kmod's blog

30Aug/130

3D printing update

No real project to tie these together, just a common tool/technology:

SainSmart filament review

A while ago I bought, and received, this SainSmart 1.75mm PLA filament.  Recently I've only been using my printrbot for making organization boxes; today I happened to need more, so I took this as a chance to test out the new filament.  It has 4.5 stars on Amazon, which is pretty good, though there's a common theme to the upset customers.  After using the filament I can see why: the filament has been printing fine so far (printed for a few hours), but the coloration leaves a lot to be desired.  It's hard to describe, but it feels cheap and plastic-y as opposed to the printrbot PLA I've been printing with which feels svelte and matte.  It's tough to tell from this photo, since the lighting is very different, but hopefully you can tell that the red filament is decently translucent, vs the black and pink objects on the table, or the white spoolholder.

Assortment of prints from different filaments

Assortment of prints from different filaments

Mechanically, and structurally, everything seems to be going great with it.  I've only tried it on one print, a hollow box, and the printer accepted it fine (which is saying something since I've been having issues with the printrbot filament), and the resulting boxes are sufficiently structural.  (Again, this is only after two hours of printing.)

Overall I'm definitely happy with the material, though I don't see myself using this color again.  I'm happy enough that I checked out their website, where they offer their filament at lower prices and with free shipping, so I might buy another spool at some point.

I also ran into this comparison of different PLA suppliers; the only component to the analysis was from a cost perspective, which is how I'm looking at the problem, but some commenters make the legitimate point that quality can be really hit-or-miss with these cheaper guys, and even though some suppliers are as much as 25% cheaper than other "cheap" options, buying a single bad spool can be hard to recoup.

Printrbot Simple upgrades

While I was browsing for filament, I went back to the Printrbot site since their filament seems quite good and they sell it at very low prices ($30/kg), though they are currently out of stock, except for pink.

Anyway, while I was on the site, I noticed that they are now selling a Simple Tower, an integrated carrying case + spool holder.  They're also selling a Simple Tower Tall variant, which works better if you buy the build volume upgrade.

Wait, the what upgrade?  They should have featured it more prominently (or emailed me about it): the small (4" cubed) build volume is my biggest complaint about the printrbot, and I'd love to extend it.  The upgrade costs $65, which feels a little steep given the base price, but I'm almost certainly going to buy it.  Plus I've stocked up on the M2 and M3 screws they like to use, so I should be able to assemble it faster :P

Current printing accuracy

Right now I'm very happy with most of the accuracy of my printrbot; I haven't gotten around to installing the endstops or fan upgrade, but I think if when I get the aforementioned build volume upgrade, I'm sure it will make sense to lump in the other upgrades at the same time.

The thing that I'm not happy about, though, is that right now parts are coming out too big.  The problem isn't that one of my axes is mis-calibrated; the motors move the right amounts, and the issue is that printing two parts that should fit together (such as a socket and a plug), they don't.  Also, if I put two parts close together but not touching, the print will usually end up with the two parts joined, which can be very difficult to fix for some more intricate models such as these captive planetary gear bearings.

At this point I'm not sure where the problem is; I don't think it's that I'm extruding too much material generally, since when creating solid layers I'll often get gaps between the fill lines, and even changing the "extrusion multiplier" down aggressively (0.75x), the rest of the print is clearly nonfunctional, but the close-together parts I was originally concerned about will still be conjoined.  At this point I think I need to start manually "slicing" some test patterns, such as laying out straight lines of plastic and measuring the width; hopefully this doesn't take to long to solve, because this problem is blocking me from building any mechanical parts.

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