PLA printing never works

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Carnivore
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Re: PLA printing never works

Post by Carnivore » Fri Nov 21, 2014 10:16 pm

I've literally tried everything to in order to get this PLA to print on my mini. I think I'm going to give up on PLA and go back to ABS.

I bought a 100c thermostat from amazon and plan to replace the 60c with it.
http://www.amazon.com/Temperature-Contr ... B008SOCBTS

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DrewPetitclerc
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Re: PLA printing never works

Post by DrewPetitclerc » Fri Nov 21, 2014 11:17 pm

Carnivore wrote:I've literally tried everything to in order to get this PLA to print on my mini. I think I'm going to give up on PLA and go back to ABS.
Hi "Carnivore"?
Some of the issues with PLA are its tendency to swell as it enters the SST hot end tube and it "sticks" to the SST barrel, this has always been an issue and the home builds (Reprap, etc) have always used a PTFE tube as the pre-melt guide, so I found a supplier of a tube design that looked promising and bought one and modded my printer again (it is quite the Frankenstein) to use it and now all my problem PLA's flow smoothly.
Here is the link to my thread and there is a link to the design files I posted, it is for the UP Plus but with a little effort you could alter the design to fit the Mini, Sorry I will not support the Mini more than this.
http://pp3dp.com/forum/viewtopic.php?f= ... =80#p41564
I also recommend the Octave temp switch mod, because ALL PLASTICS ARE NOT THE SAME no matter who you get them from, there are variations in colors and additives that need to be factored in the temp settings, I keep a chart of the settings I use for every type and supplier of plastic, but these are for my machine and yours WILL vary so it is best if you start keeping track of yours.
http://www.octave.com/p1173433212/Octav ... _info.html

Hope this helps
Regards
Drew
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
http://flash-graphics.deviantart.com/
http://www.thingiverse.com/DrewPetitclerc

Carnivore
Posts: 113
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Re: PLA printing never works

Post by Carnivore » Sat Nov 22, 2014 4:29 am

I bought that same model from Octave but never used it. Is it really necessary to change the temperature?

I thought the issue with my problem was that the stepper was heating up due to poor engineering and causing the PLA to pre-melt before it entered the chamber causing a jam? How would a temp mod help? Or would I lower the temperature slightly below my normal usage and let the stepper warm it up?

stormychel
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Re: PLA printing never works

Post by stormychel » Sat Nov 22, 2014 7:41 am

Yes, extruding a little less hot (of course the plastic still needs to flow), keeps everything a little cooler. Not much, but maybe enough.

But there is hope for people who don't want to / can't use ABS : HIPS. Testing over the last days shows that it prints as well as ABS, with strong layer bonding, and little or no smell. I don't know what your reason is to try PLA, but if it is mainly about the smell, I'd try HIPS. It also has a tendency to warp, like ABS, but much less so...

If you ave problems finding a supplier with much choice in colors, try 123inkt.nl (I don't have anything to do with them, just like their offer and service).

IF you try it, can you please add your experiences in my HIPS thread here -> http://www.pp3dp.com/forum/viewtopic.php?f=11&t=54581

Thanks!
@stormychel

Carnivore
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Re: PLA printing never works

Post by Carnivore » Sat Nov 22, 2014 9:10 am

I think a possible solution would be to keep my existing fans (2x pointed towards stepper and main reversed) then install the octave temp module.

Since PLA melts at 230, I could set my software to use ABS and bring the temp down to 220-225? Maybe that's low enough where the added heat from the stepper won't cause the PLA from pre-melting.

roller
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Re: PLA printing never works

Post by roller » Sat Nov 22, 2014 10:36 am

Carnivore wrote:I think a possible solution would be to keep my existing fans (2x pointed towards stepper and main reversed) then install the octave temp module.

Since PLA melts at 230, I could set my software to use ABS and bring the temp down to 220-225? Maybe that's low enough where the added heat from the stepper won't cause the PLA from pre-melting.
Most PLA melts at 170-190 ... I'm not sure what PLA you have there but typically ones with such a high melt point are a blend which will generate a lot less issues than normal PLA as they also soften/weaken at a much higher temp. I presonally run my PLA prints on ABS settings as I found the print quality better - not just the temp changes between ABS and PLA settings. There are other tweaks like changing the retract and filament feedrate which should change. It seems to me though that the retract in PLA mode is insufficient (it should be greater but seems to be less) and the feedrate seems too high too (to my eye) with my prints looking a little overfilled. That said, this was with an earlier version of the software and many of the regular PLA users have said it has improved in later versions.

