Bondtech or similar extruders (again)
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@burtoogle said in Bondtech or similar extruders (again):
@calvinx said in Bondtech or similar extruders (again):
See my picture below, thit is one of my PETG printers, it doesn’t print anything else but PETG. And you will notice there is NO part cooling fan because it doesn’t need one.
In my experience there is a reason for using a part cooling fan with PETG (and similar filaments) and that is when you are printing skin above support. In that situation you would like to have poor layer adhesion and so blasting 100% fan at the skin makes the support easier to remove.
I print various PETG parts and mostly use zero fan but I do have one part that has some overhang and that needs a touch of fan to avoid sagging.
Interesting. luckily I have not had any issue removing supports.
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Ok. Update.
Tried printing a benchy at 215 degrees and 100% fan. Set fan to come on at Layer 10 (2mm). That was the end of that . No layer stuck after that and no, my cooling outlet is not blowing at the nozzle but at the print.
I printed an overhang test piece firstly with no cooling and 195 degrees. Printed ok until about 50 degrees overhang when it got a bit messy. Then I printed it at 215 degrees and 50% fan. About the same quality but had no strength. Could pull it apart easily. I'm using Sakata 3d filament. Now going to try Rigid Ink filament.
The daft thing is that when this was a standard printer I could print a benchy no problem. Since upgrading to a genuine E3D and a Direct drive extruder I have had all these problems. I guess that is the answer. Revert to original.
As an aside my delta with a duet board and a E3D and Flexidrive extruder also prints a benchy no problem with no cooling.
It makes me think that 3D printing is not an exact science as some make it out to be. -
Do you have the correct thermistor values for the hotend?
Is there something mechanically wrong with it?
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Since you’ve changed the nozzle, are your thermistor settings correct? Looks to me like you’re printing too hot, and over extruding on the return after retraction, hence a zit. As you’re direct drive, retraction should be much shorter than Bowden. Are you using pressure advance too? Something definitely changes after the first 10 or so layers. Is this where solid fill ends and printer speeds up? Was the cat printed with the current setup, or before the change? If current, I can’t explain why it’s so different for Benchy!
Ian
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Thermistor values I think are correct. I did a PID tune and set the values. The temp is rock steady as is the bed which is mains powered heated mat.
The cat was printed with the same setup.
Not using pressure advance. 2mm retraction set up at moment.
Printer is set at 2400mm/min.
I print first layer at 40% speed as I find this gets a good first layer. The outline is set to 40% as well.
So first layer prints at 16mm/s with the outline at 6.5mm/s
Thereafter everylayer prints at 40mm/s with the outline at 16mm/s.
I chose the fan to come on after 10 layers as this seemed a good point to start. -
@preb1 said in Bondtech or similar extruders (again):
I chose the fan to come on after 10 layers as this seemed a good point to start.
Is this still the picture of the Benchy from the first post? Because something fairly dramatic changes at that point. Maybe the fan is causing interference on the thermistor? Or temperature change at that layer? Something about your settings is different for the Benchy from the cat.
Ian
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If it's a Gt2 Semitek from E3D your config entry for the heater should look like this on Duet Wifi.
M305 P1 T100000 B4725 C7.060000e-8 R4700 S"Hot End" -
@preb1 said in Bondtech or similar extruders (again):
Thermistor values I think are correct.
just let us double check that.
post the values that you configured in M305 and tell us which thermistors you are using. -
@phaedrux said in Bondtech or similar extruders (again):
Do you have the correct thermistor values for the hotend?
Is there something mechanically wrong with it?
+1 on that, 215 is usually enough for any PLA.
On another note, are you sure it´s PLA? It sounds more like the behaviour with ABS.
If you double check the thermistor and see if they´re the correct values, go up with the temperature drastically , like up to 260C and see at what temperature the layers stick with the cooling fan at 100%.
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This is config entry for thermistor.
M305 P1 T100000 B4138 C0 R4700I've just altered the cooling outlets to point more down so as not to blow across where the filament is laid down. Got a feeling they may have been cooling the filament as it was going down so maybe cooling to quickly.
Just printing a benchy now. -
@preb1 said in Bondtech or similar extruders (again):
B4138
that is the default value in the configurator and VERY likely to be wrong for your thermistor.
what thermistor do you actually have? -
Its from TCMUK-3d. NTC Thermistor Brass Cartridge 100Kohm
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0_1566556777334_config.g.txt
This is my config file -
@preb1 said in Bondtech or similar extruders (again):
TCMUK-3d
its says its compatible with an original e3d thermistor.
so its a semitec.
please use the values posted by Phaedrux -
OK. Update.
Printing the benchy after modifying the outlets made it worse.
Reverted back and this time I started the fan at layer 3. Fan at 75% and temp at 220 degrees. This time a marked improvement. The first 9mm (or 180 layers are ok.•No lumps and bumps) From then on it is perfect. I have to eat humble pie and say I do need cooling but I think my cooling duct needs refining as maybe its not quite hitting the right spot.
I altered the config as per values posted by Phaedrux but it made no difference to the temp. After taking readings with a thermometer the hot end is still at the indicated temp both before and after the changes.
Thanks to all for the advice. I certainly learnt something. -
@preb1 said in Bondtech or similar extruders (again):
I altered the config as per values posted by Phaedrux but it made no difference to the temp.
there is at least a 10C difference between those beta values at around 200C
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@veti that value is actually correct when using the standard model the one Phaedrux posted is using the steinhart model which is the better way but both are valid. This is probably way the op found no difference in temp (they should both have been very close to each other)
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the beta value for the semitec is 4276. at 200C there is about 10C difference to 4138.
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@veti ah I get where you are coming from now The spec for the Semitec is 4138 but that of course is the 25/100 C rating which also why the std Chinese ones that quote 3950 are so far out at print temps because they are quoted even worse at 25/50 so they actually come out quite a bit higher (4008 at 110 IIRC) this is why the steinhart I believe is better because it takes that into account but I am no expert on them and TBH I would much rather use PT100's or at very least PT1000's
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https://www.mouser.de/datasheet/2/362/semitec usa corporation_gtthermistor-1202937.pdf
The e3d thermistors are 104GT-2 Which have a beta value of 4276. See the above datasheet.Steinhard Hard is often used to derive a precise temperature of a thermistor, since it provides a closer approximation to actual temperature than simpler equations, and is useful over the entire working temperature range of the sensor.
The Semitec Thermistor is widely used and produces good results. The B3950 Thermistors as you say become very inaccurate at high temperatures as there are different ones that just behave the same in the 25-50C quoted range.
I moved to a PT1000 because of all of this as well.