Printing mendel parts

I’m not even sure I would build a Mendel if I had all the plastic parts.  But for some reason I still want to have all of those parts.  I have no idea why.  :)

I printed up a single spring out of PLA before my extruder got clogged up.  It’s my one and only Mendel piece.

Having this one piece languish next to my MakerBot strikes me as funny.

I think there’s a haiku in there somewhere.

Adventures with PLA temperatures

Kinda rhymes, no?

Given Rick Pollack’s PLA printing success and temperatures at barrel entry rather than nozzle, I should probably start delineating between temperatures at the barrel and nozzle.  If barrel entry temperature is truly a critical factor, then he’s totally right about how going by nozzle temperature is like driving a bus with just the rear view mirrors.

However, this gives me pause.  Everything I’ve read about ABS suggests it may be best to melt it right at the nozzle as quickly as possible.  I’ve found that ABS cools very rapidly too.  PLA on the other hand takes a while to cool (but, then again, I was running my extruder too hot) – with the parts being quite flexible for some time after printing.  If barrel entry temperature is that important, then it seems that PLA must need a longer time to melt.  If this is the case, should the nichrome be wrapped higher on the barrel?  If so, then Rick’s heater cores (which already seem very convenient) are downright brilliant – since you can probably easily adjust where the heat is being applied.

From Nophead’s comment I gather that I was, indeed, running my extruder too hot.  I found that at my ABS temperatures (220+) made the PLA just drip right out of the heater – and once that had basically stop it would then intermittently release little amber droplets of plastic.  I must have been really cooking it.

With the limited printing I managed with PLA I found that it printed well with my non-temperature ABS Skeinforge settings.  So, before I go back to PLA I think I’ll finish tuning my ‘bot using Nick Ames’ Skeinforge tutorial.

Uninformed advice on printing with PLA

Don’t leave your extruder on and not running too long.  It will drip, then the PLA will turn amber, and then it will clog.

That’s all I’ve learned about PLA first hand.

Oh, well, that and it’s a royal pain in the ass.

How are you printing with PLA?

I’d like to print in PLA, I really would.  No warping?  No rafts?  Smells like syrup?  Makes kittens and rainbows?  Sign me up!

Rick from MakerGear has the following suggestions for printing in PLA:

  • Have a 150-160 C degree temperature for the entry of the barrel
  • He notes that the nozzle temperature is roughly 190 C degrees
  • However, later he suggests printing at 220-235 was possible
  • He suggests not to worry overmuch about PLA in the threads – its just one of those things

Nick McCoy offered several pieces of wisdom:

  • He found that 10W-30 oil added lightly to the PLA as it entered the extruder, by adding oil to a piece of cotton wrapped around the filament, helped it print without jamming
  • He noticed that pausing the extruder for more than a few seconds would jam the barrel
  • He found he could print at 180-210 degrees (I assume he’s measuring the nozzle temperature as you would with an ABS setup)

Nick’s results suggesting a nozzle temperature of 180-210 seem to match up with Rick’s findings of 190 or so.  I think I’ll give Polly another shot and see if I can extrude at those temperatures.

Reusing the PTFE barrier

Long story short – it’s possible.

I was concerned that after having PLA ooze through the threads that I would be forced to use my backup PTFE barrier.  However, I’ve been pleasantly surprised to discover that I can print just fine with my reassembled unclogged extruder.  I’ve been able to print several things without so much as a hiccup.

So be delicate with your PTFE even after plastic has oozed into the threads – you may just be able to use it if you can clear out the plastic from the threads.

Tea cups

I designed and printed some tiny tea cups to go with my tiny teapot.  Unfortunately the two models I tried to print (one in PLA and the other in ABS) turned out very very badly due to the clogged extruder barrel.  However, I rather like the design and look forward to printing it properly.

February 11, 2010 | Comments Closed

What is burned PLA?

It didn’t actually look burned.  Is “burned PLA” the amber stuff I found dripping from my extruder barrel after I left plastic sitting warm too long?

Is this a symptom of sitting warm too long or too much heat, both, neither, something else?

February 10, 2010 | Comments Closed

Am I taking this too far?

You guys are going to have to let me know if this whole “Polly/PLA” and “Abby/ABS” thing starts to get creepy.  Ferris Bueller famously once said…  “You can never go too far.”  As far as I know, anyone who’s ever taken Ferris’s advice ended up just fine.

I’m tempted to explain the references, but I don’t want to kill the joke…

An idea for checking the temperature of an extruder at the barrel entry

Several people have suggested that the temperature at the entry of the barrel is very important to printing with PLA.  This makes sense.  If the temperature at the barrel entry is above the melting point for PLA, it can melt right there and ooze down around the threads.

Maybe I should assembly my extruder with just the thermistor on the barrel entry, and heat it until it is just below the melting point of PLA – then check the temperature at the nozzle.

Or, I could get a second thermistor and use it at the top of the barrel while keeping the original thermistor at the nozzle.  I could only use one set at a time (since I don’t know how to hack the electronics/extruder board), but that shouldn’t be an issue.

February 8, 2010 | Comments Closed