Why i always get underextrusion.

[Labern 774]

Just a little info on that. I've printed with 1.75mm on the UM2 (experimental Olsson Block) and the was no under extrusion, even at weird angles. I think this is an inherent problem of 2.85mm filament. It is just too stiff.

 

1.75mm filament will actually apply more force in the nozzle as the area is smaller so this helps stop under extrusion. But yes its not as stiff so feeds in a lot better.

I'm liking it so far.

[Labern 774]

bearings wont stop a tangle unfortunately so if i want something almost guaranteed perfect i know im highly likely to get it off the roll. i do print on the roll, but only when the filament used is too much to cut off the roll. my early prints where all on the roll, so its not completely useless, but the angle of the roll holder would greatly benefit from being at a slight angle towards the feeder as the fact that its straight means its always pulling harder towards the printer when its further away on the roll which shifts the filament and most likely is responsible for a large proportion of tangles.

 

I have used Roberts spool holder on my UM2 since my first under extrusion episode, and i have designed my own low friction spool holder to fit my UM2go ( fits UM2 and extended as well)

Yes they don't stop tangles but if you manage your roll properly you shouldn't get tangles.

I always check it when i remove it and clip the filament in place, then check it again when i install a new one. I have never had a tangle yet.

[cloakfiend 995]

I only had a few tangled prints i admit and usually got uneven layer lines due to the filament roll being stiff and gently tangled, but it was enough to affect the print. I only get under-extrusion if my nozzle is getting blocked slowly hence resorting to printing off the roll. Under-extrusion is something I normally never see now and only got it when I wasn't doing any atomic pulls, or doing them wrong. Im pretty sure that the main reason for under extrusion is a slightly (even very slightly) blocked nozzle that many people assume is clean, and just carry on, combined with the 2.85 stiffness, and having to work hard to pull and rotate the roll amongst some other factors im sure. But having to rotate the roll as opposed to not having to and a slightly blocked nozzle make sense for a likely failure. Like perfect code, anything added to it like protection and security is essentially making the code less perfect and more prone to errors. Like printing off the roll, without it you are simply taking away a lot of weight the feeder has to pull. Im sure bearings would help tons, and if i buy a UM I will definitely do the bearings roll holder, which i'm sure combined with keeping an eye on the filament and not letting it wildly untangle.

i've done 4 massive prints on the roll recently with new UM blue filament and the quality was different on essentially the same parts, but was fairly acceptable, but I was curious as to why, the next print i did revealed why. A slow jam, i got complacent with my atomic pulls and didn't check the shape closely enough, and i'm pretty sure that is what so many people are also doing wrong. with a perfectly clean nozzle, i'm not really getting any problems what so ever. Just doing atomic pulls and not actually making sure they are actually cleaning the nozzle is completely pointless. i did them hot, cold, twisted it one way from hot then, twisted it from cold, everything i could think of to clear the damn thing. It appeared that even after 30 pulls my burnt nozzle was so bad i didnt see any difference, but the pull after changed my mind. I have sorted the nozzle. Mind you if i had an olssen block, id just swap it out and problem solved. But if you just make sure you don't burn your nozzle by printing with too much flow or whatever may cause a jam and clean it properly, im sure you'll be ok. I've not changed my nozzle since i bought it and the quality is identical to my first print. I did not enjoy wasting hours doing 30 plus atomic pulls but i learnt that the nozzle is mostly likely responsible for the majority of jams and under extrusion, and feeder issues. the feeder is fine its the nozzle you need to take care of.

[danilius 118]

if you show me where to buy the parts and stuff id give it a go

 

https://www.youmagine.com/designs/another-spool-holder-base

seems to me easy and practical device

The bearings are easy to find on ebay, just search for 608 bearings. You will need some M8 bolts as well.

 

but the angle of the roll holder would greatly benefit from being at a slight angle towards the feeder as the fact that its straight means its always pulling harder towards the printer when its further away on the roll which shifts the filament and most likely is responsible for a large proportion of tangles.

 

With an external bearing based spool holder you can position your relative angles as you wish!

[cloakfiend 995]

Lol, one day.... still waiting for my electroplating machine to arrive.....

[peetersm 124]

With an external bearing based spool holder you can position your relative angles as you wish!

 

Yeah for $6 I got a really nice plastic lazy susan at the local store and just put the spool on its side, works great.