Upgrade path from MK3.5 to MK4 - Page 3 – General discussion, announcements and releases

jlf_cleaner

(@jlf_cleaner)

Member

RE: Upgrade path from MK3.5 to MK4

I just sold my 3.5 to order a 4S build kit. Still interested what the price point of the upgrade will be like. I made a part list that would have set me back by >350 Euro for the individual upgrade to MK4S. If anyone is interested though, I could share my part list here.

Posted : 24/08/2024 3:04 pm

1 people liked

Marv

(@marv)

Member

RE: Upgrade path from MK3.5 to MK4

I'd be interested to see the list.

Posted : 24/08/2024 7:16 pm

jlf_cleaner

(@jlf_cleaner)

Member

RE: Upgrade path from MK3.5 to MK4

Here is my part list: https://docs.google.com/spreadsheets/d/15Hci60HPsO0DWDzO31NLMMq59T8RtZS9lSjo8hf6j-Y/edit?usp=sharing

I just notice that it is in German, though it might be helpful for you. My starting point was the MK3.5 that already had the 10mm Z-rails from the MK4. So the list is the upgrade path from this "3.6" to the MK4S, assuming you buy the MK4-->MK4S upgrade kit and source all other parts from Prusa. Some are still unavailable, as the nextruder stepper motor and the main wiring harness.

Posted : 25/08/2024 11:06 am

3 people liked

Marv

(@marv)

Member

RE: Upgrade path from MK3.5 to MK4

Nice list, it's fine I can translate it 😊.

I tried creating a list too, but many parts are still missing from the store. Such as the "Prusa ball holder", It appears to be an injection part.

Posted : 25/08/2024 6:18 pm

1 people liked

Armin

(@armin-3)

Member

RE: Upgrade path from MK3.5 to MK4

Hi,

Glad to see that I am not the only one who came to the conclusion that MK3.5 is not the end of the road for me 🙂

I also want to upgrade to a MK3.9(S)/MK4(S). A kit would be preferrable, but I also would buy the parts individually. As already stated: not everything is available in the Prusa shop.

So, whoever from PRUSA reads this: count me in as interested in a MK3.5 to MK4S upgrade kit.

Best regards,

Armin

Posted : 09/09/2024 6:35 am

1 people liked

Neil

(@neil-6)

Member

RE: Upgrade path from MK3.5 to MK4

I am in the situation where my Buddy board is faulty, so I need to replace it as it's not under warranty anymore.

I can either spend the $119 to replace it, or spring for the Mk3.5 upgrade - since I anyway plan to upgrade all the way to Mk4S at some point.
I simply can't justify spending the $509 for the MK3.9 upgrade currently, so this leaves me in a difficult place without a 3.5 -> 3.9 or even 3.5 -> 4s upgrade paths.

Posted : 13/09/2024 9:06 am

S'Mike

(@smike)

Active Member

RE: Upgrade path from MK3.5 to MK4

I'm also quite interested, I want to capabilities of the 4KS.

Posted : 25/10/2024 4:36 pm

Anooba

(@anooba)

Member

RE: Upgrade path from MK3.5 to MK4

I asked support about this, as I like my mk4 a lot, and have a mk 3.5, so it would make sense to upgrade that when some of the components are the same.
I was told that there are no plans for a mk 3.5 to mk4s kit.

Posted : 29/10/2024 4:25 am

Ebann

(@ebann)

Active Member

RE: Upgrade path from MK3.5 to MK4

Are you sure you contacted them? I piece the parts together and it's about $400. Much less than a brand new $1,000 kit. Also when I contacted them they told me there was no upgrade path and did not offer any other suggestions. It seems strange that they would tell you otherwise

Posted : 12/02/2025 8:15 pm

Ebann

(@ebann)

Active Member

RE: Upgrade path from MK3.5 to MK4

At least you can get the gears for the extruder now but there's still some things missing

Posted : 12/02/2025 8:18 pm

Ebann

(@ebann)

Active Member

RE: Upgrade path from MK3.5 to MK4

It actually seems somewhat viable to upgrade the 3.5 to a Core One. I'm waiting for the assembly manual for the core one to analyze it but it looks like purchasing the upgrade kit for $450. 10mm rods, 2 threaded motors (the kid includes the Third) the Nextruder kit but it won't probably reuse the same short harness. It looks like we're probably around $700 bucks.

