Adding a bearing to a Penn Fathom 40 NLD2 2-speed

[jurelometer]

Boon and jurelometer
The plain bushing that I'm replacing is close to 9mm or roughly twice as wide as the ball bearing (5mm).  The thing that is interesting is that the bore that the bushing is pressed into is only about 4mm long.  My guess is that the bushing will still provide additional support and the short bore that it is pressed into makes alignment with the inner ball bearing easier.  Perhaps someone who knows more can chime in.

A longer bore generally makes alignment easier.  But the alignment here only has to be reasonable- reels are not very precise pieces of machinery.  There was probably some sort of manufacturing consideration.  For example, wall thickness on cast parts has to be close to uniform are the part will shrink unevenly during cooling. This leads to a host of problems- embedded stresses, warping, voids, etc.

And one length does not have to be the same as the other.

Bushing to sideplate is an interference fit (the bushing is slightly larger than the hole).  It will hold the bushing in place for however strong the fit is.

Bushing to shaft is an clearance fit. There is a tiny gap. The shorter the length, the greater the shaft angle before the shaft comes in contact with both ends of the hole in the bushing, enforcing alignment.  As the bushing wears under angled load, a longer bushing will distribute the load and wear over a larger surface area, and do a better job of enforcing alignment.

The reason that the original hole in the sideplate is tapered that way is because it is a molded part.  As the part shrinks as it cools in the mold, the hole gets smaller, creating it's own interference fit.  The taper allows the cooled part to be ejected from the mold.  You will see these tapered surfaces all over a molded part.

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Now that I can see the finished product, I can revise my analysis a bit:

If the interference fit on your new part holds as strong as the original, and you did not affect the seating of the original ball bearing, you probably haven't made things worse in terms of resisting angled force driving misalignment under load. It has the potential to be slightly better, as you have moved the support point farther towards the outside of the shaft.

In terms of addressing axial load (wasn't this the main intent?), you haven't really improved anything as far as I can see.  The clip is still taking axial load.  If the bearing axial load capacity is less than the clip, you actually made things worse. The weaker of the two will be the failure point, so it won't be any stronger than the clip.  But as noted before, axial load is not typically a problem for this assembly.

The advantages that I can see from your approach is that you have removed any sliding contact from the clip to the bearing surface (meh), and you have replaced a press fit wear item (plain bearing) with a more easily replaced alternative (ball bearing, angular contact is probably not necessary). 

The downside is that you have added an externally mounted, highly exposed ball bearing. The type of stainless used in these bearings is not very saltwater resistant, any you have galvanic corrosion to manage against the housing too (don't forget to use lots of grease!).

I am personally not so hot on this tradeoff, but your reel, your choice.

I did find this project interesting.  Thanks for sharing with us!

-J
 

[Geno66]

Hi jurelometer,

That is an insightful analysis and I do appreciate the feedback.  I was originally going to replace the bushing with a SS needle bearing because it would have been much less machine work.  However, two issues kept me from going that route.  The first being that the shaft wasn't hardened and second there was no easy way to create a thrust surface for the clip to ride against. I guess I could have used bronze washer but that seemed much less elegant.
 
The bearing I chose, Enduro 71801 LLB, is typically used in the cycling industry for hubs and pedals.  I couldn't find a data sheet so it would be difficult to verify their claim of ABEC 5 and 235 lb-ft static load.  Only time will tell if the rubber seals and stainless steel will last in a saltwater environment.

Does this application require an AC bearing?  Probably not.  If the engineers at Penn think that two deep groove bearings is the correct approach who am I to argue? E.g Penn Torque 40 NLD2

Was there in improvement?  Absolutely.  Without a doubt turning the handle is way smoother.  Is the improvement due the AC bearing, I doubt it.  I think any ball bearing would have worked.

I'll use the AC bearing this season to see if I run into any issues.  If I do I can always replace it with an OEM Penn bearing.