Pros and cons for Bear v2.1 upgrade from i3MK3S+  

Not a must-do upgrade

Posted by: @prusanewuser

[...] Also, Prusa said they would not provide support if I do the upgrade. I wonder if doing the upgrade is worth the troubles.  

From everything I've read, such an upgrade only provides minimal benefit in terms of print quality.

My usual perspective on questions like this is, if you have to ask, don't do it. Call me conservative or what, but I don't "upgrade" my systems unless I have a specific reason to do so. I'm sure you're going to hear from everyone who has done the upgrade and loves it but don't forget there are certainly thousands of more owners of Prusa printers that haven't done the upgrade and are happy with their machines. I don't have any hands-on experience with the Bear upgrade but I for one have not seen much that makes me believe the upgrade is worth the trouble. At least on a production machine; might be fun to do it on a sandbox system.

RE: Pros and cons for Bear v2.1 upgrade from i3MK3S+

OK. I shall forget about it. I need to replace my extruder or nozzle+heatbreak since it has been determined that bad filament contaminated my  machine and caused black dots which cold pulls could not completely remove them. Doing 6 consecutive cold pulls got a clean pulled filament but when printing again, those dots showed up on the 2nd print again. For the nozzle, shall I get the E3D Brass, Stainless Steel or NozzleX? There is a local 3D printing store but they only sell NozzleX. Also, any better extruder to use than the stock V6?

Again, you're likely to hear different perspectives on this one. I know many love the Nozzle X. In my hands, I got tired of adjusting printer profiles to address the different thermal properties (in particular as I didn't put it on all my printers). I really like the nickel-plated copper nozzles, and I also use nickel-plated copper heater blocks. 

As far as the extruder is concerned, my only hands-on experience is with the Dragon hotend. I have them on my Minis, and they work fine. I don't see any operational difference, good or bad, but they make nozzle changes a lot more convenient. On the Mk3S I have had mixed experiences. My first stab at the Dragon was a disaster. For some reason I ended up with severe underextrusion and repeated clogs. Went back to the E3D extruder, life was good again. Of course I couldn't resist, so a couple of weeks ago or so I got another Dragon. It worked great initially, just like the ones on the Mini, but a couple of days ago I noticed I can't get a stable Live Z anymore, and over the course of a print, the nozzle seems to be slipping lower—and ultimately dig into the top layer. I'll have to take the machine apart to diagnose it. Could be the Dragon not being stably mounted, or something else. I guess it goes back to what I said before, be careful with changes you make that are not driven by a specific need. Most things are not "just" drop-in replacements. For me the Dragon was a response to me changing nozzles frequently. I have an unopened box with another Mk3S+ sitting in my workshop. When I put it together, I'll just go again with all stock. 

Thanks. I heard that Dragon is just a drop in replacement. Is it better than Dragonfly? How come it is so difficult to find a Dragon? Not being sold anywhere.

Theoretically it's a drop in replacement in that it's shaped to fit into the Mk3S extruder. However, that way it can still rotate, which totally negates its main selling point (for me), which is that it allows single handed nozzle changes. So you have to fix it in place. There are a couple of designs that basically add little protrusions to the standard extruder parts to hold the Dragon in place. I used a new one that is a small piece that slides onto one of the bolts inside the extruder, so no need to replace any stock components. But now I'm wondering if the issues I'm now seeing come from a not-so-secure attachment. Will take the whole thing apart this weekend.

The Dragonfly is very different. It doesn't offer the single-handed nozzle swap.  Other advantages of the Dragon and Dragonfly such as higher flow rates are just not relevant to my use cases.

The reason the Dragon is hard to find is that apparently there was some patent action from Slice Engineering who makes the Mosquito related to the single handed nozzle swap. But you can still buy all the pieces from AliExpress, and it takes less than 5 minutes to put it together.

Thanks. Is it safe to buy from AliExpress? I heard that it is kind of big online site in China. Is it as safe as buying from Amazon? I am concerned about giving out my credit card information to unreliable companies and after sales services, returns, refund, etc.

Bought a lot of stuff there. Never had a problem. I trust them as much — or rather, as little — as Amazon. I think they're actually bigger than Amazon world-wide, so I'm quite confident that their security provisions are as good — or bad— as Amazon's.

The only downside is that shipping takes FOREVER.… But it's great for non-urgent stuff

Consider a partial Bear upgrade

The full Bear upgrade is rater extensive. Consider just doing the Bear X-axis and Y-axis upgrades. These will provide much better belt tightening capabilities, also you will need to use the associated extruder mount which is also nicer.

All the parts can be printed with PETG on your present machine.

You will not need to do a firmware change.

safe

It is safe.   I have received 100% of my orders and a refund.  

Posted by: @prusanewuser

Thanks. Is it safe to buy from AliExpress? I heard that it is kind of big online site in China. Is it as safe as buying from Amazon? I am concerned about giving out my credit card information to unreliable companies and after sales services, returns, refund, etc.