I’ve had a good few attempts at getting these tricky little SatNOGS gears to print and today I think it has all paid off and I’m finally able to share with you how I’ve been able to successfully 3D print SatNOGS Worm Screw Gears on a stock / standard Prusa i3 Pro-B clone.
- Unless stated otherwise, all of my 3D Prints are done with 1.75mm PLA at a Nozzle Temp of Aprox 185 – 187 Degrees C.
- I have also made a YT video (which I’ve included at the end of this article), but for the benefit of those not able to use YouTube for one reason or another, I thought I’d write up the information as well.
How I Successfully 3D Print SatNOGS Worm Screw Gears
If you’re here reading this article (or watching the YT Video) then I guess you’ve obviously not had much success in printing out the dreaded SatNOGS Ground Station Worm Screw Gears, huh? You’ve tried and tried and tried but still end up with a wilting mess. Sometimes you get teasingly close and then for some reason, it all goes wrong.
Fear not! You are not alone. Some people have great success with these gears from the get go, others like you and I do not.
We’ve been happily printing squares and cubes and relatively safe and simple shapes with great ease and success and now we’ve come up against a challenging part with angles, dangles, overhangs and whatsits we’re not having a very jolly time of it.
So How Do We Print This Tricky Little Worm Screw Gear Then?
First of all we need to work out what the problem is – obviously.
All of the advice that I’ve read on the internet in relation to printing tricky parts such as these worm screw gears which have large, steep and tricky overhangs all pretty much say you need cooler extrusion temperatures, slow speeds and lots and lots of cooling.
I’ve tried that method and variations of it over and over and pretty much end up with the same results in the end. A stringy, wilting and unusable messy part. Much of it likely due to the fact that I have insufficient cooling for this level of printing complexity.
What I have concluded from all these oh so close but failed attempts is that (at least in my case) slowly is not always the answer. It allows the print head / nozzle to linger on the part for too long until everything gets warm including the lower layers and then things start to droop and wilt and then it all goes downhill from there.
Jeremy Clarkson is Right – More Poweeeeer, More Speeeeeeed!!!
Love him or hate him (No Clarkson debate comments please lol) Jezza is bang on the money. To successfully 3D print SatNOGS worm screw gears (at least in my case) we need more speed!!
The reason I keep saying in my case BTW is because I can only really say what works for me. In theory, these settings should work for everyone or at least give a starting point to work from but this is not always the case. No two 3D printers are exactly alike. So please bare that in mind when using my settings. If in doubt, drop me a comment below and I’ll try my best to help – if I can.
My current working theory is that I need to get the print head in and out as quickly as possible and then keep it away from the part for as long as possible to allow the object time to cool before laying the next layer – but not so quickly it warps, curls and distorts. So with that in mind, I went fiddling about in Slic3r and made a few changes to my usual working settings based on these suppositions.
First Some Quick Adjustments Unique to my 3D Printer
The first couple of adjustments I made were more tuning adjustments unique to my machine so they’re not really relevant and you shouldn’t need to do them yourself. I’m only mentioning them for the sake of consistency.
My first adjustment was to my Extruder motor stepper driver. It wasn’t set high enough for the demand put on it. So whenever I increased the speed of my prints, the extruder motor would skip, click and under extrude. With that taken care of, there’s no more clicking now and I can up my printing speeds without any issues.
Next I took care of an issue where my nozzle has always been slightly over extruding so I dialed the flow down in the 3D printer itself using the Tune adjustments in the menu. I dialed it back to 98. Later I also dialed the flow multiplier in Slic3r down to 0.99. So in the end I had both of those values in effect making a combined flow rate of 97 (according to my maths).
This has improved the quality of my prints greatly by reducing over extrusion when printing normally and under extrusion when printing at higher speeds. The perimeter lines are much crisper and sharper which has improved the overall appearance of the outer shell walls.
My New Theoretical Slic3r Settings for Worm Gears
With those little adjustments made, I was happy and ready to start tweaking around in Slic3r. I wont bore you with how I arrived at each setting, instead I’ll just go through what the settings are and why I think it all works.
So to successfully 3D print SatNOGS worm screw gears – here’s what you need to try – assuming your printer is all set up, level, dialed in and working good.
I’m using repetier host and the Slic3r configuration GUI from within Repetier Host BTW so I’ll go through the Slic3r settings tab by tab. I will only cover the settings I’ve altered. If I don’t mention a setting it is because I’ve not altered it and it’s still set to software default.
SLIC3R PRINT SETTINGS TAB
Layers & Perimeters
- Layer Height and First Layer Height = 0.3 (thicker & quicker while maintaining some resolution detail)
- Perimeters = 1 (more perimeters = more time the nozzle spends over the print)
- Solid Layers = 2 Bottom & Top.
- Quality = Extra Perimeters = UNCHECKED, Avoid Crossing Perimeters = CHECKED, Detect Thin Walls = CHECKED, Detect Bridging Perimeters = UNCHECKED.
