extruding greater than 1mm

before i try this i thought i would get peoples opinions of extruding 3mm to 1mm or even 1.5 for those repstrappers who aren't too concerned with resolution but just want to make a mendel. Then getting a .3 nozzle.

1.5 seems to be the smallest drill bit i have so i might try that.

Could anyone point out what would be the correct length of the extrusion hole?

It seems like it might make more sense for your repstrap to use 3mm extruded to 1-1.5 for quickly making the big mendel parts, (though you would probably have to buy all the gears), save your pennys to get a nice 1.75mm extruded to .3/.4 nozzle for that printer.

unless you're making a nice repstrap like the hydraraptor...

my repstrap however was kinda thrown together just to get me to a mendel, not designed for long term use.

oh and also i want to try and design it so i can make it on a drill press (although initially i will use a lathe to check it can work)

You could certainly make the large brackets with a big nozzle but quite a few of the smaller parts that would need a smaller nozzle, not just the gears. The Prusa Mendel has less fiddly bits but still I think even 1mm would be too big.

I made an extruder with a 0.6mm welding tip. Somebody told me afterwards that "0.6mm" tips have a bigger hole because that is the size of the welding wire, so there is some clearance.

It extruded ABS at about 0.8mm after the die swell. I build objects using 0.75mm filament and 0.6mm layer height with it. That was great for making large things, strong things, in a reasonable time.

The length of the hole is not too important when the hole is that big. With fine nozzles I try to keep it short, about 0.5mm to keep the pressure low, but at 1.5mm you will have no problem with pressure!

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[www.hydraraptor.blogspot.com]

maybe a screw on nozzle like makerbot would be more handy but with varying holes so you can swap between say 1.5 for large and fast print, .7 for inbetween, and .3 for detail.

i think someone already posted something something similar but about making an automated version where the nozzle can automatically switch during a print for the infill but that would be a hell of a lot of work

I think "plug-and-play" interchangeable nozzles would be an excellent idea. Maybe Makerbot had the right idea there.

Not sure about the automated switching mechanism though. That sounds like it would be simpler just to go with 2 extruders instead.

Edited 2 time(s). Last edit at 01/17/2011 02:11AM by An Original Name.

only problem is that you can easily swap nozzles but then you have to re-calibrate your z-height each time... because 1st layer height changes with nozzle orifice size,

two ways i can think of getting around that is:

1/ work out first layer height for your smallest nozzle, then work out how much higher your other nozzles will require and compensate through skeinforge somehow + that .2 or whatever onto every Z height (could probably do that in excel)

2/ machine the different nozzles so they slightly vary in length and all leave the correct gap for printing in that size.

thoughts?

Better to have the machine be able to detect the length of the tool in use, otherwise someone will forget to tell it what Z offset to use and the print will fail or the head will crash.

Nopheads tool sensor:
[hydraraptor.blogspot.com]

Should do the job.

oh that's a better idea. i might try this cheap microswitch:

[ausxmods.com.au]

actually you will need different skeinforge profiles for different nozzles anyway so i think compensating for first layer gap could just be done there