Cold Assemble your hotend

YES YOU STILL NEED TO DO A FINAL TIGHTEN WHILE HEATED AT THE END... 

OK, the general rule is if changing a nozzle or heat break tube that you need to fit it while the whole unit it hot. And, in truth is still going to give you the most reliable connection to prevent slipping or leaking of molten plastic popping out between the nozzle and heat block, or out the top between the heat break tube and the heat block. But, a good tight seal can reliably done while cold if you take the right steps. These step can also be applied in a hot assembling to prevent snapping the heat break.

 - First off though, you need to take a few precautions. Mostly the whole thing needs to be clean and free of any material. If a new install/build, not an issue but if rebuilding you need to do a cold pull, then inspect and remove anything plastic material left behind after taking it apart.

Once everything is clean, you'll need just a couple tools, a socket is best but a wrench that fits the nozzle will work. and a wrench to fit the heat block. make sure not to bind, pinch or otherwise damage any wires coming from the heating element and sensor, or damage the items themselves!

Now the steps are easy and will work reliably if done in the correct order.

• Install and tighten the nozzle to the heat block, make sure it is seated but you don't need to crank it down. (note there are a few hot ends that want a small gap between the heat block and the nozzle, make sure to check with your manufacturer) 
• Install and hand tighten the heat tube down to the nozzle.  just a snug hand tight.
• Back off the nozzle a full 1/2 turn.
• Hand tighten the heat break tube down to the nozzle again. Just a snug hand tight.
• Now you can install the hot end if you can get to it on the machine, or if not, heat up lying on a heat safe item (Boro glass bed or alum is fine, things like Build tak and such you'll need to protect.)
• Now use wrenches on heat block and nozzle and tighten up nice and tight. Obviously being careful not to over tighten and strip the threads. 

You may not get back the full 1/2 turn, which should be OK. If there is an excessive gap then loosen the nozzle, back off the heat break tube a 1/4 turn and install/tighten nozzle again.

** You still need to heat and tighten once installed, but should be just snugging it up at this point not trying to fiddle and assemble steaming hot parts**

If you follow these simple steps. you should have no issues ever again with leaking or loosening hot ends.

Centering on your bed

    (Original post from the 3D Printing Experience blog) 

Updating info Nov 5th 2017- updating to match latest marlin firmware and to straighten out some of my image rotating which confused some people with orientation. Also to add a few extra bits and info. 

If your printer is like mine you may have noticed that prints really aren't centered on the bed of the printer.

Now some printers have adjustable end stops so you can just turn a screw and set where the printer aligns it's self, But most don't have this. And honestly, unless it's really off, or you are going to print something right to the edges of your printers limits, it's not going to matter. But, it bothers me, so I went and learned how to center it. And it's not really all that hard to do. It took me a few days of reading and research to figure it out, and once I did I found it takes very little time to actually center it. So I wrote this so others can do it without having to spend the time figuring it all out.

Now you will need to be at least basically familiar with Marlin firmware and using Arduino or other software but it's not all that hard to figure out.

First step is to make sure your printer is all leveled and set correctly. It's best with this to use PLA, on a taped bed so you can mark it all up. you can just print what ever and take measurements from the edges if you don't want to use a marker on your bed, but this makes it so much easier.

Tape up you bed and move your print head to extremes, Mark the nozzle location as it often time will hit a carriage before it gets to the end of the printers bed

Draw Straight Lines down the edge of the bed where the nozzle actually stops

draw lines from corner to corner to create an X at the center point of the printable area.

Also if you write where your end stops are it will keep you from getting it spun around after printing and you go and take the glass (or what ever you are using) off. 

Now download the centering target file, and slice it. 

Download  --> Centering Target <--

Best use is if you can print at your highest resolution your printer can do and not use any rift or brim if possible. This will allow you to see the marks on the bed through the print. 

VERY IMPORTANT - Now make sure you right click on the target and select "center on platform" (this is with Cura, others may have a different command to make the target centered Make sure you use it) 

save the Gcode and print it out. After printed take a look at where it lands on the bed. the lines are 5mm space.  my X lands right in the corner of the 1st 5mm box, actually just inside, right at the corner. So I'm gunna just say -4.5mm for both X and Y in this case

Now that you have measurements, you can open up your Marlin firmware file and select the "Configuration.h" tab ..

Scroll down to the bottom of the "Z probe Settings" ("End Stop Setting" in older version of marlin) 

These are the spots where you will enter the measurement you got from the print.

