Best Way to Fix Spur Gear to Circular Shaft

[dchib]

I've struggled with this problem for a while and , to date, no solution seems ideal.  I work in wood on a relatively small scale (toys and gadgets for the grandkids).  I  am happy to use plastic or metal components if these offer a good solution for fixing a wooden gear to the shaft.

I would like to lock the gear to the shaft but still have the flexibility to release it to make minor rotational adjustments before locking it again. 

To my mind this requirements for minor adjustment precludes using a gear with square or hex hole fitted onto a corresponding square or hex shaft.  Anyway, here in Australia  I'm having difficulty sourcing square or hex shafts of suitable size (say 9.5mm -3/8", or 12.7mm-1/2"). 

A pin through the gear hub and shaft locks the gear to the shaft but also lacks adjustment capability.  Likewise a keyway.

A clamp appears the best option but I have yet to find anything suitable that is not bulky.  I've made some clamps some out of 6mm MDF, using a 3mm bolt to tighten it up, but it is tricky to machine and bulky. 

It seems to me this would common issue for model builders worldwide but I've scoured hobby shop sites but not yet found anything suitable.

So I'm looking for a better solution and would greatly appreciate any assistance from anyone. 

Thanks
David

[ArtF]

One way I have used on wooden shafts is to machine the gear with a very large shaft hole, say 2-3" then
bond permanently a small disk (2 - 3") to the shaft which fits into the large gear shaft hole. If you leave the
gears hole with a lip that holds the disk, its fairly east to add a clamp to the lip that locks the
disk in the gear at the right spot and is adjustable.
  All depends on size in there of course, but larger surface areas of contact make it far simpler to clamp a
gear into position. 

Art

[dchib]

Thanks Art,
Your responses on all my queries have been prompt and very helpful
Cheers

[ArtF]

Hi David:

  Thank you. I have always tried to answer swiftly any questions that come up,
but take note that sometimes I get lost in the code and dont manage to check
as frequently as I should. If you ever feel ( or anyone does) that I've missed
a question or not quite answered it enough, always feel free to bump the
question or re-ask it as if your speaking to an idiot, there are times I am
definitely that. :)
 
  I dont release as frequently as I once did, but the things I investigate for
additions are getting more complex so I sometimes wander endlessly,
wondering just how the hell that can work..


Art

[Dan Mauch]

While not knowing the diameter of the shaft but lets says it is 6.3 mm dia shaft. Buy a chunk of square stock lets say 11mm. You then drill a hole on center the diameter of the shaft. Then cross drill  it and tap it for a set screw. Now you make your gears with a tight fit on the square stock. Then tighten the set screw where you want it or rotate it for  a different different position. You could make several of these to fit various shafts .

Dan Mauch

[John T]

I guess it depends a lot on the torque that the gear must work with.  On my clocks I use a set screw through the face of the gear and normally grind a small flat on the shaft for the set screw to "set" against. The gear is threaded just using the actual set screw soaped up an worked bak and forth so as not to strip the wood.  My usual shaft diameter is 1/8".