Stormychel is spreading a few red herrings about placing so much blame on heat coming up from the hotend. The heat is largely coming from the extruder stepper in most cases. How do I know - when I first sought to get to the bottom of the heat issue I decoupled my hotend and ran a job. Within 20 minutes my drive gear was reading 60C and my stepper was 85C. The hotend was about 20cm away and to the side so not contributing to heat around the drive gear at all.

Carnivore
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Re: PLA printing never works

Post by Carnivore » Sat Nov 22, 2014 10:40 am

So I should remove the 2 fans pointed at the stepper and put 1 fan focused more towards the extruder?

Also are you suggesting to put it on ABS settings with 170-190C with the octave?

roller
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Re: PLA printing never works

Post by roller » Sat Nov 22, 2014 11:21 am

Carnivore, First I am suggesting your PLA might be a superior one - print it at whatever temp it recommends. PLA usually has a lower temp and by the time it hits 210C+ it has very low viscosity and just runs with very litle control possible for the extruder. Personally, I try to print at the coldest temp any filament will safely handle. I walk the temp down (using a mod) until it jams and then step back up 10C. Any hint of jamming or signs of shredded filament in the gear and I give it another 10C. It's a methodology I learned from reprap and it seems to work well for me.

If I am printing a part needing extra mechanical strength then I up the temp 10C again.

I think I might have confused you with both poorly explaining the terminology I used and the fact I was really responding to two posts not just yours.. The extruder usually refers to everything, stepper (motor that pushes the filament), drive gear (part that actually contacts/bites the filament), hotend (bit that heats up). I was saying the hotend is commonly presumed to be the source of heat issues but it is not due to the stainless feedtube and heatsink/fan. The issue is the stepper motor and you are right to load it with fans BUT for some of us (me included) this is not enough - getting cooling air in and around the drive gear gets the best results. Cooling the hotend achieves nothing for the more you cool it the more the heater unit will try to heat it and you will actually create more heat in the metal feedtube (longer explanantion required and I don't have time for that just now). So don't worry, I wasn't suggesting to cool the hotend ... I was just confusing you because I was attempting to address something someone said earlier too.

Was that more clear?

stormychel
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Re: PLA printing never works

Post by stormychel » Sun Nov 23, 2014 8:41 am

roller wrote:
Carnivore wrote:I think a possible solution would be to keep my existing fans (2x pointed towards stepper and main reversed) then install the octave temp module.

Since PLA melts at 230, I could set my software to use ABS and bring the temp down to 220-225? Maybe that's low enough where the added heat from the stepper won't cause the PLA from pre-melting.
Most PLA melts at 170-190 ... I'm not sure what PLA you have there but typically ones with such a high melt point are a blend which will generate a lot less issues than normal PLA as they also soften/weaken at a much higher temp. I presonally run my PLA prints on ABS settings as I found the print quality better - not just the temp changes between ABS and PLA settings. There are other tweaks like changing the retract and filament feedrate which should change. It seems to me though that the retract in PLA mode is insufficient (it should be greater but seems to be less) and the feedrate seems too high too (to my eye) with my prints looking a little overfilled. That said, this was with an earlier version of the software and many of the regular PLA users have said it has improved in later versions.

Stormychel is spreading a few red herrings about placing so much blame on heat coming up from the hotend. The heat is largely coming from the extruder stepper in most cases. How do I know - when I first sought to get to the bottom of the heat issue I decoupled my hotend and ran a job. Within 20 minutes my drive gear was reading 60C and my stepper was 85C. The hotend was about 20cm away and to the side so not contributing to heat around the drive gear at all.
I know the main problem is the stepper, that's why I cool it with fans. But I believe that keeping heat as low as possible everywhere can make a slight difference, which might be just high enough to keep the PLA flowing.

It is interesting that you mention printing the PLA at ABS setting, to have a lower flow rate. I will try the spool of PLA that I can't get to work on ABS setting at the same temp as I try to print it now (190), and see if that makes a difference...
@stormychel

Carnivore
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Re: PLA printing never works

Post by Carnivore » Thu Nov 27, 2014 5:30 pm

Any luck with setting it to ABS?

I just removed the stock thermostat and replaced it with a 100 degree C thermostat and now my ABS adheres quite well to the perfboard and can print ABS just fine.

I have the octave temperature controller hooked up to my UP mini. Should I start at 190 degree C and increase the temperature until the extruder stops jamming?

stormychel
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Re: PLA printing never works

Post by stormychel » Thu Nov 27, 2014 5:48 pm

Hope same problems, will keep this spool for my reprap...

I'd start with the temp on the label -10.

If you can print ABS well now, is there still a reason to use PLA?
@stormychel

Carnivore
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Joined: Thu Oct 17, 2013 8:38 pm

Re: PLA printing never works

Post by Carnivore » Sun Dec 07, 2014 9:39 pm

Any updates?

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