In the middle of a series of experiments, offering yet another premature observation.

In the middle of a series of experiments, offering yet another premature observation. When I switched from a 0.4mm nozzle to a 0.8mm nozzle, found I was hitting the thermal limits of the hotend at (roughly) 30 to 40mm/s.

(This is a basic mk8 hotend. To be replaced with a V6 hotend shortly. Likely other things later.)

When testing with a 0.4mm nozzle, pretty sure I was hitting both the thermal limits of the hotend, and the mechanical limits of the printer. Deciphering the results were not at all clear.

My point is that when evaluating a hotend, you should start by slapping on a large nozzle, and characterizing the thermal limits (as with fat extrusion the printer mechanics are not really challenged). Once the thermal limits are known, you can better isolate the software and mechanical limits with smaller nozzles.

Also, if your interest is more small/detailed prints, then a 0.2 or 0.1mm nozzle on a basic mk8 hotend might be all you ever need. You can declare victory and leave this discussion. :slight_smile:

As my interest is larger functional prints, I very interested in figuring out present limits, and how to get further.

The online evaluations of hotends that I have seen do not start with large nozzles to establish a baseline, and I am of the opinion that is essential. Seems a major omission.

Please feel free to point how I am wrong. :slight_smile:

By 30-40mm/s do you mean travel speed, or extruder speed. Because travel speed won’t be a direct comparison, however extruder speed is.

I’ve personally never got an extruder with e3d v6 + 0.4mm nozzle to extrude faster than 10mm/s before it starts to stall or click. Die swell is pretty big at that speed too, like 200%. No idea what the limiter is there, but the backpressure must be pretty high.

The clearest example is single wall “spiralized” prints. So pretty much continuous motion and extrusion.

What I’m saying is you can decouple the movement and just extrude in air. It’ll tell you your max feedrate, which can determine max print speed based on volume. Then a little bit of math will tell you max movement speed for each layer height.

What I am saying is that with “fat” layers and a “fat” nozzle the main limitation is going to be the thermals of the hotend, not anything else. Once we grasp the thermal limits of the hotend, we can make more reasoned guesses when movement is more a factor.

This object is printed at 0.5 x 1.0mm layers (with Inland PLA+ at 240C in this case) with movement set at 40mm/s. Height is 300mm, and width is 150mm (with the basic mk8 hotend).

As to 10mm/s from a 0.4mm nozzle on a v6 hotend, that sounds rather low. Give we a week, and I will have numbers. :slight_smile:

We’re talking about G1 E speeds?
something along the lines of this gcode gives you either plastic or clicks if you hit the throughput of the hotend

M104 S225 ; set extruder temp
G1 X50Y50Z50; move to somewhere
G1 E1 50 F2400 ;50mm @ 30mm/s
G1 E1 50 F3000 ;50mm @ 50mm/s
G1 E1 50 F6000 ;50mm @ 100mm/s

depending on what the max feed rate is set (marlins M203/#define DEFAULT_MAX_FEEDRATE ) you’ll struggle to get filament through the extruder faster than whatever that is

Best to measure extrusion distance when running that code too, like mark the filament and check to see if it actually extruded that much filament. Much easier than listening to clicks, and more accurate.

That’s 20 cubic millimeters per second. If you buy the v6, take a copper volcano block and nozzles with it. It will easily double your extrusion rate. At 30 cubic mm/s only 10W of heating power go into the filament.

10 mm^3/sec is pretty widely reported as a reasonable limit for PLA through a typical all-metal hot end like an E3Dv6 with a 0.4 nozzle, at normal printing temps. If you’re willing to crank up the nozzle temps or use ABS, you can go a lot faster.

It’s a good idea to do flow rate tests on a big flat/boxy shape with lots of straight lines, so you have a majority of extrusion happening at full coast speed rather than during acceleration slowdowns. Depending on your firmware and acceleration settings, spiral prints may be slower than you think.

FWIW, measured the rate of extrusion (by timing 100mm of filament entering the extruder) at ~9mm^3/s doing a large spiralized print. This with a mk8 hotend, 0.8mm nozzle, 0.5 x 1.0mm layers, 40mm/s movement. Using Inland red PLA+ (just bought) at 240C.

Rather hoping the V6 hotend can do better. :slight_smile:

And on a random note, the small marks on the filament tinted a couple of layers (maybe 500mm of travel) fairly uniformly. Must be some extended mixing going on in the hotend.

@Preston_Bannister At 240C it probably can. Pretty hot for PLA.

@Ryan_Carlyle About that … I just find lower temperatures, say below 220C, pretty much unusable for most of my printing. Might be the filaments I tend to buy. Might the current crop of PLAs print hotter than what was used in prior years. Might be I am always trying to push speed. Manufacturers recommendations for what I have:

190-220C 3D Solutech PLA
205-225C Inland PLA+
235C Maker Geeks PLA
190-210C eSun PLA

Not like I print temperature towers for every spool. :slight_smile:

Mostly I just use 240C and drop to 220C if that is too much heat in some part of the print.

@shauki that’s a good way to jam an all-metal hot end

@shauki what type of filament were you using?

@shauki Ok, I haven’t heard of somebody doing that before, will have to think about it a bit. Since you say you have done it, I can’t say it’s impossible :slight_smile:

My experience with all-metal hot ends is that PLA will jam with cold zone temps >35C and ABS will jam with cold zone temps >65C or so. I have never had a PETG cold zone jam that I can think of, but I also don’t print it a lot. Curious now if there is a higher temperature where filaments will not jam…

@shauki Thanks. I appreciate your confidence in me. :slight_smile:

At the same time, @Ryan_Carlyle has more mileage on this subject, so I do listen closely to what he has to say. But then I run tests…

When I printed PETG, with a basic mk10 hotend, I had to slow down prints to get good result, and I hate slowing down large prints. So I have not printed a lot with PETG.

Part of the reason for putting in a V6 hotend was to see if higher temperatures allowed printing PETG at acceptable speed.

Also, I am about to go dark. Starting a new job, building software for phased array radars. Turns out one of my online friends has been working on algorithms that might increase performance by a factor between two and a hundred. As one of my sons is in the military, I am OK with work that might protect my son and his friends. Not the first time I have gone to an outfit and had this effect. But also not likely a public topic.

@shauki Out of curiosity, have you done any tests with Ubis hotends? To my eye, the thermal design looks better, but there might be other issues.

@shauki Fair enough. I might be from a rich country, but for large parts of my life have been on thin budget. We do what we can with what we have. Then figure out the rest.

@shauki To be clear, your translated messages come across as pretty weird.

Also, please keep trying.

(Have an old friend from Syria. Perhaps should track him down.)

What is happening to your country and people is a tragedy, both ecologic and political. National governments are … not perfect.

Also the notion of beer in Prague sounds good. :slight_smile:

@Preston_Bannister Shauki has proved me wrong before by trying things I didn’t think would work :slight_smile: that is one of the nice things about this community… lots of people trying things so we all learn…

Trying it > Theorizing about it