I have had loads of problems with bronzefill as well as the bamboofill, and generally all to do with under-extrusion. My UM2 doesn't do 'small' at the best of times and intricate is also a struggle - cuz it's small. A few things that helped me (but not yet to the point of having an intricate bronze print as good as regular PLA) are in the ramble below. I note you have some experience - more than me, so apologies if anything sounds like I'm stating the obvious, but maybe it will help someone else as I couldn't find any info at first either :-P
flow rate - yep, I use 108%, Colorfabb recommend 104 to 108 because nozzle swell does not occur in bronzefill, but again this does absolutely kill "intricate" :mad:
First layer - Originally I found that the difference in one "click" on the bed levelling process moved the print from having no adhesion to no extrusion. So I used the no adhesion 'click' and adjusted the bed screw underneath at the back until the paper had resistance. Now all prints have the elephants foot but generally nothing comes off the glass until it gets to under 45 degrees and I don't use tape or glue any more.
Also, still slow the first layer down. For generally PLA I print first layer and outer shells at 20mm/s and the rest at 40 at 205 - 210 degrees. With bronzefill you want material flowing pretty much all the time, so like you I print at 50-60mm/s but the first layer is usually 30-40mm/s.
Temperature - as with @skint, I can also print at 205 during a usual day with a warm room, but overnight prints are usually done at 210-215. The absolute worst thing is to come back to half a print with dark brown spikes... which leads nicely to...
Atomic cleanout - if you're not familiar with this, learn it now, and use it often. The exotics seem to kill my machine if I don't get it exactly right, and even after a successful print in bronzefill I still suffer from clogs if I don't clean out regularly, and rarely get 3 prints in a row.
Switch off retraction and increase travel speed - bronzefill doesn't ooze as much as regular PLA but the constant pulling and pushing of material led to a load of under-extrusion for me. I use a travel speed of 250mm/s to reduce the time any oozing has to occur, but generally the nozzle seems to arrive primed and ready to print.
Alternatively increase the travel speed and set the minimum travel distance to be big so that it never really retracts, and add a z-hop. Your UM2 will sounds like its having a real party in it's pants but I get a much better top layer generally with the z-hop - no drag lines which I was getting even with combing enabled. Not sure of the benefit in bronzefill though.
I found that the filament path around the back of machine, tight winds on the spool and the 45 degree angle into the bowden grinder caused a lot of pressure. I designed and printed a set of rollers for the filament spool and the filament feeds directly off the spool into the bowden feeder now without any twisting or routing. There are a lot of these out there, so I'm not going to sell you on the benefits of mine, but you really should use one with bearings in - when retraction is occurring the spool actually rewinds - that's a lot less friction than before. Loading and unloading of new filament has also seen significant improvements because of this.
With the setup above I can get some really great prints in natural PLA, and good prints in some of the colours, but bronzefill is still not up to the standard I would like, although compared to the first prints I tried, well, at least I can finish a print now :-P
Hope some of that helps.
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skint 61
It is recommended to increase flow to approx 105-108% although some users don`t increase flow at all. I too found that the base layers were more difficult to predict and they look much worse than standard PLA layers. I would perhaps put a larger diameter circle around that object to allow the material to get flowing nicely before it reaches those more intricate parts. I also had some success lowering my temps to 205-200...although not sure this was just fluke.
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