I'm considering a project that will need some custom gears. I only got
into this hobby in the last year, and haven't bothered contacting any
custom gear shop yet. I've never had any custom shop parts done at all
before; I am just curious what a ballpark figure might be.

These are somewhat odd, in that they need to function both as mechanical
drives part of the time, and as a gear (fluid) pump at other times. So
the teeth need to seal against each other as well as reasonably
possible. The mechanical load is not very much though, a couple HP,
perhaps 500 PSI (fluid pump) pressures.

Size is 5.5" diameter, tooth height is maybe 1/2" (kinda big I know),
tooth angle 30° or so. Both wheels the same size/# teeth. Width is 3/4",
material = carbon steel (flame hardening I am not sure of the necessity
or not, would depend on the cost) Centers bored 1" w/a keyway, aligned
identical on all the wheels.

I would need three pairs of these gearwheels. Anybody care to make a
guess as to $?

I bought a pair of car engine timing gears that looked promising (they
are not the exact sizes I wanted but may be close enough) but they don't
meet exactly perfect; the tips of the teeth do not extend all the way to
the bottom cuts of the opposing wheel. These cost about $50 a pair....

On Sun, 27 Mar 2011 07:19:30 -0500, DougC wrote:

I'm considering a project that will need some custom gears. I only got
into this hobby in the last year, and haven't bothered contacting any
custom gear shop yet. I've never had any custom shop parts done at all
before; I am just curious what a ballpark figure might be.

These are somewhat odd, in that they need to function both as mechanical
drives part of the time, and as a gear (fluid) pump at other times. So
the teeth need to seal against each other as well as reasonably
possible. The mechanical load is not very much though, a couple HP,
perhaps 500 PSI (fluid pump) pressures.

Size is 5.5" diameter, tooth height is maybe 1/2" (kinda big I know),
tooth angle 30° or so. Both wheels the same size/# teeth. Width is 3/4",
material = carbon steel (flame hardening I am not sure of the necessity
or not, would depend on the cost) Centers bored 1" w/a keyway, aligned
identical on all the wheels.

I would need three pairs of these gearwheels. Anybody care to make a
guess as to $?

I bought a pair of car engine timing gears that looked promising (they
are not the exact sizes I wanted but may be close enough) but they don't
meet exactly perfect; the tips of the teeth do not extend all the way to
the bottom cuts of the opposing wheel. These cost about $50 a pair....

If non-custom gears cost $50 a pair, then custom gears are going to cost
a _lot_ more.

Is there a reason you can't use some sort of stock gear for power
transmission, and an automotive oil pump for pumping? AFAIK the
requirements for a good power transmission gear somewhat conflict with
the requirements for a good gear pump impeller.

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