How to turn down gear hubs?

[sanddrag]

How can I turn down and/or take off gear and sprocket hubs. I don't want to clamp on the teeth (at least not too hard) for risk of damaging them. How should I go about this?

[Cory]

Mill the hub off.

[sanddrag]

Woudl I just lightly clamp it in a vise? Maybe with some lead jaw covers? That works good for facing off or removing the hub, what if I want to turn it down (remove diameter)?

[Aaron Lussier]

Take some small pieces of cloth, and put them inbetween the Gear and the chuck jaws. This was the gear teeth do not get scrached.

-Aaron

[Jimmy Holmes]

Drill a couple of holes into the sprocket and screw it to a plate that has the same hole patteren as the sprocket and then clamp the piece to the mill. You could also try the same method with a lathe. The sprocket holder would just have to have a rod to go into the jaws of the lathe. Just some thoughts, I hope it helps, good luck

[Greg Needel]

if you have acess to a lathe you can run a shaft through the center (mount the sprocket) and then use that in the jaws of your lathe then you can turn it to what ever dimentions you want.

[Matt Reiland]

Sanddrag,


Last year I attached the hub to a shaft with a trantorque then milled it down. The trantorque kept the hub perfectly centered and you can reuse it over and over.

[sanddrag]

Originally Posted by Matt Reiland

Sanddrag,


Last year I attached the hub to a shaft with a trantorque then milled it down. The trantorque kept the hub perfectly centered and you can reuse it over and over.

What is a trantorque? Is it something a well equpped machine shop would have? Google Image search didn't give me too much. Thanks.

[Matt Reiland]

Originally Posted by sanddrag

What is a trantorque? Is it something a well equpped machine shop would have? Google Image search didn't give me too much. Thanks.

Quick-Mount Keyless Bushings Since there are no keys, cap screws, or other components to slow you down, you can torque up one of these bushings in just seconds. Match bushing OD to bore of your sprocket, pulley, or gear.
Each bushing has inner and outer sleeves. As you tighten the collar nut, the inner sleeve contracts onto the shaft while the outer sleeve expands to hold your component. Bushings accommodate shafts that are slightly out of round. They're quick and easy to install and remove.
Stainless steel bushings are made of Type 303 stainless steel.

THis is from McMaster, Small Parts also sells them

[Gui Cavalcanti]

If I were going to take the hub off, I'd clamp it in a vise with aluminum inserts ("soft" jaws) so as to not damage the teeth. I'd think this would only work if you have an even number of teeth, though; I think it'd get shaky with an odd number (clamping down on 3 instead of 4 teeth).

If I was going to take the diameter of the hub down, I'd do one of two things. If I wanted to do it absolutely right, I'd do what someone else suggested and mount a keyed shaft in the lathe and mount the sprocket/gear. If I wanted it done faster and cleaner I'd mount the gear to a rotary table and take off the hub with a milling machine, or mount it to a CNC's vise and say "give me a small circle here"

[kiracofe8]

Originally Posted by sanddrag

How can I turn down and/or take off gear and sprocket hubs. I don't want to clamp on the teeth (at least not too hard) for risk of damaging them. How should I go about this?

Here is how I saw an experienced machinist hold a sprocket in a vise last year: take some small pins (like maybe small dowel pins) and put them in between two teeth. Then you can clamp down on the pins, which transfers the force to the root of the tooth (which is much stronger than the tip of the tooth). Now that you have your sprocket clamped in your vise, just mill whatever you want.

[Kevin A]

Last year I wanted to take the hub off a gear so I clamped it in a vice and attacked it with an angle grinder. --Not a joke--

[Justin Stiltner]

Also, on most sprockets that i have seen of more than around 2.5" diameter or so, they were made by welding an hub to a hubless sprocket blank, if you look closely and see a weld bead at the hub/sprocket interface on the outside of the hub try just cutting that out with your lathe, for us the hub would then just drop right off.