Prusa i3 - new build, works for a few layers then struggles

Hey,

New to reprap, just got my Prusa i3 aluminium frame in the post and built it after much hard work and head scratching, there was no online guide for my exact model :-| Comes with the E3D v6 hotend

My bed level test works no problem, I even managed to print some phone stands with minimal issue.
When ever I get to anything with infill or small movements it just gives up and ruins my day, I changed print speed in repiterhost from 70 down to 30 which improved things a bit.

I am trying to print the 20mm hollow cube test object, the first few layers go down fine (the first layer is a little squished,the last infil is maybe slightly over extruded).
Then at layer 5 or 6 it just starts spitting out little bits of filament rather than a constant stream, I then look and the hobbed bolt has stopped pushing the filament through and has started biting in.

I have turned up the pot on the extruder motor a full half turn as it seems to struggle.. I don't think the two cogs are perfectly round as at default 1/4 turn it gets stuck in random places on each turn. I am not sure how much higher I can turn this without causing possible issues

I am starting to tear my hair out and don't know what to do next. have cleaned up my hobbed bolt again, got some better filament (faberdashery) and now am looking at my printer wondering what I need to sacrifice to make it work.

Might have helped if I had attached the right picture.

This was the cube, I walked away for a bit so didnt cancel it straight away. on the right bottom part you can see the first bit where the print starts the fail with the really thin parts then a normal side 'bit'.

Check for a lip on the shiny side of the gears. When they were printed, the first layer would have been smooshed down and may be wider than the other layers. If it is, grab a nail file or needle file and file the lip down. Don't get over-enthusiastic on the filing, though.

File and turn the gears by hand until you get them moving smoothly, but only if there's a lip there in the first place.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Thanks, the gears do look a bit squished and have become slightly 'whiter' on the edge, will file away and see if this improves the play.
Do you think this is what is causing all my woes with feeding the PLA through? Or just one issue to resolve of possibly many :-)

Chances are this will give you a fair improvement, but with a self-build you'll be tweaking and tuning often.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Yes fully understand that, was just lost as to what to actually tweak so thank you for your help!

Have you got a cooling fan on your hotend? Maybe your filament gets warm/weak above your extruder, wich would cause that your hobbed bolt is no longer able to grab the filament correctly.

Did you try to fasten or losen your extruder idler?

How do you place your filamentroll? Could it be that your filament is pulling on the extruder?

There is a cooling fan on the barrel of the extruder so don't think that's an issue.

MY gears one the large ones Base Layer was slightly larger and catching, I have filed it away and need to re test if this helps.

Have also tried loose and tight on the pins (do you have a recommendation?) have a loose 10m sample pla just loose so should be no pull on anything, but previously had setup a 100m spool on bearings at top of printer.

Wow re-reading my last reply sorry for the terrible English, I wont reply via my phone again that's for sure.

So gears sticking, as 3dKarma predicted the large gear had a slightly squished base layer, this resulted in it sticking out ever so slightly and catching on the small gear attached to the motor, filing this off and the motor has not got 'stuck' since.

Still looking into filament, seems to continue to get 'stuck' somewhere and then the bolt is unable to push this through so just digs in making the problem worse.

I am going to turn the pot on the feed motor down slightly and try manually feeding filament through the hotend to see if there is a jam/problem with this.

Any other suggestions I will be glad to hear them!

So used a different filament, turned heat up to 230C and got maybe 15-20 layers done before it jammed up, tried some other filament, 2-3 layers then it jammes up.

Have gone through 5 different filament colours
Blue PLA 3mm provided with printer, at 230 managed 15ish layers of a calibration stepped cube, then started to fail everytime
Black PLA 3mm, from amazon print me 3d, same few layers then hot end jam's
Orange PLA 3mm from faberdashery, printed at various temperatures, same thing manages maybe 1 or 2 layers then the hot end jamm's up.
Pink PLA 3mm, from amazon printme 3d, manages a few more layers maybe 4 or 5, then jam's up.
glow in the dark PLA 3mm, from faberdashery. 2 layers fine, then hot end jam's.

I am starting to think the filament is not the issue, but there is something with the hotend/hobbed bolt that is causing all of this. will continue to investigate and see what i can find, any pointers would be most appreciated!

It sounds like you're getting heat creep up the hot end, through to the cold end, causing the filament to expand and block in the the cold end.

Dial the temperature down to about 185 for PLA (230 is way too hot) and you will probably get more layers printed. Point a fan at the cold end and you will cure the heat creep issue.

You can check for heat creep by printing until you get a block, then backing the filament all the way out of the extruder and checking for wider (expanded) filament toward the end. There will be a small area of expansion immediately before the end of the filament, but it's more than just a few mm in length, you're getting heat creep.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Attached is a pic of the last two bits of filaments when it jammed.

Trying to measure the expanded bit at the ends and it looks like its about 5mm long.

Will try the temprature lower, was on 200C as the default but tried it all the way up just to see what effect if any it would have.

thanks again for your help with this.

Doesn't look like heat creep. Can you post a picture of your hot end?

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

I certainly can, attached. If you want to see anything else just let me know happy to snap away.

i just moved the fan from front on to the side to see if that helped cooling from your previous cooling as there is the holder directly behind it.

Tried 185C print and it jammed instantly, think I need a bit more temperature to get it printing for this PLA at least.

E3D V6 with a Wade's. Good choice. I've been printing with that on an i3 for a while and had zero problems, so I don't think it's down to the hot end. I have found that 195 gives me best layer adhesion.

Have you tried cleaning out the hot end, to see if there's any gunk blocking it?

Heat the hot end to 230C and let it stabilise.
Reduce the temperature to 90 C and let it stabilise. This is a little above the glass transition temperature of the PLA.
Retract and remove the filament from the extruder. If you go the temperature just right, you'll see what looks like a straw at the end of the PLA. This means the PLA was successfully dragged out of the melt chamber, hopefully with and debris. If you don't play with the temp until you get it (raise / lower by increments of 5C).
Rinse and repeat a couple of times to make sure the hot end is clean.

Also, install a dust cleaner. Loads on thingiverse.

Edit: you posted it was an E3D at the top. My bad for not re-reading.

Edited 1 time(s). Last edit at 09/13/2014 03:58PM by 3dkarma.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

I will bump it up to 195C for printing and try to give it a clean out as well see if that helps. Thanks again!

I just have a feeling I am missing something obvious now, it seems like a good piece of kit, and if I raise the hot end and 'air extrude' it seems to work ok (although not at 185 :-) )

The set was this one if you are interested: [www.emakershop.com]

Good choice - Greg Colbourn sells quality stuff.

If you think it may be the filament, PM me your address and I'll send you a sample of the stuff I print with.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Thanks for the kind offer, I have at least 3 brands of filament already so I don't think that was the cause!

Just managed to print a 20mm hollow cube without issue(apart from the top of the cube having a few gaps which I think is a mix of speed and layers as it was only 2).

cleaning out the hot end resulted in a few black specs which was first filament I used and a bit of blue, also printing at 195 seems to work fine for me, ill dial it back down to that from the crazy temperatures I was testing with!