New and Worried  

RE: New and Worried

The Prusa I3 series is a great product, and I've always thought of it as being higher on the pecking order, both operationally and print quality wise, than the Creality models.

The Ender 3 uses manual bed leveling, correct?  The Prusa MK3S uses a mature and stable sensor for start-of-print bed level correction.  Once the Z calibration is dialed in for each type of build plate that you use, you do not have to futz around with leveling.

Please look over this forum for hints on building the kit.  It's not fool-proof, but it's quite do-able for anyone with common sense and a good mechanical aptitude.

One hint I will emphasize.  Please RTFM, as in the online assembly manual long before you start assembling the printer.  Be sure to read the user comments, as those will give you a heads-up to anything that might be tricky or need special attention.

When assembling, if anything does not fit as you think it should or does not look right, STOP and find out why!  Ask specific questions here if you need to.  Don't force anything to get it to fit.

I would suggest a close inspection of all of the plastic parts.  De-burr them as needed and chase out all holes with a drill bit prior to assembly.  One tricky thing, as one user expressed frustration over a few days ago, are the small square nuts.  Carefully inspect the rectangular holes into which those nuts go, and clean them out if there are burrs or stray filament bits.  Also, you should chase out the nuts by threading them onto a bolt and being sure they thread properly.

I consider the quality of the prints done on the Prusa I3 series to be superior to and more consistent than that of the Lulzbot Taz, the various Creality, Makerbot, and various other usual suspect machines.  In my not so humble opinion, the prints rival those done on the Ultimaker and the Uprint.

I would not be worried, but be careful.  Pay close attention to detail when building the machine and going through the initial calibration.  I would also suggest printing and critically examining the simple test prints (Prusa logo, tree frog, calibration cube) and adjusting/troubleshooting if needed before doing any more rigorous prints, even such thing as the Benchy (Boaty McBoatface) which can be difficult to do on a machine that is not performing as it should.

RE:

Speaking from my experience. As long as you make sure you put the extruder together right it works great 😂 wonder how I know…. Mine has 1000+ hrs on it and is printing awesome. I will gladly put my printer up against any other desktop printer and 9 out of 10 times it will beat in quality. A Ultimaker may beat (for 2x the price) but if a Ender 3 will beat it is either really modded or the person running the Prusa lacks experience.

RE: New and Worried

I'm not a cheerleader, but I own 3 of them 2 are about 5 years old and still purring. just general maintenance, a couple of bed thermistor and cooling fan replacements over the years. Print quality is still wonderful, and the Slicer software, as compared to other software's is still ok.

It's printing on a budget so of course you still have to know what your doing and learn things.

I built all three of my machines, my opinion, it's the best way to go.

Regards

Swiss_Cheese

RE:

I had an Ender 3 for some time and eventually purchased a MK3S+ (kit). I never even powered up my Ender again after using the Prusa!

The Ender could produce very high quality prints when dialled in so don't expect significant improvements in this area though (bear in mind that the Prusa is printing much faster using default profiles).

I never used the Ender again because the Prusa just works every time and failed prints are very rare. The Ender is a great machine for the money but requires more fiddling (bed levelling etc.) and you do end up with more failed prints. It was good to learn on though.

RE: New and Worried

I will echo what @jsw suggested above re the online manual and comments; a wealth of information there.

I would also suggest chasing out the holes in the aluminum vertical frame, the XX aluminum heatbed platen, and the mounting holes in the PSU with the appropriate machine screw prior to assembly. The powder coating on those parts can make some fasteners difficult to start or align properly during assembly if you skip this step.

Happy hunting.

RE: New and Worried

And I wish I had read about packing the linear bearings with fresh lube, apart from that straightforward assembly, good instructions and gummi bears 🙂

RE: New and Worried

Posted by: @hawai

And I wish I had read about packing the linear bearings with fresh lube

Let me ask this question, yet again.

* Has anyone who has assembled the MK3 series kit according to instructions (no additional lube necessary) and regularly cleaned/lubricated it had a failure due to the supplied lubricant being inadequate?

Let me ask a few additional questions.

* Has anyone been told, directly from Prusa support, anything that contradicted the instructions in TFM that no additional lubrication is necessary?

