Small captive shaft design

[RManley]

Hey all,

I have to design a small part and I'm having trouble coming up with an elegant solution. It is very similar to a small pull handle that screws into a threaded bracket except that the detail on the handle must remain or be made horizontal. I cannot fettle the part to fit, it must be made so that it can be fitted immediately.

The main body is in aluminium, and as I only have 2mm of M4 thread to screw into, would like the 'screw' part to be steel. I was thinking of something where you can screw the 'axle' into the bracket and then click the body over it so it becomes locked onto the shaft but can be rotated with a bit of friction into its right place, this is the bit I cant get my head around. Trouble is, its quite small, must be Very easy to make and have the minimum number of parts. The axle cannot come through the body. See attached image for rough size.

Any ideas? Prize of a slice of cake is available to the best idea

(cake is non refundable)

Thanks, Rob.



View attachment SKonica_Acc11121610360.pdf

 

[Ken I]

Rob,
Use a captive snap ring cut from a spring - the groove must be deep enough to contain the wire and the gap in the snap ring must also be big enough to allow it to close sufficiently for the knob to pass over.

The angle of the snap groove (in the knob) determines how hard it is to pull the knob off again - make it steep enough or a half diameter groove and its never coming off again.

By bending the spring slightly into a saddle shape you will get the benefit of frictional resistance to turning.

Where's my cake ?

Ken

 

[gbritnell]

Quite simple actually. When you make the handle drill through the side for a small set screw. When you thread the handle onto the shaft and get it to the proper orientation just snub of the set screw.
gbritnell

 

[Ken I]

Rob, I think I misread your post - if you don't want the knob to turn - George's method is much more simple - but the grub screw is obviously visible.
If you want nothing showing just locktite it onto the shaft - you can always get if off again with a bit of heat.

Ken

 

[bezalel2000]

Hi Rob

If I understand your requirement correctly an M4 nut and a 15-17 mm length of threaded rod should work.

Plug tap the blind hole in the ali part M4. adjust the locking nut on the thread to achieve horizontal when tightened.

Hope it works out for you.

Bez