Boxford Little Giant Toolpost Grinder Bearing Preload

[John from AUParticipant @johnfromau]

I am replacing the bearings in my Boxford Little Giant Toolpost grinder.  I have attached a photo of the parts in order of assembly.  Having no manual I was looking at the Dumore Series 14 toolpost grinder as they are ver similar.  I noticed on the pulley end of the spindle the Dumore has a washer (34) and flat spring (33) before the bearing that was not in my Boxford.  Im assuming the Dumore setup is to set the bearing pre-load.  My question is are these parts missing from my Boxford?  The only parts that contact the inner race on my setup are the spacers. The bearing caps are relieved in the centre.  How should I set the pre-load on assembly?

[noel shelleyParticipant @noelshelley55608]

Should there be any preload ? Are the bearings angular contact or ordinary ball races ? High speed spindles often use special bearings , possibly match pair and certainly not cheap ones. Good Luck Noel.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi John, it looks like you have deep groove ball bearings, which don’t normally require any preload, however, in this type of arrangement, the bearing at the working end is normally clamp in position in the housing by the end cap, and the other end is free to move in both directions inside the housing, and this is to take account of expansion and contraction by changes in temperatures to prevent binding in the bearings. I’m not familiar with the Boxford tool post grinder though.

Regards Nick.

[John from AUParticipant @johnfromau]

Hi Nick, I think your explanation is on the money.  I’ve made some notes on the attached photo which would indicate it is designed as you explained. Many thanks

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