3D Printed Screw Compressor V3 

I was a service technician now a sales representative for a very large screw compressor manufacturer. To get high pressures usually have a two-stage compressor. The first one goes to 35 pounds the second stage of bringing it up much higher the temperatures of an oil less two-stage compressor at each stage is somewhere in the range of 360 to 420° and the rotors are cooling from the air that’s moving across them

Great project! I'd recommend thrust bearings on the low pressure end and placing your timing gears (and motor) on the high pressure end. You can also offset the axial bearings according to the tolerances and play to get a better seal at full operating speed (knowing the forces and directions of force while in operation allows to minimise clearances by designing for the dynamic state rather than the static). Nikola Stosic has really done fantastic work to modernising screw compressor design and I'm very grateful for his work. I'm working on a long term project that incorporates variable geometry screw compressors, hoping to be able to CNC machine the main components for the prototype, but I'm not sure I'm up to the mathematics required!

Excellent work!

Well done

I agree with your assessment however that’s not very “fun”. Print it out of high temp filaments and go right for the full send. This is RU-vid not LogicalTube.😂

Respect!

Look into regenerative blowers. They are awesome because they are relatively simple for how capable they are.

Impressive result, really! Definitely add some thrust bearings if you revisit this. I only just added them to my own hardware vitamin collection and I wish I'd done so sooner -- they're not expensive and are an easy way to add really solid axial constraint versus solutions that only rely on standard bearings.

Great job, I used to test the real thing. It could get exciting from time to time

Good work on this. I think your original rotors may still be usable because screw vacuum pumps are a thing. They work well, but they are a HUGE pain when a contaminate gets in there. Someone below recommended thrust bearings. A thrust bearing+ball bearing would work well, but you can also get angular contact bearings which does both (but not as well as the 2 separate bearings).

Bravo! This is very similar to the oil pumps we use for fuel injector oil pumps on our big boilers. Main reason is they can handle #4 oil which is dirty and they are very reliable. If you have a 2 meter drop on the intake pipe, you can get almost a perfect vacuum and if used for that, you can extract all gas exhausting into a warm tank. Try it! I have wanted to do this in plastic using water with mineral oil/sulfur which is basically cutting fluid for machining- but it would be easier to watch someone like you try it first😊

Put some Duraliner kind of a rubber layer on those rotors, and see what happens.

Amen Indeterminate Design. I got a huge smile on my face for you and your accomplishments. You got it figured out! Great Job. I had been wondering if the main rotor had to be larger than the gate. The previous discharge will work now that the rotation has changed. Eaton has some additional slots adjacent to the opening that my guess if for sound....Pressure is not the performance metric you want, it's flowrate and air temp differential actually mass flowrate not CFM for application I am interested in. Got to have flow to keep the SC cool. My gut tells me plastics have too much expansion for the clearances needed even w/ the air flow to last any substantial time but look up the coefficients of expansion for various material and you can make the assessment. I believe the rotor exhaust end face to case clearance is a big contributor to performance any why thrust is so important. Tapered roller bearing and timing gear mod to include oil bath definitely needed in next model. I believe the main can not exceed 360* twist. If it does the air would be trapped in the gate at the sealing lines made by the two contacts by the main. The blow hole will have more of a negative affect on flow including at the suction port. Increasing temps could also. I hope you try again. It's easy for me to say since I'm not doing the work; but, if it were me I'd fix the damage, cut open the top of the case enough to get a good look at the rotors, put clear acrylic or hardware cloth over that and any other opening, timing gears, belt or pinch point for personnel protection (I like you humor), slow the motor down enough to see the rotors mesh (30 RPM maybe slower) then put it on my office desk...Demonstrations at lunchtime only. LOL I think you know what I mean. Really good job explaining a very complex and multifaceted project design. Best I've seen. No reason for me to do any more studying now.

Can't wait to see your attempt at a Lontra Blade Compressor.

You can enhance the frictional properties of 3D printed parts made from resin by filling the resin with a small amount of PTFE. At least if you print yourself.

Have you applied this to multi zone compressor screw s like would be useful in filament extrusion? The cad design of these things does not seem trivial (or within my capabilities, at least 😉)

Great stuff! I know the 3DP dimension fudging dance all to well. It's annoying because if you ever change to a better manufacture method, then you have to un-fudge them.

Used to work in a compressor/tool sake & repairs shop. (Untill stress triggered undlying Fibromyalgia) This is awesome work. I Am noticing that grinding noise. I would gues its from the screws making contact with rough print surfaces. Have you condidered marking an alignment point, coating the screws in a lapping compound, match them up, seassemble, let then gribd/match/self surface themselves in? At relatively low/rock tumbler speed, for a considerable time. That should let then polish/grind themselves out. This Would also tell you how Well they screws mesh.

