Does anyone know how to determine what size filament I should be using? I bought a kit from Canada off of ebay, and the guy told me 3mm, which will not load into the extruder (and yes the bolt is knurled) I can no longer get any replies from him but I thought maybe someone here would have an idea of other sizes I could try. while I do not want to keep buying expensive rolls of filament to try to test diameters, it maybe my only choice ((. The documentation on these things is horrible.

I only know of 2 sizes 3mm & 1.75mm. I use 3mm, 0.35 j-head hotend & Greg's Accessible Extruder.

I had an issue when I first built the machine where I thought I got a 1.75mm instead of the 3mm I ordered. With the hotend on the extruder i couldn't get the filament to feed into the hotend so I tore it apart. when the hotend was removed from the extruder it slid right in.. put it back together and hasnt been an issue since..

Thanks for that 6of1. I wish I had another prusa mendel to look at so I could tell what I have. I also did some checking and found only the other size you mentioned. I cannot even get the 3mm PLA to start into the extruder. The guy I bought this from gave me no information. I only managed to put it together and get it running by finding 3 different manuals, but how to losd it and print with it, I have not a clue as the documentation sucks It has been sitting for months now.

As a simple test, if the nozzle assembly is made for 3mm filament, it should easily accept a 3/32 drill bit (~2mm) inserted (shank first) by hand. If it is made for 1.75mm filament, a 3/32 drill bit should pretty much stall out going into the nozzle assembly.

take some pictures of your machine and post them (hotend, extruder, etc).. I'm pretty new to all this stuff myself but ppl here seem to be extremely helpful and willing compared to other forums on the net.. also YouTube was helpful in visualizing all the stuff you see in txt.

hi xlando. I am not sure what shank means. Is this the tiny metal tip? of so, the tip has a much smaller hole than 3mm. I would suspect smaller than 1.75mm as well.

Can you post a picture of the extruder?
The issue you would normally have if the filament is too large is it wouldn't enter the Hotend.
He's referring to the shank of the drill bit, I.e. the not pointy end.
The hole of the bottom of the nozzle will be between 0.3mm and 0.5mm depending on what you bought.

Well guys, thanks for the advice. I took the extruder apart, and realized the Extruder itself had too small of a hole. I drilled it slightly over 3mm, and now the PLA goes through it now. Maybe the extruder printed part had a slightly undersized hole???? Thanks to all of you.

jj, the shank of a drill bit is the end that goes into the drill chuck. I suggested using the shank as a rough width gauge because it's the same width as the working end except it has no real cutting edge that might compromise internal components (specifically the PTFE collar)

1 3/32 drill bit will easily go into a hot-end assembly made for 3mm filament and will not go into one made for 1.75mm filament. (or should not anyway)

edit: and no, not the extruder nozzle, that's far too small. Of course I meant the end into which the filament is fed, not the one thru which the heated plastic is extruded.

Edited 1 time(s). Last edit at 10/07/2012 04:42PM by xiando.