[Blabber] Aluminum Prusa i3 Opinions?

James Carpino jamescarpino at yahoo.com
Wed Apr 13 04:42:13 UTC 2016


additional note, I'm preferring the "full Graphic smart controller" LCD over the "2004" text LCD control panels (though the latter seem to be more common).The cheap 2004's frequently malfunction (screen garbage).  I've seen it on different kinds of printer controllers (RAMPS, Ultimaker clone, Printrbot adapted to generic LCD), so I definitely think it's a hardware flaw in the display.  I met a seller who refuses to sell controllers with his printers because he had complaints across the board.  I've never seen the graphic LCD's fail.  

James

      From: James Carpino via Blabber <blabber at list.hackmanhattan.com>
 To: Chris Stratton <cs07024 at gmail.com>; Hack Manhattan! <blabber at list.hackmanhattan.com> 
Cc: James Carpino <jamescarpino at yahoo.com>
 Sent: Wednesday, April 13, 2016 12:30 AM
 Subject: Re: [Blabber] Aluminum Prusa i3 Opinions?
   
The Folgertech is probably not so bad, but I predict you will do some upgrades out of necessity very soon.  Whether you spend $300 up front or $400-$500 up front is your call.  I don't see that you can easily predict what will be wrong with a more expensive kit (which suppliers are giving you more for your money, vs. charging more for the cheapest stuff).  The exception is the geared feeder I mention below, and alternate designs such as bowden feed.  Perhaps if you see that, I think it is the mark of a scrupulous seller.

Overall you get what you pay for.  I don't think you have to pay $600 to Josef Prusa, but I paid $280 or $290 for my i3 kit and I probably spent an inordinate amount of time fixing it (plus, guessing about $100 in upgrades) and recovering from lost time.  I think it's unlikely for a $300 kit to be trouble-free.  The $270 Folgertech aluminum looks like you get your money's worth; you'd have a hard time sourcing all the parts for just that much, in single-unit quantities.  It is like the early days of PC building.  Buying a barebones kit was generally a good way to start, and sourcing everything on your own was always trouble for a first-timer.

Feeder/Extruder/Hotend: The HM Makerbot clone and my Prusa i3 had the same problems in the Mk7/Mk8 feeder and hotend/nozzle.  On the MB clone, there were frequent problems with jamming, just as I had with my i3 until I switched it out. 

Looking at the Folger pages, it looks like they sell the new Mk9 feeder, but doesn't look like that's what you get in the kit.  (I looked at the pictures and manuals and I don't see the Mk9 lever.)  You can ask them which they are shipping Mk7/Mk8/Mk9 with the kit.  The Mk9 has a release lever and spring-loaded idler.  The Mk7/Mk8 does not.  You can upgrade it.
This is the upgrade from various sources,
http://wanhaousa.com/collections/hotend-parts/products/mk9-dual-extruder-upgrade 
http://folgertech.com/products/spring-loaded-injection-molded-mk9   
http://www.ebay.com/itm/like/262324891278   
Image Search Mk8 feeder for the old version (and see Folger manual pictures).

Because of the non-springloadedness, if the Mk7/Mk8 gear bites away some filament, it no longer grabs (and spins away willy-nilly) leading to jamming or underextrusion.  So, that aspect may be significantly improved in the Mk9, plus there's a quick-release.  I was disappointed to see that our MB clone had the non-spring system. 

Also, with the tiny feeder motor provided, it's hard to find the sweet spot in the motor current adjustment. It transmits heat to the feeder gear if it gets warm, so you can't really overdrive it.  I've had that problem on early Printrbots as well.  (People often put fans on extruder motors, in lieu of spending the time to find the correct power setting.)

Because of that, I'm a big fan of the Greg's/Wade feeder with the clunky gear.  This gives the motor more advantage (about 4:1) and it is compatible with a wide range of nozzle options, better for hackers.  
http://3dprinterczar.com/shop/3dprinters/prusa-i3/ 
http://www.ultibots.com/prusa-graber-i3-wades-extruder/  
https://www.youtube.com/watch?v=0PiO9ljPpgE  
https://www.3dhubs.com/3d-printers/Prusa-i3  (hard to see but this is geared)

An image search for Prusa i3 gets you a survey of how many printers use the geared feeder.  A lot of them do, because it works reliably.   ( https://www.google.com/search?q=i3+wade  )
I switched to an E3D all metal hotend and that occasionally jams.  I ALMOST NEVER get jams with a PTFE-lined (non all-metal) hotend, but you can only go up to about 275C with the PTFE.

