Tips for Printing Gear

[JustinDS89]

Hello again! I know this has to do with the common thin wall issue, but thought I would see if anyone had some advice.

I am trying to print a 20mm gear with 20 teeth. The teeth are fairly small. It shows in the print preview window when looking at it by later that it is attempting to fill the teeth in, but when it actually prints they are hollow.

Im not sure if it's even possible to get these to fill in, but thought I would check.

Thanks,
Justin

[dkightley]

My best advice is to if at all possible, print this (and any gear) with a 0.2mm nozzle.

Here's a couple pf previews....one with a 0.4mm nozzle, one with a 0.2mm nozzle:

0.4mm nozzle

0.2mm nozzle

The best fill can be achieved with the infill overlap set to a high value.....75%......and with the thin wall overlap enabled and set to its max....50%.

btw...I have extrusion multiplier set at default value.....upping has an effect on the fill, but I find it can cause more problems then what it solves!

Hope this helps.....and good luck!

[upsm]

I trick that I use when I don't have access to the small nozzle is to edit the gear a bit to move the "tips" of the gears further from the part. This is not hard to do when you are making gears from scratch, editing the STL - not that simple..

Then I print it with thinnest "extrude diameter" as my printer can safely print (for .4 nozzle it's .25mm) and I print it as slow as it will reliably work. What happens is that when you reach the "tips" of the teeth the stretching of the filament will pull them in and compensate for the edit I made previously. To get this to work you also need to use the thinnest layer height you can survive (0.05mm is what I used to use)

This works for "thin" gears.. ~3-5mm thickness works rather nicely, after that the excess plastic deposited in the tips (due to rounding) will start to become a problem, you will see tips go up and nozzle will start catching them and nocking the print out of the bed..

it's not the best way but it helps with these small ones... I personally stopped printing small gears few years ago all together since I figured out it's easier (and cheaper) to just cut them out of hdpe instead of printing them but this trick might help you. You can try it even without editing the gear shape. What would be good for this type of over-stretching filament is if slicer would "pause" at the tip of the gear.. there were some plugins that do that in some old slicers and some old firmwares, when the "corner" angle is under 45 degrees "stop" at the tip for few ms ..

[JustinDS89]

My best advice is to if at all possible, print this (and any gear) with a 0.2mm nozzle.

Here's a couple pf previews....one with a 0.4mm nozzle, one with a 0.2mm nozzle:

gear.4.JPG

gear.2.JPG

The best fill can be achieved with the infill overlap set to a high value.....75%......and with the thin wall overlap enabled and set to its max....50%.

btw...I have extrusion multiplier set at default value.....upping has an effect on the fill, but I find it can cause more problems then what it solves!

Hope this helps.....and good luck!

Well I didn't have a 0.2mm nozzle available at the time, but I did adjust the settings according to what you suggested and used a 0.3mm nozzle and this appeared to work great and fill in pretty well.

Yes, I tried messing with the extrusion multiplier initially, but this of course made the whole rest of the print look pretty rough and I still had gaps in the teeth.

Thanks for all the help.

Justin

[JustinDS89]

I trick that I use when I don't have access to the small nozzle is to edit the gear a bit to move the "tips" of the gears further from the part. This is not hard to do when you are making gears from scratch, editing the STL - not that simple..

Then I print it with thinnest "extrude diameter" as my printer can safely print (for .4 nozzle it's .25mm) and I print it as slow as it will reliably work. What happens is that when you reach the "tips" of the teeth the stretching of the filament will pull them in and compensate for the edit I made previously. To get this to work you also need to use the thinnest layer height you can survive (0.05mm is what I used to use)

This works for "thin" gears.. ~3-5mm thickness works rather nicely, after that the excess plastic deposited in the tips (due to rounding) will start to become a problem, you will see tips go up and nozzle will start catching them and nocking the print out of the bed..

it's not the best way but it helps with these small ones... I personally stopped printing small gears few years ago all together since I figured out it's easier (and cheaper) to just cut them out of hdpe instead of printing them but this trick might help you. You can try it even without editing the gear shape. What would be good for this type of over-stretching filament is if slicer would "pause" at the tip of the gear.. there were some plugins that do that in some old slicers and some old firmwares, when the "corner" angle is under 45 degrees "stop" at the tip for few ms ..

Sorry about that, it appears that I missed your comment.

I will say I did get this to work great with some suggestions in another post on this thread.

The geared part turned out great with these modifications that were suggested, but I will definitely take your recommendations into thought for future projects.

Appreciate the help!

[upsm]

Sorry about that, it appears that I missed your comment.

No need to apologize

For the "small and tiny and precise" parts listen to dkightley! From what I see he's printing those uber small miniatures for a while so his experience is serious in that regard. You want to read what he writes about "small/miniature prints with details" at least twice and if you are not sure you understand ask him.

I just wrote what I used to do while back when printing gears for the repraps in case it helps someone; trigger some idea, nowadays I buy aluminium ones, don't remember last time I had to print anything smaller then those big herringbone gears for wade (and those print easily so..). I mostly print big, chunky, strong parts that have very little details so compared to dkightley I have a very different target to what your questions are about. Anyhow those tricks used to allow me to print very precise and strong 1mm pitch gears that still work so when you have time, play with the idea.

Thinking about modern firmwares, in theory (have not tried it), if you drop the jerk settings to 0, and you drop acceleration to some fairly low value, you will experience exactly the movement that's ideal for gear printing - the head will "stop" for a bit at the tip of the gear, so stretching filament can make pretty precise shape even without "elongating" tips of the model.