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suminvent

Prints well in the front but not in the back of the printer

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Hi guys,

I searched the forum for this feeder problem, but could not find anything that answers my question.

My problem is that the printer prints fine in the first half of the printer, but as soon as i print in the back half of the printer the feeder doesnt seem to push the filament any more.

Someone had this before ?

We changed the nozzle, cleaned the feeder, changed the filament, but no luck.

Any hints ?

Thanks,

Marc

Edited by TheDeugd

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Hi Marc,

Thank you for your post.

It may be because when the printer is printing at the back of the plate the curvature in the bowden tube is stronger compared to the front of the bed.

You could try to reduce the friction to add 1 or 2 drops (not more) of sewing machine oil in your bowden tube.

It always helps to include some images as well :)

 

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Or it could simply be a case of bed leveling being a bit off. Re-check that to make sure that the bed isn't tilted down towards the front. If the bed is too close to the nozzle towards the back of the printer the filament wont be able to squeeze out of the nozzle.

Also it would be helpful to know if you have an original Ultimaker or an Ultimaker2

 

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Yes Sander, it does, at least for me it did. But I was a bit 2 quick as it is an UM2 (and I have ONLY an UM1 :).

I could re-produce, that there were more issues (underextrusion) at the back of the print, especially with retraction ON. I even made pictures :mrgreen: . I can not say it was at the back of the printer but at the back of the print. Also, sometimes it would not extrude well at all. At the end, after replacing the teflon thingy, all works well.

 

Back (orientation was backside of the printer, nogood):

2014 05 03 00.00.26

 

Front (good):

2014 05 03 00.00.12

EDIT:

just saying, does not mean it's the problem described, but might give a clue. Picture might help! :)

AND, picture from the carved out teflon piece (I guess, as it was carved out quite a bit at the end it somehow bent over a bit with the force of the bowden tube?

carved out Hot End Isolator Coupler

 

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@suminvent - please post pictures. What you see as underextrusion could be something else. It could be a fan/temp issue. It could be a bad nozzle (deformed nozzle due to damage). It could be the bent tube. It could be a lot of things. I doubt it's leveling unless it only happens on the bottom layer.

Oil will not make any noticable difference to your print other than allow the material through the tube better. Plastics are made from oil by the way.

To post pictures:

http://umforum.ultimaker.com/index.php?/topic/4525-how-to-upload-an-image-to-the-forum/

 

 

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Damn it. This changes everything.

You didn't say it was only the first layer. That's a leveling issue. I can't tell if the head is too high off the bed or too low but I strongly suspect too high.

It could be you have bent rods or something. In the gantry. Hopefully not.

I know you said you leveled a few times. Here's what I recommend.

1) Assume nothing is wrong with the printer - level one more time but this is 3 point levelling and you don't level for the left rear directly - instead the rear screw and the front right screw control the back rear the most. If the front right screw is too high (too close, too tight on the paper) then the back left will be to loose. So make sure you have the *same amount* of friction on the paper as you slide it in and out. Try printing one more time. Also in Cura set your bottom layer to be .3mm thick (this is the default). There is a homing bug on some machines (will be fixed with software soon). To avoid the homing bug make sure the bed is not all the way down before levelling and again before printing. It needs to be at least 5mm off the bottom position.

2) If that doesn't work - assume (temporarily) that the rods are bent (or the glass?) and test for flatness. Look visually at the printer - does it sit flat on the table or rock on two corners? Look at rods and glass - does it seemed warped or bent? Probably not. To test for flatness more accurately install pronterface:

http://koti.kapsi.fi/~kliment/printrun/

 

Connect computer with pronterface to the UM2. Tell the printer to go to Z=0 position. I think you can do it with the buttons or you can type command:

G0 Z0

Even better go to .1mm up

G0 Z0.1

Then push the head around with your hand to the 4 corners and check leveling with paper. See if there is a "low spot" in the back left corner but *not* a high spot in front right. If there is a low spot *and* a high spot you just didn't level it well enough so rotate those thumbscrews some more and get it perfect.

 

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OK, i leveled it again, and now with a thicker paper.

As you can see, the printing in the back goes better, but you can still see that the density of the printing is getting less, and when it continues to print in the front, the problem continues to get worse.

 

I don't think the problem is competely due to leveling, but of course i can be wrong.

 

Testing with pronterface now.

 

Marc

 

 

 

 

IMG 2657

 

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OK, here are my findings with pronterface:

I put z at 0.2, so the paper could just pass under the nozzle (paper = 160 Gr)

Back

No friction OK No friction

No friction Heavy friction No friction

OK Heavy friction OK

Front

What i can decuce here is that the bed is not ok but slightly curved !

If its ok on one position, its not on another position.

I rotated the glass plate on its back, and now its better.

Going to try again. Nozzle is blocked :-(

Cleaning first.

Marc

 

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