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davidgeller

Edge-to-edge repeatable accuracy of UM3 vs Prusa i3 MK2

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I have a Prusa-assembled i3 MK2 which has successfully printed hundreds of objects. However, when I've tried to be more efficient and layout the same model multiple times I've been largely unsuccessful.

Sometimes I've had stringing issues and sometimes dramatic layer shift issues. Recently I experimented with Simplify3D's multi-process option where I'd attempt to print 5-10 cm in one corner, move to the next (and down) and continue printing. I carefully positioned my models so that the head assembly would never touch. Still, the Prusa had a tough time - almost as if it lost precise positioning ability going down and restarting a new layer. Add to that the fact that a firmware upgrade forces a painful (and often challenging) recalibration step - I'm thinking of moving into a new class of FDM printer.

Can I expect the UM3 to have precise, repeatable accuracy across the entire printing area?

If I wanted to stack multiple pieces vertically and use the water soluble material (perhaps only a few layers) between pieces am I likely to be successful?

Thanks in advance for any feedback you can share.

-David

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layer shifts are likely to be that you didn't tighten the pulleys enough. tighten the hell out of those prusa pulleys. Same goes with ultimakers.

As far as comparing um2 or um3 to the i3 I recommend you spend $20 and order something on 3dhubs and insist it's made by the um2 and nearby where you live and then go pick it up and talk to the owner and look at the quality of the part.

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I was really getting excited about the UM3 until I watched this video: https://www.youtube.com/watch?v=pt8axoVuE9o. Now I'm not sure it's a smart investment. Maybe these and many other issues, across lots of brands and products, is the nature of FDM printing.

well, i'm disagreeing with the video.

if you look closely, he has one of the first printers (look at the styrofoam on top and the black spool holder) , very early firmware, and early cura (2.5).

there have been known issues with PVA printing with those earlier versions and the older firmware.. if you look at the issue he has with the print core at 7:35 he did something naughty, that caused him to take the core out while a lot of filament was still there.. so unsure how he managed that..

then printing the brain did not work out because he did not follow instructions the first 4 times regarding the print plate handling, then he did use the glue stick but he forgot to verify if he had enough filament.

as far as the print head stopping and the cores remained hot, i'm not buying it. i've had crashes with the earlier firmware and the cores always cooled down. they never stayed hot.

then the problem with the "infinite loop" is what you get when you have 2 materials with nfc tags but did not load them with the nfc detection. resolved in later firmware too.

then the clogged bb core. i've honestly never experienced that. not being able to buy acupuncture needles because you have a medical license is just strange. we all have ebay.

his conclusion is laughable.

yes, i agree that the form2 is a better printer for medical applications. that has nothing to do with reliability but everything with the advantages of SLA over FDM when it comes to medical applications.

all the other conclusions as far as reliability, buildplate adhesion those are all simply down to experience with a particular printer. granted, some of the things he ran into were caused by old versions of software/firmware but that has all been resolved. I run my printers 24/7 and I have over a 99 percent success rate.

for me, the final minute of the video said it all. look at him using that pair of pliers like a caveman. the entire printer bounces up and down.. that just makes it one large trolling attempt to me.

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as far as accuracy;

I've handled multiple orders with 500+ identical components.. without any problem. that being said, seeing as Prusa is printing his components in house, that should not be a problem for the Prusa either..

so yes, you can expect the UM3 to have repeatable accuracy across the entire printing area... I can vouch for it :)

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I disagree. He is not an expert and frankly does not know the boundaries of the machine. If I were new and were told to do a cold-pull, I would have struggled like him when trying to yank out the filament. He already stated that he was afraid to break the printer.

The firmware did behave in an unexpected way and that can't be the user's fault either.

Since the UM3 targets professional users, there is no excuse for shortcomings in the setup experience of the printer.

Any of use would have handled it way better, but that's because we have lots of experience with these printers. New users do not have that and frankly if I were a pro user and had so much trouble with one machine, I wouldn't have bothered with it again :/

The only thing one can blame him for is that he didn't ask for support earlier.

The situation has improved greatly since then. The firmware is stable and much clearer than before. But still - if you loose one customer like this, I doubt they'll reconsider.

Edited by Guest

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I disagree. He is not an expert and frankly does not know the boundaries of the machine. If I were new and were told to do a cold-pull, I would have struggled like him when trying to yank out the filament. He already stated that he was afraid to break the printer.

The firmware did behave in an unexpected way and that can't be the user's fault either.

Since the UM3 targets professional users, there is no excuse for shortcomings in the setup experience of the printer.

Any of use would have handled it way better, but that's because we have lots of experience with these printers. New users do not have that and frankly if I were a pro user and had so much trouble with one machine, I wouldn't have bothered with it again :/

The only thing one can blame him for is that he didn't ask for support earlier.

