1 Topic by johnnyh66

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Topic: Extruder problems

Hi, I have not had a sucessfull print with my new SD3.

I was having sticking to the bed problems to start with
but after I changed the filament, that's the least of my problems.

I kept aborting the prints because nothing was sticking and I started to notice that the abs that was coming out was very thin and pink.
I had replaced the stock red with white.

Today I finally drew a sharpie line on the filament and realized it wasn't really moving.
So I tightened down the pressure screw on the wheel drive and the filament started bunching up in the print head.

So I stopped the printer. Removed the filament and cut a clean section then fed it back into the extruder.
That seemed to fix the problem but then I noticed that it seemed to be skipping.

I decided to let it go and at one point my print bed went to high or something because the head dug into the bead and tore the plastic off the the top.

A great deal of pressure was put on the extruder head and I think it might be bent.
Maybe it was like that before, I can't really say.


For my first problem, Is my extruder head clogged?
Is there a way to clean it?


I'll get some pics when my cell phone charges.

Any help would be appreciated... I'm having a very bad time with the SD3.

2 Reply by johnnyh66

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Re: Extruder problems

ok, I just tried another run and the head dragged across the bed!

I made one change, I tightened the Z Screw down further and the bed came higher... isn't that backwards?

3 Reply by pcpoirier

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Re: Extruder problems

make sure the temp is 200

4 Reply by johnnyh66

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Re: Extruder problems

How do I permanently lower my bed?

I just put a big scratch in the film over the bed... down to metal.

5 Reply by ronsii

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Re: Extruder problems

turning the ztab screw CW from the top should lower the bed???



http://wiki.solidoodle.com/first-layers … e-z-offset

6 Reply by johnnyh66

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Re: Extruder problems

that's what I thought but I have it almost all the way down and I swear it's worse.

I just figured out that you can lower the bed with the 3 screws in the face of the bed.
Trying to print again.

7 Reply by ronsii

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Re: Extruder problems

Yes, tightening all the leveling screws will work also.. but there must something else going on if the ztab screw won't do it. when you raise the bed what happens when you activate the ztab switch on the back left side of the bed?

8 Reply by johnnyh66

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Re: Extruder problems

This last one was a little better, the head didn't dig into the bed but it's still too low.
I think that's when the filament is skipping, it's getting smashed into the bed.

Here's the bad part, I have the Z Depth screw and the bed leveling screws all the way down.

I need to adjust it in the software but do not know how.

I have not tried to flip the switch manually but will give it a shot.

9 Reply by ronsii

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Re: Extruder problems

Are the switch mounting screws secure and the switch not loose to move up or down?

10 Reply by johnnyh66 (edited by johnnyh66 2013-03-24 22:55:04)

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Re: Extruder problems

Flipping the switch manually did set the bed lower.

My extruder still isn't moving a lot of filament through.
It was at 200 c
It seems that the filament is skipping between the wheels... it makes a sorta popping sound.
I tried tightening and loosening the screw, it does it both ways.

11 Reply by fredhag

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Re: Extruder problems

You may have done the obvious, but check the extruder motor drive gear as a clog will typically cause the drive gear to eat a divot into the filament (you may notice it as the plastic is retracted out of the extruder).  The plastic powder coats the drive gear and lowers its ability to move fresh plastic (even if you retract it and start with a fresh end).  I take a can of compressed air with the little straw and blow out the powder around the gear when that happens.

One theory might be that your z-level was out of whack and the print attempts were too close to the surface such that the back pressure of the plastic back up the nozzle caused the divot.  That would lend some support to the idea that the printer later scraped the surface.

BTW, I occasionally do quick checks of filament being driven by pinching the plastic and seeing if my fingers are drawn toward the extruder.

Cheers,
Fred
Fredrick C. Hagemeister
http://blog.richmond.edu/ti3d

fredhag's Website

12 Reply by johnnyh66

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Re: Extruder problems

I can see buildup on the drive wheel!

Is there a way to back out the filament using the software?
Or, do I unscrew the tension screw and pull it out?

13 Reply by fredhag

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Re: Extruder problems

Yeah, in Repetier, go to the Manual Control tab.  Look down to where you see Speed, Extrude, and Retract.  I set Speed to 200.  For retracting the filament, 50-75 should be enough, but you may need to help the motor along by pulling lightly on the filament (since the drive gear is not very effective at the moment).  Click the upward arrow to have the motor retract the filament.  In general whenever backing out plastic, I loosen the tension and pull out the lever so I can slowly pull out the last of the filament - this is because I notice a couple boluses (bulges) of plastic near the end of the thinned filament, and I've had times where they are ripped off and left in the extruder channel, needing to be carefully fished out.

Cheers,
Fred
Fredrick C. Hagemeister
http://blog.richmond.edu/ti3d

fredhag's Website

14 Reply by johnnyh66

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Re: Extruder problems

I found a longer screw (I build rc trucks) so I;m going to try it again...

15 Reply by johnnyh66

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Re: Extruder problems

ok, I fixed the bed height with the longer screw... but my filament is still skipping.

16 Reply by fredhag

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Re: Extruder problems

I know you already tried loosening the tensioner, but that is normally the thing I would do if I was testing with it extruding in mid-air, and it was still skipping.  Another possibility is trying to extrude too fast and the heater not being able to melt the filament quickly enough. Further down the list is the less likely but more painful possibility that there is an obstruction in the nozzle or the filament is fused with the plastic insert in the hotend.  The latter is very unlikely unless the hotend got too hot - I haven't heard people mentioning that problem unless it went over 220, but it happened to me at 205 with my SD2.  I ordered a new hotend and then disassembled mine and carefully drilled out the filament from the middle of the insert until i got to the nozzle.  I reassembled and was able to begin printing, but I did switch out the hotend with the new one once it arrived a couple months later.

Cheers,
Fred
Fredrick C. Hagemeister
http://blog.richmond.edu/ti3d

fredhag's Website

17 Reply by GoolGaul

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Re: Extruder problems

I've been getting alot of clogs lately...  One thing that helps is an acetone soak for the nozzle.

What most folks do is to remove and disassemble the whole hot end assembly, but I think I found a better way.

I take a shot glass that has a deep recess on the bottom, pour some acetone in, position it under the nozzle, and raise the bed until the nozzle is submerged about a half inch or so in the acetone.

Let it soak for about 20 minutes.  You may need to replace some of the acetone, as it evaporates...

After the the 20 minutes, remove the shotglass, pour any leftover acetone back into the container, and heat up the hot end.

Extrusion at it's finest.

Nonetheless, I will be getting a new hot end soon, as I am tired of losing big prints to small clogs...