How to attach Bevel Gears to shaft when they are not keyed or have set screws

Ok my team had ordered some bevel gears from mcmaster (6529K11 Steel Plain Bore 20 Deg Angle Miter Gear 16 Pitch, 16 Teeth, 1" Pitch Diameter, 3/8" Bore) and they came without a keyway or a set screw (or a place to put a set screw). This is a problem because as far as my team can figure there is no way to drive a shaft with these bevel gears. Is there a way to drive a shaft without a keyway or a set screw using these bevel gears or did we get shafted and need to return these bevel gears?

If you want to use them, I guess you have to key them or drill a hole for a set screw then. I think the only other option would be glue (DO NOT GLUE THEM!!! :ahh: ).

“Plain bore” is an important part of the description of the product. They are furnished with the expectation that you will broach a keyway in them or otherwise modify them to suit your needs.

Some times you can drill and tapp a hole between the shaft and gear than run a screw in if you have no way of putting a key way in. Or you can cut it with a small metal blade. You can check with a local machine shop and they may do it for you.

Funny thing, 1727 also ordered 3/8 inch bore bevel gears. I could have sworn that we ordered them finished, but they came as plain bore. In fact we may have ordered the same gears, did you get them form McMaster?

Anyway… we simply drilled and tapped them to fit 1/4 20 bolts. We will probably order set screws for them. We would be done, but a freshmen went and broke our last tap.

As for attaching the set screws, you may want to dremel a flat part on your shaft, or get the shaft with a flat side to it specifically for set screws. Or you could machine keyways, I guess it depends on your resources.

Set screws have never not failed me.
Last year we made lots of shafts with pins.
Just drill a 1/8" hole through the middle and into the shaft. Then we used steel welding rod as the pins.
You may also have success using sheet metal screw as pins.

Indeed. Plain Bore items come with a hole in them, but as madison noted, it is expected you you will bore the hole to some specific diameter that you need, then add a hole for a set screw or broach a keyway. These items are made of steel that is easier to machine, and not having the keyway or setscrew hole keeps you from breaking lathe tools as they pass over the ‘gap’.

Finished bore items are often much harder steel, and more difficult to machine. Then you have the ‘gap’ (keyway or screw hole) that can break the lathe tools, combine them and it makes you wish you just had ordered them the right size to begin with. Oh, the finished bore sprockets that I have experience with are too hard to drill, too, so you’re really in trouble…

The funny thing is we had bought bevel gears from Mcmaster before and even tho it never specified from what we could tell if they where plain bore or not. The bevels we got all had set screws, so we where kind of surprised when these came plain bored (thanks all for the reminder of the correct term). The good news is we didn’t take them out of there package so we can just return them. However we still need to find suitable replacements, does anyone know where we can get keyed or set screwed 3/8" bore bevel gears from besides mcmaster carr?

This will be our second year running with the plain bore bevel gears.

We just use 1/8" roll pins to attach the bevel to an axle.
Roll pins can be found here

If you really want to use a set screw, you can purchase those from McMaster as well. On the page with bevel gears. Part number 6843K11 or 7655K1 for a 3/8" axle.

Finished Bore Miter Gear

Two lines below the plain bore on the McMaster website.

They are twice the price. For the price difference of four of these gears you could but a Dumont #00 broach kit and never have this problem again.

Good luck.

Alternatively, If you’re feeling brave, you could weld the gear to the shaft, assuming the metals are appropriate for such.

I would reccomend pins over setscrews. With bevel gears, both radial and axial position are very important. Even if your setscrew is tightened into a flat on the shaft, the bevel gear could still slide along the shaft.