High quality prints

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HLA
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Re: High quality prints

Post by HLA »

Kjetilei wrote: The extruder arm is tightened so much that I have to force the filament in and it's not slipping as such but the stepper tries to turn the axle but fails. With the filament stuck and the stepper's constant "micro movements" the filament is eventually "filed" down.
@Kjetil: It may seem paradoxal, but these symptoms have a high chance to be resolved by tightening the extruder arm. In my case it was not different: the extruder was filing down the filament with nothing coming out from the other end. In case the hotend gets clogged, the filament shouldnt get filed down but rather the extruder stepper should start skipping steps, otherwise you have too little tension per se.
There is a good way to adjust this after you clean the nozzle: gradually increase the tension in the extruder arm until the stepper starts skipping steps when you extrude. Reduce the tension slightly and this should be good ;)

Kjetilei
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Post by Kjetilei »

HLA: Not that I'm arguing with you (and I really appreciate your help) but the filament never slips when extruding normally and the stepper starts skipping steps before the filament slips. But with a complete jam there seems to be enough force in the repeated tiny small movements of the stepper to eventually file down the filament since it is stuck. I wish I had taken a small video of it to be able to show it to you.

If I tighten the extruder arm any more I'm unable to feed the filament at all and I also seem to remember that thirteen it more stalled the stepper :)

HLA
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Post by HLA »

Please excuse my perseverance - it just stroke me that I had a similar issue. Anyway, 3D printers are not simple devices, and reasons for similar symptoms can indeed be different. I recently found an interesting collection of failed prints on repraps with potential reasons why the prints failed - the list of possible reasons is quite long... I really hope you can resolve the problem soon and I look forward to the pictures of your prints ;)

Kjetilei
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Post by Kjetilei »


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gfeliksdal
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Post by gfeliksdal »

I finally found time to post the nautulus wheel pictures. The only thing left is the torture test.
P9160500.JPG
P9160501.JPG
P9160500.JPG
@ Kjetil: Have you already checked the tolerances of the filament. Must be within 1.6 and 1.95mm. I once had filament which had a range between 1.5 and 2.1mm. Too small and the filament will creep up the barrel and to big will obviously not go through the barrel at all. There is definately some crappy filament out there.

@HLA: Nice touch the aluminum plate on the extruder part. Did you see some improvements? I think it can definately help with ABS. I've been experimenting with a different heated bed, which got to 105 degC the extruder parts became soft because of the heat.

It is definately cool to organize this more often, we could bring this printer to the next level :)...I think with software finetuning alone a lot can be improved. It would be cool to create a part which can somehow be a benchmark print for all felixprinters.
Attachments
P9160505.JPG

HLA
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Post by HLA »

@Kjetelei: The flickr Gallery is the one I meant. Thanks for posting other links!

@Gullaume: Well, I printed the owl again, and there was an improvement in quality: layers are now better aligned, and the details got crispier. The overhangs got better but still not perfected. The funny thing is that the right cheek of the owl has more problems than the left one, despite that both of them are symmetrical :? I will post the pictures when there is sufficient light for the camera.

However, it's difficult to say whether the aluminium plate is responsible, given that other adjustments including tightening the sliding bearing and replacing the broken parts were also done. But I noticed that the hotend part which is touching the plastic is not getting as hot as before - a good sign for using ABS. I have attached the DXF file for the plate, but it's mess if you want to use it on a CNC-mill (need to convert splines to lines/arcs).

What heated bed did you try? I am curious how you solved the problem of the maximum available current of the RAMPS board.

CAD-file of the Al-plate: https://www.sugarsync.com/pf/D7636517_2945689_6541425

black1q
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Post by black1q »

@Kjetilei
I dont know if this helps, but I once my filament gets stuck, and I take a 0,30 mm drill in my hand to reopen my nozle from the oposite site, I also heated it up a little more and I cleaned the brass wheel with a needle and then it worked again.

