Filament issue - does this sound right?

Without a long backstory, I modified my TAZ5 to use 1.75mm filament (new hexagon 1.75mm head, .35 nozzle). I had it tuned in really well printing with PLA, at 193 degrees.

I wanted to print some larger items (15+ hour prints) that didn’t need to look pretty, and I thought I could really up the speed by using 3mm filament and a larger nozzle (.5), but the thought of swapping the original head back in (and out agai8n every time I wanted to change filament) sounded terrible so I bought a new extruder, now I can simply swap the 2.

I put the 3mm/.5 in and readjust some settings. I find that my prints are terrible. After much messing about, I turn to temperature. By pushing the temp from 193 to 210 it solves a lot of issues.

So 2 questions:

Should 1.75mm and 3mm filament need different temperatures? I know it takes more energy to melt the 3mm - so a higher initial temp will keep the temp balanced? Am I correct in assuming that?

Second: This 3mm is from a different manufacturer. Should different manufacturer PLA be that different of a temperature requirement?

Thermal mass = more heat reserve 4 more material mass = yes

Different fillers and different mixes of materials used, along with possible % of recycled during manufacturing.

I frequently swap back and forth between 1.75mm and 3mm. I have built a number of tool heads (extrusder, extruder mount, gears, stepper motor, hot ends and fans) to make this easier.

I do need to make sure that the home nozzle height is correct after every tool head change. Other than that, I do not find huge temperature changes to be required.

I do find interesting changes going between filament manufacturers. I would suggest that you purchase an infrared thermal thermometer and make sure that the temperature sensors in both hotends are working correctly.

Last 2 prints I made with this filament failed because the filament snapped off at the bolt mid print.

I’m printing it now with the 3mm red LULZBOT PLA that I bought with the printer. I forgot to tweak the heat settings - after it prints I’m going to try some prints at the 193 I calibrated my printer to use for 1.75mm PLA and see how it does.

I’m 99% sure this 3mm yellow I bought is utter garbage. I’ve never had a filament break off mid print before.