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SecretSquirrel
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Sat Oct 13, 2018 11:02 pm

Pictures!!!!

What happens when you really mess up in the slicer....
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All the internal structure was missing because it was set to only print the surface contour.
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This is what it is supposed to look like.
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I've spent a lot of time learning how the various settings impact the print and fine tuning. In this series, you can see the layer seam. Each print want adjusting one or two parameters, until the last one, the seem was almost completely smooth. There is still a bulge where it transitions from a shell to solid infill near the top, but in general the surface is very smooth. The changes were mainly to retract, unretract, coasting, an linear compensation settings.

Another "oops" in slicer settings. This is actually an incredibly hard shape to print smoothly because of the extreme angle at the top.
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Here is what it is supposed to look like.
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Benchy. I have some spikes at the retract points. This was printed from pre-sliced gcodes included with the printer. Beyond the spikes and a few strings, it printed quite well. I have a bit of ringing in the X axis as the belt is probably a bit tight, but I'm not taking it apart at this point. It's not enough to annoy me and I'm afraid it will take an large amount of time to get things back to working this well.
[img]http://www.kovarindustries.com/coppermine/albums/userpics/10001/normal_IMG_20181012_192233714.jpg/img]

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I have been doing a little bit of CAD work as well. These are some pretty simple bits, but they turned out quite good.
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Its been a lot of "work" and I still have lots of learning to go. It will be a good while before I have a feel for the proper print settings for a model without printing a test first. I've been playing with both Slic3R PE and Cura and wish I could combine bits of both. The print simulation in Cura is quite handy and it is way more powerful. Or, at least it has way more settings and knobs to turn -- perhaps too many. Slic3R is easier to use and the ability to visualize the various types of print feature, as well as to readily highlight the retraction and unretraction points are also nice. Lots of learning to do...

All this printing has really taken a toll on my helper. She is just tuckered out...
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--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Mon Oct 15, 2018 7:00 am

Crazy impressive for just a month of self-education. Thanks again for sharing. That last fin print is just bonkers.
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SecretSquirrel
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Mon Oct 15, 2018 12:11 pm

drfish wrote:
Crazy impressive for just a month of self-education. Thanks again for sharing. That last fin print is just bonkers.


To be fair, I grew up building things from scratch, went to school in engineering, and have been programming computers since before I was a teen. As hobby/home users go, I'm probably in the group most likely to have success. Investigatory patience is key, doubly so we you start working with slicer settings as there are dozens, many of which interact. Change one at a time and understand its impact on the print quality. For that fin print, I cut the model down to the upper 15mm or so and printed about a half a dozen with different settings.

My biggest problem at the moment is time. Even with a small part of a model, its a 30 minute cycle time to test a change. At best, I might get three or four attempts in an evening, if I don't have anything else pressing. Large prints are in the 8-12 hour range, so I try and start one shortly before bed and another before I leave for work in the morning. If its particularly complex and takes much over about 10 hours, I might not get two prints in a day. Yet another reason I'll likely get a second printer in the not too distant future.

One thing I didn't mention -- space. The printer is obviously not small and takes a fair amount of desk space. One of my concerns with a second printer is where I will put it.

--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Mon Oct 15, 2018 12:18 pm

SecretSquirrel wrote:
The printer is obviously not small and takes a fair amount of desk space. One of my concerns with a second printer is where I will put it.

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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Tue Oct 16, 2018 9:38 am

SecretSquirrel wrote:
One thing I didn't mention -- space. The printer is obviously not small and takes a fair amount of desk space. One of my concerns with a second printer is where I will put it.

--SS

Bob Clagget (from YT I like to make stuff) has both of his under a desk he also has it enclosed to better control dust and temperature.
https://www.iliketomakestuff.com/buildi ... workbench/
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Tue Oct 16, 2018 4:20 pm

(spoiler, zero experience with 3d printers, proceed with skepticism)
noticed the strings on the boat test you did, then 3 days later see a video speaking about moisture buildup in filaments whose thumbnail showed that same boat test print, one with excessive strings (much more than your print), one with no strings.. along with print quality, the video (on a single set of tests) shows that excessive moisture in the the filament can also cause degraded layer adhesion strength which may be of interest to you especially for your RC plane wings, along with ways to resolve the issue

here is the link if you're interested https://www.youtube.com/watch?v=FAXUjZZER5E
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Tue Oct 16, 2018 9:36 pm

godforsaken wrote:
(spoiler, zero experience with 3d printers, proceed with skepticism)
noticed the strings on the boat test you did, then 3 days later see a video speaking about moisture buildup in filaments whose thumbnail showed that same boat test print, one with excessive strings (much more than your print), one with no strings.. along with print quality, the video (on a single set of tests) shows that excessive moisture in the the filament can also cause degraded layer adhesion strength which may be of interest to you especially for your RC plane wings, along with ways to resolve the issue

here is the link if you're interested https://www.youtube.com/watch?v=FAXUjZZER5E


