#SaintFlint It’s either feast or famine. I destroyed 7 or 8 flint wheels, meant to get back to it with the bowden on the other side, then saw @Michael_Memeteau playing with RC gears…bought a $3.25 17 tooth steel gear, fired everything up, and the 5 pack of MK7 gears showed up. (The ones I ordered for $15, shipped, in a drunken rage)
So it’s roughly the same amount of money as a couple of Bic lighters, you’re just not throwing away 99% of the Bic lighter.
I think the saintflint extruder, much like diesel motors, will end up being one of those designs that just runs on anything.
Gotta try that…I got away from Bowden due to the precision of the retract…seems like I get better prints with a direct drive. Does this type of extruder help that?
Quality of the bowden counts for some. I’ve had ‘PTFE’ and I’ve had PTFE that was REALLY slippery. I’ve got no problems printing hair-free prints. This particular design is dirtcheap and prints really easily. You’re looking at $12 for the motor, $2 for 608 bearings, some PTFE tubing, 2 cap-screws, a couple of nuts for the bowden and mid-tube, and whatever you come up with for the driven wheel.
Mike we don’t undestand…why you destroy flint…shauki have 9 printer in 2 year with it and @Michael_Memeteau same without isssue i restart print soon (currently i print with #bicdrive 1h with old #flintfeeder and with saint make only dry test.) but we work for find alternative more solid.
@Mike_Miller Apparently, you have the loop not on the threaded side. Any reason for that? (Not that it won’t work, but I find generally that makes it easier to load and not to forget the ring that you would have to pass into the bowden). Which version it is? It look like you could use a larger one.
I started to invent a nomenclature and it goes like this:
08-42-175-608
Where:
08 - Diameter of the hobbed wheel/flint/whatever
42 - Size of the step motor (NEMA 17 => 42 / NEMA 14 => 35)
175 - Filament diameter (Either 175 or 300. 300 is in the work but is more tricky as the space available for the larger nuts is requiring some non-straight inner routing, ouch!)
608 - Bearing used (625 or 608. NEMA 14 only works with 625).
It looks like you need a 09-42-175-608 or something?
@Mauro_Manco My experience with the bic flint wasn’t totally spotless. I have a collection of lighter now (and I’m no smoker). I really think that I struck gold when I’ve got it right but it took some encouragement from both you and @shauki . Having the coil constrained axially and glued with epoxy is no stranger to the flawless operation now, but getting there takes some grit (again, not your mother’s extruder!). Like you said, we’re still looking for a simpler alternative.
@Michael_Memeteau , man that’s just BEGGING for a single OpenScad file with the dimensions as variables…honestly, I figured the Bowden side needed more support due to the forces, I’ll turn everything around.
That may be a little too tricky to get this level of details with OpenSCAD (I’ve discussed this already with someone else recently). My current setup isn’t bad for this kind of work: Onshape. It’s a browser enabled CAD system that works like Github for versioning. You can work on two separate version and merge them together. The problem here is more complex as the geometry is heavily influenced by the option (i.e. 608 won’t fit into a NEMA14 or the nuts that comes associated with a 3mm bowden are too close to each other to allow a straight path). To make it short: it’s not the ideal candidate for OpenSCAD…
Which kind of support you’re speaking about for the bowden? The line are getting out on the side? Mine is totally quiet and fixed.
Oh, I haven’t seen ANY issues with #saintflint bowden retention. I was just looking at two pieces with different length slots and figured the longer ones held the bowden as it would be the point with the highest stresses (retract, cold-pull, etc.)
Not really, it’s just a question of packaging all in a compact format, that what prevented me to it symmetric. On one side, you have regular pulling which relatively low speed but a mode in which most of the time is spent. On the other side, retraction is more aggressive (in particular with a long bowden tube). If you want more support on the more aggressive side (that would be, for me, the exit of the loop) and if it’s not compatible with your current step direction, you could print it again mirrored.
Really looking forward to trying this out (printing for a MK8). It looks like it’s really important to keep the filament through the PTFE loop in tension, or at least with minimal play? Love the use of a cable tie for pressure
@George_Kidd The tension in the loop will build-up automatically. The first pass will actually pull more filament than the second if it’s left unconstrained by the PTFE (not much but enough to be visible after a minute or even less, just remove the loop and try it by yourself! The retraction is too short to actually reverse the situation so, all is good). This is also what gets us to avoid a SPOF (Single Point Of Failure): If for any reason the grip is lost “locally” on one of the pass of the filament, the other should be able to take over until the balance is recovered. If not, there’s probably something wrong somewhere else in the system and it’s not good anyway. Does it make sense?