* Has anyone received, directly from Prusa, a copy of that 'notice to relubricate bearings' that has been floating around (from Mitsumi?) and told to follow it?

* Joan? Shane? Any other mod or Prusa representative?  Would it be possible to get a clarification directly from Prusa regarding the peer-supplied advise to remove the lubrication supplied in the bearings and re-pack them?  What, exactly, is the lubricant that comes on the bearings supplied from Prusa?  Is it indeed the 'shipping-only  lubrication' referred to in that (Mitsumi?) bulletin or is it something else?

* On the pre-assembled MK3 series kits, do they have any different/additional bearing lubrication than that used on the kit bearings?

My take on this is that the folks at Prusa are not stupid, and they are not going to intentionally discourage or overlook correct lubrication of their products.  If the bearings were failing right and left due to inadequate lube, Prusa would have received countless support requests on it.  Prusa also runs hundreds of these machines at a high duty cycle in their farm rooms, and should the bearings be prone to failure, they would know it.

I really wish that Prusa would clarify the 'advice' that has been floating around that contradicts the assembly instructions.

RE: New and Worried

Posted by: @jsw

* Has anyone been told, directly from Prusa support, anything that contradicted the instructions in TFM that no additional lubrication is necessary?

As I will be assisting my son assembling an MK3s+, and I am a bit irritated about this permanent bearings discussion in the forum, I have asked the Prusa support today via chat about whether the bearings need to be lubed or not. Here´s the answer:

"...the bearings are already pre-lubricated. So there is no need to lubricate them again. In case you want to do it, then yes, you can, but make sure to clean them properly in IPA and then lubricate it."

RE: New and Worried

Speaking to JSW question.  I had 3 of the original bearings fail within the first 6 months of use.  2 that were install on the Y axis and on the the X axis. I didn't think of it at the time, but while assembling the printer the bearing balls would not stay inside the tracks.  I thought it was odd that he installation instructions listed a maximum number of balls that could fall out and still have a viable bearing, but I used them anyway because of I was impatient.  My experience with them since tells me that if properly greased none of the balls should fall out while handing the bearing.

I still recommend the MK3S printer and fully support reading all the user notes during assembly, but I have to emphasis JSW's recommendation that you carefully inspect/groom each part, hole, and slot before putting together.  I didn't and I broke several pieces during assembly, which is a big deal because I am usually very good at putting things together.  Just remember, these parts are mass produced and not completely perfect when you get them.  They should be, but they are not.  I generally agree the the Prusa staff know what they are doing, but I also know that their in-house quality control does not catch all the flaws. Otherwise there wouldn't be so much chatter on these forums that focus on specific components, nor advice such as pre-grooming your parts before assembly.

Concerning s pre-grease of the bearings I would do it. I generally don't clean out the original grease on new bearings, because I feel is unnecessary when using one of the grease injection tips to force the new grease into the housing. Also soaking the bearings to dissolve the grease must be done with very specific solvents, as the grease shields are easy to chemically damage. 

RE: New and Worried

@jsw regarding the bearings:

My comment referenced the many posts and suggestions to add some more lubricant to the bearings. I completely agree with you that the guys at Prusa know what they're doing, but even they got a few things less than optimal (live-z calibration, process of re-assembling the heater block with the consequence that a lot of people have to do it many times until they get the "gap" right).

I simply assume that some more lube would make for less noisy operations. Admittedly I haven't disassembled my printer yet to re-pack the bearings but every time it squeaks and squeals I wish I wouldn't be that damned lazy 😉 

RE: New and Worried

Posted by: @hawai

every time it squeaks and squeals I wish I wouldn't be that damned lazy 😉 

If it squeaks and squeals, something is wrong!

If it's a new(er) printer, assembled according to instructions, all you should hear is a 'whooooosh' when the Y axis moves and kind of a 'whirrrrr' when the X axis moves.

With the belts released, do the X and Y axes move without obvious friction?  Do you periodically lube the rods according to instructions?

Are there any obvious score marks on the X and/or Y axis rods?

I would most definitely find out and correct any squeaking or squealing noises.