Moisture is definitely an issue. Doubly so since it has rained something like five of the last seven days and is supposed to rain off and on for the next week. My back yard squishes when I take the dogs out. Only so much I can do about that. That said, I'll try and post a couple of pictures tomorrow of some test prints from wing sections. The surface it probably about as nice as I could hope.

The Prusa gcode lays down a purge line outside the print area to prime the extruder and I have had at least one case of "explosive" bubbling from, what I assume is, excessive moisture.

--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Tue Oct 23, 2018 10:11 pm

Well, it looks like I get to tear down the hot end. :cry:

This evening, I ejected the filament to change back to silver and suddenly the extruder gears started skipping. The filament goes a ways in and then hits on something quite solid. Based on the approximate length, it looks like it's hitting on the lip of the heat break, where the PTFE tube sits in. If I had to guess, I'd say a bulb on the end of the filament, at some point in the past, pulled the PTFE tube up to the very edge of the heat break and it finally worked its way out.

So, now I have to decide whether to deconstruct the majority of the x axis and adjust the belt tension, or just to take the hot end out. I know I can take the hot end out with the x axis in place, as I have done it before.

--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Wed Oct 24, 2018 8:56 am

I had to take apart the extruder assembly once, when I was first trying to use flexible filament - at default speeds it would jam up in the nozzle and then filament would start shooting out the side of the feeder assembly, and somehow or another it tied itself in a knot. Fortunately, having followed the instructions to assemble the extruder in the first place, it really wasn't that hard to take the thing apart and then reassemble it properly. Another point for good documentation. Also, I realized that slowing the printing down helped a ton with flex filaments.

I haven't had any problems with humidity so far, but I've got central air in the house, and it's usually not all that humid here outside of a month or so in the summer. I gather it can be a terrible issue with PLA especially.

Also, I realize that you're dealing with a misaligned PTFE tube, but have you picked up any cleaning filament to help keep particles from clogging in the extruder? I grabbed some cheap eSun cleaning filament early on, and I use it whenever I'm switching filament types, or just every few weeks in general. It's cheap, and a little goes a long way, and I figure it should help.
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Thu Oct 25, 2018 8:30 pm

Turns out I was wrong. It wasn't that the PTFE tube had dislodged, though it had pulled up slightly. There was a small chunk of filament that had broken off and was lodged in there. I ended up having to completely disassemble the e-axis. I pulled the heater and thermistor out of the heating block. Then pulled the entire hot end out of the x carriage. To get the piece out, I had to unscrew the heat break from the heat sink. I dusted and checked the x-axis cable tension while I had everything apart.

Everything is back together and its printing again. It only took about an hour to do the tear down and rebuild. I spent probably two hours re-calibrating things after I put it back together. I still haven't gotten the first layer back as good as it was, but the print quality is still fine. Once I put it all back together, I wiped down the the x and y rods to get the residual gunk off and lubed the rods and bearing with good ole 3-in-1.

I was a bit annoyed that I hadn't printed the various parts I wanted to upgrade since I had the hard bits taken apart. Once I get finished printing the current set of jobs, I'll probably go ahead and print out the parts and put them in the corner for the next time I have to do maintenance.

I haven't worried about cleaning filament to this point as I haven't printed anything but PLA to this point. However, I'm about to venture into the realm of flexible filament, and well as PETG for the upgrade parts, so I went ahead and ordered some.

--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Sun Oct 28, 2018 8:50 pm

Today I made the first attempt a printing something other than PLA. Did I got to PETG, or some other stiff filament? Of course not -- NinjaFlex or die! I've done a good bit of reading and was prepared to spend most of the afternoon fighting with it. The parts were pretty simple: the main gear and tail wheel tires for the 3dlabprint Edge 540. So, what was the result?

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That was the first attempt.

Part way through the print, you can see the infill.
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Printing the first solid top layer -- there we three more after that.
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You can see the stringiness in the wider shot, after the print completed.
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All cleaned up and installed on the wheel.
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So my profile likely needs more tuning, if I we going to do something silly and print something like a benchy out of NinjaFlex. It works fine for tires though. I used PVA glue on the bed to provide a release agent. I was able to peel the tires off the build plate with only a bit of effort. I probably went a bit overboard with the glue stick, especially on the second main tire. It makes the bottom surface a bit less smooth. A good process seems to be to rub on a thick layer of glue, then take a damp coffee filter and smooth it down to uniform layer. Seems to give a good surface and releases well.

