Next 3D Printing Adventure

[k7zpj]

A mysterious black box from the Czech republic full of 3D printer parts magically appeared on my door step today. (That is the story for the wife )

The shipping invoice stated that parts for a PR i3 MK3 was in the box. It was also noted that the Multi Material unit was on back order and should start shipping late May. Sadly the Master Chief Unit announced on 4/1 isn't available.



Updates to follow as the adventure progresses.

[k7zpj]

Unboxing and Inventory.





I am now sorting through all of the boxes and parts to conduct the inventory. The most important part, the Haribo gummy bears were easy to find. They are required to complete several steps in the assembly process.

Next step is to assemble the frame.

[Devil Inc]

Nice. Those are nice machines.

[k7zpj]

Prusa does have a really good design. It is the design that most of the Chinese clone makers are copying.

The MK3 is Prusa's new model that was released for pre-order last fall.
It has several new features:Removable PEI spring steel build plate

• Optical filament sensor to detect run out and jams
• Restart of a print after a power interruption
• No end stop switches
• New electronics that enable faster and near silent printing.
• Detection and correction of layer shifting.
• Support for the Multi Material Unit for multiple color / soluble supports

With all of the changes and updated electronics, it will take a while before the MK3 has all of the bugs worked out. I wanted to be able to contribute to the Open Source community so it seemed a good way to get involved.



By buying a "Original Prusa" printer, it also helps support research in new Open Source 3D printing designs.


You even get a bag of Haribo Gold Bears with the printer. ( They are the good ones made in Germany not the US clones.)

[JatoTheRipper]

Congrats! You got an original Prusa!

Do the Gummi Bears taste the same as the US ones?

[k7zpj]

Originally Posted by JatoTheRipper

Congrats! You got an original Prusa!

Do the Gummi Bears taste the same as the US ones?

I need to do further comparison testing before I can give an answer as to which Gummi Bears taste the best.

I did notice that the colors on the "US" version are a lot brighter. Flavors in the German version correspond to different colors than the US version. Plus a larger number of flavors in the German version.

The big shocker was to find that the US Gummi bears are actually made in Turkey.

[k7zpj]

In addition to researching Gummi bears, I did get the frame for the printer assembled.

Prusa does a great job of sorting and packing the parts so that you have all of the parts you need for each step. It's almost like doing a crawler build and you can use your crawler tools instead of the low cost ones included with the kit to save wear and tear on your hands.



The frame parts are cut, machined and drilled very well. It took almost no adjustment to get it square. You do have to make sure you don't twist the extrusions while tightening the screws.

Prusa has updated their frame in the MK3 and using aluminum extrusions instead of threaded rods.



The Y-axis is next.
If you want to see more details here is the link to the instructions:
2. Y-axis assembly - Prusa3D

[durok]

Following with interest... hoping to join the 3d-design & mfg community as a B-day or Xmas gift to myself this year (got a ways to go, Nov/Dec - should be some fantastic deals by then...).

BTW - my visit a few years back to this store in Hamburg blew my mind:

Startseite - Bären-Treff

They are the "alternative" to Haribo.

Check it out (yes, jalapeno-flavored gummis):

[k7zpj]

Originally Posted by durok

Following with interest... hoping to join the 3d-design & mfg community as a B-day or Xmas gift to myself this year (got a ways to go, Nov/Dec - should be some fantastic deals by then...).

BTW - my visit a few years back to this store in Hamburg blew my mind:

Startseite - Bären-Treff

They are the "alternative" to Haribo.

Check it out (yes, jalapeno-flavored gummis):

That is great.
Would be interesting to mix some of the jalapeno bears in with the normal ones and watch the reactions.

[k7zpj]

After too many Haribo Golden Bears, I got back to working on the printer's Y-axis.

The parts for each of the axis's come in their own part bag with the list of the contents, part number and picture. This is the parts required for the Y-axis.



The first part of the y-axis assembly includes attaching the rod holders, stepper motor/mount and idler to the frame.



The next step is to attach the belt holder and attach the linear bearings to the bed using u-bolts. You have to be really careful about not deforming the bearings by tightening the U-bolt too tight or not having it equal on both sides. After you mount the bearings, the rods are carefully slid into position.



The bed is placed into the rod holders and snapped in place. Tie wraps are used to secure the rods into the rod holders. You then adjust the rod holders so that the bed slides smoothly front and back. Finally the belt is installed and the tension adjusted so that the belt won't skip over the motor pulley. (Probably the hardest part of the Y-axis steps).




Link to Y-axis instructions:
2. Y-axis assembly - Prusa3D

[k7zpj]

The X-axis assembly is supposed to be the easiest and shorts of the assembly sections. Well.....

The first step is to press a nut into a recess on one side of the block. The instructions call for you to thread a 18mm bolt through the block into the nut so you can pull the nut into the recess. I got the bolt started into the nut, and did one full turn on the bolt and heard a sharp crack go off. The head of the bolt cracked the side of the part. The area where it cracked is very thin (1.5mm) and couldn't take the pressure.



Ordering a new plastic part was going to mean a 3 to 4 week wait and cost about $25 with shipping. So I decided to print a new one.

I also decided to edit the part in Meshmixer to make the side that broke 2mm thicker. I was able to print out the replacement part in PETG. I only had black PETG so the x-idler block is going to be black instead of Prusa Orange.



There several post print processing steps for the part using a 8mm drill bit to ream out the holes for the rods. You also have to take a needle file to clean out the nut slot that is used to attach the trapezoidal nut to the end block. It came out ok and I was able to install the idler pulley and shaft without breaking the part again.