Posted : 13/02/2025 12:49 am

Dutch

(@dutch-2)

Active Member

RE: Upgrade path from MK3.5 to MK4

there should be a way now, i went through the mk4 list all parts are now available, not saying its cost effective but it can be done

and then you of course need some bearings, and nozzles etc. but this should be what you need to build a nextruder

Posted : 27/03/2025 3:11 am

iuh7978

(@iuh7978)

Member

RE: Upgrade path from MK3.5 to MK4

I am about to look into this myself to upgrade my MK3.5S. Just double checking to see if you've discovered anything else worth sharing before I dive in.

Posted by: @dutch-2

there should be a way now, i went through the mk4 list all parts are now available, not saying its cost effective but it can be done

heater
https://www.prusa3d.com/product/heater-40-w-120-mm-2/
hot end fan
https://www.prusa3d.com/product/hotend-fan-mk4-3-9-xl/
heat sink
https://www.prusa3d.com/product/hotend-heatsink-xl-mk4/
heat sink thermistor
https://www.prusa3d.com/product/mk4-heatsink-thermistor-ntc-100k-90-mm/
love board
https://www.prusa3d.com/product/loveboard/
filament sensor
https://www.prusa3d.com/product/hall-filament-sensor/
cable
https://www.prusa3d.com/product/nextruder-main-cable/
mk4s fan
https://www.prusa3d.com/product/print-fan-blower/
nextruder gear and ring https://www.prusa3d.com/product/set-pg-assembly-pg-ring/
washer
https://www.prusa3d.com/product/spacer-5x10x0-1mm/
extruder pancake motor
https://www.prusa3d.com/product/stepper-motor-e-axis/
nextruder thumb screws
https://www.prusa3d.com/product/thumb-screw-m4x8/
mk4s fan holder
https://www.prusa3d.com/product/fan-holder/
if you do the mk4
https://www.prusa3d.com/product/print-fan/

and then you of course need some bearings, and nozzles etc. but this should be what you need to build a nextruder

Posted : 03/04/2025 8:39 pm

Václav Blaschk...

(@vaclav-blaschke)

Active Member

RE: Upgrade path from MK3.5 to MK4

Guys, don't be so strict. I would too appreciate an upgrade from MK3.5 to 3.9. I have several MK3.5, MK4 and Core One and changing plate profiles again and again and again are getting quite annoying.

But... upgrade politics of Prusa is quite unique. He thought a lot about his customers and their old machines. But you can't think of everything and support every combination that comes to mind. Sometimes you just need to let an aged product finish his days and go into new road. They already have so many products, that it must be a logistical hell.

And that's exactly what I'm going to do. I'm going to let my MK3.5s live with dignity and replace them with modern machines in time. From Prusa, of course.

After all, with Core One and a bunch of competing printers on market, we probably have to admit that whole bedslinger concept is a dead end.

Posted : 07/05/2025 1:33 am

cwbullet

(@cwbullet)

Member

RE: Upgrade path from MK3.5 to MK4

Posted by: @vaclav-blaschke

And that's exactly what I'm going to do. I'm going to let my MK3.5s live with dignity and replace them with modern machines in time. From Prusa, of course.

After all, with Core One and a bunch of competing printers on market, we probably have to admit that whole bedslinger concept is a dead end.

I would agree with half the comment. You are right that if you upgrade to the MK3.5S, you might as well just buy a new Core One or what ever to replace it, but a well designed bed slinger will always have a place in the Market. Especially with small entry level printers or larger ones.

--------------------
Chuck H
3D Printer Review Blog

Posted : 03/07/2025 12:32 pm

BMC

(@bmc)

Active Member

RE: Upgrade path from MK3.5 to MK4

Did you end up building the printhead yourself? If so, what was the final cost for parts and where did you find the instructions?

Posted : 18/08/2025 9:01 pm