Worm Gearbox Help

[epanzella]

I always wanted to make a gearbox from scratch and I finally have a use for one. I want to make a 40 to 1 worm drive gearbox to power the head lift on my mill. I'm trying to identify suitable worm wheel materials but I keep getting steered to bronze and brass. The 4" x 1" blank is so expensive it's cheaper to just buy a gearbox but I WANT to build a box. This is a light duty intermittent application so I'm wondering why I can't just use steel for both the worm and the wheel. I have plenty of thick steel plate on the shelf and would like to use that if possible. I also have plenty of aluminum plate and plan on using that for the gearcase. What say you?

 

[matthewsx]

I don't see why steel wouldn't work for this application, lots of gears are made from steel.

John

 

[jbobb1]

We always made them out of Ampco 45 bronze, but it's tough to work with.
Never seen a worm gear made out of steel, so not too sure that's the answer.

 

[benmychree]

Steel is likely to gall if used as a worm gear, a better choice would be a steel worm and a cast iron worm wheel.

 

[francist]

Maybe one of the parts could be made from a nylon or acetal type material to get away from the cost of the bronze? I seem to recall some tablesaws used a nylon/steel (maybe cast iron?) combination on their mechanisms for changing blade elevation.

 

[dirty tools]

How much torque is required

 

[stupoty]

I don't see why steel wouldn't work for this application, lots of gears are made from steel.

John

I think it's due to the high ware ratio between the two gears, the wheel needs to be softer than the worm for long life.

Some sort of plastic might be good as Francist says, depending on the load on the gears I guess.

Stu

 

[epanzella]

How much torque is required

I don't know an absolute torque requirement but the gearbox would be replacing a 6 inch hand crank that was moderately hard to operate.

 

[epanzella]

Maybe one of the parts could be made from a nylon or acetal type material to get away from the cost of the bronze? I seem to recall some tablesaws used a nylon/steel (maybe cast iron?) combination on their mechanisms for changing blade elevation.

No matter what material I will ultimately use I'll make a prototype worm wheel out of PVC to make sure I don't ruin any good material.

 

[34_40]

For an intermitant operation I don't think I'd be overly concerned about the wear rate. Besides it's your first attempt, it's likely it won't be perfect but service-able. I'd say run what you have and just do it. Then you'll discover things you like or dislike. If needed and you dislike it that much, you'll re-do the box or a part and make it better then! FWIW,my point oh two, yada yada yada..