Pressure Advance impossible with Flex3Drive?

KeithW

Hi,

After recently updating my firmware I kind of caught the bug again and decided to get my printer calibrated as best it can be. I have everything working pretty well now but when trying to calibrate the pressure advance, no matter what I do the results always look the same. I have tried the various PA test available in Orca Slicer but as you can see there is no variation in the tests.

Line Test

Pattern Test

Tower Test

What I have noticed is as the PA setting changes the Print slows down significantly. I have read elsewhere that a low e-jerk setting will cause this if pressure advance is enabled. Now, I use a Flex3Drive and so the e-jerk setting is recommended at 0.1mm/sec, I assume this is due to the gear ratio and the parts being unable to handle anything higher?

Does this mean using Pressure Advance is impossible with a Flex3Drive?

oliof

PA will be difficult on a remote extruder because of windup in the flexshaft driving the wormgear. I would suggest switching to a NEMA8 direct on the Flex3Drive or moving to one of the sub 130g extruders using the round NEMA14s.

Personally I think flexshaft remote extruders are somewhat of a dead end because the expectations of extruders have changed and direct extruders have become so light. If you want to replace with a sub 100g extruder, look into VDE-100.

KeithW

@oliof

Thanks, This is on a Delta Printer with a smart effector. Can you suggest a suitable extruder for this?

oliof

@KeithW VDE-100 would be quite good choice (but you would need to get ahold of a suitable hollow shaft extruder); there are adapters for Orbiter2; Sherpa micro and Sailfin would be a bit smaller and lighter.

KeithW

@oliof

Thanks, I had not seen this type of extruder before, Will need to look into how to adapt it to the smart effector.

KeithW

I have been looking into direct drive extruders which will fit on the smart effector, It seems there aren't many and none are ideal. I really don't like the way the VDE-100 works, the Sherpa Mini/Micro and the Sailfin are interesting but I wonder what experience others have had?

Any more recommendations or suggestions?

oliof

@KeithW I've been running the Sherpa Mini with great success on my bedslinger IDEX. The micro is even lighter, but I had no incentive to swap.

o_lampe

@KeithW I'm running a beefed up sherpa mini on my selfmade Delta effector. The hotend needs an 8mm offset to make it fit between the rods.

There are tilting adapters for other extruders to make them fit on a regular SmartEffector, but they end up being top heavy.
That's why we started to tinker with hollow shaft motors. The VDE-100 is only one option.
There is also the "screwder" which uses orbital rollers instead of flanged bearings.

KeithW

@o_lampe

Thanks, I was hoping someone with a working solution for the smart effector would chime in. What problems does the top heaviness from mounting the extruder on the tilting adapters cause? Do you not experience that with your self made effector? The only mention of a Screwder I can find is your post that I am replying to, do you have any links for that?

o_lampe

@KeithW I had plans to redesign the sherpa mini in such way that the stepper motor sits below the 50 teeth gear (not above).
That would lower the COG but extend the length between filament gears and hotend. It's a pest or cholera decision...

The tilting adapters would raise the sherpa/orbiter even more.
Maybe a combination of both is the golden way?
I hate doing CAD, so I won't try it until I had to.

The Scewder runs on a BLDC motor, that's why it isn't very popular.
I had to add a step/dir interface and a simpleFOC compatible driver to make it work with RRF.
But the BLDC motor is worth it.
The rollers are available at alixprss