Printing PLA with the H1, Oh crap...

[cquinby]

Well I ordered some silver PLA from Protoparadigm and ripped it out of the packaging as i had to see what it would do.

I lowered my temp on the extruder to about 365 - 375f. All was good, I was happy till about the 6th layer at 0.3mm. It quit extruding.

I tore out the nozzle and the teflon tube and found that the filament was all hosed up in the teflon tube. I cleared it out, put it back together and tried again after changing some settings in Slic3r. Well again, about the exact same spot it stopped extruding... I was cursing up a storm and trying not to wake the kids up.

pulled the PLA out and tossed in the glow in the dark ABS and made a gecko for my daughter to make me feel better...

This morning I started thinkin about the issue and thought, well just maybe the dang filament is too hot in the barrel. I lowerd the temp a bit more and no go, same issue. Thought about it a bit more again and thought, well maybe the barrel needs to be cooled a bit.

I opened up Inventor (used it like twice in my life) and started to design a 40mm fan holder to blow air onto the extruder.

I came up with this cheesy part.

Had to drill out the holes with a 1/8" bit to slip the 3mm bolts thru but not big deal.

Mounted it up, cranked the temperature back up just under what I print ABS at (about 400f) and let it rip.

Dang if a part didn't print!!! Just a little air is all it took. Here is the second print I did.

I am now trying to make adjustments to Slic3r as I am getting more ooze out than with the ABS. I think I about have it, once I do I will post screen shots.

If anyone wants the STL for this fan holder let me know and I will post it up.

[mhackney]

Nice fan holder Peter. As you discovered, PLA does need to have the extruder barrel cooled or it will plug up as the PLA melts up the teflon tube. Since I wasn't able to print at the time, I made my fan mount from a pice of copper wire!

[img]http://mhackney.zenfolio.com/img/s3/v38 ... 6255-3.jpg[/img]

It actually works well but I'd love to print yours. You should be able to upload the STL to this thread.

cheers,
Michael

[cquinby]

Michael,

Printed in ABS with 0.3mm layer height, 1 Perimeter and fill density set to 1. Takes about 8 minutes to print. When you get past the bottom layers and you start to build up the narrow sections you will want to reduce your feedrate down to about 60% to keep the part cool and prevent goobers. Nothing like adjusting speed on the fly!

I notice your fan is on the backside. Maybe I should do that since the thermistor is protected by sealant. Hmmm....

Part3 fix.stl

(108.63 KiB) Downloaded 286 times

[mhackney]

Awesome, thanks!

cheers,
Michael

[Polygonhell]

Ha I was just about to design a fan mount almost exactly like that.

I can successfully print 4043D PLA without a fan, but you have to be really careful with temperature, you want to print as low as you can go, I am currently running the first layer at 190C and subsequent layers a 185C, if I try and print for extended time in the 200C range it will jam, it's just a question of how far into the print.

I have a couple of different hot-ends on order to see if they are less sensitive to PLA jams.

[srsCNC]

I also had problems with PLA jamming and the PTFE tube mushrooming.

In the end I made a new insulator tube support (the cross piece that bolts to the X axis) out of aluminium to act as a heat sink and added a 40mm fan. I also adjusted the size of the support so that the peek insulator tube went slightly deeper into the hotend. It now just about touches the top of the nozzle so the PTFE tube can't mushroom.

Since then I have not had any problems with jamming.

The new 3mm hotend looks to have better cooling for the peek tube.

[Fiero2M6]

When you get past the bottom layers and you start to build up the narrow sections you will want to reduce your feedrate down to about 60% to keep the part cool and prevent goobers. Nothing like adjusting speed on the fly!

Does Slic3r have an option to slow the feedrate as you get closer to the top of the part?

[mhackney]

No it doesn't. It has a bottom layer speed ratio to slow down putting the bottom laters down.

However, one of the beauties of Mach3 control is that you can control the speed dynamically as you print. It does require manual intervention but it is a great way to experiment and learn. Once you have the speed you need, you can go into the gcode and edit it.

I do this all the time machining metal on my Mach controlled milling machines.

cheers,
Michael

[Dave_Sohlstrom]

In this blog http://richrap.blogspot.com/2012/01/sli ... t-and.html Rich talks about how you can edit you Gcode to adjust for parts getting smaller at the top good information.

[WVISION]

That's great I like your bracket... I had the same frustration as I am a PLA guy as well.. Mine was out of a couple bolts and a wiring anchor. Although I need to move it to the inside to center the flow more. I kinda get a swirl going which is ok than having one side get a hot spot.