Nylon or acetal gears to replace baltic birch known to work

[woodguy2]

I make a light duty woodworking power feeder from mostly baltic birch and hardwood. I know most potential customers are turned off by its home made appearance. It works great for the things it's designed for, and I think if it looked better and used more conventional materials, I'd sell a lot more.

My current gears are made from 12 mm baltic birch. Mod4, 9 teeth to 19 teeth, 7 gears per unit, with two pairs of coupled gears giving me about a 74% speed reduction from the power source rpm. The power source, a brushless motor hand drill, runs at about 15-100 rpm. I've had no reported failures from several hundred buyers over about 4 years (except for a few blades run into them --good for Sawstops!).

I want to have them made from machined acetal or nylon, or injection molded from suitable material. All things being equal, which material and production method would be better, how should they be made, and how thick should they be to be comparable in strength to the plywood, or assure no failures?

I've been using an 1/8" roll pin through a hole in the 1/2" shafts that fits into a mortise in the gear to keep them from rotating on the shaft, held in place laterally with a retaining ring in a groove on the other side . Could I simply use a keyway with these?
Thanks!

 

[memphisjed]

I kinda like the flinestone wooden gears…
The people who make eat and breath gears might frown on it… for your tool, kinda cool btw..

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Think of a better cleaner axle design. That part you still have a bit homebrewed in non cool way.

 

[dgfoster]

And you need to have yours custom-made vs buying off the shelf Acetal gears from a variety of vendors at about 5-10 dollars a pop for low volume purchases?

Another possibility that might be worth exploring would be FDP printing your own PLA (likely plenty durable for your application if properly configured with extra infill and thicker perimeters) with your logo on the gear face. It is possible to combine metal hubs and printed teeth if added hub strength is needed.

Denis

 

[EmGo]

Easy parts. You need to say how many you want tho.

 

[???]

No key ways in the acetyl, stress raiser and it will crack. Gear trains of plastic gears are often acetyl on nylon for frictional properties. I’ve 3d printed gears with no issues but if you’re trying to get away from the agricultural look I wouldn’t use them. Find the closest size in stock gears and change your design to suit them is the easiest way. Injection molds are expensive and molders don’t like short runs.

 

[Limy Sami]

Nylon is more forgiving, though where you'll find 4 Mod Nylon off the shelf I know not.

 

[woodguy2]

Thanks for these replies. I'm looking for more than a few....used in sets of 7, and I'd order 100-200 sets at a time.I haven't found anything off the shelf close. I can get the acetal to make a set for $13. I've been paying $10/set for these in baltic birch.
Any suggestions for off-the-shelf sources, especially with a good quantity discount? maybe I could change the Mod. I thought larger teeth would be stronger.

 

[Overland]

Thanks for these replies. I'm looking for more than a few....used in sets of 7, and I'd order 100-200 sets at a time.I haven't found anything off the shelf close. I can get the acetal to make a set for $13. I've been paying $10/set for these in baltic birch.
Any suggestions for off-the-shelf sources, especially with a good quantity discount? maybe I could change the Mod. I thought larger teeth would be stronger.

I'm guessing the people making your plywood gears are machining them somehow. Could their process use acetal/nylon instead of plywood ?
Might be your cheapest route, initially at least.
Bob

 

[EmGo]

I'd order 100-200 sets at a time.I haven't found anything off the shelf close.

That's enough to be worth doing. These are easy parts, if there's nobody near you then pm me. I'd make a couple of changes tho ... probaly go aluminum on the pinion and plastic on the idler. And if you can, adjust things a little, your pinion has hellacious undercut. Nothing big, just some small improvements.

Any suggestions for off-the-shelf sources,

You're not going to get what you want off the shelf. This is not that difficult to do the right way, you don't need to butcher it.

 

[Houdini]

You could buy a prefab injection mold for say $3000
Have a injection mold builder build it out, maybe another $2-3000.

 

[Joe Gwinn]

What lots of folk make such gears from is laminated phenolic, such as that by Garolite, which would be a direct replacement for wood.

 

[memphisjed]

That's enough to be worth doing. These are easy parts, if there's nobody near you then pm me. I'd make a couple of changes tho ... probaly go aluminum on the pinion and plastic on the idler. And if you can, adjust things a little, your pinion has hellacious undercut. Nothing big, just some small improvements.

Having gears made by a gear maker is easy choice….

Steel and phenolic, steel and bronze… plastic and aluminum do not have the same classy appeal.

 

[Scruffy887]

George Washington had wooden teeth, made from baltic birch?
Anyway, making gears from acetal rod sounds cool. Made with a form cutter (like router bit)? Easy. Need a form cutter for each and a lathe that can mill a lot of them and cut them off, run by itself while I do other things.
Craploads of Acetal turn/mill is one of the things I do.

 

[Comatose]

If you can run it for $2 a gear yourself out of acetal, just do that. You won't magically find someone cheaper than the material cost. Even in China.

Can probably go a little thinner and come out a wash. Acetal is stronger than Baltic birch.

 

[technocrat]

I'll just chuck in the idea of resin casting. Silicone rubber mould from a painted and polished birch cog. Plenty of filler like sawdust or shavings to keep the resin cost down. Face on lathe to finish the pour side. I don't know the costs.

 

[EmGo]

If you can run it for $2 a gear yourself

I looked and looked and didn't see anywhere he said that. All I saw was materials currently run him $10 a set.

(If the big one is an idler, there have to be other gears. Where's the drawings ?)

 

[john.k]

OP is using various gears .....far too many for individual moulds........maybe get one mould to turn out 10 different gears a shot......If the wood gears work ,why change ?

 

[Houdini]

I make a light duty woodworking power feeder from mostly baltic birch and hardwood. I know most potential customers are turned off by its home made appearance. It works great for the things it's designed for, and I think if it looked better and used more conventional materials, I'd sell a lot more.

My current gears are made from 12 mm baltic birch. Mod4, 9 teeth to 19 teeth, 7 gears per unit, with two pairs of coupled gears giving me about a 74% speed reduction from the power source rpm. The power source, a brushless motor hand drill, runs at about 15-100 rpm. I've had no reported failures from several hundred buyers over about 4 years (except for a few blades run into them --good for Sawstops!).

I want to have them made from machined acetal or nylon, or injection molded from suitable material. All things being equal, which material and production method would be better, how should they be made, and how thick should they be to be comparable in strength to the plywood, or assure no failures?

I've been using an 1/8" roll pin through a hole in the 1/2" shafts that fits into a mortise in the gear to keep them from rotating on the shaft, held in place laterally with a retaining ring in a groove on the other side . Could I simply use a keyway with these?
Thanks!

Ok so how many different sizes?
How many sets of those sizes per machine?
How many sets per order.
And what price is needed?

 

[john.k]

OP quotes a set of 7 gears for $10........70c each?.....Would go as high as $13 .......$2 each?..........Maybe Xometry can fix him up with a supplier at those rates.

 

[Houdini]

Those sound like overseas injection molded prices.
I know multiple injection shops, molds are cheap, but that's a lot of plastic.