Adding a negative number shifts the bed toward the end stop, (the print away from the end stop)  adding a positive number can't be done. Why? because that would make you buildable area out beyond your end stops, which it just can't do, cuz, you know,.. it'll hit the end stop. 

Enter your measurements you got off the print, compile and upload to the printer. you should be set now and all your prints should be close to center on the bed.

And print the target again to check and make sure you did it correctly... 

All centered!

Now you're prints will be properly centered on the bed from now on :)

Video

Square is as important as level!

    (Orginal post from the 3D Printing Experience blog) 

OK, if you have been 3D printing for more than a day you've heard the term "leveling you bed" it's not so much actually getting the bed level as it is getting the bed parallel to the plane of the extruder's movements. Level is very important so the first few layers adhere the the bed as well as having them being an equal thickness.

    But, this isn't about leveling your bed. This is about how "Square" your frame structure of the printer is. Square is all the axises being 90º from each other,  which though not as important to getting the first layer to adhere, but just, if not more important to getting items to print properly, especially if you are trying to print mechanical item that need to fit together and have reasonably tight tolerances. If you're getting prints that are leaning, or just don't fit right, it's likely you may have the frame out of square. Below is an image of the 3 main issues of out of square frame   even though the nozzle is leveled with the bed.

results of out of square frame.

(note, Z axis can be out front to back as well as the side lean displayed)

Mostly applies to Prusa i3's and such with moving Y plane bed.

   Though the above image it's very visible because I exaggerated the issues, it may be much more slight in your printer to the point it's hard to actually see, but can give problems when printing fitted parts that need to align and work together.  I have designed a simple triangle thingie that you can print to check your printer for square.  Now you can print any old box, or what ever as long as the bottom, one side and front or rear has a flat straight plane, I just personally like the triangle thingie as I think it looks cool!

Thingiverse -Triangle Square Thingie

   Now print it (or what ever) out. Once printed, take a square and check just how well your printer is doing. Honestly, its best if possible to leave the item on the bed. that way it's easier to tell in which direction/what side is out so you can fix or adjust it.

 print the little triangle thingie- leave on bed if possible

X to Z axis,  lean side to side and tilt front to back.

X to Y axis

   Now a "speed square" will work, but the combo-slide square work best in this application as it allows you to lift the bottom edge just a tad to clear any brim or border you may use to adhere the print to the bed. 

notice I lifted the edge of the rule to avoid false reading from brim

  After checking if you find something out of square you'll need to adjust it.  It's going to be widely different depending on printer model and style so I won't get into that whole thing, but you can consult your manufacturer or hit up many of the groups and forums for your particular model.

But, once you have checked and fixed any issues with your printer being out of square then you will notice not only mechanical parts fit better but also organic prints should improve in visual quality.

Square (Level) X and Y Axis before leveling bed

    (Orginal post from the 3D Printing Experience blog) 

Well, this applies basically to the Prusa i3 and clone style printer more than others as they have the Z and Y axis separate. But many people have had issues with their bed seeming tilted after leveling it to the nozzle. The most likely the reason is the X/Z carriages and rods aren't level or square to the Y rods.

Notice when the X and Y aren't level (square) it makes the head lean

 As the above image shows when the X and Y axis aren't square to each other then you'll get a lean in your bed. this will also transfer to a lean in the print.

By using this Simple tool designed by mangtronix from Thingiverse you can adjust your X-Y to be level and square then level your printers bed to get a more even 1st layer and improve the print quality.

 link - Tool to level X-axis of Prusa i3

I also redesigned it just a tad, mostly just made it taller as with my printer his wasn't tall enough to reach once my printer had hit it's end stops.

 Link - X to Y Axis alignment/leveling tool

MAKE SURE YOU POWER DOWN THE PRINTER BEFORE USING THIS!!
You can easily bend the rods if you use the motors to mover the carriage and have the tool in place!! It's pretty easy to do.. Disconnect at least one of the motors (they can often produce enough energy to motor the other side with it depending on your mother board) slip the tool onto one of the Y rods, lower the Z/X carriages down to just touching the ledge on the tool. move to other side and repeat. check and recheck each side till they are even. Make sure the resistance when sliding the tool back and forth is equal on both sides. when done. Plug in motor and power up printer. Now level your bed like you normally would. Here's a video on how I do it.

 Leveling or Squaring the axises to each other can stop many printer issues like banding in the Z axis on the print (the nuts are binding on the threaded rods because they are twisted) as well as leaning models do to, well the whole printer leaning in general.