3d printed cooling fan

[awake]

Attached are files to generate a fan that can be 3d printed without supports. As designed, the fan has a hub that extends further than the blades, with a groove in it; the idea is that the fan will be mounted on a shaft using flanged bearings, with an o-ring or similar belt to drive it:

This was originally modeled in FreeCAD, but I also created an OpenSCAD version. Both of these are attached; both allow you to change parameters as desired for the hub OD, ID, overall fan blade OD, number of fan blades, etc. - fully configurable.

I have never used .step files or .iges files, so not sure exactly how they will come through - my little bit of experimenting makes it look like it may not be in a form that allows adjustment of the parameters - ? If that is the case, here is the quick version of how I produced the blades (I'm assuming the hub will be no problem to reproduce): I generated a sketch of the "root" of the blade - a parallelogram located at the origin, angled 30°, with the top leg of the parallelogram constrained to a horizontal width of 1.5mm, and the overall parallelogram (not the leg, but the overall shape) constrained to a vertical height of 10mm. I generated a second sketch of a similar parallelogram, but this one is angled at 60° and is located at a distance from the origin equal to the radius that I want the fan blades to be - in this case, 29mm:

From there it is simply a matter of lofting from one sketch to the other, doing a polar transform, and a bit of trimming.

I put a GPL license on all of these files. My intention is to retain credit (cough, cough - yes, a bit of vanity on my part) but to make them completely available to anyone to use however they wish. I'm not sure GPL is the right license - does it allow someone to use these in a commercial project? If not, I'm happy to change it to something that does.

As long as you do not exceed 60°, most 3d printers can print this without supports:

Feedback is welcome!

 

[jack620]

Thanks. I will have a play with those files later. In the meantime it occurred to me it would be quicker to turn up an aluminium hub to glue into the fan in its current form. I want to fit the fan to a 3mm shaft.

 

[jack620]

I was able to modify the step file in Fusion360.

 

[johnmcc69]

Nice work Awake! I like to see folks share their files.!

John

 

[CFLBob]

Andy, I've got two things going on that this helps with. I've just gotten a 3D printer and gotten it going, and I'm looking to replace my 3D CAD program, Rhino3D, with, well something. I'm trying to get started in FreeCad, but haven't heard of OpenSCAD until recently.

Maybe this isn't the place to get into those programs, but since you mention both, can you talk about them? Maybe you use them for different tasks, with FreeCad for one and OpenSCAD for the other? Maybe you're drifting from one CAD program to the other, that sort of stuff.

Ultimately, I like Rhino, but I'm using ver 5 and it's likely to be getting even more obsolete now that they're at ver 7. When they released ver 6 a couple of years ago, the emphasis was a programming language for pretty designs and renderings, which doesn't match with the machining hobby very well. I had no interest in going to ver 6. Rhino was an easy transition from AutoCAD, which I learned at work. I found Fusion360 really hard to dive into.

 

[MrMetric]

CFLBob. You might want to take the plunge and try to get into the "mindset" of programs like F360. Yes, I agree... It is a pain if you are fast with traditional CAD such as AutoCAD. I still have difficulty there. But, these newer generation (IMO) CAD concepts really are very neat. The downside with something like F360 is that I don't believe for a second that in 3 years time AutoDesk won't pull the same switch-er-oo that they did this last September. Therefore, you might as well assume that you are going to have to pay a subscription fee for it. If this is a problem (it is for me, which is why I have shied away from F360) then look at SolidEdge. They have a perpetually free (none of this subscription stuff) educational version that might work for you. If you want to do CAM, you'll need to research what will integrate to the educational version. SolidWorks also has educational versions if you join some organizations. However, you should be aware that those are yearly subscriptions so God only knows if those programs will last. Finally, there is Alibre and MeshCAM, both of which are reasonably priced and are *real* purchased, not subscriptions.