But the feeder portion is one of the *two* problems; the other is the heater tube.  There has been considerable talk about quality of the steel insulator tube that goes from cold to hot.  It can be made badly, even if it is made to spec.  I tried several, but never bought an expensive one.  I'm of the opinion that it's a design flaw, since Makerbot owners complained of jams even after they went to their "smart extruder"- but I have seen exceptions and I think that's due to lucky or deliberate manufacturing quality differences.  I know two people with working Makerbots who don't have frequent jamming problems- one got a tube upgrade, and the other bought his used from a former Makerbot employee.  Some claim there is a matter of rough/sloppy cuts in the tube, and people sell $10 or $20 tubes with special coatings or metals.

The tube is the focal point of jamming.  If there is an accidental retraction or temporary jam, a plug will form in the cold area of the tube, and that plug becomes impossible to feed.  (And this leads back to the previous problem; once it jams, the non-springy feeder fails.)
(Marlin bug note- NEVER feed extra filament by the control panel (priming)- always push by hand to prime, or reset printer afterwards.  A geared feeder makes it easy to prime the nozzle.)   

see here for an example of the tube discussion, "With PLA this cause the end of the filament to mushroom out, and melt further up the stainless steel tube.  Once it has mushroomed out, it will not fit into the nozzle anymore and will stall the extruder."
https://groups.google.com/forum/#!topic/makerbot/yWk6ezD9dm4[1-25] 

Again: I get virtually no jamming in a conventional ptfe hotend, including my homemade miniature, and the Printrbot original Ubis hotend.  No jamming.  Never angry.  Ultimaker Original is similar and only jams on accidental retractions (pulling filament out partway).  The Makerbot nozzle has caused me and my friends so much grief, sometimes I think you can make a better nozzle by drilling random holes in random household objects.
Regarding the i3 aluminum extrusion frame:  I suspect the new one is more rigid, just tighten everything up and you can easily add a brace if you do have problems.  Also, the forces on the frame don't usually trigger the wobbling, because it's stable left-right and front-back is not happening in the upper part.  For me it's more about the fact that moving the printer from place to place, even working on it, will change alignment, and cause loosening.  And I think that's probably improved with the new aluminum frame design, not knowing firsthand. 

haha regarding the wobbly i3 design, look at what someone did to stabilize it:
https://www.thingiverse.com/thing:723748 
and check out the other pictures!  It's not that bad.  You don't have to do that.  I'm okay just leaving it on a table.  But I can see why this person went to great lengths.
Anyway, additional comments:  I bought the Folger kit without much concern, since I'm in the habit of building and upgrading printers, but I admit I was thinking that all the hardware out there is the same (bearings, feeder tubes), and it's clearly not.  The first bearings to go bad were the X axis belt idler, and the Folger kit actually included a spare bearing so I suspect they knew it was a problem.  Then the Y axis idler and one of the Y linear bearings went bad (LM8UU).  Maybe some oil or lithium grease would have prevented that, but we don't think like that anymore in the new era.  
(Imagine if you had to oil a hard drive.  haha)

I have a laundry list on the i3 kit.  It came with no cable routing accessories or spool holder (but the alum kit has some).  The Z axis homing was sub-par, difficult to adjust, I had to print upgrades.  The Z axis leveling has almost no range of adjustment, with the provided screws; this is common...  The aluminum frame cracked during assembly (but you're getting aluminum).  I met two people who bought Folger i3 kits, and both said their bearings went bad.  The firmware was set for very slow operation.  LCD was not included, but this is common.  The motors provided were all small except for Y... needed to upgrade X, and extruder.  The 3d-printed X carriage didn't fit the LM8UU bearings; I had to customize and reprint.
... If you want to see what people did to upgrade their Folgertech i3's, look here,
http://www.thingiverse.com/search/page:3?q=folgertech+i3
100's of items.  That in itself should not be held against them; there are upgrades for every printer.

