Filament to Nozzle Ratios

Hello,

In the past few weeks I have dived into building myself a RepRap Prusa Mendel. Being on a college budget, I made sure to try to save as much money as possible. This means soldering the RAMPS 1.4 and Arduino Mega 2560, in addition to making my own hotend. I was able to get printed parts from a friend who has a RepRap Darwin for $20 (about the cost of 500g plastic) and the total cost of my RepRap came to around $350.

Now that I'm waiting for the final parts to arrive in the mail, I'm getting concerned about my choice of hotend nozzle and filament size. Since I plan on having it print overnight while I am asleep and don't care about a slow printing speed, I chose a 0.25mm nozzle and plan to use it with a NEMA 17 (43lb/in) powered Wade's Geared Extruder using 3mm filament.

Since buying the hotend block from eBay, I've noticed some of the pre-assembled hotend/extruder designs offer formats such as "3mm filament with 0.50mm nozzle" or "1.75mm with 0.35mm nozzle". Is my nozzle size too small for 3mm filament, or is this not an issue? Hopefully I won't have to order another hotend heater block of a larger size, it takes weeks for items to arrive in The Netherlands.

Main question: Will having a 0.25mm nozzle in combination with 3mm filament produce any problems (eg. the NEMA 17 not being powerful enough).

Thanks.

Edited 1 time(s). Last edit at 08/13/2012 04:37AM by Lodorenos.

The first question is are you planning on printing with ABS, PLA or something else?
A 0.25mm nozzle for ABS is tough to get calibrated to start off with )a 0.50mm nozzle might be easier).
For PLA it is easier because it is much more fluid and can be made to flow easier by raising the temperature.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

I plan on using PLA to start off with, as it doesn't require a HBP which I still need to build. As soon as I get the machine calibrated I plan to switch to ABS and start making Prusa Mendel sets to sell at no profit (just plastic cost + S&H + $5 machine maintenance). I got a 0.25mm nozzle because I prefer print quality over print speed.

How much of a visible quality difference does 0.25mm make in comparison to 0.50mm on a well calibrated machine?

Hopefully someone else can answer that question as as of now I have only used 0.5mm nozzles.

I had a 0.25mm nozzle that I sold and have two 0.35mm nozzles that I intend to try out.
I can print with a layer height of 0.2mm with no problems.
I suspect that I might be able to do 0.1mm but haven't tried it yet.

I also suspect that it doesn't make that much difference.
With a 0.5mm nozzle I can print 0.5mm down to 0.2mm (maybe 0.1mm).
With a 0.25mm nozzle you should be able to print from ~0.3mm down to 0.1mm without any problems.

I generally print with 0.3mm layer height unless it is something that really doesn't need it such as a Mendel vertex.
Such objects I generaly print with a 0.4mm layer height.
I use 0.2mm only for very fine objects, and have used 0.5mm on a rare occasion.

I suspect that using the proper slicer settings and having smooth running mechanics is more critical then the nozzle hole diameter.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

The minimum feature size is halved and you get sharper corners with a small nozzle. If you print large things with smooth curves and no corners there wont be much difference at all except it builds much slower. Small detailed things will come out much better.

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[www.hydraraptor.blogspot.com]

Thank you for your replies. I suppose I'll wait until my Prusa is finished and give it some test runs. I plan on buying/making several hotends for different purposes as time goes by anyway. I'm glad to hear that the smaller nozzle will create sharper corner detail, as it's quality, not speed, that I'm after.