PTFE Sculpting for Tight Fit on BNBSX
Here are more details of how sculpted PTFE tips for the BNBSX are created with the sculpting guide. Results in more constrained filament path for flex filaments.
Chamfering tool is used like a pencil sharpener to create 60 degree chamfer at bottom end of PTFE if E3D hot end. For Mosquito, the bottom end is simply left 90 degree flat cut.
"Bottom" end of PTFE is positioned against end of trough in Sculpting guide.
M3 bolts and nuts clamp PTFE in sculpting guide. PTFE support plug is inserted with its flat side against uncut PTFE tube.
RE: PTFE Sculpting for Tight Fit on BNBSX
Although you can sculpt the PTFE with a #11 hobby knife, a much cleaner result is possible with a sharpened 8 mm pipe. Bunnies created one from a 8 mm OD stainless steel tube from Amazon https://www.amazon.com/gp/product/B07KK35MNY
The INSIDE of one end was beveled with a Dremel conical stone and then sharpened with a diamond needle file. After outer burr was removed the cutting pipe was ready.
Hand drill at medium speed easily cuts bite from PTFE. Spin and cutting direction are such that PTFE is drive towards into rather than out of sculpting guide.
After 1st bit is cut, PTFE support plug is moved to opposite hole. Round end of support now fits into new cut bite. If support plug is loose, wrapping some scotch tape around it to tighten.
RE: PTFE Sculpting for Tight Fit on BNBSX
Sculpting guide creates correct length PTFE for BNBSX extruder with either E3D V6 or Slice Mosquito.
Completed bites here are for the E3D. If Slice Mosquito, the other two guide holes would have been used.
Cutting pipe tool creates nicely sculpted bites.
Form tips by cutting across center of isthmus to form 45 inner bevel.
RE: PTFE Sculpting for Tight Fit on BNBSX
Debur PTFE with small drill bit hand rotating in REVERSE.
PTFE installed in E3D V6. With BNBSX extruder, only the motor plate and top cover need to be removed to replace the PTFE. No need to remove fans or hot end cover.
Tips of PTFE are rotated to fit between Bondtechs.
Lateral view showing filament going between PTFE tips
BNBSX PTFE sculpting guide is at https://www.thingiverse.com/thing:3819794. Be sure you get the B2 version files. Those are sized to accept the 8 mm cutting tube tool.
With sculpted PTFE tips, the BNBSX can successfully extrude TPU even with door idler tension set tight.
RE: PTFE Sculpting for Tight Fit on BNBSX
Woah, that's neat!.
I see you got your Capricorn XS as well. 😀
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: PTFE Sculpting for Tight Fit on BNBSX
Are you posting these in a Bear Wiki somewhere?
This is a great guide, but by the time I need it - it will have aged into oblivion...
RE: PTFE Sculpting for Tight Fit on BNBSX
It will probably end up in my GitHub after I figure out the dimensions for also doing it for the MK3, MK3S, and Short Ears extruders.
RE: PTFE Sculpting for Tight Fit on BNBSX
Added PTFE sculpting guides to Thingiverse for...
Prusa MK3S stock R4 or R5 (1 mm longer PTFE than BNBSX)
BNB Short Ears MK3 (5.5 mm longer PTFE than BNBSX)
Now one should be able to sculpt tight fit PTFE tubes for the above in addition to the BNBSX
I don't think Prusa MK3 stock is suitable for this mod due to high stress on PTFE during hot end insertion
BTW BNBSX is being revised to better constrain above Bondtechs and improve support of sculpted PTFE tips. Needs some testing but anticipate STLs available in a few days.
RE: PTFE Sculpting for Tight Fit on BNBSX
Sorry link for Thingiverse got broken. Should be at https://www.thingiverse.com/thing:3819794
RE: PTFE Sculpting for Tight Fit on BNBSX
Sneak peak of how much tighter PTFE and filament guide tips are in upcoming BNBSX rev Bo8.
Thus far tested in PETG. Now verifying will print properly in polycarb.
RE: PTFE Sculpting for Tight Fit on BNBSX
Sculpted tips are definitely not just for BNBSX extruders.
Bunny scientists now have PTFE sculpting guides for....
Bunny Science
- BNBSX MK3S Short Ears Extruder
- BNB Short Ears MK3
- Bunny and Bear Geared MK3 Extruder
Original Prusa Stock Extruders
- MK3S (R4 and R5)
- MK3 (R3)
There is a comment from a MK2.5 owner who was stuck with Ninja flex at 50% speed (Prusa profile). Any faster and filament would coil up under the Bondtechs. After adding sculpted PTFE tips, he can now print Ninja flex at 100% speed.
RE: PTFE Sculpting for Tight Fit on BNBSX
Thanks for sharing. This is absolutely great!
RE: PTFE Sculpting for Tight Fit on BNBSX
Thanks Guy, I have all the parts printed for the Bunny & Bear geared extruder already and was waiting till I had to do a rebuild with new rods and bearings to do everything at the same time so I'll do this at that time.
Going to fit connectors into all the wiring at the same time to make future changes easier.
Tree Frog in Ninja Flex on BNBSX, 1st attempt
Got some Ninja flex to try myself. This is my first print with it on the BNBSX. It is far from having settings and speed tuned, but already you can see soft, Ninja filament is successfully handled. Idler door tension has been reduced to about 1/2 usual to better match the filament. PEI print bed is coated with Elmers Ultra glue stick as a releasing agent.
Version B08 onward of BNBSX features has more constrained filament path and pairs well with highly sculpted PTFE tubing. Ninja Flex is printing here at 220C nozzle, 45C bed, 15 mm/sec.
Ninja Flex 1st attempt, part 2
A bit further along. Overhangs are horrible. Definitely need better filament settings.
RE: PTFE Sculpting for Tight Fit on BNBSX
Ninja Flex tree frog attempt number 2
This time at 225C nozzle, 50C Bed and 10 mm/sec. Retractions minimized. Getting much better overhangs.