Change the nozzle?

[Mebyon]

Hmm. I’d like to change the nozzle on my new SM machine. (I’m printing some hefty drawers and 19 hours per print is a tad long using the supplied 0.4mm nozzle).

But how do I actually fit my new 1mm nozzle? I guess I need to heat the existing one and then unscrew it? Then heat the head again to screw in the new one? I’ve looked at the supplied spare hot end and it looks a tad flimsy. I suppose I could try disassembling and fitting the new nozzle to that, but it would have to be done cold.

What’s more worrying is the fact that SnapMaker included such a comprehensive tool-kit but no 6mm wrench for the nozzle. Also does that mean that I’d void the warranty by fiddling with the hot end?

[edf]

You should be able to unload the filament via the touchscreen, then maybe leave the nozzle heated at 250 C until any remaining filament drips out. After that, I don’t think any heat is necessary to remove the nozzle. Not sure the thermal expansion will help on a threaded connector that isn’t rusted together or otherwise seized.

A 1/4 or 7mm socket will handle the nozzle, unless I am mis-remembering.

The trick is to prevent the hot-end from rotating while you turn the nozzle. Most people remove the hot end and hold it in a crescent wrench to do this. I used some needle-nosed pliers to act as a wedge on either side of the hot-end, preventing it from turning, and removed the nozzle with the hot-end in-place. I do not recomment the needle-nosed pliers specifically (too easy to damage what you’re holding) but really any sort of wedge will work.

Hmm, maybe I should go measure and print something.

EDIT: Just realized the question is only five minutes old. We must be having lunch at the same time

[Mebyon]

Sounds doable. Let me run through what you’re suggesting as I’m quite well known for getting the wrong end of the stick; or nozzle in this case!

1. We don’t do this on the spare nozzle, we do it on the one in the machine.
2. Heat, unload, wait so no filament in the works.
3. open the flap on the extruder module.
4. Grip the exposed finned cooler block; that’s where your needle nosed pliers came in?
5. Unscrew the old nozzle and fit the new one. (Holding the finned block again).
6. Bring the nozzle up to temperature and finally tighten the nozzle.

Maybe 7. Send an email to SnapMaker support to tell them that I’ve screwed my warranty?

Lunch? Hey, it’s 6:30 PM here! The real reason I’m in sync is because I have very little else to do than to try and get this pesky machine to behave itself. As you remember I’m the chap who has taken SM calibration to almost an art-form. Adhesion lost again, even with hair-spray. The new firmware upgrade says that the gap should be 0.1mm but, feeler gauge used, it’s still not right. The weird thing is that it’s only that first layer; the rest of the print comes out beautifully. Arrgh!

[edf]

No need to do 3 or 4, just need to wedge the hot end that the nozzle is screwed onto. That silicon-covered block visible at the bottom of the 3D print head moves when you try to unscrew the nozzle with a socket.

I whipped this up in OpenSCAD but have not been able to test it yet, as I have a print ongoing:

The openscad code (based on caliper measure of 10.75 for hit end width):

 difference() {        
        union() {
            translate([0,6,6]) 
                rotate([90,0,0])
                    cylinder(r1=4, r2=4, h=44, $fn=6);
        
            rotate([0,0,45])
            cylinder(r1=12.75, r2=15.75, h=12, $fn=4, center=true);
        };
        translate([0,0,-2])
        cube([10.75, 30, 8], center=true);
};

Here’s an STL if you just want to throw caution (and filament) to the wind:
sm2-nozzle-change-wrench.stl (8.4 KB)

[Mebyon]

Hey! Thanks for that file. The trusty Ender 3 is working on it as I type.

I’ve taken the print head off the SM machine and, now I can look at the underside, I see what you mean. As there’s no filament loaded into it just now I’ll give your wrench a tryout in 34 minutes, the time that Cura says the wrench is due to take printing.

Thanks again, I’ll report back.

Chris

[Mebyon]

Ah. 'Tis never that straightforward! Ender didn’t like those very thin base lines. No problem, rotate in TinkerCad, slice off the chamfer at the end and try it again…

[Mebyon]

Yes. Much happier tipped up on end!

