WTD: Someone to 3D print a small plastic gear wheel

[Vinny]

IIRC, injection moulded nylon, which is typical for stuff like this needs a few % water in it

Extremely unlikely as extrusion/moulding temperature will be a long way above 100C. In all my experience, polymers going to be melted are dried to within an inch of their lives before being processsed, otherwise steam will produce blow-holes/porosity.

That said, despite what people imagine, each plastic has an (tiny) equilibrium water content which is quikly picked-up after processing - plastics are a very long way from impervious to water vapour.

 

[Vinny]

Searching, it is very far from easy to find anything at all about lubricant induced enbrittlement of plastics. In fact, I can find nothing. The nearest is this - Compatibility of lubricants with elastomers and plastics (gacol.pl)

An awful lot of engineering grade plastics are actually oil-filled so as to be self-lubricating.

 

[Mike P]

It looks like there are companies that can print the gear from a suitable material if I can get a CAD file done.

https://www.igus.co.uk/info/3d-print-gears

 

[hp1]

Perhaps the mech is not made by Teac/Esoteric so perhaps a look at some mechs on google to see whose it is or what else its used for.

 

[a.palfreyman]

Had that thought myself but according the what I could find it's made in-house.
Mike, what about contacting a transmission/bearing supplier? If you have the overall dims (big and small gear diameters along with number of teeth as well as length of gear) you might just find something.

 

[hp1]

have a look a motion co.

 

[DarrenW]

Hi Mike, probably a very daft idea but could you slice off the base of the gear and reverse it so the broken teeth are at the bottom and epoxy it in place?

 

[Mike P]

Today I handed over the broken gear to an engineer friend who's offered to have a go at modelling it in a CAD programme.

Fingers crossed.

 

[a.palfreyman]

Mike,
If that doesn't work, I reckon you could drill the centre out and fit something like this, glued into the top of the old gear with epoxy:
https://www.motionco.co.uk/spur-gears-spur-gears-c-32_33_34.html

 

[garyi]

Having now used my 3d printer for a fair few months, I dont think you are going to successfully print a part that small and intricate in a material that wont fall to bits as soon as its used.

 

[Mike P]

Having now used my 3d printer for a fair few months, I dont think you are going to successfully print a part that small and intricate in a material that wont fall to bits as soon as its used.

Yeah, a few people have said that. My engineer friend reckons there's a big difference between domestic and pro kit.

This company offers 3D printed plastic gears that they claim are strong and durable and they'll print a CAD file you've uploaded.

https://www.igus.eu/info/3d-print-gears

The 3D printing is just one option but I think it's worth attempting before a irreversibly try to repair/modify the original part.

 

[hp1]

looking at the picture could you not lift the cogs with some washers , level the broken off teeth and reduce the height of the guide ring which is built on the side of the larger cog.

 

[Mike P]

looking at the picture could you not lift the cogs with some washers , level the broken off teeth and reduce the height of the guide ring which is built on the side of the larger cog.

I like that suggestion! My friend has the gears now but when I've got them back I'll have a look to see if that'd work.

 

[hp1]

A couple of minutes with a lathe should do it.

 

[a.palfreyman]

I like that. A small bolt to act as an arbour so you can grip it and off you go. I've a small model makers lathe and could do this if you want Mike.

 

[Mike P]

I like that. A small bolt to act as an arbour so you can grip it and off you go. I've a small model makers lathe and could do this if you want Mike.

Great, thanks. If the 3D printing idea doesn't look like a goer I'll contact you.

 

[paulski]

I have a document shredder which has recently become scrap due to a single plastic gear wheel stripping it's teeth... driven by a metal gear wheel! It is "only" about £25-30 for another machine but most annoying that the whole thing is scrap for the sake of that gear wheel valued maybe 10p. As expected google revealed that spare parts are only available at all for expensive office grade professional shredders.

If a shredder costs £25 to £30 then you know it cannot be made of quality parts and will inevitably fail probably sooner rather than later. And you also know there will not be spares available.

 

[a.palfreyman]

^^^

Don't incur the wrath of Gob!

 

[Dan K]

I'd be tempted to build up some shuttering around it with tape and then fill in the gap with original spec Areldite. After a couple of days file back the teeth profile with a set of needle files.

You could also cut off the smaller gear and then bond/ screw another from maybe an RC car(?)

 

[ansis]

Having now used my 3d printer for a fair few months, I dont think you are going to successfully print a part that small and intricate in a material that wont fall to bits as soon as its used.

Depends on printer technology. On fused deposit printer (which is oldest commercially available tech) most likely, but not on more modern ones. Friend of mine made these for ALPS input selector, works flawlesly, but he uses stereolitography printer, there is available resins with different strength levels.