Ultimaker2 Feeder System - Improvements and Ideas

[flashp0int 0]

@EldRick: I designed a slightly longer Yoke (0.8 mm). Happy to send you the STL if you want it. The original was working, except with PET and Nylon. That's why designed it.

It is pretty much the only change.

I might create one that is maybe 0.4-0.5 mm longer, because the new one results in inconsistent experience with NinjaFlex or FlexPLA (the original Yoke was better).

I have the spool under the table, but the filament moves fine through the feeder.

But after a lot of checks, my E-Step value is definitely 300.

So starting to wonder if our MK-8 are really the same :???:

 

[Blizz 53]

300 for an MK8? Seems a tad low to me.

I've had it set to 365 when I was using it (temporarily reverted back to the stock gear for now).

The value for the original one is 282.

 

[flashp0int 0]

300 for an MK8? Seems a tad low to me.

I've had it set to 365 when I was using it (temporarily reverted back to the stock gear for now).

The value for the original one is 282.

 

Well, in order to extrude the right amount of filament E-Step need to be 300. Really tested this extensively with Pronterface.

But I agreed that the value difference is weird. Therefore I am wondering if my MK-? has different specs.

I recall I ordered mine from a RepRap shop in Denmark, would need to check the invoice to be sure.

 

[Blizz 53]

Not saying you are wrong or whatever, I just used the value that was mentioned here in the forum and the prints seemed okay to me.

What I find weird is that the difference between your value and the stock value is so low. If you measure the gear diameters the MK8 is about a mm smaller than the stock one. Logic screams to me that it should be a bigger difference.

 

[eldrick 65]

@Flashp0int

The issue I'm contemplating isn't just a longer yoke - seems to me that the holes at the top and bottom of the body need to be moved over to accommodate the smaller-diameter hobbed Mk8, to avoid bending the filament on the way through.

 

[Blizz 53]

EldRick that is the reason that I went back to the old wheel.

I also had the impression it was bending the filament with the MK8. I'm not really a modelling wiz so I just went back to the previous stable situation.

 

[IRobertI 520]

If you let me know how far the holes need to move I might fix it. Depending on how much of a pain it is to do (lots of curves that depend on each other...).

 

[Blizz 53]

The diameter difference between the original wheel and the MK8 is about a mm (but I'd have to remove the original again for a precise measurement). So in theory everything would have to move + 0.5mm

 

[IRobertI 520]

0.5mm surely can't make much of a difference? I thought it was something like 2mm difference or something from the way it sounded. Hell, I'm sure you could move the thing that much just by loosening the screws and pushing it to one side as there's a bit of slop in the mounting holes.

 

[flashp0int 0]

On the original one, if I nearly fully loose the screw, it works with PLA and FlexPLA. But PET and Nylon did not.

With the 0.8 mm longer yoke, i sort of fixed that. The difference is really small, but I could not loosen the screw more at that stage.

I'll measure exactly the wheel.

 

[Blizz 53]

Robert, I think the problem for me personally is mainly the yoke.

I probably have to try that longer yoke.

I have to tighten it to the limit to with the MK8

 

[3poro 9]

If you let me know how far the holes need to move I might fix it. Depending on how much of a pain it is to do (lots of curves that depend on each other...).

 

My original knurled wheel has diameter of 7.95mm and the MK8 I ordered has precisely 1.00mm less. I don't know if PLA in warm environment under tension bends that much over time, but I have had to improvise some tightening for your feeder design twice to keep it in operation. Nothing serious.

I haven't yet taken the MK8 into use, as I noticed it would require some (minor) modding of the feeder again - and I'm now running tests with new temperature sensor.

 

[rcexplorer 0]

I'm aslo running the MK8 Wheel and Roberts Feeder.

I had to sand the back of the feeder to get the yoke to push properly on the wheel.

I can also confirm that the filament is being bent in order to contact the MK8 wheel, even with the stepper motor pushed all the way to the left.

I would love the holes to be moved 1 to 1.5mm

Other than that the feeder works beautifully. I'm printing ABS exclusively and have the screw on the spring cranked almost to the bottom to get it to grip properly. But I've printed a whole spool of 1kg ABS without to much trouble.

It would be great though if the holes where moved a little and maybe tad longer yoke to increase the pressure on the filament.

Awesome job Robert! Keep it up.

 

[rcexplorer 0]

Here are two pics of the feeder with the MK8 wheel:

 

[donmilne 2]

What are people making Robert's feeder out of? I've used standard Ultimaker PLA (white), but I'm concerned by reports I've read around here that PLA will sag when kept under constant load.

 

[Blizz 53]

PLA.. But no issues here so far. I broke the arm on my first one, but since Robert modified the model to print the arm in the other direction things are fine. I did print a second copy of everything as a spare, but that's just because I like having spare parts, not because I'm expecting it will break

 

[donmilne 2]

Hmm. Spare parts... Good idea! I guess it's no good waiting until the feeder breaks before trying to print replacements. :smile:

(Seriously: I still have the original feeder as a fallback, but all we know how awkward that is to fit).

I might try making the spare copy out of XT though.

 

[ultiarjan 1,223]

Think it can be good to use xt for most parts but I would not use it for parts touching the fillament...like the body.. if you get some wear you'll get particals with a higher melting point than pla in you nozzle potentially causing clogging at lower temps.

[donmilne 2]

Good point. Thanks. Robert needs to do a version of his feeder with his dust wiper widget built into the top side.

 

[ultiarjan 1,223]

Back from holiday ... finally published my "Ultimaker2 rail system" as presented on page 33 ....

You'll find evererything here:

https://www.youmagine.com/designs/ultimaker2-rail-system-u2rs

https://www.youmagine.com/designs/compact-low-friction-spool-holder

Have not done any serious testing on the best possible position for feeder and spool holder, but the test report published by Bas shows the friction caused by the bowden tube is significant .... optimisation of the spool & feeder location seems very usefull...

 

[Nicolinux 288]

Very nice rail system. I also like the idea that it is reversible (i.e. only the feeder motor needs to be spliced out of the main cable holder). Now it looks way less scarry than the first prototype

I don't have the acute necessity for such a mod, but I'll keep it in mind if the need arises.

Maybe incorporating a loose spool holder might be a good idea too. Martin's spool holder is especially nice and fits on the default spool holder (you could augment your rail system to fit his spool holder):

• https://www.youmagine.com/designs/loose-filament-holder-v3
  

[ultiarjan 1,223]

I did not see that loose fillament holder before, thanks for the tip, will be usefull...

I was also thinking to create some sort of "breakout box" on the back of the UM with the 2 feeder motor connectors.

Would it be ok to add an "extension cord" of +/- 30 cm on the feeder motor cable ? I would use the original connectors ... (conrad has them).

 

[Nicolinux 288]

I think that's pretty easy to come by. I would do it (if I am implementing the mod).

 

[korneel 176]

I just printed the rail system, Ultiarjan, what did you use to extend the cable? You should be able to add an extension cable, whioch cable did you see at Conrad?

 

[ultiarjan 1,223]

Korneel,

I did not make an extension cable yet, had the components in backorder at Conrad. The motor cable is long enough to place the motor outside.

I'm still planning a few things for the rail system, f.e. an extension cable with a break out box for the 2 motor connections (to be prepared for a dual extruder) & a stronger version of my feeder combined with a mountplate (when you remove the feeder from the original place there's more design freedom to make the parts bigger & stronger)

In the meantime I got the components from conrad, now i just need to find time.....