While I’m waiting. Just a thought. Has anybody taken one of the SM linear rails to bits? I thought that the shiny stainless steel ribbon was some sort of belt drive but it doesn’t move. So I guess there’s a screw thread that drives the carriage but then how does that move the pesky thing if the screw is inside and the carriage is outside? Most strange!

[edf]

Ah, yeah I probably should have run the handle all the way to the end so it would stand on end better.
Still getting used to designing-for-printing. Also two facets of the four-faced cylinder don’t need to be tapered and that sure doesn’t help.

Replace that first translate…rotate…cylinder with

  translate([0,24,4]) rotate([90,0,0]) cube([8, 4, 36], center=true);

…and it should print much better on its back. Though a square handle is much less fun than hexagonal.

[Mebyon]

Oh-kay. Doesn’t fit! I think that the gap in your module is wider than in mine. But all is not lost. Thinking about it, we only need to restrain the block on one side. A collection of feeler gauges, (2.25mm in my case), should jam the block in place. I’ll give that a try tomorrow but it’s getting late here so I’ll pend everything until then,

Anyway, printer head now re-attached and I think I’d prefer to do this faffing about with the head off the machine.

Still puzzling over how those linear rails can possibly work. Maybe an engineering genius will pop in here and explain a conceivable mechanism. That’s one of the nice things about the Ender, it’s all very obvious how it works!

G’night,

Chris

[edf]

I based it on the width of the hot end, as I have a six-hour print going (three hours left) and couldn’t measure the module itself. Will take a look tonight when the print finishes and get proper measurements, maybe even see if it works. Probably shoud have measured the jaws of the needle-nose pliers and referenced off that.

Pretty sure the stainless steel ribbon on the linear module is just a dust cover. Probably flexes around the carriage mount, but haven’t looked at it closely. The SM page for cleaning a linear module just shows the ends being taken off and wood dust being poured out.

BTW, how is that between-modules tray working out? I downloaded it but have not yet got around to making it. These prints take so cussin’ long.

EDIT: D’oh! Diameter used for radius. Thought it looked a bit chunky.

$taper_min = 1.0;
$taper_max = 3.0;
$hot_end_width = 10.75;
$hot_end_height = 8.0;

difference() {   
    union() {
        // handle
        translate([0,24,4]) 
            rotate([90,0,0]) 
                cube([8, 4, 36], center=true);

        // wedge
        r_base_side = $hot_end_width + (2*$taper_min);
        r_base = sqrt(2 * (r_base_side * r_base_side));
        r_top_side = $hot_end_width + (2*$taper_max);
        r_top = sqrt(2 * (r_top_side * r_top_side));        
        rotate([0,0,45])
            cylinder(r1=(0.5 * r_base), //($hot_end_width + (2*$taper_min)), 
                     r2=(0.5 * r_top), //($hot_end_width + (2*$taper_max)), 
                     h=(1.5 * $hot_end_height), $fn=4, center=true);
    };

    // hot-end cutout
    translate([0,0,-2])
        cube([$hot_end_width, 30, $hot_end_height], center=true);
};

[Mebyon]

Hi there, sorry for the long delay in responding; I’ve been a busy chap this morning.

I tried losening the nozzle with the module off the machine but it’s glued in solidly. I think the hot end needs to be heated to soften any filament left inside. That means that a 3d printed wrench won’t do the business as it’ll also melt.

I measured the width of the heater block. <14mm. We know the gap between the block and the module is >2mm. Armed with these numbers I went searching for Alipio our village blacksmith. (Yes, we’re that small here!) Unfortunately he’s not working because of the Covid business but he promised to ‘knock something up’ when he gets back to his forge.

All in all I’ve given up on changing the SM nozzle. I can easily change the one on the Ender 3 so that’s what I’ll do.

As for the 'tween rails drawer. It’s badly under width. Check your between rail distance and amend the stl file before printing. Still quite useful but not as handy as I had hoped. Mainly because the bed in the SM moves so far forward that it’s really difficult to grovel under it to retrieve a tool during a print. That’s why I quite fancy making a set of drawers to fix to the wall beside the machine for tools.

