I was a little surprised by just how much heat that much filament sucks

3D Printing
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I was a little surprised by just how much heat that much filament sucks out of the hot end. Extrudes like a dream though.

Originally shared by paul wallich

I finally got around to trying the 0.75mm nozzle on my Metal Plus. It arrived before the holiday, but I didn’t have the time to make a custom wrench for it (the flats appear to be just a hair too far apart for the quarter-inch open-end wrench I got at…
http://invisibleturtles.org/2015/11/30/3d-printer-nozzle-wars/

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The E3D volcano has a longer hot zone for a reason. 0.75mm is big. Print slower or get a volcano.

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You should try PID auto tuning using the mcode commands. I read up on this on linkomatic’s page. He is extremely smart.

You can google PID auto tuning to find out more. This isn’t necessarily the answer, but it is peace of mind knowing your hotend heater is dialed for s specific target temperature.

Secondly, since we don’t yet have precise control over volumetric flow, you will have to overshoot your target temperature due to massive amount of heat the filament pulls off the heater when printing at a certain speed.

I say “at a certain speed”, because for a given constant speed of extrusion, a constant amount of heat is pulled off at s constant rate… Double the speed, you should see a predictable amount of increased heat pulled off-- making the hotend work harder. A few short tests at a constant temperature, but different speeds, should allow you to see a pattern that is somewhat linear.

You can always shoot in the dark, with the desired filament temp and the desired speed first, then increase the temp in 5 degrees at the same speed and compare a shirt print over and over until you find a better temp to run at that gives the best sweet spot for print results.

You mentioned spiral case- it’s an interesting case study, because the flow is constant. Any time you print a non-spiral case print, the extrusion stops and starts- the longer the stop, say for a travel move, the more potential heat you store up and overshooting becomes s problem.

So, without trying it myself on that print you showed, here are a couple things to try… Use the fastest travel speed your boy can take without skipping to limit heat build up. Use as little retraction as you can live with, so the heater doesn’t spike too much on travel moves with no filament in the melt zone. On big, solid prints with fewer travel moves, you should be able to crank up the temp and go fast. On thin-walked prints, or prints with little infill, you will have to slow down AND use a lower temp to avoid wild fluctuations. Use the same speed for outside perimeters and infill as the rest- don’t slow down for features or the target temp will be elusive with the speed always changing.

At first, I thought acceleration would be your enemy, because it changes speed so much, but it also changes the extrusion speed do this shouldn’t matter. You could try a predictable spiral print and compare results with and without acceleration enabled to see if there is any benefit to using it.

I found the 1mm tip is harder to dial in than the .75mm tip due to all these moving targets- but I’m sure you could dial that in for a specific print with a little trial and error.

Big volumetric flow is a beast, but a fun challenge I will be throwing myself into this month to accommodate a big printer I am building. I think the takeaway is that large tips just don’t act like smaller tips. It will take time to
Learn this black magic.

All the Ubis hotends take a different approach to design than most other hotend manufacturers. Carl doesn’t use an overpowered heater- he builds in exactly as much power as he needs. He likes things efficient and responsive. I tell him the target is.4mm tips, so they are all set up for that and a 60-80mm/sec speed. While I’ve seen prints well above 100mm/sec, that is the top end of practicality for good resolution printing. Run 3x the plastic through and it starts to get wild. In addition to building lower power hotends than others, he also hates thermal mass. He hates big heater blocks for a variety of reasons. Low thermal mass means quick heat up times and faster cool down times, but should result in more accurate readings of temp since it responds quickly to input. You can increase the frequency of temp readings in firmware I believe, but talking trough this w my guys doesn’t leave me with confidence that it will help.

I guess the proof is in the results.

A longer melt zone does help- we see the Ubis 13 is not built for speed because really fast speeds simply don’t give the filament enough time in the melt zone to absorb the heat. The Ubis ceramic is much better at speed with a longer melt zone.

When Carl delivers on the dual core heater for the Ubis 13 Pro, it will be interesting to see what decisions he makes. He has kicked around different sized heaters and even two thermistors to manage preheat temps higher up separately from the lower final heat the plastic received before it exits.

Too much talk, not enough of me printing!
Brook

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@Brook_Drumm Thanks for the lincomatic suggestion – I’d forgotten that page. But I think I’d need to be running filament through at the target speed while doing the autotune, and that makes me a little queasy. (Albeit @Tyler_McNaney is just one town away, so any balls of spaghetti I make can go right back in the grinder.)

During the prints I’ve made so far, the temps have been pretty stable (maybe a range of 2-3 degrees so I think I’m just going to try cranking the target up. With a metal hot-end and t-glase (or other PET variants) there’s plenty of headroom.

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I like the simple approach. Do take my suggestions on slicing though, it will minimize pesky issues. The Ubis ceramic can go to 175 so have fun!

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Paul you are always welcome to swing by and get some filament recycled!

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Thanks, Tyler! Do you folks do PETs yet?

FWIW, I printed something else with the target temp set up to 242 and a fastish print speed, and the extruder spent most of its time between 222 and 224. So maybe that is just all the heat the Ubis13 can muster. Maybe I can do some tests of flow rate vs max temp and report back.

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You may have hit a limit for that speed. Slow it until the max temp desired us achieved

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We can grind PET, working in the extruding part.

We have a printer using the .75mm, printing at 60mm. Found that it helps to turn off fan to keep the heat up.

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Hmm. I could unplug the fan on the hotend during extrusion, but that would require careful supervision (i.e. not walking away before a print ends). Might be worth 60 mm/s

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You can use the M107 code to shut it off, unless your pruning with an SD

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M107 shuts off the cooling fan for the print. There’s also a fan for the hot-end heat sink that’s wired to be always-on (in part because the controllable fan circuit only has a tiny FET, in part because with an all-metal hot-end active cooling of the heat sink is needed to keep bad things from happening. Heat won’t leak upward much while extruding at speed, but if you pause/stop it could get interesting.)

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@Tyler_McNaney
Oops, turns out for some (not all) of these prints the cooling fan was on too. Have to either get rid of auto cooling entirely or set a really short layer time. Extruding into thin air at 60+mm/sec only drops extruder temp a few degrees.