If you want to stick with 2D, then you have two good options I can think of. The first is QCAD (which runs on Windows, Mac or Linux). There is a CAM module that you can get with this for a very reasonable price, or you can use the free version. QCAD is a bit of a paradigm shift from AutoCAD for 2D CAD, but it isn't bad. Alternatively, if you are entrenched in ACAD command syntax, then look at NanoCAD. It is really quite good. I have to admit that I'm always a little worried about Russian and Chinese developed software (more the latter), but hopefully there is enough critical mass to keep it honest. Unfortunately, the paid version of NanoCAD moved to the subscription model, which I refuse to suggest, but there is a very good free version out there still. It is older, but I have yet to find a flaw in it.

I've personally never made the bridge to 3D CAD using AutoCAD type variants of programs (I used DraftSight for a long time before they went to subscriptions) which I regard as more 2D products. I know you can do 3D, but when I tried it (early on) it was very cumbersome for me. My personal opinion is that applications such as F360, SolidEdge, SolidWorks, Alibre, etc do a much better job of 3D.

Anyhow, hopefully there is some useful information here for you.

 

[MrMetric]

Awake:
I'm curious how well these blades work on your engine. What I'm really asking here is how durable they are. I've not had really great luck with my 3D printer. It was given to me along with a bunch of PLA. I don't think it is a bad unit, but i've never had great luck printing things with it (probably the reason I was given it in the first place! duh!) I don't know that I'd really want to try spinning a blade I built with mine because I would fear that the blade would simply disintegrate. I'm just wondering if this is truly my printer or if you have had any issues using your blade in its intended application

(note: I've learned that PLA will absorb moisture, so it has a true shelf life even in a sealed bag. It could be that my problems are simply related to old PLA)

 

[CFLBob]

(note: I've learned that PLA will absorb moisture, so it has a true shelf life even in a sealed bag. It could be that my problems are simply related to old PLA)

The guy who helped me getting going in printing said to get a waterproof box and desiccant packs to store PLA. He showed me a box he picked up at Home Depot that had a gasket and was marked IP65. Together with a humidity sensor from Amazon and the desiccant, he can monitor how dry it is, and cycle the desiccant packs through the oven to dry them out. I think the symptom of the PLA absorbing moisture is that it breaks off in the extruder and interrupts the prints. Edit to add this:
https://www.homedepot.com/p/Ezy-Sto...oof-Clear-Latch-Tote-IP-67-FBA34063/314733533
Hope that's useful. I need to ponder on your longer post to me.

 

[MrMetric]

CFLBob.... It does, actually. I've thought about doing this in the future. One caveat is that if you have a SmartThings automation hub, you can even setup a humidity alarm. I did this with a small wine fridge I've got. A common problem with it is poor electrolytic caps. Those failed and the switching power supply failed, causing fan to fail. In the end, my Peliter Junction became a heater, not a cooler... that ruined 6 bottles of nice wine. Now I have a temperature sensor (which includes a humidity sensor) in there should I suffer the same problem in the future (although now I have higher quality caps in the unit). But... the point is... I am familiar with setting up humidity sensors and alarms. BTW, I also keep a few in the garage to help alert me to potential moisture that may cause rust on my machines/tooling.

Do you know if it is possible to reclaim PLA by reheating it in an oven much the way you can restore desiccant bags? Or, will dry bags be sufficient to drive out the moisture of older PLA (clearly over months, not hours)?

 

[CFLBob]

Do you know if it is possible to reclaim PLA by reheating it in an oven much the way you can restore desiccant bags? Or, will dry bags be sufficient to drive out the moisture of older PLA (clearly over months, not hours)?

I've never seen anything on that, but it's worth asking my friend. I'll pass it on.

 

[jack620]

I'm curious how well these blades work on your engine.

I printed this fan in PLA and mounted it to a brushless DC model aircraft motor. I ran it at many thousands of RPM and it held up. It works nicely.

 

[awake]

Wow, step away from the computer for some quality garage time, and all sorts of posts pop up! I'm so glad that you all are finding this little project helpful (or at least interesting)!

Jack, great to hear that you could modify the step file, and even better to hear that you printed and ran the fan without problems!

Mr. Metric, I haven't run this on my engine yet, because I've been stalled on the engine - not because of running into problems, but rather having other things get in the way. Work has been rather intense the last 12 months, and when I have been able to get out to the garage (like today), I've had other projects with higher priority. Someday, someday, I will get back to the engine ...