{Sigh] Adhesion problems continue on the SM machine…

[ElloryJaye]

I haven’t actually taken one of the linear rails apart, but by my understanding, the steel strip is a dust protector, and yes, the real driver involves some kind of threaded rod. If I had to guess, the strip is probably threaded through the carriage in some way.

[Mebyon]

Dead clever though. I suspect we’re going to have to wait until one of these rails fails and then someone will take the dead one to pieces to see just how clever these Chinese chaps have been.

I had rather folornly hoped that the good folk at SnapMaker were reading our posts and would jump in with a sketch of how they managed to transfer the movement of an undoubted nut on a lead-screw to the bracket we bolt our modules to. Just another of life’s imponderables!

[brent113]

@Mebyon

I suspect we’re going to have to wait until one of these rails fails and then someone will take the dead one to pieces

That’s already happened about 50 times on here already. Best pictures are here

Excessive play in x-axis linear module bracket

Finally got a chance to pull it apart. (I swapped one of the Y’s with the X to get by). Arnold’s video was helpful, but incomplete and also a couple things wrong. I didn’t have time to make a video but I took a couple pictures. Here’s the procedure (note that this is how I did it and not official. Since all I got from support was “Need to adjust the sliders” and “it’s difficult” I’m considering that as sufficient instructions that I can proceed without voiding my warranty. Proceed at your ow…

Support posted a full assembly video here:

How to install the stainless steel strip of Linear Module?

[Mebyon]

Magnificent! Thanks for posting that video; all is now clear.

You say that the question has been posed and answered around 50 times. Just shows how difficult it is on any site of any size to find what you’re looking for! Although I must admit I didn’t really spend much time looking as it was a random thought that flashed over what passes for my brain while I was waiting for a print to finish. Condition normal for me!

[brent113]

Yea, I just happen to remember specific instances of it, but if there’s something specific you’re looking for never hurts to ask.

@geared has done extensive work on the electronics side, he has several posts with good pictures of the PCBs. @Streupfeffer is another. Many many others have fought a bad batch where the lead screw pitches were different between the 2 Y or 2 Z axes causing a loud pop and jerk in the movement. Lots of history as this product initially got off the ground, ha.

[Mebyon]

Thanks. I, of course, have a million questions! The major difference between the SM machine and my Ender 3, (apart from the huge cost difference!), is that every aspect of the Ender is on display and understandable. Because of the ‘modularity’ the workings of the SM are all tucked out of sight. This thread all started with a simple request to change nozzle size and look where we’ve wound up. Still 0.4mm nozzle in the up-market machine and the 1mm nozzle will be screwed into the Ender. Is this progress I ask myself!

[edf]

@Mebyon

I tried losening the nozzle with the module off the machine but it’s glued in solidly. I think the hot end needs to be heated to soften any filament left inside. That means that a 3d printed wrench won’t do the business as it’ll also melt.

Interesting. I was able to get one off a few weeks back without heating - swapped it out to see if a bad nozzle was the problem I was having (it wasn’t). Thought about milling an aluminum wrench for the purpose (which, ultimately, is what the 3-D print would be a model for). Might even be able to do it with a bit of U-channel. I need to verify there’s no chance of touching the circuit board, though.

[eh9]

@Mebyon

change the nozzle

No one’s said it, so I will. You’ll get better results overall by taking out the hot end assembly and changing the nozzle with the hot end out of the tool head entirely. You have no risk of damaging other parts this way. You can get the mounting torque correct and have no risk of torquing the head or the bearings onto the linear rail.

Even more importantly, it allow you to inspect that the nozzle is seated against the heat break and not against the hot block that holds both the heat break and the nozzle. Performing the installation on the machine does not allow adequate clearance to see that the nozzle stays off the block.

[Mebyon]

Thanks guys. Lots to consider. But now, with the Ender 3 happy, I’m going to get designing that drawer set to fit on the wall. Actually a new shelf may fit in there instead and then the drawers could sit on the shelf; save on uncertain fixings to the rather uneven wall.

Chris