The situation has improved greatly since then. The firmware is stable much clearer than before. But still - if you loose one customer like this, I doubt they'll reconsider.

Thank you.

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I disagree. He is not an expert and frankly does not know the boundaries of the machine. If I were new and were told to do a cold-pull, I would have struggled like him when trying to yank out the filament. He already stated that he was afraid to break the printer.

The firmware did behave in an unexpected way and that can't be the user's fault either.

Since the UM3 targets professional users, there is no excuse for shortcomings in the setup experience of the printer.

Any of use would have handled it way better, but that's because we have lots of experience with these printers. New users do not have that and frankly if I were a pro user and had so much trouble with one machine, I wouldn't have bothered with it again :/

The only thing one can blame him for is that he didn't ask for support earlier.

The situation has improved greatly since then. The firmware is stable much clearer than before. But still - if you loose one customer like this, I doubt they'll reconsider.

Glad to hear the firmware has improved. Does the printer now detect when filament has run out and allow you to add new filament and continue printing with the hot-end returning to its last position?

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as far as accuracy;

I've handled multiple orders with 500+ identical components.. without any problem. that being said, seeing as Prusa is printing his components in house, that should not be a problem for the Prusa either..

so yes, you can expect the UM3 to have repeatable accuracy across the entire printing area...  I can vouch for it :)

Thanks. That's very helpful.

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layer shifts are likely to be that you didn't tighten the pulleys enough.  tighten the hell out of those prusa pulleys.  Same goes with ultimakers.

As far as comparing um2 or um3 to the i3 I recommend you spend $20 and order something on 3dhubs and insist it's made by the um2 and nearby where you live and then go pick it up and talk to the owner and look at the quality of the part.

Good advice. Thank you.

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I disagree. He is not an expert and frankly does not know the boundaries of the machine. If I were new and were told to do a cold-pull, I would have struggled like him when trying to yank out the filament. He already stated that he was afraid to break the printer.

The firmware did behave in an unexpected way and that can't be the user's fault either.

Since the UM3 targets professional users, there is no excuse for shortcomings in the setup experience of the printer.

Any of use would have handled it way better, but that's because we have lots of experience with these printers. New users do not have that and frankly if I were a pro user and had so much trouble with one machine, I wouldn't have bothered with it again :/

The only thing one can blame him for is that he didn't ask for support earlier.

The situation has improved greatly since then. The firmware is stable much clearer than before. But still - if you loose one customer like this, I doubt they'll reconsider.

Glad to hear the firmware has improved. Does the printer now detect when filament has run out and allow you to add new filament and continue printing with the hot-end returning to its last position?

No there is no end-of-filament detector.

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Cura tells you how much filament every print will use. Exactly how much. If you print from the usb stick I believe the printer also tells you this. It's a good habit to take a peek at the filament spool before you start and if you aren't sure, unwind it and measure to make sure you have enough. I only have to do this on 1% of my prints when I'm near the end of the spool.

You *can* pause a print and change the filament part way through but you have remember to do this.

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I really feel for him, as the marketing tells us the UM3 is for professionals, is easy to use and so on. But, if you have never had a 3D printer before, I can see the many issues he ran into are of being a new user.

A few thoughts...

Upgrade your Cura and Firmware.

Use less PVA! Cura has a features where the support material boundary will help. Rather than using so, so much PVA, you could use the PLA support and then a thin layer of PVA between model and support. That should dramatically reduce some print times and use a lot less [expensive] PVA. (Which leads me to again, wishing Ultimaker would make high quality Cura tutorial videos demonstrating these features. The 3D techies know where to find these things, if you haunt here daily...but "professional" users would sure benefit from tutorials on advanced topics)

As for the prints not sticking, perhaps @gr5 can link in his wonderful video on improving adhesion. Just coating the bed with diluted wood glue would help you out. Glue stick doesn't always apply evenly and on the stick I have, sometimes small pieces come off.

It sounds like you are a good doctor trying to learning how to use 3D printing in your practice. Like any technology, it'll take some learning. (I worked for Information Systems at a medical center for 7 years. I know how doctors embrace new tech, but need some assistance taking advantage of it.)

Hope our comments are useful.

Don't give up. The UM3 is a wonderful printer (I miss having the loaners I had!)

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You may be right that a 3d printer is not for you. You can always order prints online. 3d printing takes in my opinion quite a bit of learning. It's not like a 2d printer. buying and learning a 3d printer is more like buying and learning a milling machine. It's not too bad but you need patience. I don't know of any other FDM printer more reliable and easier than the UM2 or UM3. But it's not trivial.

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I really feel for him, as the marketing tells us the UM3 is for professionals, is easy to use and so on.  But, if you have never had a 3D printer before, I can see the many issues he ran into are of being a new user.

A few thoughts...

Upgrade your Cura and Firmware.