The next step will be to finish the x-axis assembly

[Devil Inc]

I'm glad I have 2 printers myself. My newer printer is capable of much better prints than the older one in their current states. I started my longest print tonight making a whole upgrade package for the older one that suffered being knocked off a table by one of my kids. A few zip-ties fixed it, but it's time for a facelift.

[k7zpj]

Originally Posted by Devil Inc

I'm glad I have 2 printers myself. My newer printer is capable of much better prints than the older one in their current states. I started my longest print tonight making a whole upgrade package for the older one that suffered being knocked off a table by one of my kids. A few zip-ties fixed it, but it's time for a facelift.

Having a 3d printer making 3d printer parts is what the RepRap project's goal of self replicating machines is all about.

[k7zpj]

After getting over the shock of breaking a part and getting out of Haribo rehab, I got back to working on the x-axis.

Picture was taken before breaking the idler end block.


In the process of getting the part that I printed ready to use, I found that the rod holes in both end blocks were too small to accept the rods and had to be reamed out using a 8 mm drill bit. I also found that the slots used to capture the m3 nuts used in the next step were also too small. I ended up using a needle file to make the slots the correct size. It would have been a lot harder if I had found it after the x-axis was together.

Finally got the x-axis together. Sp much for the quick and easy 30 minute step. The black idler block on the left is a bit noticeable but it wasn' t worth the time or money to get the correct Orange PETG from the Czech Republic.



If you would like to follow along - X-axis Instructions:
3. X-axis assembly - Prusa3D

Next Step will the Z axis.

[k7zpj]

The Z-axis assembly section has 3 parts:

• Mounting the z-axis motors.
• Putting the x-axis on the z-axis lead screws and installing the bearing rods.
• Installing and adjusting the x-axis belt.

The manual didn't call out getting the x-axis rods and almost missed the step where there are installed. Which explains why they are missing from my parts picture.




The actual installation of the z-axis motors is pretty easy. The key is to take a square to make sure the motor mounts are perpendicular the frame. There is enough play in the screw holes that you can get them out of square. That would result in the lead screws not being parallel and binding on one or both sides of the z-axis.


Getting the the trapezoidal nuts installed in the x-axis was a bit of a pain due the slots that the 3m nuts that are used to attach the lead screw nut were too small and had to be enlarged with a needle file.


The X-axis is just threaded manually onto the z-axis lead screws so that they are started straight. You turn the rods so that the axis is level then insert the rods into the x-axis bearings and the z axis motor holders. If everything is square the rods just slide into place and you put the top holders on.


The belt installation and adjustment was a bit tricky and took most of the time spent on this step.





Looking more like a 3d printer now.



If you want to follow along here is the link to the manual.
4. Z-axis assembly - Prusa3D


Next step is grab another bag of Haribos, and get started on assembling the extruder.

[MaxxPain]

Looks great, I just got one last month. Love it. Still learning how to print but really enjoy it.

[Robbob]

Im curious about something with this ..... 3 support bearings on the bed plate. I understand 3 point bed leveling but is there a benefit to the bed plate being on 3 bearings vs the 4 like most of the taiwanese ones?

[k7zpj]

Originally Posted by Robbob

Im curious about something with this ..... 3 support bearings on the bed plate. I understand 3 point bed leveling but is there a benefit to the bed plate being on 3 bearings vs the 4 like most of the taiwanese ones?

A 3 bearing carriage produces fewer vibrations which would show up in the print as ghosting or waves in the print.

The side with 2 bearings is the fixed guide which allows the motion in the direction of the axis. The side with the single bearing is the floating guide. Its purpose is to prevent rotation (tipping) of the carriage around the axis.

If both sides are fixed ( 2 bearings), then it constrains the motion of the bearings on both sides which causes the bearings to slide on the rod instead of roll. The sliding alternates from side to side which will show up as waves/ghosting in the print.

If your bearings have lots of play (cheap bearings) you can get away with 4 bearings since they have so much movement they don't bind and slide.
But they do have lots of other issues such a y axis wobble due to allowing too much sideways motion.

[k7zpj]

I got the parts out for the extruder. My first thought was: "OMG that is a lot of stuff that is going into a very small space" Followed by: "This is going to take a lot of Haribos to get this step done."



The MK3 extruder has a filament sensor that allows the printer to check for jams or running out of filament so you can reload filament and resume the print. Sensor is on the left side of photo.



The extruder uses a pair of BondTech dual drive extruder gears that grip/drive the filament from both sides. On the right side a little below the idler you can see the filament sensor pins and towards the center the hole in the extruder body for the sensor.



It took almost 2 hours to get this far so I am quitting for the day before I break something. Plus ran out of Haribos so I have to go restock before installing the hot end.

If you are following along, here is the link to the step in the manual:
5. E-axis assembly - Prusa3D

[Robbob]

Originally Posted by k7zpj

A 3 bearing carriage produces fewer vibrations which would show up in the print as ghosting or waves in the print.

The side with 2 bearings is the fixed guide which allows the motion in the direction of the axis. The side with the single bearing is the floating guide. Its purpose is to prevent rotation (tipping) of the carriage around the axis.

If both sides are fixed ( 2 bearings), then it constrains the motion of the bearings on both sides which causes the bearings to slide on the rod instead of roll. The sliding alternates from side to side which will show up as waves/ghosting in the print.

If your bearings have lots of play (cheap bearings) you can get away with 4 bearings since they have so much movement they don't bind and slide.
But they do have lots of other issues such a y axis wobble due to allowing too much sideways motion.

Very interesting. My new bed plate will let me do either setup so guess the rebuild is gonna be 3.

Thanks for the explanation!