Mini Lathe Headstock Rebuild With Angular Contact Bearings

[The Aussie Shed]

Mini Lathe Headstock Rebuild With Angular Contact Bearings.
New Video up in my Mini Lathe Rebuild Series.
Cheers.

[DIYSwede]

Thanks again, mate!

1st: -How did you find the sweet spot for the bearing pre-load?
2nd:- Isn't a matched 7206 BECBP pair almost 1/4 of what the entire lathe cost you?

(-Yup- I'm pressed hard for being a DIY cheapskate in this issue,
and then: -Are the headstock even machined to take the full advantage of a matched pair?
Considerations, considerations - it's all in a day's work for a mini lathe owner...)

Cheers, Johan

[The Aussie Shed]

Hi Johan,
Awesome, I wondered when anyone would ask about bearing preload.
Hard to slip anything past you my friend.
Basically It was a guess, I am un aware of the correct method in this situation.
I used a plate to push outer & inner race both together so as not to load only the inner when pressing & just feeling the press.
I erred on the side of caution to not apply to much over force when the outer race bottomed on the housing.
Careful easy going, & cooled the shaft in the freezer over night to help ease the pressing.
I have the machine running now & it seems okay, for now, fingers crossed.
To tight, to loose, I guess we will see, hopefully if anything the latter & I can add more preload maybe.
The Bearings I can get locally, (Chinese no Brand) very cheap, Quality??? we will find that out too.
So if they fail, no big deal. I too am a cheapskate, its a sickness.
I re cut the register BTW & did some work to the chuck all looking pretty good now. .0007" runout on 10mm rod in the chuck with quick setup. lots more to do though to properly align everything.
Cheers Mate.

[DIYSwede]

Thanks for your elaborate reply. "Attention to detail" is the life of a mini lathe owner.

Doing a quickie search (for some blog entry i stumbled upon a year ago) I found this instead:
https://www.arceurotrade.co.uk/machi...ange-Guide.pdf
which unfortunately seem to just state "21. Fit lock nuts, set bearing preload and lock the nuts."

Not very helpful, eh? Well, finally found Zoltan's "Benchtop Machine Shop", which might be of help:
http://benchtopmachineshop.blogspot....reload.htmlaea
"Breakaway torque measurement" seems the most operational, easy and repeatable way to go...

Further reading: https://www.skf.com/binary/21-299896..._12-299896.pdf
(Neither affiliated to this company, nor waving a flag for 'em)

Personally I'm in the middle of my headstock alignment suspense:
"Now I just" have to nudge the headstock's chuck corner another 0,1 mm (was 0,15 before 1st scraping) towards the front,
while lowering the same corner's top 7 microns (thin kitchen foil-thick), as the chuck's centreline hits above the tailstock centre by 0,23 mm!

Also waiting for a few (4 bucks apiece delivered) 210XL037 timing belts for DIY-ing a 3:1 speed reduction instead of an EBay 80 buck + postage version.
Found 15 kg of Delrin offcuts in a Tech lab dumpster at work, that'll provide the pulley blanks...

"My Mini Lathe saved my entire Summer vacation from Honey-Do's, relatives, travels and other ungodly pleasures!"

Cheers & keep it up!