFE.. but im not sure what would happen once it entered the E3D if there is no PTFE in there? Probably chaos with flexibles..im guessing.

 

Hahaha oops. 6 down. I think i have been miss measuring in MOI...I have my Rep2 thats printing the parts while the robo is just hanging out

 

Thanks waldo, yea i have done all of that .. I thought i had it right but i measured my latest with calipers and I must have moved it 2mm over on accident.

anyway I'll figure it out. It probably really is not helping that I'm usually a few beers deep when trying to mod files at night lol.

I'm drawing it all out on paper this time so I do it right. At least all my failed prints are on a $15 spool of JustPLA i got awhile ago on sale on amazon.

 

Yea I did that originally and there isn't enough room to feed anything through even with no PTFE tube.. I'm pretty sure im just screwing up my math...which is funny because I have a BS in math lol. I will get it..eventually lol.

I'm basically starting over.. plugging the original holes for the PTFE and the bottom, and measuring correctly this time.

EDIT:
Ok I started over and I'm more confident this time.I quit trying to mess with the center of the original file, and plugged and filled the original model and calculated how it should work myself this time, rather than printing moving printing moving...etc.
I put some guide lines in my model that go from the actual hobb bolt center to the top.
the calculation on how far to offset should be this

Eqation: (halfHobbDiameter) + ( half filament diameter ) - fudgeValue

In my case my hobb bolt at its cutout smallest centerpoint is 7.5mm

Printing again but this time with really low infil so i can test.

Note this screenshot is for a test with NO PTFE..( I don't have anymore right now so until it gets here im goint to try with a 2.2mm hole and a cutout in the base for a tiny bit of ptfe for the e3d)...but the new guidelines from the real center of the hobb bolt helps

 

On a completely unrelated topic. Does fusion let you name anything? with a object list? thats the main thing I HATE about 123D is I cannot name objects or lines or whatever in a list. Moment of Inspiration lets me do it and so thats why I use it. It was worth the money for me.

Oh yea LOLZ fails.... good thing its $15-16 JustPLA I got on sale on amazon.

 

Yes you did exactly what I have done like 7 times already lol. I have the correct sized hole, for 4mm PTFE tube and 1.75 filament.

The problem i'm running into is that in reality the tolerances for the hobb bolt to grab it I Think are just too small for it to work.. there is more wiggle room if using 3mm filament. Not sure i'm describing the problem very well..just trust me.

 

Probably. I might try that version today.

 

Printing another test now .

I'm determined to make it work somehow/someway, just not sure how that is quite yet.

 

So I just about got this working. My issue now is that my Hobbed bolt is uneven. one side of it has a deep grove but the other side has almost no groove..so basically the filament is tight then loose then tight then loose as the bolt spins.

Not sure what to do about that other than order a new/better Hobbed bolt.

 

I'd go for one like the Hobb Goblin that has precision cut grooves. http://www.filastruder.com/collecti...ies/products/hobb-goblin-8mm-hobbed-shaft-kit

 

Thank you that looks perfect, just ordered one. I like that its adjustable.

Pretty confident this will end up working out. my last test i was able to feed ninjaflex or pla through by turning the gear by hand ( hot end was off though ).. It would slip on the deep side of my hobbed bolt though.. new hobbed bolt i think will make it all work out. Although I will probably have to re-adjust my filament hole offset again..with some test prints.

 

I may have to ditch the PTFE tube altogether, other than maybe a small piece from the E3D into the bottom of the extruder.

I haven't been able to get the tolerances right while using PTFE tubing. The general problem is in order to get it in the right place when I go to drill it out(cutting the moon shape) it doesn't go all the way through the PTFE. And if I move it further so that the PTFE does get a full cutout/opening in it..its then too tight on the hobbed bolt. Kinda an annoying chore to get this setup.

However I can get it to work if i just print with ~2.2mm hole and feed the filament directly..that seems to work.