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dubtec

Help - strange problem - fixed

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Not sure why but I keep getting a gap along all front edges during infill, the back and sides are percent. I'm using simplyfy 3d, with 15% infill over lap.

Its just happened all of a sudden.. i use an Ulticontroller and SD cards, wonder if I've "knocked" a setting bi mistake?

any thoughts?

The front of the Ultimaker is the left, as I have rotated 90 so I can get to the extruder.

gallery_28782_547_155536.jpg

 

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Looks a bit like chocolate... :)

Most probably you are haunted by the famous backlash ghost. Check especially the short belts, they should be very tight. Check also the long belts; they should be reasonably tightened (check

if you don't know it yet). You can also check if one of the pulleys have come loose.

btw: at what temperature and speed are you printing? And on what (looks like paper)?

 

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Cheers. Printing at 50mm/s and 235 with faberdashery filament.

All I have done come to think of it is tighten up the front long belt as it appeared slack. .. I will tighten up the belts and check pulleys. .. Do the belts stretch? As u have just bought a newer one which has no belt tightners. .? And they are really tight, quite tuneful when you flick them..

Last question. I struggle to push faster then 70 without the extruder slipping. I can't really tighten it up any more as it's in its sweet spot. Is the vs bolt worth the upgrade. . Thanks dave

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235 degrees is quite high for 50mm/s. I print faberdashery at 210 degrees for this speed and it looks ok. It seems you are suffering of some underextrusion most probably due to the extruder slip. The bolt of the extruder with the spring underneath should stick out of the extruder mechanism about 11-12mm (on my UM1, it's rather 12mm). You should see the teeth marks on the filament but it should not be grinding. I bought the newest versions of both the knurled drive bolt and the extruder mechanism so I can't say anything about designs before the present ones. The present ones work nice.

The belts do stretch with time but very slowly. This is rather not the source of a sudden backlash. Usually it's the screws which fix the x or y motor that get loose.

Be careful not to tighten the long belts too much. Two months ago I was hunting a shift effect for nearly three weeks which was caused by too tight long belts.

 

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It doesn't look like underextrusion to me. The infill completely covers the whole area except for the edges. I think it's backlash due to either something loose or something too high friction (both can cause backlash paradoxically).

Check out this explanation plus the post above that shows photos of parts with backlash:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=14474

Grab the nozzle tip and push it around and make sure nothing is loose. Backlash is usually the belts but sometimes in the print head assembly.

 

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I hate to say its back :sad:

Still doing it..Front edge gap, and rh gap.. even if I increase the flow to 115% its still there, just over full (raised) with gaps on those two edges. Bacl and LH edge are fine.

I have printed out new tensioners for the belts, and realigned, loosening all pulleys and c plates, used the axis alignment tools, and then tightened everything. Lubricated all rods with graphite Kabba lock oil.

i can push the head around by hand its a little tight.

the short belts I cant tighten any more, they are on there end stop, how tight is "very tight" for these? The machine is old, and considering how slack the belts are (without tensioners, I wonder if the small belts have stretched? it would be great if someone could squeeze their short belts together and let me know the minimum gap between them.

I can't see anything obvious.

All I did orignally is tighten the front belt, but now I have started from scratch, all belts have equal tension, and can be bent about 5mm down.

I have ordered new belts.

i REALLY welcome your help, as my orders are queing up ;-(

 

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What I did to test qualitatively for backlash was to push and pull at the print head with steppers ON. Not with brute force of course. Ideally you should not be able to move it when applying reasonable force.

The other test you can do (if not done already) is to push the print head around with steppers OFF. You should be able to push the head with your little finger. If you're not, then at least one of the long belts is too tight.

I don't have the short belts anymore due to direct drive but I remember having the tension of the short belts in the range you just described; they should be ok.

If you got your UM Original as a kit, you may have received some silver colored grub screws. They are replacements for the black grub screws of the pulleys and are supposed to give a tighter grip if I'm not wrong. If you haven't replaced them, it might be a good time to do now.

 

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Ok will look at this tonight.. This is a used ultimaker I bought from eBay. The X y motors are really hot. Too hot to touch.

I can just about push the head around using my hand.. so I'm wondering if I've over tightened the xx belts. Whilst the problem is stretched short belts? I'm looking to print adjustable tensioner. .

Thanks for your swift response.

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@dubtec: If you solved your problem in the meantime, just forget about the following.

I had today the situation that the hotend temperature was fluctuating quite a lot. The result was a print that looked quite like yours. I then remounted the contacts of the hotend thermocouple on the amplifier print on top of the print head. After that, temperature was stable again and the next print of the same model came out perfect. Maybe this information can be of some help to you.

 

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Thanks for your help.

I think it was a combination of things.

I reprinted adjustable tensioner and follow video and got all the belts to sound the same. I also tightened the 6short belts by levering the motors down.

I've replaced my strange drive bolt with the new v3.. wow now I can print fast ..

The bolt installed doesn't look like it was an original ultimaker.. what do you thinkhttp://umforum.ultimaker.com/index.php?/gallery/image/3685-20140219-224048/

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