Newbie questions on PLA filament and MBMini short review

This is the confession of a new Makerbot Mini owner.

Once some initial birth pangs are over (part of printer broke in initial shipment, etc) it prints OK.

I purchased several rolls of filament from Makerbot. Good filament, but very expensive.
$18 for a half pound roll.

I did a purchase of another brand - esun3d.net 'premium' 1.75mm filament from SamsClub.
It was OK, but jams every few minutes. $22 for 1Kg.- 1.71 to 1.73 diameter

Also tried Matterhackers.com 1.75 PLA. Not at bad at jamming, but still an issue with jammin.
$29 for 1Kg, 1.68mm dia measured

I have also used the MatterHackers.com Pro PLA 1.75 and it works like a champ. Not as expensive
as Makerbot, but still more expensive $42 for 1Kg - 1,72 to 1.76 diameter

On the 'less premium' filament, it feeds OK. No 'popping'.or apparent voids in any of it.

Any suggestion as to what I should do to make these other filaments 'work'?

I have been able to clear jams without opening up an extruder till last night. It was apparent the
'smart extruder' (not the new + version - I should have one here in a couple of weeks), has a
pinch point just above the cooling fins on the cold side of the hot end.metal parts. At least that
is where I found a quarter inch long mushroom shaped slug, and no way to pull it out or get
enough heat there to melt it. - Overall I am impressed by the engineering of the current smart-extruder
but with the issues I and others have reported, ... Let's just say I am looking forward to give their
next version a try.

BTW, I am just using the Makerbot software. Similar to Cura in some ways, even though I have
not been able to find anything but the Makerbot software to drive this machine.

Off topic:
There seems to be a small switch near the top of the extruder, to detect filament out.

The next sensor is a free spinning wheel that rolls as the filament is pulled in with a reflective sensor
on one side with small pie-shaped reflective/non-reflective strips - I didn't count but about 32 or so
'pie slices' for the reflective sensor detector.

Then it goes through the pinch roller system into the hot-end.

Just before the hot end, that is spring mounted to push the extruder 'down' is a small piece of plastic
with a weak spring around it. That has a 'finger' that goes up further inside the etruder housing with
a small magnet on the end, to trigger a hall-effect magnetic sensor when the extruder is 'pushed up'
as it does during detection of the level of the build platform.

I am guessing they are depending on geometry and faith to ensure bed leveling. It is such a small
bed, this might not be a bad assumption. (100x100x125 high build volume).

Their concept was good, but the price point is to high, and some of the engineering decisions
are questionable, but it is their product. IMHO, they pushed to hard on the extruder to get it
out the door and didn't do testing on other than 'premium' filament. I totally understand only selling
premium, but the hardware should be designed to handle 'out of spec' material too.

Their 'network' service, so you can monitor / start/review it from your cell phone works OK.
My problem is it consumed my monthly allowance of 15G of internet data in just a week or so.
It seems to send the built in camera feed all the time, chit-chatting with their reflector. Turning
off this 'remote control' option, makes even the wifi connection for cell phone app not work, even
if on the same local network.

The Mini is either USB attached, or can, after initial setup, work without an attached
computer. There is NO control panel, and, NO SD card slot available, so it is only driven
from a USB or wifi connected computer.

I have a cheap RCA Android 5.0 tablet, and it cannot run the Makerbot app, because the App REQUIRES
cell service. -- This should not be, if you just want to use it WIFI only, why require cell service?
Again, some things are not thought through, or at least not communicated so it will 'sell' to this customer.

Yes, the machine is mainly plastic. Polycarb sides and door, but still pretty well made.
The built in camera is not high resolution, and you can't see the bed well during a build, but once done
it positions the build platform nicely in the frame for viewing a complete unit.

I was impressed with the error/jam/out of filament detection and reporting. They work pretty well.
Now fi the next gen would just 'fix it' instead!!

Would I recommend it? If it worked as hyped, yes, especially for the $400 I got it for at auction, new on Sams.com
Would you believe I purchased it by 'accident'? Well, that is true, and the story I told my wife, so I am sticking to it!

Interesting printer! Thanks for the review, lots of things I would never have guessed without hearing it from someone who owns one. That extruder sounds fascinating, but disappointing that with all that tech in there it's still not doing the basic job of shifting plastic. Most of the normal advice for reprap style printers may not apply so easily to your machine, things like checking the extruder motor current, tightening the idler tension, polishing the throat and making sure there is plenty of cooling on the heatbreak. Your best bet may be to try a different filament type. ABS generally extrudes more easily than PLA. In fact, pretty much everything extrudes more easily than PLA.

JamesK,
Thanks for the great reply.

With all the 'printing for dummies' and nice engineering, they did leave many of the adjustment 'knobs' that other printers allow to be used (like additional tension on the idler, access to the throat for additional 'polishing' or smoothing.

REVIEW Addon comments: Oh yes, I did want to mention that the extruder is held on with 4 rare earth magnets, and the 'drive shaft' has a toothed connection so the stepper is NOT built into the head, but into the carrier. All the electronic/electrical connections to the extruder come through a set of pins that just push against some connection plates (not into a socket of any kind). At times, these can be hard to get to seat. I am sure that using a hard rubber eraser on them gently would help when issues occur.

This printer is 'designed' for PLA only. No heated bed, and I think the hot end may be under-powered to do much more than about 230C. Makerbot doesn't suggest using anything but PLA with the Smart Extruder.

That is why I am planning on building another machine (signal: wife cringes in the background!). But this one is giving me a place to start learning. As much as I like it, I wouldn't have purchased it knowing what I have seen now.

I also have an issue at times with some clumps of plastic that seem to get embedded at times, but they cause ugly surface irregularities. They look like 'pimples' or 'zits' from the outside. At times I have seen little 'droplets' of plastic (typically with the lower quality filament) left on or around the build surface.

Any idea what causes these? Or on how to handle the different PLA qualities?

Ooh, that sounds more and more awesome. Love the idea of magnets to hold the extruder in place and the electric probe contacts - provided they are reliable of course It really sounds like they have tried very hard with the 'consumable' engineering aspects. Just a shame they seem to have coupled that with so many limitations - I suspect the interference of a marketing department.

As far as print defects go, I'm afraid I'm still in search of perfection. Varying degrees of defects are very much par for the course for me, especially when printing bridges or overhangs. And as you suggest, there is great variation in different plastics. I don't think there is any one magic bullet, but slowing down is often a way of improving things, so it's always worth giving that a go.

It's a shame that they don't recommend abs, with an enclosed design like that you'd think it would be perfect. Again, there's lots of variation, but I'm printing red abs from filaments.ca at the moment that extrudes well at 210C. Unfortunately, without an enclosure I have problems with delamination, so I'm gradually increasing the temperature to try and fight that. (enclosure - also on the todo list. The rep-rapper's curse.)

I think the ideas from MB could be made/incorporated into a DIY version of a extruder, but I doubt it would be as compact. I just don't want anyone to find out how litigious that MB could be.

But being a bit bigger is OK, if it makes it maintainable and easily useable by folks and properly 'hackable' with relative ease. ... I would even like to see how to make a 'plug compatible' extruder to put in place of their Smart Extruder. That way folks could have a choice to hack and grow with.


The not having ABS on this printer is just trying to keep down the variables to make it more bullet proof, but that decision also limits the audience that would be interested in this machine.