Returned on working in the Mendel

And here I am again.
I've gone in trying with a 3mm filament and changing extruder. Took a maker bot one with the wade adaptor this time, and mounting gone more smoothly than last time.

Now, I'm not sure what the issue may be, maybe the extruder hole is too tight?
This filament is bigger so i guess it takes even slightly more to liquefy, but also pushed down harder... at least i guess the hobbed screw is working better on a wider one.

Explaining video: [www.youtube.com]

It seems that even in the end of the nozzle in certain moments the filament just won't come out...
Yet tho i'm not entirely sure on what is the issue.
I've read somewhere, maybe in the wiki, that the barrier of the hot end could be drilled to enlarge the 3mm hole... but since it is an irreversible operation, wanted to hear opinions first?

It appears to be feeding too fast, or trying to. Current setting on stepper driver is too low causing it to loose steps. Possibly temperature is too low. It doesn't appear to be slipping, common when the hobbed teeth fill up with plastic and normally the result of any blockage. The nozzle doesn't appear to be plugged.

Right off the bat, I can see that there is a problem with your extruder motor. The problem is most likely one of the following.

1. Stepper motor current is set too low (Most likely)
2. ...too high
3. Hobbed bolt is slipping (not very likely)

Strange though cause iv'e tried in both configurations with the potentiometer (is it called like that?) that sets voltage on the motor from the board (using a gen6). And the result was the same.
I believe there could something actually obstructing or either not moving inside... but can't detect from assembled, and can't guess from disassembled.

I don't think either the bolt is slipping cause I'm hearing the distinctive 'stunks' it makes...

Could it be that, using an adapter for the wade extruder, the nozzle is slightly unaligned with the upper part?
Hard to watch from above closely though...

The way the big wheel is shaking in the video is the indicator that the motor is not getting enough current. Maybe you need to re-crimp the wires going to the motor.

Inside the stepper motor two of the wires are paired in a coil, and make a complete circuit. If you turn the motor by hand, and while doing so, touch a(+) and a(-), you will notice that the motor becomes a little harder to turn. The same for b(+) and b(-). Connecting any a to b should have no effect. If this is not the case, then there is and open wire.

Mhh... set the target temperature to 200C...
Trimmed the screw-resistance up even *more*... it seems to have enough force now... but also getting warm/hot, the motor...

The extruder motor should be hot, but not so much that you can't hold it for more than five seconds without pain.

Extruder motors can run very hot without having issues. Our extruder motors all run between 65 and 75 degrees quite happily. PLA extruder blocks on the other hand, don't like it that much.

Before you go cranking up the power too much, you have some mechanical issues that should be resolved.

First and foremost, The big gear is backwards on the bolt. It should be mounted like this.

Alternate Hobbed Bolt Installation

As the picture shows the bolt is......

raffaelesWades.jpg

Assembled properly the shaft will be much easier to turn.

Also, I didn't see any springs on your idler block in the video and running without springs leaves a very fine line between tight enough and too tight. (The 1.75 filament in the picture looks really squished to me). With 3mm filament, too tight can widen it enough to make it very hard to push through the tube.

Edited 1 time(s). Last edit at 12/19/2011 09:42PM by Bruce.

Mhhh. I guess trying the springs would be the next move then.
About the bolt too tight, that was an error at first mouting and then just remained... another thing I'll do is printing a new extruder set of plastics, of course, along other pieces that are breaking around (still too tight screwing)...

Now though that I've adjusted with the adapting kit it seems to have improved a little.
And also found the right tightness without squishing the filament, it seems...

As long as I can at least print few adapting parts, without ordering more stuff again (I've been trying and ordering stuff quite for a while now, started building Mendel in March/April AFAIR... so want to avoid it now).

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Curiosity: What does it change about the gear reversed? If it's tight anyway, doesn't it give the same rotation to the bolt anyway?
Or is it because it could touch the extruder itself?

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Now I've got decent spitting of it anyway somehow... just having issues finding a sticking surface...
Interesting enough, when i tried printing it on actual paper (drawing heavy paper, rough type) it sticks pretty well...

As long as it's working, I would print as much as I could. I didn't want to comment on the quality of the parts, but by the look of the extruder block, I would say the rest of the parts would probably break fairly easily.

If you have problems finding springs you can also use thick rubber washers. I took the rubber seals from some old roofing screws that I just happened to have. They work great.

The main problem with the gear being reversed and the bolt being too tight, and I can't really tell from the picture, but if you put the washer against the bearing it will gradually grind the seal away and ruin the bearing. And of course, if anything is rubbing it will be harder to turn. Mounted properly the first jam nut sits beside the bearing, the contact surface is small enough that it can ride on the inner race of the bearing without rubbing against the seal.

Reversed the gear...
And returned to printing tests.

Did anyone actually try to print on paper? It seems quite good to me when it comes to sticking (on this type of paper at least). And also removing isn't very difficult, as long as you use foundation layers.

This is a test of foundation layers I made:
[lh5.googleusercontent.com]

Now it seems though that the flat panel isn't really flat... But it's slightly sinked in the center (I sat this while it was printing)... maybe i'll try with another flat rigid surface over and *then* using paper again.

I also tried with tape, dunno if it's the right one cause didn't find the blue type, but it says it's made to be painted on. Though it sticks too randomly there.

I also read that glass is a good way, but that needs to be heated right? Don't have a heating bed system though.


Edit:

On a second test I noticed that there is still my first problem:
When the extruder has to stop a line and begin another, it makes that 'rollback' movement. Rolling the filament up, for re-injecting it after for starting a new line. The new reinjection is though too much, and it creates a bubble 'point', that tends to make it stuck when it passes over it afterwards, and then reattaching to it, and carrying around all the printed piece...

I was wondering if there is a parameter to say that, ie. how much rotation to give when re-injecting...
[lh4.googleusercontent.com]
[lh6.googleusercontent.com]

Edited 3 time(s). Last edit at 07/31/2011 05:18AM by raffaele.ragni.