Did you try pumping water? The higher viscosity might help compensate for the gaps.

Rolling bearings if not specially designed for high speed usually fail at speeds higher than 10-15k rpm due to the dynamic loads. For high speed and high load applications the use of sliding axial and radial bearings should be considered. I don't use very often screw pumps at work but I haven't seen an industrial one to work at rpm higher than 3000 - 4000. But they are also with a larger diameter of the screws. I am really astonished by the amount of efforts you have invested in this project. Thanks for the video and the explanations.

Man imma try printing it on my SLA machines in abslike and see what happens :D. Who knows, maybe I can get it working well enough to cast the parts and build one to attach to my car. If I succeed at all I'll try to get a video and of course I'll credit you with the design. (to be clear just for fun, i dont do anything commercial)

I had a real screw compressor like this brought into my shop to have the endplates touched up a bit. What I noticed was this 5:6 ratio between the rotors, BUT, the timing gears had exactly the same number of teeth, as though the rotors turned at 1:1. I couldn't get my head around this. I told my father about this, and remember that he remarked "That's impossible". So I invited him for a looksee himself. It was as i described it. What's the explanation?

did I miss the flow measurement? could be fun for as a compressor for part cooling on a 3d printer

I wonder... If you want a bigger & better idea to persue next; The geometry Should work even with Oversized or uneven screw diameters.. (oooh, they're multistart screws..riiight; sorry, just found this content) Anyway, uneven screws; why? Because these pass unholy amounts of volume. So if you make a screw hollow, w a one wsy bypass Through it.. can you improve the efficiency via the air in motion creating suction effect? A venturi suction effect? If it wo4ks, does it work w double oversize screws?

Coding algorithms has been my lifelong jam, my bread and butter. If someone wants to pay me I can code up a little app to generate profiles for compressorz.

They're 3d printed rotors... Print the gears directly on the ends of the rotors, even inside the case maybe. Herringbone 3d printed gears work great, and you're already oiling it. You can cut the part count in half while also having gears at both ends (or other options)? Just spitballing.

Could a double system help with thrust loads and balance? Like, two mirrored screws on each axle, that move air from each end, towards the middle? Having the timing gear in the middle, and bearings, might also help improve things.

What if you pump water mixed with air and seperate the two after compression? The water will seal the gaps while allowing more air through!

You can utilize patented designs for your personal use. You just can't sell them or use them commercially.

spray on some soft self abbrasive coating to make better seal.

I know that sound, you might get more with several microphones spaced out some feet away and mixed back together. Its not the same watching it with out the high pitch scream.

man i was hoping youd get them printed in teflon

you can't make it short ?

why not with pistons like a driven 4 stroke engine ?

If you want a good high temp 3d printing material, I have had great success with pet cf

Mate, use a herringbone gear for the timing gears and the left and right axial thrusts will cancel out…

As to measuring the performance, I think measuring the volume of air, (CFM or lbs/min) would be a better scale of performance.

Rather than directly driving the timing gears, you should use stepped gearing to get up to speed. Yes, it will introduce efficiency losses, but it will also increase the overall durability of the drivetrain and enable you to better address waste heat. Both linear geartrains and epicyclic ones have different pros and cons here. Another idea that might increase the life expectancy of the drive train is to use a couple of timing belts to isolate both the timing gears and the motor shaft from wherever you mount the geartrain suggested above. On a slight tangent from the topic of epicyclic gears... Do you think a cycloidal drive gearset with a strong helix to it might work well as a screw compressor, or would there be too much loss from the eccentric motion? What about using twin-screw style mating tooth profiles on an epicyclic gearset with the carrier also providing inserts between the planet elements as a constraint path for the pressure medium?

Please could you confirm the prices involved. The numbers on the invoice were a bit difficult to read in mu old age. Thank you.

Man, dont use nylon. To keep small tolerances you need high rigidity. PETG & Nylon has good chance to rub on the walls from centrifugal forces at high RPM. Since PLA is out of question (comlressing gas generates too much heat), then the next rigid material coming to mind is PC. ...or maybe ABS. After all it copes with heat better in short term (not melting) and long term (not creeping due to heat). And ABS can be vapor smoothed by cheap and easy acetone trick to get surface finish you are looking for.

Have you heard of conical screw compressors?

So much for the 500$ parts from JLC 😂

Are there examples of "soft" rotor compressors? Think peristaltic pump. The objective is a quiet low pressure compressor...

Try a star rotor.

You need to lube your timing gears. And don't use PLA for anything but decorations.

promo sm 🌟