I have not been overly concerned about this disintegrating, but I have been concerned about whether it will soften and distort due to the heat. For that reason, I plan to print the one I use on the engine in a higher-heat plastic such as PETG. It may be that even that will not stand up to the heat radiating off of the cylinder ... or it may be that it does just fine. I look forward to the experiment!

Meanwhile, on your printer - there can be quite a few reasons not to get good quality prints. Some of these may be due to mechanical issues in the printer - loose belts or rollers, for example. But others may be due to "tuning" - tweaking the settings of the printer so that you are getting the right amount of extrusion, the right distance from the build plate, and so on. What kind of printer is it?

CFLBob, I'm happy to offer some thoughts about OpenSCAD and FreeCAD. The latter is analogous to Fusion360 or other 3d programs - I've not personally used anything other than FreeCAD, so can't directly compare them, but based on the various YouTube videos I've seen where someone has walked through a Fusion360 design, I think there are at least some points in common. Some observations about FreeCAD:

• It is able to do everything I have needed (and much more), and it continues to improve rapidly; the current stable version is .18.04, but they are on the cusp of releasing .19, which has some major improvements.
• It is modular in design, meaning that you have a variety of "workbenches" that let you approach or support 3d modelling in different ways. Some of these are focused on particular "sub disciplines" - e.g., the Arch workbench is all about modeling architecture. Some of these provide different ways to accomplish similar tasks - e.g., the Part workbench lets you build up a 3d model by "constructive solid geometry," combining, intersecting, and subtracting basic shapes; the Part Design workbench, by contrast, builds up the model by making 2d sketches which are then "extruded" or rotated or "lofted" into another sketch or so on. You can switch from one workbench to another as needed.
  • One upside of this modular approach is that, in addition to the standard workbenches that come with the program, there are lots of additional, specialized workbenches that various users have contributed.
  • One downside of this modular approach is that the user interface is not always consistent between workbenches - even those that are standard. This is an area of active development, so it is getting better.
• There are lots of tutorials on FreeCAD, but be aware that this is very much an international project, and as a result you will find tutorials in a variety of languages (but probably the majority in English). Also, because the program continues to undergo rapid development, it is very important to pay attention to the version that was used in the tutorial - if it is much different from the version you are using, it may be more confusing than helpful.
• FreeCAD includes a Path workbench, which is its version of a CAM module. I have not (yet) used this, but am eager to give it a try ...

OpenSCAD is an entirely different animal. For one thing, it really only knows how to generate .stl files - great for 3d printing, but not what you will likely want to use for CAM, nor can you produce a set of drawings from the results (yes, you can do that in FreeCAD). For another, it is programmatic / procedural: you write a program to tell it how to build up the 3d model, then run the program, and then you see the result (and can export the result as an .stl file). For someone like me, who has done a lot of programming, it feels very easy and natural to generate a 3d model this way ... but if you have not done a lot of programming, it may be clear as mud. On the other hand, because it is programmatic, everything is entirely parametric - you can easily change any dimension and re-run the program. (FreeCAD is parametric, but some changes may cause hiccups - that's a lengthy discussion.) Some observations about OpenSCAD:

• If someone has written an OpenSCAD program well, all of the parameters will be clearly labelled up front, making it easy to customize the result - you don't have to understand how the model was produced; just change the numbers and re-generate.
• Because of the ease of customizing (and tweaking), for something that will be 3d printed, I most often generate the model in OpenSCAD. Sometimes I do an initial model in FreeCAD and then work up the OpenSCAD version. FreeCAD can export .stl files (and many other file types), but it is a good bit less obvious how to tweak the output.
• OpenSCAD has distinct limitations; one of the most significant is that it does not have any good way of adding chamfers or fillets to edges. (There are ways to achieve this, but that can become both much more complicated and much, much slower to generate.

I hope this is a helpful start - please don't hesitate to ask questions!

