Restoring decayed gears

[caution]

I was asked to see if I could reproduce a couple of deck gears that decayed. You know the ones, they're kinda rubbery to reduce vibrations, but the chemicals doing the softening escape over the years, reducing its strength to that of an almond - scrapes away and cracks apart very easily.

One broke during shipment despite excellent packing, but I got all measurements after reassembling it. A lot of time spent with a jewelers loupe and caliper, re-re-checking and adjusting until I zeroed in on something nice and close. I wasn't able to get their exact shape from any gear design tools, so I drew them manually, doing a 50/50 overlay with images to confirm. My camera aim isn't 100% straight so there's some perspective misalignment and sides of teeth visible, but still good enough to confirm. Based on how they're meshing in the first pic, it will be a close fit and may need adjustment if it ends up on the high side.

 

[Reli]

Nice, was this for a Philips or Grundig?

 

[caution]

Hey thanks. It's from one of Grundig's Party Centers.

 

[ralrein1]

Very cool. Can't wait to see it when its fixed.

 

[Fatdog]

Wow! Your abilities never cease to amaze me, Eric.

 

[Radio raheem]

Wow! Your abilities never cease to amaze me, Eric.

this, superb as usual

 

[BoomboxLover48]

Eric the Magician is always at work!

 

[caution]

Thanks guys! Crossing my fingers, they're printing now.

 

[MesaAZGuy]

I admire the talent you guys have.

 

[caution]

I attached a few to save costs, so when they arrived I had to sand off the sprues. I bored out the holes a bit since they were intentionally undersized to let me create a smoother surface inside. Winner! The teeth mesh as expected.

 

[Superduper]

Fantastic work! Eric is 3D magician.

 

[docs]

Bloody legend.

 

[BoomboxLover48]

That is AMAZING!

 

[trippy1313]

Dude. Wow.

 

[baddboybill]

That is very cool Eric!!!

 

[geoffhartwell]

wow, great work

 

[caution]

Thanks guys. Despite being tedious at times, measuring over and over to be absolutely certain, there's a lot of satisfaction bringing these parts back from the dead.

Bill was nice enough to send me the notorioius Magnavox gear, it's printing now, fingers crossed!! The overlay image shows the outer teeth off by about a degree, but it doesn't matter. The gears that mesh with it turn independently.

 

[Superduper]

Hmm, interesting. Just curious, if the number of teeth is the same, how can they be off by a degree? Each circle has exactly 360* right so as long as the # of teeth is the same, I’m thinking the rotational spacing should be the same too?

 

[docs]

Thinking with there being an angle too, that would affect the spacing accuracy too. Not sure but very nice work.

 

[caution]

Yeah, the angle makes it a little tougher because the shape you see at the surface is a 30-degree cross section of what you need to sketch out for the tooth. Spacing them apart evenly is easy, but the shape of the tooth takes more time to get right. I had to use a jeweler's loupe to get close enough. You can see in the green pic how the gaps between the teeth aren't quite enough, so I had to adjust the shape a bit to make a bigger gap. I would imagine their shape needs to be nearly perfect to avoid vibrations and noise, like if the gap is too much the gears may chatter a bit, but if it's too little, it might jam up or break.