@Guilliaume
Maybe you should print the critical part of the extruder in ABS so it wont melt on higher heat.

danielkschneider
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Post by danielkschneider »

I personally do not yet understand the physics of extruder jamming (no filament coming out after a while). I just noticed a repeating pattern:

I happens only with non-translucid PLA and only either on small towers (e.g. little finger sticking up) with little fill and wide roofs (e.g. 10cm X 10cm) that are built on either a fill or little objects underneath. So far I got the following hypothesis. Iff the extruder arm, the filament and the temperature is right, extrusion may still may stop in the following condition: Filament coming out can be out of contact with filament underneath (overhangs) and in addition there are areas where no filament can come out (irregularities in the layer below that will inhibit filament to come when it wants to ...).

So far, I use these strategies (I am talking about "normal" printing with 0.2 or 0.25 layers here):
- Always extrude about 500mm of plastic before the real print. Plastic must flow regularly and create nice little cylinders if z is down by 20 or so. If it doesn't, adjust the extruder arm. Though if I tighten a lot, there is some noise I don't like too much...
- Use translucid PLA (it seems to be much friendlier)
- Print slower. In particular, I print the first layer at 12mm/sec. If something goes wrong there, there can be bumps in the next layers and will badly affect printing. Either manually (speed override) or better do it in the SFACT slicer.
- Change the fill pattern: bee (hex) pattern is nicer, but somehow more difficult than straight lines. Also, using a denser fill helps.
- Wide roofs over small (0.15- 0.2) filling: I raise the temperature a lot (e.g. 215 for the non-translucid red PLA I got from Guillaume). I know that this is counter-intuitive with respect to quality, but it works ;). There are three major sorts of PLA (4032D, 4042D and 4043D) and I don't know which one I got. It's specs are very different. I think I got 4042D which normally should extract at 190, but I also heard rumors about people using 220. http://edutechwiki.unige.ch/en/PLA
- Of course, there also can be a problem with the filament roll (filament crossed over in a way that it can't spool) or the filament (uneven size).... can't do much about that. Anyhow, make damn sure that your filament holder is working properly. One big slow down is enough for sabotaging a print, since there must be constant pressure in the nozzle.

Disclaimer: I am not sure about anything...

If you read this Guillaume: Do you have an idea what type your PLA is ?
- Wide rolls with transparent PLA ?
- Narrow rolls with transparent PLA ?
- Narrow rolls with non-transparent PLA ?

Btw. just before I got the Felix I got a (pilot-program) fabbster. Its extruder was designed to work with sticks, but back then sticks were not available. Printing was very very difficult for people who never owned a 3D printer before and extruder jamming the normal condition. The solution I found was to print neither too slow (this is related to the extruder design which won't work well with filament rolls) nor to fast. Also, I printed at 270 for ABS (as opposed to the 245 that are more normal). Some guys printed a 290 but then got really ugly results plus jams related to overheating the plastic.

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gfeliksdal
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Post by gfeliksdal »

Thanks for the tips!
I would like to dig into the extruder jams more, as I don't seem to be able to reproduce most of them. What PLA are you using? I can print with translucent and solid colored PLA without having extruder jams. I can remember you received 2 types of filament from me the small diameter and large diameter. I still have both and I notice that with the large spool diameter I had to set the temp 10 to 20 deg lower than the small spool diameter in order to have good results.

All in all I didn't have to do all the tricks you are descibing to prevent the hot-end jams.

I've asked my supplier what kind of filament they sell, but waiting for an answer.

Kjetilei
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Post by Kjetilei »

Guillaume: the Nautilus wheels turned out great! looking forward to see how the torture test goes :)
Filament: I have filament that varies down to about 1.6mm and filament that varies up to 1.9mm! I sure would like to have filament that was more or less 1.75mm all the way :) I think my troubles are caused by a combination of problems: varying filament dimensions, old PLA residue and other contamination left in hot end and maybe too big gap between peek and hot end and/or cold end. Hopefully I'll get the problem sorted soon :)

black1q: ! have bought tiny drill bits but never used them since I have pulled the filament out after removing the cold end and or peek part. The last time I disassembled the cold end and then heated up the hot end to regular temperature before I used a tweezer to pull out the rest of the filament that was stuck. It was a quick and diety solution and prevented me from cleaning the hot end as much as I might should have to avoid the jams.

Daniel: thank you for sharing your experiences!

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