this post was submitted on 10 Mar 2025

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Unexpected use of FR2 of the week: Phenolic gears (aussie.zone)

submitted 3 months ago* (last edited 3 months ago) by [email protected] to c/[email protected]

7 comments fedilink hide all child comments

FR2 is the brownish material that many cheap circuit boards are made of. It's a mixture of phenolic resin and paper. Apparently it's quite useful to make gears out of:

Phenolic Gears exhibits superior shear force, help reduce machinery noise, absorbs destructive vibration unlike metal gears, phenolic is non-conductive, protects the mating metal gear train, and are known to outlast metal gears under severe continuous service. (source: https://www.knowbirs.com/phenolic-gears )

(Main pic stolen from here)

(Many more pics here)

Has anyone seen these used anywhere? I've read a hint regarding pool equipment, but I have never seen them there. I assume the fibres allow them to last longer than plastic/resin only gears.

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[–] [email protected] 4 points 3 months ago* (last edited 3 months ago)

Old big EMCO lathes had phenolic gears in their gearbox. I know because I got to rebuild one and that was one surprise I came actross and that day I learned about phenolic gears.
Probably also useful as a safety shear point. Better to grind a phenolic gear to dust that to break something expensive.

Also I will never forget the smell of the gear oil.

[–] [email protected] 4 points 3 months ago

Older engines had them in their timing gears - they were in 6 cylinder Holdens, for example.

They give an amount of cushioning/vibration dampening that you can't get with steel gear sets.

[+] [email protected] 3 points 3 months ago* (last edited 5 days ago) (3 children)

[deleted]

[–] [email protected] 3 points 3 months ago* (last edited 3 months ago)

There are some youtube videos of people machining them (sadly my browser does not support smell). Looks like you treat it like any other solid material: hobb or mill the teeth. This is much more expensive than 3d printing.

You might be surprised by your 3d printed gears. If you keep the detail size large they work really well, but backlash is definitely an issue.

[–] [email protected] 2 points 3 months ago (1 children)

@Gronk @WaterWaiver

I printed 2 gears for my 7x12 lathe out of a filament from Igus.

https://www.igus.com/product/20322?artNr=I190-PF-0175-0750

Been in use for over 5 months and from inspection are in good shape. Quieter and unlike the originals durable. One is sacrificial and will shear if the lathe jams. When I jammed it it loaded the motor pretty heavily then let go so it did work. Some replace that gear with a metal one but I wanted the sacrificial feature so I do not blow the motor and speed control.

You need a heated chamber and they recommend heat treating it before use which I did not do since I was not certain it would not change the dimensions.

They have a few other filaments that are also useful. I went to this after multiple attempts to 3d print delrin. Even made a wood bed and finally gave up.

It's not cheap but I still have over 90% on the reel left after printing 3 gears.

[–] [email protected] 2 points 2 months ago (2 children)

I replaced the original gears for my pools in-ground cleaning system with 3d-printed versions and they lasted several seasons. I had originally intended to simply keep the system running while I waited for replacement parts to arrive.

[–] [email protected] 1 points 2 months ago

@liquefy4931 @Gronk

The impeller for my pool heater failed several years ago . They did not sell the part and my attempts to glue the old one failed after a short time The temporary impeller I made with the printer is still going strong . Removed it awhile back and it looks fine.

Speaking of fixes, the air compressor I bought to inflate tires was useless as it took forever to inflate a tire. Thought it was bad so returned it and bought a new one.

Turned out its a safety feature they lower the output to the point it is useless. I took the regulator apart and figured if I redesigned one part it would allow more air to flow . 2 new o-rings to seal it and a bit of silicone lube and I've been inflating tires happily since. The old setup took over 10 minutes to bring a car tire from 28 to 32 PSI. It now does it under a minute.

[–] [email protected] 1 points 2 months ago

@liquefy4931 @Gronk

Speaking of fixes, the air compressor I bought to inflate tires was useless as it took forever to inflate a tire. Thought it was bad so returned it and bought a new one.

Turned out its a safety feature they lower the output to the point it is useless. I took the regulator apart and figured if I redesigned one part it would allow more air to flow . 2 new o-rings to seal it and a bit of silicone lube and I've been inflating tires happily since. The old setup took a few minutes to bring a car tire from 28 to 32 PSI. It now does it under a minute.