Somehow or another I managed to get a pinhole in my second main tire so it isn't completely sealed. Luckily it doesn't matter for my application. Still annoying, as the first one seems to be completely sealed.

For all the concern I had after reading about people's efforts at printing TPU in general, it turned out to be a bit "non event". I've got some PETG printing I should do now.

--SS

*edit* One thing I learned when printing these tires -- the print cooling fan makes a horrible noise when run at less than 100%. The TPU profile I was using had the fan set at 30% after the first layer. Apparently the PWM frequency for the fan speed control is well within the audible range. The fan itself is a three pin fan, the the controller is PWM modulating the actual fan power, and not just a control signal. Poor design and quite painful on the ears if you need something that is not 0% or 100%.
Last edited by SecretSquirrel on Sun Oct 28, 2018 9:25 pm, edited 1 time in total.
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Sun Oct 28, 2018 8:56 pm

Oh, an in case anyone thinks all I print it airplane stuff...

My daughter was home from college for a long weekend. She has been lobbying us to let her take one of the dogs back with her, which she isn't ready for yet. But, as a compromise, I sent her back with her own puppy. :wink:

Still on the build plate, with supports.
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All cleaned up.
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She also happens to love elephants.
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--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Sun Oct 28, 2018 9:20 pm

My thoughts, a bit over a month in...

I'll buy another Prusa I3 MK3 kit, probably in the spring.

It's not perfect, buy any stretch. The power supply is undersized and almost certainly will fail at some point for people running on 120V. The y-axis belt alignment needs some work. The power failure detection and restart is way too touchy and may or may not save your print anyway. It works, but I ooze enough filament during heating that restarting leaves a huge blob. The filament sensor is apparently nothing but trouble -- I have no experience with it, it has remained disabled on my printer from the beginning. All that said, the base platform seems to be solid and I found it relatively easy to dial it in to the point of producing relatively high quality prints.

Could I get equivalent quality from a cheaper printer? Probably. However, I get the feeling that it would be more of a crap shoot. So, if I get a $400 Chinese clone, then spend hours and a couple hundred dollars on upgrades and fixes, I might as well go with something I'm already familiar with. As it sits, I figure it's about $100 is upgrades/replacement parts for the MK3, with the main items being the power supply and springs for the bed.

Would I recommend a MK3? Yes, with caveats. If money is more valuable than time, then you can probably get by with a cheaper clone. If you are looking for a ready to go, out of the box, printer, you can probably spend another $500 and get a more ready-to-go solution. I see the MK3 as filling to upper end of the DIY space, and it seems to do that well. Also, as I have noted before, I like supporting those trying to do open source hardware, so buying from Prusa, rather than a knock-off, is a plus for me, even at the higher cost.

--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Sun Oct 28, 2018 9:30 pm

Thanks again for these updates. :)
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Fri Dec 07, 2018 1:48 pm

Somewhere early in this thread, someone mentioned that they would be interested to see what my thoughts were after a significant amount of time with the printer. So far, I think it has been generally positive. While I had may share of issues to address, and it is certainly not a put it together and go type situation, since I have addressed those issues, the printer has worked without issue. I have run into one longer term problem. The linear bearings for the Y axis have started to score the Y axis rods. Early in the Mk3 life, Prusa shipped a number of printers with un-hardened rods. You can find several discussions in the Prusa forums. The unhardened rods would get scored rapidly. My printer has the proper hardened steel rods, and still, one of the two (left looking at the front) is showing signs of scoring. The design of the linear bearing attachment to the print bed makes it very easy to deform the linear bearing casing and cause one or more of the ball bearings to seize. Over time, this will score the rod. The bearing attachment is just a U bolt through the print be frame and if you over tighten, the U bolt puts pressure on the bearing case in a very small area. So, the scoring is likely an assembly problem on my part, but its a weak design that allows it in the first place. The spring kit will uses bearing attachment parts for Thingiverse (something like this: https://www.thingiverse.com/thing:3214732). In the mean time, I rotate the Y axis rod about 15 degrees so that the bearings will wear on a different part of the rod.

Now, I still have print problems from time to time, but they are all of the type that are common to all 3d-printers. Occasionally I'll get bed adhesion issues. Most of the time, print problems are because I screwed up a slicer setting and asked the printer to do something silly, or beyond its capability.

