Small spindle head

[bambuko]

The rear bearing should float ...

That was my original plan and I have turned the housing with sliding fit for the rear bearing (as opposed to front one, which is interference fit).
I was considering using Loctite on rear bearing after assy to keep things "solid" as I didn't expect the spindle to heat appreciably at my target max 5k rpm. But I am probably running in circles, changing my ideas every five minutes - so I will stick with original idea (rear bearing floating) and see how it works.

...BTW interesting article on Bob Warfield's site about using standard deep groove bearing in a spindle:(scroll down a bit)
http://www.cnccookbook.com/CCMillBeltDrive.html...

Yes, this is in my favourites,

...And this is from a bearing expert:
Practical Machinist - Largest Manufacturing Technology Forum on the Web - View Single Post - Tapered roller vs angular contact ball bearings

Practical Machinist - Largest Manufacturing Technology Forum on the Web - View Single Post - Tapered roller vs angular contact ball bearings

Thanks for the links!

[bambuko]

You are welcome Peter,
but I doubt that your Chinese lathe is using German spindle.
It's more likely American spindle?
Have a look at Lathe Spindle Nose & Backplate Fittings at lathes.co.uk
Chris

later edit:
It would appear (from this web page) that C6 has copied some aspects of DIN short taper spindle, but missed the most important ie "taper".
In which case it looks like it is "Sieg special" and it does not conform to any norms?

[bambuko]

latest update:
Finished tip for DTI to be used in clocking the tapers.
Here being set up vertically:



Almost ready to start turning the spindle ...

[bambuko]

Today got a chance to try clocking the taper.
My idea was to use actual collets to set the angle - clearly an iffy idea because they are not solid, but worth a try before using something more complicated.

When preparing the spigot I made sure it's diameter was the top of the collet range - ie when using 9mm/8mm collet, the spigot was 9mm.

Also having clocked the largest collet, I than turned the spigot down and clocked smaller collet and checked whether the readings were the same for both:



I have managed to clock the taper to within +/-.0008 for both collets.
I don't know if this is good enough ... but I will try to go with it

[bambuko]

I have turned test piece, using topslide set as described and ...
It would have probably been good enough for most other jobs,
but I wasn't happy - I am blue all over :heehee: but the fit of the collets in the spindle is not up to my expectations .
Mostly to do with the boring tool (stiff one was too big, and the next one I had, was too flexy). So need to make better one, just right for the job.
Also will try another/better method of setting the angle.

[BillTodd]

Also will try another/better method of setting the angle.

Try chucking a test bar* - to give you an edge parallel to the centre line, then use a sine bar against the edge of your compound slide. If your compound slide has no reliable straight edges expose as much of the dovetail as you can (remove the slide if necessary) then use a rod in the V (make sure you use the none gibbed edge) to give you a straight edge to work from and a combination of 123 blocks and parallels to get it to the centre height.


See:
http://www.frets.com/HomeShopTech/To...nefixture.html

*or turn a long parallel section on any old bar between centres

[bambuko]

thanks Bill,
Good link and good advice!
Haven't got sine bar, but intend to improvise using two ball bearing housings (on account of their accurate ground dia) and ground parallel bars.
Easy to work out all the distances and even with vernier caliper accuracy of 0.01mm should give me reasonable result.
Will report as soon as I have chance to try.