Designing Knurled Interference Fit 1

[Johnson_123]

I have a knurled interference fit between a shaft and a gear.
With an interference of 0.007 in, I am achieving an experimental slip away torque of 7 ft-lb and bending the shaft in the process.
What could I possibly do to achieve a higher torque without bending the shaft during the assembly?
Both the shaft and are made out of 303 SST.
Thanks in advance.

 

[MikeHalloran]

Make the shaft and hub one piece.

Mike Halloran
Corinth, NY, USA

 

[MintJulep]

Increase the shaft diameter.
Use a spline.
Use a key.
Use a taper.
Use a QD.
...

 

[BUGGAR]

Is the knurl directional? I see a lot of knurls that are more like mini splines, aligned with the shaft.

 

[chez311]

Piggybacking off of BUGGAR - what does the knurl look like? Only knurling parallel to the axis of the shaft will result in significant increase in slip resistance.

Alternately to add to the list you could weld them or pin them.

 

[RolMec]

Proposal: skip the knurl, use a shrink fit procedure and calculate / design the interference fit to your needed torque.

Roland Heilmann

 

[Stick.]

Have you looked into using a Taper-Lock style bushing?

 

[Johnson_123]

@BUGGAR and @chez311
It is a straight knurl. Diametrical Pitch 96.

 

[Johnson_123]

@stick
Tapered- lock bushing will significantly increase the cost. Perhaps not feasible as a result.
Shaft diameter is 0.163 in. Bore diameter is 0.156 in.

 

[kjoiner]

How about Loctite shaft retaining compound?

http://dm.henkel-dam.com/is/content/henkel/RetainingDesignGuidepdf

Kyle

 

[Johnson_123]

@Kyle
Loctite is already in use.