I haven't actually been printing a lot since Thanksgiving due to my lack of time to do things. I decided it would be good to print some things from Thingiverse since the printer wasn't doing much else.

This is a model of an automatic transmission. Its a fully operational 6 speed transmission, plus reverse. Fully printed, no external parts. You can just barely make it out in the picture, but the brakes used to hold the sun gears in place are actually printed as integral parts of the frame. They just snap loose after printing. Their pivots are printed in place. Was actually pretty impressive.

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Yesterday afternoon, I stumbled across this Christmas tree. You can only slice it with a slicer that lets you assign different print processes to different parts. I used Simplify3d, since I have it.

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Once I printed it, I decided it needed a "tree topper", so I went and found a star and scaled it down to a size that worked with the tree.

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Last night, I decided to print a DNA desk tchotsky as it is rather appropriate because of where I currently work.

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The first image really is the print sitting on the buidl plate as it finished. No supports. For size context, its about 6" tall and the runs are about 2" in length. If you look very closely, you can see a slight convex shape to the bottom of the rungs due to sagging, but there is no layer separation and the whole thing is quite smooth, even at 0.2mm layer hight. I started the print right before I went to bed and I was a bit nervous about what I was going to find when I got up. I was pleasantly surprised, to say the least.

I'm traveling with work next week, and if I can get time to take some measurements this weekend, before I leave, I'm going to try and use my evenings to do some CAD work on an enclosure for a project I'm working on. I will, of course, post an update when I finally get it done and try and print it.

--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Tue Dec 11, 2018 10:44 pm

I did my first multi color print. Note that I don't have the Prusa MMU, so I'm doing it the old fashioned way -- manually changing the filament.

Image

Image

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This is also a pretty good test piece for the printer as well. The helix is printed without support so the "base pairs" are completely bridged sections. The one in the picture on my desk was printed as fast as the printer would run. It took about 2hr 50min to print.

Short video of one of the "base pair" segments being printed.
https://youtu.be/bNO2kDUSjEs

The multi color printing turned out better than I was expecting. That said, doing a complex multicolor print with manual filament changes would be tedious at best. I also still have a bit to work out with Simplify3D, to make it generate g-code that I don't have to edit afterwards.

--SS
 
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Re: My thoughts on the Prusa I3 MK3 3d printer kit

Thu Feb 07, 2019 4:56 pm

Just wanted to come back after several months of printing and give some more thoughts. I've gone through an entire roll of PETG. Other than fuzz on some prints with multiple parts on the plate, I've had almost no problems at all with PETG. I'm using Magigoo as an adhesion/release agent on the build plate. Good stuff. To this point, the only change I have made to the printer is to switch from the Prusa spool holder to a pair of these. Definitely worth it. Makes for a much smoother filament feed.

I have run into a few problems, though generally minor. On the very minor side, the fuzz on PETG prints has a tendency to collect on the heater block and melt. It explains why some of the nozzle/heater block pictures I have seen were so ugly. I'll wipe off the nozzle and heat block with a coffee filter every few prints, while its hot to clean it up. Less minor, the black PETG I'm using does have a slight tendency to trigger the filament run-out sensor. The good news is that the prints all resumed and completed cleanly. Its a known problem with the Mk3 filament sensor. Also related to PETG is the cooling fan PWM. If you aren't running at 100%, the PWM frequency is very audible and makes for a very loud fan, especially since the default PETG cooling settings run the fan at 30%. There are a couple of suggested fixes in custom firmware that all have their downsides.

One of the reasons for all the PETG printing is that I'm getting ready for the first major maintenance/tear down. Actually, major may be an overstatement. I'm not planning of tearing down the extruder or X axis. I'm getting ready to put it in an enclosure, which means removing the power supply. I'm also going to replace the Y axis motor mount and idler/tensioner, the Y axis bearing U bolts are getting replaced with straps. I'm also going to replace the PLA Y rod mounts I printed early on with PETG prints. While I have the Y carriage off, I'm going to check the rods and bearing and lube them up well.

Almost six months in, I'm happy with the purchase. For what it is, and what you pay, I think the only real weak spot is the power supply. Yes, there are some other minor issues, but this is still a DIY/hobbyist printer. Admittedly it is at the upper ends on the price range, but for 99% of the fiddling and print issues I've run into, its be a PEBKAC issue and not the printer's fault in any way. I'd love to have the money and time to pick up something like a Creality Ender3 and an Ultimaker 2 Extended, or something similar, and see what the value proposition really is. However, without anything to compare it too, I'd say I'm happy with it, and if budget, time, and need are there, will get a second one.

--SS

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