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Old 10-24-2021, 01:09 PM
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Default Material suggestions

I'm getting closer to the day I have to cut a 51 tooth gear for my drill press.

This gearbox is not filled with oil, it runs dry like a angle grinder gearbox.
The existing gear is a 3/4" micarta gear meshing with a steel gear. I obviously am not going to use micarta. I would like to use a self lubricating material. I have been thinking about bronze for that, or go with aluminum, nylon, or cast iron.
The meshing gear is steel that can be easily cut with a file, so it is mild. If it was hardened, I could cut a mild steel gear.

So, what does the brain trust suggest?
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Old 10-24-2021, 01:15 PM
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Shade Tree Welder Shade Tree Welder is offline
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I'd go with bronze if you can afford it. Can you grease the gears?

Angle grinders use grease.
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Old 10-24-2021, 01:47 PM
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Originally Posted by Shade Tree Welder View Post
I'd go with bronze if you can afford it. Can you grease the gears?

Angle grinders use grease.
Yes, the gears are greased. Angle grinders use a sintered cast material.

I'll have to see if I can afford it. My scrap pile does not go up to 4.25" that I need.

EDIT
Ok, bronze is out of the race at $770.45US per ft. I need an inch of it.
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You got freedom of speech, if you don't say too much.
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When a liberal screams racism, you can bet they were also born with white skin.
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Old 10-24-2021, 02:40 PM
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Quote:
Originally Posted by Ironman View Post
I'm getting closer to the day

So, what does the brain trust suggest?
Happy Birthday !
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Old 10-24-2021, 10:25 PM
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What is the face width? I have some 5/8" and 1 1/2" thick Al extrusion. I should have a hunk of brass around too, but can't lay my hands on it ATM. Free sounds a lot better than $700/ft

I've had this stuff more than 20 years. Unlikely I'll miss it.
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  #6  
Old 10-24-2021, 11:32 PM
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Micarta is a rather generic term that applies to a variety of products made from a plastic resin with reinforcing fibres. Micarta made from phenolic with linen reinforcement was quite common for some gear applications--quite possibly what your original gear was made of. Better stuff now is phenolic with fibreglas reinforcement (or if you want the really good stuff go for carbon fibre reinforcement). You can buy it in sheets of varying thicknesses and while it is pricey it should still be a lot less than bronze.

As for brass/bronze I'd stay away from 360 brass, it tends to be brittle so I'm not sure if it would be a good choice for a gear. There are lots of smaller gears made from it but for something a bit larger I'm not sure how much load it will take. A better choice would be 660 brass (932) or, better yet, 954 aluminum bronze--sadly it has become very expensive.

In steel a good choice would be 8620, a good tough material that's still easy to machine. I think I've got a large enough piece at the shop but I'll have to check tomorrow.
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  #7  
Old 10-25-2021, 08:10 AM
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What size do you need Gerry? I may be able to help you out.


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  #8  
Old 10-25-2021, 09:52 AM
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Many times the gear is also made soft to be a fuse, to protect more expensive
parts downstream.

IF you make from steel, might want to put in a soft shear bolt.
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  #9  
Old 10-25-2021, 10:55 AM
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Quote:
Originally Posted by GWIZ View Post
Happy Birthday !
Gee Wiz!
You got me there. I'm sort of choked at being 73. One day older and closer to dead.
I spent the day doing stuff around here and working on wiring buddy's solar system.
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Gerry
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  #10  
Old 10-25-2021, 11:02 AM
JBFab JBFab is offline
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I would consider oil impregnated Acetal or Nylon. If you're open to spending a bit more Garolite would probably be best IMHO.
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