- Seam Position = Aligned, External Perimeter First = UNCHECKED.
- Fill Density = 50%, Fill Pattern = HONEYCOMB, Top/Bottom Fill Pattern = RECTILINEAR
- Combine Infill Every = 1 Layers, Only Infill When Needed = UNCHECKED
- Only Retract When Crossing Perimeters = CHECKED
Skirt & Brim
- Loops = 2 (allows the extruder to get flowing nice before printing the main part)
- Perimeters = 50mm/s
- Small Perimeters = 30% (that’s 30% of Perimeter Speed [50mm/s])
- External Perimeters = 25% (that’s 25% of Perimeter Speed [50mm/s])
- Infill = 60mm/s
- Solid Infill = 45mm/s
- Top Solid Infill = 30mm/s
- Support Material 30mm/s – (Not Used for Printing SatNOGS Gears.)
- First Layer Speed = 15mm/s – CRUCIAL – FIRST LAYER MUST NOT BE RUSHED!
- Infill Overlap = 3% (this is how much the infill overlaps on to the perimeter wall. We don’t want to disturb or warm up the perimeter wall at all once it’s been laid so we don’t let the nozzle get too close to it when infilling. Especially when we’re only using a single perimeter.)
SLIC3R FILAMENT SETTINGS TAB
- Extruder First Layer= 190C, Other Layers = 187C
- Bed Temperature First Layer = 65C, Other Layers = 65C (I manually turn off the bed about half way through the print at the printer using the tune menu.)
SLIC3R PRINTER SETTINGS TAB
- Retraction Length = 2mm
- Lift Z = 3mm
- Speed = 40mm/s
- Extra Length on Restart = 0mm
- Minimum Travel After Retraction = 25mm
- Retract on Layer Change = CHECKED
- Wipe While Retracting = CHECKED
Now to Make the Whole Lot Work….
Once the settings are configured, it is important to place the objects as far apart as possible from each other in your 3D printing software. In my case, I printed out two of the worm screws at a time. With one screw placed at one end of the print bed and the other worm screw placed as far away from the first as I could get.
By placing more than one object on the bed and spacing them apart the print head isn’t continuously hammering away at the same object until it wilts and resembles a well used candle. The combined time it takes to move the print head from object to object and to print a layer before returning to the first object again is enough to allow the objects to gradually cool between layers being added.
Since I don’t have a nozzle mounted print cooler / blower I’ve stood a 40mm fan at the side of the bed blowing across the parts as they print to assist with cooling them in between passes.
My Word These 3D Printed Worm Screw Gears Look Rough……
Now I will admit the inside of the threads of the finished screw gears doesn’t look pretty. There are stringy, ropy bits in there but the part is 100% functional and when ran together against their larger counterpart gears they will bed in nicely. The important parts are the top surfaces and the outer edges of the screw threads . Provided they’re well formed and sturdy, the teeth of both gears interlock nicely and surprisingly with little to no play or wobble in them.
Any loose strands of filament and roughness can easily be cleaned up. It took me about 10 minutes to clean mine up. I just kept rotating the worm screw against the teeth of the larger gear to bed the two in together until both gears ran smooth.
To be honest, I sort of did it without thinking too much about it. It became sort of like a fiddle toy keeping my hands busy while I watched the TV.
While my screw gears were printing I’d occasionally glance at them and think “oh my, what a mess“, but if you just allow the printing to continue they tidy themselves to some degree. Yes there will still be some roughness and stringy ropy danglers inside the threads left behind from trying to print overhangs in mid air but the teeth of the larger gears don’t penetrate that deep into the threads of the worm screw gear so none of that really affects the performance – that I can see.
So as long as the top faces of the worm screw teeth are flat and the outer edges are well formed and sturdy the worm screw gears will work once worn/bedded in. I also think some suitable PLA friendly lubricant would help once everything is assembled and installed prior to use.
I Can Definitely Use These
Given that I’ve printed these worm screw gears out on an unmodified Prusa I3 Clone, using the stock head, with very little cooling, I’m really happy with the results. Yes they could be better aesthetically and yes people have printed them out without all the crazy stringy bits inside the threads but as long as they work, they’ll do for me.
In the end, they’ll be inside a box and I’ll probably not see them again until I open it up to do any necessary maintenance or upgrades. For me it really is more about functionality over beauty. If I want high definition I’ll go build or buy an SLA printer =]
So that’s how I successfully 3D Print SatNOGS Worm Screw Gears.
Hopefully this article has armed you with enough advice and tips to point you in the right direction and that the settings I’ve given provide you with a good starting point from which you can tweak around and adjust to suit your own printer.
With a bit of luck and some patience, you should soon have a set of SatNOGS worm screw gears of your own to play with.
If this article has been of help to you then why not let me know in the comments below. If you have any pictures of your 3D Printed Worm Screw gears then please post them along with your comments. I would love to see what results other people are getting based on my settings.
Thanks for reading!
Successfully 3D Print SatNOGS Worm Screw Gears YouTube Video