Small spindle head

[Robin Hewitt]

And as for pre-loading the bearing - it is internal in the double row bearing so I don't need to (and couldn't) do anything about it. Ijust need to secure the bearing in place.

Not pre-loading, just loading. As drawn it resists a push but not a pull.

If the double race is tight in the housing you could put a sleeve down inside so when you nutted the pulley on the top you pinched the double angular inner ring.

That'd do it.

Edit: I do have experience, here is a double angular bearing loctited on a spindle from my junk box

[bambuko]

Sorry, I understand you now
The spindle is meant to be interference fit in the bearing as well, so this is as good as loctiting it, but I was also thinking about either a sleeve or a nut behind front bearing.
Most likely something like this:



Chris

[bambuko]

Edit: I do have experience, here is a double angular bearing loctited on a spindle from my junk box

And what was your experience of them like?
Am I wasting my time?

[Ross77]

Nice work, it will be interesing to see how you get on.
Have you seen the "Diy spindle design" thread? It might be worth a read as I seem to remember he had an initial issue with putting to much preload on it and it got very hot. If you have it adjustable then you can get the balance between removing play and to much friction.....

I'm interested to see what you are going to drive it with? I have the Er11 spindle but not tried to power it yet. I've got a 100amp esc and Rc motor but not sure wether to belt or direct drive it?

[bambuko]

thanks Ross,
DIY Spindle design is one of my favourite threads.
Main difference is that he wanted high speed router at 20k rpm, my target is 5k rpm - my application is different.
My pre-load is not adjustable. It is set by the manufacturer of double-row, angular contact ball bearing that is used in the front.
If I was doing high speed spindle I would use the usual design of matched pair with adjustable pre-load, but I am hoping that at lower rpm I will get away with what I am proposing.

[Robin Hewitt]

And what was your experience of them like?
Am I wasting my time?

The nice thing about the double angular bearing, unlike your average single angular bearing, is that it comes with rubber seals. Pop the top one out and add oil, something like Castrol GTX would do nicely, and I don't think you will have a moments worry with it.

I eventually went for stretching the shaft between two singles with Belleville washers. I have become a big fan of Bellevilles since I started aiming for truly zero backlash on everything. A thrower ring on the base to keep the crut out and not overly generous with the oil.

I ran it up to 6000rpm then started winding the speed up on the digi phase controller. I was heading for 12,000 but started worrying about the belt driving it, felt pity in my heart. Probably be okay, but you do need a noise level that everyone in the shop can live with for those long cuts :whistling:

[Ross77]

Ah. so you dont need such tight tolerances at low rpm then?

That would also explain how the other spindles I have work. Couldnt work out where the tensioning nut was

[bambuko]

Ah. so you dont need such tight tolerances at low rpm then?...

Didn't quite say this
It's a combination of target (comparatively low) rpm and light duty, that makes me think I can get away with a simplified design.

BTW, you have also asked:

...I'm interested to see what you are going to drive it with?...

Didn't give much thought yet. Definitely nothing fancy until I am convinced that I can make it work OK.
For the moment I have (don't laugh) sewing m/c motor and that will do for the testing.

[Ross77]

Sorry it was more of a question than a statement, Im still learning.

dont think I can laugh at the sewing machine motor, I'm one of those fools converting a pillar drill to a cnc mill :heehee:

[bambuko]

Before continuing with the spindle I needed to take care of my DTI.
Up until now it was all a bit Heath-Robinson and this was reflected in "variable" :heehee: results when it came to taper turning.
So first thing was to make a bracket for DTI, which would allow fixing of the clock directly to QCTP:



While at it, I have also checked my lathe (Prazimat from the old DDR)

My usual clock (with 0.01mm resolution) detected hardly any movement, so I used my new clock from Draper (0.001mm resolution):



Prazimat uses DIN55027 spindle head, size No3 and one can get chucks with this fitting on the back,
but they are rather expensive , so mine are all with usual backplate arrangement.

The reading on my Draper DTI was +/- 0.0015mm (total movement of 0.003mm) and just to check it I have tried my best DTI (with 0.0001" resolution):



The reading was below one division, roughly about +/- 0.00005" - 0.00008", with the total movement of about 0.00015

Now, the only thing I still need before setting the topslide with the DTI, is the straight probe for the front (instead of the usual ball-nose)
to overcome my usual difficulty of setting the clock exactly at the centre (usually ending with the taper not exactly replicating the original :naughty:)
Chris