Shaft coupling question

(3.25 fl/lb) torque.

ed to handle a large propeller.

ve a larger shaft/bore diameter.

and supports a prop hub.

oth ends so I don't have

k collet assemble on the motor shaft.

almost nonexistant and the duty cycle will be

Hi, Paul. I can't give a tested answer to your question, but have you thought of grinding a small flat on the shaft for a set screw? You surely have access to machine tools, so turning a bushing for a gear to fit the shaft shouldn't be a problem.

You wrote of both a propeller and a pump. Is your motor driving both or what?

another Paul

fl/lb) torque.

to handle a large propeller.

larger shaft/bore diameter.

supports a prop hub.

ends so I don't have

collet assemble on the motor shaft.

almost nonexistant and the duty cycle will be

Putting 4+ Hp through a tiny setscrew attachment just did not feel right to me. The motor was designed to drive a prop, I'm driving a pump.

Its for the 2009 version of this:

Yes I can turn bushings, flats, center drill shafts etc... I just do't have any feel for building rotating machinerery so I was asking....

Seems like way too small a shaft to transmit that much power.

This is radio-controlled-airplane tech, margins are designed thin to reduce mass. Since no human life is at stake the margins are often a lot thinner than aerospace.

To the OP: most gear suppliers can supply with no bore in the center at all, you do the machining to match the shaft. You won't know until you call, most of the catalogs lead you to believe that only standard bores are available.

Tim.

...

Well, if it's designed to work with a collet, build a collet. You might find it easier/more robust to use a 1/2" shaft that you can drill/bore for 8mm and slit for the collet function while still having some meat on it, as opposed to a 3/8 shaft. Cut tapered threads on the exterior and clamp the bejeezus out of it with an external nut. This is going from my understanding that you are wanting to extend the shaft to another set of bearings, so I'm suggesting you collet the end of a thick shaft, mount the gear on the thick shaft however makes you happy, but not right at the end where it takes the 8mm shaft, and the 8mm shaft is clamped into the colleted end by an exterior nut running on tapered threads.

Or make a tiny knock-off of a QD system. Sheaves or gears with tapered bores, and flanged tapered inserts that collet onto the shaft as they are drawn into the bore by screws.

Or go to the irritating agony of a real shrink fit, but I hate those as they are often impossible to get apart without breaking something - heating the gear and freezing the shaft work better when they are disassembled - it's hard to separate the heating from the cooling when the assembly is assembled.

The more robust forms of loc-tite can emulate a shrink fit.

First, I think your shaft size is to small for the power you expect to couple, but be that as it may. The solution to a coupling is a friction drive. Although these can be purchased for larger diameters, you can make your own. bore a hole in your gear with a 10 degree taper say 9/16 or 5/8ths major diameter. Then machine a bushing with the correct ID for the shaft. Then turn the OD to to a diameter slightly larger than the od of the bored hole in the gear. Taper the OD of this bushing to 10 degrees. Take a slitting saw and cut a small slit in the bushing. Then machine a clamping plate that when screwed to the side of the gear wedges the tapered bush into the tapered bore of the gear. The clamping force is phenominal. It is bidirectional and never works loose. This coupling does nothing to compromise either the integrity of the shaft or gear. Steve

On Mon, 15 Dec 2008 10:51:04 -0800, the infamous snipped-for-privacy@netburner.com scrawled the following:

(3.25 fl/lb) torque.

to handle a large propeller.

a larger shaft/bore diameter.

supports a prop hub.

ends so I don't have

collet assemble on the motor shaft.

almost nonexistant and the duty cycle will be

Man, clean your vidcam lens!

A pump? You'll be making a truly ultimate Super Soaker, will ya?

the experiment.

Wouldn't a spline system work better, both in reinforcing the mechanical connection and lightening both the shaft and gear?

-- It is pretty hard to tell what does bring happiness; poverty and wealth have both failed. -- Kin Hubbard

Plan the job so you can turn the bushing and bore the gear hub with the same compound setting, which means you have to be able to remove and accurately re-center at least one of them.

Alternatively you could cut pipe threads on them and screw them tightly together.

Jim Wilkins

(3.25 fl/lb) torque.

ed to handle a large propeller.

ve a larger shaft/bore diameter.

and supports a prop hub.

oth ends so I don't have

k collet assemble on the motor shaft.

almost nonexistant and the duty cycle will be

I think you're asking for an 8mm pretzel, but that's your problem. 4+ horsepower delivered to air isn't quite the same as 4+ horsepower delivered to gear box and pump. What I would do is to take the (hopefully) available collet prop hub and turn it into sort of a "flex plate" ala car automatic transmission. Your gear box would supply support for the outboard shaft end via a nub on the hub and a matching divot in the center of the gear box drive plate. Probably a simple "X" form on the hub driving 4 pins on the disk on the gear box should do the job, actual dimensions left as the student's exercise for the day.

Stan

I posted the wrong vidoe. I meant to post this one, the whole thread will make more sense now.

I have a good CNC drive on my converted chinese lathe. So the compound does not enter into it.

Paul