Print Plate Temperature is Never Truly Uniform
You intuitively know that your print plate isn't the same temperature across the entire surface, but we pretend that it is. Even to the point of being surprised when large prints warp off near the edges. The temp simply is not going to be uniform, but varies with location, density of print objects, and how recently the print head warmed an area.
Here are some picts to illustrate. First an empty print plate in process of warming up
Even empty, the plate simply is not the same temperature everywhere.
RE: Print Plate Temperature is Never Truly Uniform
Here is a different plate, but with an active print job.
Take home message is that the edges are cooler than the center (surprise!) and we should plan our object placements accordingly.
RE: Print Plate Temperature is Never Truly Uniform
I'm curious how that changes in an enclosure to keep drafts and convective cooling to a minimum.
I've been able to print PETG with a 70c bed in mine but if it's not enclosed it'll warp off something fierce even if the bed is meticulously clean.
RE: Print Plate Temperature is Never Truly Uniform
These are inside an enclosure and a warm room. Bunnies shudder to think what it would be like out in the open.
RE: Print Plate Temperature is Never Truly Uniform
Bunnies have a macro lens attachment. Now we are ready to look more closely at circuit board components.
https://www.thingiverse.com/thing:3863852
Some picts of a Raspberry Pi3...
RE: Print Plate Temperature is Never Truly Uniform
Did the bunnies get a new toy recently? I'm jealous.
See my (limited) designs on:
Printables - https://www.printables.com/@Sembazuru
Thingiverse - https://www.thingiverse.com/Sembazuru/designs
RE: Print Plate Temperature is Never Truly Uniform
Is it the Flir or the other brand? And if Flir - is it the 60x80 or 120x160 sensor? Wait - maybe HTI-19 is a clue... sigh.
RE: Print Plate Temperature is Never Truly Uniform
I've been considering adding some insulation to the underside of the bed, but worry about the increased mass causing ringing in the prints.
I guess polystyrene might be light enough, but it is also quite flamable.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: Print Plate Temperature is Never Truly Uniform
For a time I had the entire bottom insulted with furnace insulation tape, but removed it because my enclosure was not warming up enough and it took forever for the bed to cool down. Now I'm considering insulating just the periphery to even things out.
Not a FLIR. Bunnies don't have that large a science budget. HTi is a Chinese maker. This was the right price, had enough resolution and I knew one could add a lens to get macro capability. 320 x 240 is the claimed resoluton, but I have not confirmed it. However, it is good enough to render the attached in thermal only (no visible light overlay). This is on an E3DV6 with silicon sock mounted in BNBSX extruder. View was from right of extruder. Heat block looks a bit confusing because you also see its reflection off the hot fin.
RE: Print Plate Temperature is Never Truly Uniform
Thanks Guy - thatimage of the heater block and fins confirms my measurements and my expectations. The fins are so cool they can't melt PLA. Begs the question of how PLA or other material is melting above the heat sink at the extruder gears when heat from the heater block is so well isolated: leads to a suspicion the cooling fan is off or worse in those cases.
RE: Print Plate Temperature is Never Truly Uniform
Don't have a problem with cooling down as I pop the plate off and place it on a cool table to bring the temperature down.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: Print Plate Temperature is Never Truly Uniform
I wonder what the dust content of the China fabric is?
RE: Print Plate Temperature is Never Truly Uniform
Dunno yet, going to find out when it arrives, but I was already thinking about how to attach it and dust / loose fibres and thought Kapton tape the whole underside of the heated bed, since I don't want to ruin it. Use aluminium lagging tape on the insulation for the bottom side to stop dust and stray fibres then depending on how strong the textile is, high temp silicone adhesive it to the Kapton tape, maybe may have to tape this side before siliconing it.
For the price it's worth a punt.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: Print Plate Temperature is Never Truly Uniform
If it turns out to not be dusty crumbly, then maybe an offcut to the top of the heater block between the heatsink and heater block?, just an idea, but like you say, probably dusty crumbly Chinese stuff, but maybe we are both wrong. Not everything is complete garbage from China, I bet half the parts of the printer are made there.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: Print Plate Temperature is Never Truly Uniform
More Mosquito magnum and E3D in thermal. Both are in BNBSX extruders. You can easily see the extended melt zone implemented on the Mosquito magnum. Red ring on 1st mosquito fin is probably IR reflection.
That horizontal band across E3D heat block is my garter wire going around its silicone sock.
RE: Print Plate Temperature is Never Truly Uniform
I wonder what the dust content of the China fabric is?
Ermmm, quite high!. 🤧
I thinks the kapton tape jacket is in order here.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: Print Plate Temperature is Never Truly Uniform
The infra red image, assuming the colour scale will be about the same due to min and max temperatures being so close:
The Mosquito seems to have a warmer heatsink (Green)above the block compared to the E3d (Blue). I would have thought it would be the other way round the way the mosquito is being hyped by it's creators. It may just be the thermal imaging though.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: Print Plate Temperature is Never Truly Uniform
You are reading the thermal image correctly. The Mosquito Magnum is warmer above its top heatsink fin than the E3D is above its bottom fin.
With both hot ends heated to 245C x 15 minutes, I rechecked with a bare bead thermistor. Immediately above the Mosquito Magnum's top heatsink disk I get 56.5C. Above the E3D's lower most heatsink disc, I get 50.3C. The higher temperature reading for the Mosquito is seen by both thermal imager and contact thermistor. Does not appear to be a sensing anomaly.
Both are with the Noctua fan. Mosquito hot end sees a smaller total air volume passing through its small fins. It is hotter, but the total calorie release by the Mosquito is lower as attested by how much warmer my enclosure with E3D gets when printing at same temperature. Temperature is higher despite the lower thermal flux of the Mosquito due to the small amount of air volume carrying away heat. If the Mosquito had E3D size fins, it would be cooler.
Thankfully the Mosquito temp is not so much higher that it melts filament above the heat break.
RE: Print Plate Temperature is Never Truly Uniform
[...] Begs the question of how PLA or other material is melting above the heat sink at the extruder gears when heat from the heater block is so well isolated: leads to a suspicion the cooling fan is off or worse in those cases.
By happy coincidence, I watched the YouTube video by TeachingTech on the BondTech extruder upgrade for the Mk3 today. The best nuggets in a lot of YouTube videos are in the comments. I noticed this one in a long response by Chris Warkocki about 7 comments down. Chris does a lot of excellent work, and his comment echoes problems noted last year (2018) during the "heat creep" discussions:
... cooler motor operation and no residule heat to the gears. This is an issue with direct 1:1 extruders where motor heat is transfered to the gears.
I unfortunately have no way of testing this myself, but would love to see what the temps over the entire assembly look like on a long "problematic" print. If the motor is directly driving the Bondtech gears along a metal path and the motor gets hot, this sounds like a possible contributing factor, subject to all the contributing factors that combine to turn an annoyance into a problem (over-tight extruder tension, stuck idler gear, excessive retraction settings, temps, etc.)
Unfortunately, Chris has a tendency to produce long, meandering, multi-hour videos so I'm not going to be able to sit through all of them, but I'll be looking for any testing he's done on this. I wouldn't expect him to comment without having a high degree of confidence.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Print Plate Temperature is Never Truly Uniform
Lay a small piece of filament on your extruder motor: let me know if it melts.