Use less PVA!  Cura has a features where the support material boundary will help.  Rather than using so, so much PVA, you could use the PLA support and then a thin layer of PVA between model and support.   That should dramatically reduce some print times and use a lot less [expensive] PVA.   (Which leads me to again, wishing Ultimaker would make high quality Cura tutorial videos demonstrating these features.  The 3D techies know where to find these things, if you haunt here daily...but "professional" users would sure benefit from tutorials on advanced topics)

As for the prints not sticking, perhaps @gr5 can link in his wonderful video on improving adhesion.  Just coating the bed with diluted wood glue would help you out.  Glue stick doesn't always apply evenly and on the stick I have, sometimes small pieces come off.  

It sounds like you are a good doctor trying to learning how to use 3D printing in your practice.  Like any technology, it'll take some learning.  (I worked for Information Systems at a medical center for 7 years.  I know how doctors embrace new tech, but need some assistance taking advantage of it.)

Hope our comments are useful.

Don't give up.  The UM3 is a wonderful printer (I miss having the loaners I had!)

Thanks for your feedback. Just an FYI - I'm not a doctor. The video I found was a physician using the UM3 to print some anatomic models.

I've been 3D printing for a year. Assembled a few Original Prusa i3s (and donated them to our local school system) then moved to the Original Prusa i3 MK2 (bought an aseembled one). I designed some parts for Tesla users to manage their charging cables and have been printing them with my Prusa. I print more than enough to pay for UM3s and, recently, had some issues with the Prusa - perhaps after running through about 75KG of filament. That has been my motivation to consider the UM3.

Plus - I really like the idea of stacking parts and using the water soluble material between pieces and then allowing the printer to do its thing for 24 hours or so. Hopefully that's something that's practical and would allow me to place several parts and print them unattended.

What remains concerning, though, is some stuff I see that makes that more challenging - like being able to detect low materials and pause print jobs. The Anycubic i3 clone does this beautifully.

Otherwise - I think, based upon the comments I'm reading here, I'll take the plunge.

While I'm more than capable of assembling low-cost FDM printers, I'm now looking for a work-horse and want to spend less time worrying about spaghetti jobs being created while I sleep.

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Cura tells you how much filament every print will use.  Exactly how much.  If you print from the usb stick I believe the printer also tells you this.  It's a good habit to take a peek at the filament spool before you start and if you aren't sure, unwind it and measure to make sure you have enough.  I only have to do this on 1% of my prints when I'm near the end of the spool.

You *can* pause a print and change the filament part way through but you have remember to do this.

So the print head will remain where it is, or retract and then return to its last good position? Is there documentation online that explains this in more detail?

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If you pause a print or use the change filament in the firmware on the printer, it will pick up exactly where it left off.

Also, I tend to try not to let the tech do all the work for me. In my opinion, while it is good to have tech do a lot of things for you, it can fail and it usually fails at the worst time.

So, I have no issues with having to keep an eye on my filament spools. And, I have been caught with my pants down a few times with that one. I just firmly believe in a solid set of physical procedures/checklists to do.

Also, the problem with seeing a first-timer do a product review is not good. A person who is intuitive with machines or tech will make it look like a snap. A person who is not so good with those things, and need tech help, will make it look like a nightmare. An experienced printing person will be able to tell you why something is an issue and what the comparative values are.

And, with something like FDM/FFM printing being susceptible to environmental issues (humidity being the worst in my experience) can make a difference. I can do the same print here in Brooklyn with no issues, but the same print could fail in a tropical/humid environment without proper humidity controls.

My biggest wish list for Ulti-Santa is the ability to pick up a print from where it left off in case of a blip in power or something like that. I have my printer on a battery back-up, but, if I am not home, it will not last for hours until I return.

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PVA is difficult and fidgety and not as reliable as PLA.  But it's just support so when the pva fails in some way the print is usually still awesome.  But if you were to pancake your printing with layers of pva between...  I don't think you will like that.  You can lay PLA on top of a pva structure just fine.  But not the other way around so much.  If you print PVA on top of PLA it will not stick well at all.  So there is this nice cura feature just for this purpose: "horizontal expansion".  It means the pva sticks out from the pancakes (like syrup?) and reaches all the way to the bed.  This helps tremendously.  

Also bits of pva worms get everywhere (because - it's sooo different from PLA in mechanical properties and doesn't stick to itself so well).

Also pva is quite expensive.  And switching nozzles takes typicaly 5 to 10 seconds which doesn't sound like much but this is an extra delay on every layer.

But the UM2 and UM3 are really great work horses.  That I will agree with.  Strongly consider the UM2 though - fewer filaments means less setup time and fewer things that can go wrong.  People seem to think the UM3 is better, but it is just... different.  it can do 2 materials instead of 1.  But the UM2 has been around longer and had many improvements (the plus!) and is a great machine and much cheaper.

Or get a few i3 printers, lol.

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