 

[awake]

Do you know if it is possible to reclaim PLA by reheating it in an oven much the way you can restore desiccant bags? Or, will dry bags be sufficient to drive out the moisture of older PLA (clearly over months, not hours)?

Yes, at least up to a point. I have never needed to dry out my PLA this way - it seems to stay dry enough in a bag with dessicant - but I have dried out nylon (which is REALLY bad about absorbing moisture) and PETG - put the spool in an oven at 250°F for a couple of hours, then put into a bag with dessicant.

 

[Ken I]

Here's another example:-

This is a replacement 66mm diameter radial fan for a 12000rpm industrial application - printed in ABS and sealed in an Acetone vapour bath.

Personally I was surprised that it could stand the strain.

We have run a 50mm version up to 24000 rpm and it held together.

Regards, Ken

 

[xj35s]

I'd really like to know why Desin spark mechanical is never mentioned? I have used f360. I switched to DS mechanical because it's easier to rework .stl files, but the overall form and function is very much like f360 but easier interface.

You can save as .STL to send directly to your slicer. I guess fusion caught up on that too now. DS Mechanical is free for hobbyists and students. I even just renewed my free use. No restriction on the program, just what you do with the work. It's all personal hobby stuff for me. I designed a cutter tooth for a tooth bar on my front end loader bucket. I 3D printed one to pove the concept then had a friend CNC cut the teeth from 1/4 flat stock.

Please take 5 minutes to watch one of Jim Taylor tutorial on it and I think you'll immediately understand how it works.

This video is 16 minutes but really shows all the how to's you need to know to make just about any part

 

[Greg]

I've never seen anything on that, but it's worth asking my friend. I'll pass it on.

I have read that putting filament in an baking oven is not recommended as the temperature control is not great, and overshoot is common. Repurposed food dehydrator is a common way to get a lower temperature to dry filament.

EDIT
Here are a couple of links that show recommended times/temperatures for filament types:
How to Dry Filament: PLA, ABS, & Nylon | All3DP
PrintDry Filament Drying System
Drying Times and Temps in Dehydrator
Guide: How to Make a Filament Dryer for $30 - Let's Print 3D

 

[CFLBob]

Bearing in mind what Greg said about ovens overshooting temperature, both of the ovens I've measured do that, the guy who recommended dry boxes for filament said it can be dried out in the oven but didn't give much in the way of details. They overshoot the most when you first set the temperature. It seemed that was deliberate because people would preheat the oven, then open the door to put the food in, which makes the oven lose a lot of heat. Overshooting made up for the bigger loss of heat. I figure the extruder for PLA is running 200C so I wouldn't go much past 200 F to dry it. Nylon is worse about absorbing water, but I don't know about that filament at all.

Thanks for all for the detailed comments on design software and xj35s for mentioning DesignSpark software:
https://www.rs-online.com/designspark/mechanical-software
Years ago (2013) I was doing freelance writing and wrote a piece about the DesignSpark world. It's really intended for low volume manufacturers and includes electrical (my day job in those days) and a bunch of tools. I had totally forgotten. I think I'm going to take a look at that one, too.

 

[awake]

I've not worried about the overshoot - just keep the nominal temperature low enough, as CFLBob suggests, and all is good.

Here's another example:-
View attachment 122807
This is a replacement 66mm diameter radial fan for a 12000rpm industrial application - printed in ABS and sealed in an Acetone vapour bath.

Personally I was surprised that it could stand the strain.

We have run a 50mm version up to 24000 rpm and it held together.

Regards, Ken

Very cool (no pun intended)! Even though there are overhangs, it would just be short bridges - should print well without supports. What is the temperature environment in its intended application?

 

[Ken I]

It's a motor cooling fan - so its cool ambient air only - although in our summers in a factory that can be 40°C.
We use high speed / high frequency spindles in robotic applications for grinding etc. - the cooling duct cover and fan have been smashed in collisions or from dropping it from the toolchanger - Chinese - no spare - velly sorry - buy 'nother.
So I 3D print replacement cowls and fans. So far no failures (apart from physical abuse.)
Regards, Ken

 

[awake]

A great example of a place where the common FFM 3d printing has more-than-just-hobbyist value!