RE: New and Worried

I was overstating things a bit.

All axes move without binding and the rods are smooth without marks.

It seems to be making funny noises only when it's laying down plastic at some oblique angles. Probably some resonance thing.

But after about 2 years I definitely should get around to do some serious maintenance...

RE: New and Worried

That 'singing' is not unusual at all.  It happens on various printers as well as the Prusa.

Mine sounds almost musical when drawing some arcs and circles.

That is totally unrelated to mechanical issues such as bearings sticking.

As far as periodic maintenance, I am in the habit of putting a drop of oil (generic hardware store synthetic machine oil) on the rods every so often, and rub some Superlube on the rods every so many so oftens.

* Has anyone who has assembled the MK3 series kit according to instructions (no additional lube necessary) and regularly cleaned/lubricated it had a failure due to the supplied lubricant being inadequate?

Not me.  I followed instructions and I have never packed the bearings.

I do, however, run a monthly clean and lubricate maintenance procedure.

    https://help.prusa3d.com/en/article/i3-printers-regular-maintenance_2072

I have, as it happens, replaced two linear bearings, but they had not failed.  An idler bearing had collapsed and scored the side of of the carrier so when ordering a replacement idler pulley I also ordered the two linear bearings in the carrier as a precaution and replaced them too in a new part - without extra lubrication.

Four and a half years so far and no squeaks, no scratches and no lost balls.

Cheerio,

RE: New and Worried

I also remember the admonitions about the missing balls from the bearings.

I carefully inspected each bearing, checking to be sure that no balls were out of place, or elevated to the point that they might get pushed out by the rod insertion.  All of the rods went in smoothly, as expected.

RE:

I just put together a kit about 3 months ago (3s+). I didn’t lube anything.. I’ve got maybe 400 hours of printing and no issues. The squeaky sound on curves is just part of the x/y quick motions.. There is an OctoPrint plugin that I think can make this quieter by exchanging some of the G codes, if you want to tinker. 

However, the kit is not ‘easy’ to put together. It requires an investment in time and attention. I’d recommend pre-reading the online assembly instructions and read all the comments of each section. They are invaluable. I highly recommend 2 WIHA screwdrivers or equiv.  263125 and 263130. Although hex wrenches are provided, these can make assembly nicer. Use the ‘pull’ method to get all nuts firmly into their position and then insert the final screw. Don’t force rods too hard into a hole opening. If you suspect a hole opening is too small measure with a caliper and contact Prusa support. (Get a caliper, even cheap one will do). Some type of rat-tail file might help smooth any burrs that might exist on the plastic holes, but I did not have to sand/file anything on my parts.

I took about 4 days to build and thoroughly enjoyed it. The goal is not to put the kit together, it is to learn how each assembly works..  So take your time and think through each step to see how it works.. Do not rush!  

One thing I did wrong was that I didn’t PAY ATTENTION TO CONNECTOR PICTURES to see which connector is on which end. I reversed the heat bed connectors, and after they are routed it can be a lot of work to fix. 

Don’t route the ribbon cable inside the metal, print a part that holds them and binds into the channel after. 

The kit and instructions are very high quality and as an electronic engineer I’ve put together a lot of stuff.  I have done almost zero calibration on my printer.. and it just works with 3 different non-Prusa brands of PLA and PETG. If you can afford it, and if you print a bunch of PETG, the rough sheet works super. If you use the smooth sheet, make sure you use some release agent or you might ruin your sheet. (Windex, glue, tape, etc). 

I contacted Prusa support once about my connector issue and they were more than helpful. So I had nothing but a positive experience. 

RE: New and Worried

I've been 3D printing since 2013 and bought the MK3S just about 3 years ago. The 2 biggest differences to me compared to other printers I've owned is Prusa is not afraid to source quality parts like the E3d V6 hot end or the quality power supply. But the other and bigger difference is the auto calibration built in. I find if it passes that it will print well after nozzle height adjustment and it's going to print a good part if I follow the filament temp recommendations. As long as I pay attention to the minimal maintenance required it's going to print reliably print after print. Worth the purchase to me to not have to spend countless hours calibrating like I used to have to.