My first nozzle change


#1

That wasn't fun.

Having just designed several parts which go together for a prototype, I was anxious to get them all printed for a test fitting. Unfortunately, I tried over and over again with the bottom to get it to just print. And time and time again, the first couple of layers were being really inconsistent.

My initial three attempts were using a brand new Shaxon Natural PLA so I had no experience with this. It just wasn't adhering and it wasn't very consistent. I switched to a brand I knew and kept going.

This one was failing, too. Okay, so maybe it's the new relative extrusion setting in Cura (or the new version of Cura itself)? I sliced again with absolute extrusion. Still no good.

I thought I had one that was working and went grocery shopping. I came back to see it "air printing" a few layers above the part. I noted zones where it just wasn't printing at all and then "played catchup" where it pushed too much plastic. I cleared the clog and tried again. And again.

It finally dawned on me that after a year of printing (and a kilo of carbon fiber PLA run through it), it was time to change the nozzle. I did have the right parts but rather than risking breaking something in the hotend area, I bought some tools. Fortunately I keep printer spares for just such an emergency and I had the exact type of nozzle.

I moved the assembly to the front of the printer, retracted the filament and next heated the extruder to 265 degrees C. I carefully observed where the hidden (fragile) connections were in the back before using any tools. Once the extruder was at temperature, I carefully turned the nozzle counter-clockwise to break it free. I then used a pair of needle-nosed pliers to slowly remove it, catching it in a porcelain cup. Reversing this with the new nozzle, I carefully tightened it down under heat and then cooled the extruder. (In hindsight, I would have liked to have turned off the stepper motors but I was afraid if this would also turn off the hotend, too.) I homed all the steppers before continuing.

That was it. It's now printing beautifully. It was unnecessary to fine-tune the Z offset since it was the exact nozzle as stock.


#2

I usually unscrew the nozzles with pliers, but, when I screw them back in, I just lick my fingers and start screwing it in until I burn myself, then I switch to the pliers

I find that it's easier to get the threads started with my fingers than the pliers

Were you using the steel or brass nozzles ?


#3

I use a crescent wrench of the appropriate size for the nozzles, and a pair of pliers to hold the heat block, so it doesn't spin free of the tube/heat break and damage the wires. I generally do all of this cold (if possible), and then tighten under heat, but they're also all-metal hot ends, so the tube/heat break actually mate into the nozzle.

I do keep spare nozzles, etc, too, though, for just this reason. I also have a ton of nozzles of various sizes and materials (hardened steel for abrasives, high lubricity nickel coated brass for everyday use).


#4

Brass in this case.

I found that using a friggin HUGE open-end Craftsman wrench, horizontally-aligned, to hold the block from the front was the way to go on this. The little 7mm open-end wrench I bought specifically for this didn't seem to want to be wide enough for the nozzle so the smal adjustable wrench had to do for that one.


#5

I use open/box end wrenches, then crescent wrench, then needlenose, then slipjoint pliers in that order to get the nozzle off. Reverse the order for holding the block.

Been printing ABS, which for whatever reason puts tons of nasty deposits on the nozzle and the block. Still seems to work, so ..? I'll leave it for now.

My fail of the week was getting MINTEMP errors, so I just swapped out a thermistor. I think I damaged the previous one. I am using microfit connectors, so I have to do some crimping and fuss for a bit to prep a new thermistor.


#6

I come from a CNC shop in experience and I have to say that this FDM world needs a faster means of changing out nozzles.


#7

Well, from what I've seen, printers like the CR-10 have screws through their heater blocks stock, so you'd just need a wrench that fit the nozzle. Of course, as soon as you upgrade that to a Micro Swiss all-metal hot end, you have a grub screw that holds the tube into the cooling block, and the two screws come out, so I'd imagine you wind up with the same stuff, or putting the screws in first.

Definitely need a better way. Some more expensive machines like Ultimakers have easily swappable hot end units, but I'd imagine you're trading time for money there.


#8

I'm thinking cam lever here for this.


#9

I can see how a cam lever would absolutely technically work, and is a great idea, IF the nozzle itself was the only problem

In my own adventure into swapping the nozzle the other day, I'm still not certain if it was just the nozzle, or the combination of all the other things I did as well. I took everything apart, cleaned stuff I didn't have extra parts of, and replaced stuff that I did. Heck, I even swapped out the printers motherboard