[Cura beta 4.1 bondtech um3]

19 minutes ago, pdzamore said:

Are you planning to use exclusively 1.75 mm filament? Why not just convert everything and use a 1.75 mm Bondtech extruder? For many years I had a Fusion3D printer with dual 1.75 mm hot ends and matched 1.75mm Bondtech QR extruders. 

I stil have quite a bit of 2.85 mm filament, but yes I am considering to switch completely to 1.75 mm. Found the Bondtech feeder as part of the Ultimaker QR 3 Upgrade kit... so I didn't realise there was also a 1.75 mm version. I will think about it.

[UM3 Feeder limitations on print resolution]

On 6/13/2019 at 5:46 PM, gr5 said:

3dsolex also has a 0.15mm nozzle and 0.1mm nozzle for that conversion core.  I sell this stuff too.

 

The existing UM3 feeder works fine for 1.75mm filament.

Smaller nozzles might indeed be very helpful to increase precision, but it doesn't solve the issue with my feeder (minimum extrusion volume). 🤔

Or would you recommend switching to 1.75mm filament when printing with smaller nozzles.

[UM3 Feeder limitations on print resolution]

On 6/14/2019 at 1:32 AM, johnse said:

Doesn’t retraction also play into this? If you print a shorter line than one step’s worth of feed, it will retract at the end of the feature.

 

Could you explain that in some more detail, it sounds interesting. If I understood your point, the printer will retract the filament by one step if the line printed requires less filament than one feeder's step to prevent excess material on the print plate/object.

 

Let's say I want to print two separate lines, each of them requiring an amount of material that is just 50% of the minimum feeder' step. For printing the first line the filament is moved by one step. Supposing I print at a speed that exceeds the rate at which the material flows out of the nozzle (what would that be aprox?), I can stop printing by retracting the filament by one step at the end of the line. This step's material is then only used by half, so for the next line, one step will just extrude the other half of the volume that is left in this step. Did I get the principle right?

 

It might work like this in theory, but doesn't the print cores have some internal volume of melted filament within them whicht might affect such extrusion of such tiny bits of material?

[experience with Bondtech QR 3.0 feeder on Ultimaker 3]

I am considering changing the original feeder on my Ultimaker 3 printer to a third-party Bondtech QR 3.0 feeder. At the first glance, it doesn't seem to make a huge difference regarding its precision (369 steps/mm original, 492 steps/mm Bondtech). I have heard though, that the Bondtech feeder works a lot better with stiffer filaments (e.g carbon fibre added filament).

 

Would anyone be willing to share their experience with the Bondtech QR 3 feeder on a Ultimaker 3?

 

Does anyone use the Bondtech feeder with 1.75 mm filament? I knwo it's designed for 2.85mm, but I have heard the original feeder can deal with 1.75mm filament, so I might do both modifications at once.

[Cura beta 4.1 bondtech um3]

On 5/23/2019 at 1:41 PM, pdzamore said:

(1) I print mainly carbon- and glass-fiber reinforced materials. 

(2) with the Bondtech, I can print Ninjaflex and other flexible filaments at reasonable speeds. 

 

And even with the improvements to the Ultimaker extruders, the Bondtech QRs are still much better. 

You're using 2.85mm filament, right? I am considering switching to Bondetech 3.0 but would like to print with 1.75mm filament and I'm not quite sure if it works. The original feeder seems to work with 1.75mm filament (thinner tubes provided...).

[UM3 Feeder limitations on print resolution]

22 hours ago, gr5 said:

However the actual value on the UM3 I think is 369 steps/mm (according to some json file in the firmware I just checked). 

 

 Your math seems pretty good but the effective diameter of the feeder sleeve is probably closer to 8.7mm which makes your formula work out.

 

Anyway, 16 microsteps is about right - that's the same value used for X,Y and E for UMO,UM2,UM2+ and the Z drive for some of those is 16 microsteps and for some it's 8 microsteps.

That's good to know, thanks for your help! Both the microsteps and s slightly smaller feeder sleeve diameter make sense. As the feeder sleeve has some sort of bumps on its surface (probably to increase grip) I might have measured the outer diameter (including the bumps) rather than the actual diameter of the feeder sleeve.

 

With 369 steps/mm, the 250 Mikron nozzle and a layer height of 60 Microns I would get a single line minimun printing lenght of ((2.85mm/2)^2*3.1416) * (1mm/369steps) / 0.250mm / 0.06mm = 1.15 mm per step

That seems a lot more realisitc than the 20mm I calculated in the first place and might fit the detailness of your model prints. I was hoping to create even smaller structures, but probably that's how it is 🤔 I will print some more test lines...

[UM3 Feeder limitations on print resolution]

Does anyone have any experience regarding the minimum resolution I can print with? Any help or ideas shared are highly appreciated 🙂

 

According to the UM3 manual, the layer resolution is:

Quote

 

0.25 mm nozzle: 150 – 60 Mikron

0.40 mm nozzle: 200 – 20 Mikron

0.80 mm nozzle: 600 – 20 Mikron

 

 

Thus, I expected the minimum printing resolution to be x: 0.25mm; y: 0.25mm; z: 0.06mm However I'm not getting good results for my fine structures.

 

I then had a look at the Ultimaker 3 feeder:

• Moons 17HD6482_01N stepper motor (200 steps/round)
  • powering a 11-tooth gear
• Transmission to a 36-tooth gear
  • powering 10mm diameter feeder wheel

These characteristics lead to a minimum filament feed lenght of: 1/200*11/36*10mm*3.1416 = 0.048mm / step

For the 2.85mm diameter filament, I thus assume a minimum extrusion volume of 0.048mm*(2.85mm/2)^2*3.1416 = 0.306mm³ per feeder step.

For a line printed with the 250 Mikron nozzle and 60 Mikron layer height I get a single line minimun printing lenght of 0.306/0.250mm/0.06mm = 20.4mm per feeder step

This value seems quite high I think. Am I really limited to print such long lines when it comes to a small printing layer hight? Is there maybe an errror in my calculations and assumptions?

 

Does anyone have any experience what happens when the amount of required material for a structure is below the minimun volume to be extruded by one feeder step? (e.g. printing a single line, 5mm long, 60 Mikrons layer height, 0.25mm nozzle)

I have the impression that in this case, the feeder stays still and the print core moves along the printing path, but doesn't extrude/print significant amount of matrial. However, I couldn't confirm my suspicion so far. Probalby I need to check my printed structures under a better microscope to measure width and hight of my line/layer.