My advice is, this is okay, but if you care about quality, resist the temptation to go for the absolute lowest price (as I did, and everyone else I know), and look for differences that reflect quality production, like cable routing features, nice colors, injection molded parts, structural improvements, quality Z axis leadscrews, and the geared feeder I mentioned (or Bowden feed, or Bowden feed with a geared feeder).  You may wish to upgrade various things (color mixing nozzle comes to mind), and that is the main reason to choose a mainstream design, but i3 is already a hackable design whichever one you get.

James




      From: Chris Stratton <cs07024 at gmail.com>
 To: James Carpino <jamescarpino at yahoo.com>; Hack Manhattan! <blabber at list.hackmanhattan.com> 
 Sent: Tuesday, April 12, 2016 11:51 AM
 Subject: Re: [Blabber] Aluminum Prusa i3 Opinions?
  
Thanks James!  Though that is discouraging news.  I'd been hoping I'd
be able to get prints out of the base folger tech configuration and
upgrade primarily for new capabilities (all metal hot end, etc).  But
it sounds like I'd need to budget for basic functional fixes too.  If
sourcing something by parts didn't have so many details to chase down
I'd be tempted to go that route.

Could you comment on what was wrong with the feeder (extruder?) - I'm
trying to figure out if the design you had is the one that is still
current.

I wonder if I'm better off with one of the $400+ range machines and
hope less has to be replaced, or just risk as little as possible on
the factory's sourcing judgement in the "base kit" and be more ready
to replace things that seem deficient from the start.

Still kind of hoping the extrusion frame, maybe sitting on a double
thickness of 3/4" MDF might prove sturdy.

Having not been around a lot, how did the "makerbot clone" (I'm
assuming the CTC sitting next to the ultimaker) turn out?

On Mon, Apr 11, 2016 at 7:26 PM, James Carpino via Blabber
<blabber at list.hackmanhattan.com> wrote:
> Almost every bearing in my Folgertech acryclic i3 went bad.  That includes
> at least one of every kind of bearing, including one of the Z motors.  And
> not heavy use.  Several bearings went bad early.  (And the stock feeder was
> just a nightmare.)
>
> Also, Prusa i3's are inherently wobbly and you will find them flexing if you
> don't pick a rigid flat table to run it on, and don't move it around.  In
> contrast with mendelmax, makerbot, ultimaker, which all have rigid frames
> (and deltas/rostocks which have the *potential* to be rigid framed).  Also
> in contrast with the Printrbot style printers which are wobbly but
> unaffected by transport.
>
> Disclaimer, I have no direct experience with the aluminum extrusion-based
> i3's, they may be more rigid, right?  but I think most of the hardware is
> the same, and the configuration, and the inherent flexibilities may remain.
> Judging by looking at it, I think it's a good starting point, just needs a
> little shoring up... but I said that about our Makerbot clone and look how
> that turned out.
>
> James
>
>
>
> ________________________________
> From: Chris Stratton <cs07024 at gmail.com>
> To: Hack Manhattan! <blabber at list.hackmanhattan.com>
> Sent: Monday, April 11, 2016 12:20 PM
> Subject: [Blabber] Aluminum Prusa i3 Opinions?
>
> Does anyone have personal experience with any of the low-end aluminum
> frame Prusa i3 derivatives?  I'm looking to get a printer of my own,
> and while I like the mechanical integrity of the flashforge/ctc/etc
> box designs, I hesitate at the limited Y travel and that fact that it
> will forever be a large object - my apartment is rather cramped, so
> I'd prefer something where I have the possibility of disassembling the
> vertical pieces from the horizontal and storing or transporting it
> flat.  Hence the Prusa i3, and for durability either an aluminum plate
> or extrusion frame.
>
> - Any opinions on plate vs extrusion?  I get the sense plate may be
> stronger (and quieter) but extrusion offers more ability to alter the
> design in the future
> - what about Z axis motors on the top vs. bottom?  I take it 5mm
> screws are preferred to allow the smooth rods to dominate positioning?
> - how bad are RAMPS electronics?
>
> Specific machines of current temptation are the Folger Tech extrusion
> machine at under $300 or the Geeetech plate - which unfortunately
> seems to have recently gained $100 in price pushing it well north of
> 400.  I worry the Folger has a reputation for being louder, and the
> carriage designs seems quite overhung, but it seems a cheap collection
> of starter parts...
>
> Or anyone have a disused i2 or i3 project/machine they'd like to unload
> cheaply?
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