He's added a fourth axis

[GeorgeD]

I hope the bearings you bought arent those advertised as 'transmission' or 'wheel' bearings... their tolerances aren't anywhere good enough... then again with only a ruler and no DTI you'd never know how bad they really are....

Now,now Irving just because you lot can't sort the £24 power supply out,no need to take it out on us gentle folk.

I've had bearings off this blokey before and the tolerence was within their bore diameter ie they were a tight fit and had to be pressed on with tube and rubber mallet

Its a well known fact that the further south you go the higher the prices get.

ps I do have a Micrometer and I know how to use it.:whistling:

[irving2008]

....the tolerence was within their bore diameter ie they were a tight fit and had to be pressed on with tube and rubber mallet...

That wasn't what I was refering to.... there's more than one tolerance spec on a bearing and the one one the central bore diameter is one of the least important...

[GeorgeD]

That wasn't what I was refering to.... there's more than one tolerance spec on a bearing

Axial forces or Friction?

[Tom]

Axial forces or Friction?

I fancy a "Friday night pub quiz"....

George, the question is in two parts:

1) What is the difference between these two identically sized bearings? The answer I'm looking for is not £12.03
http://simplybearings.co.uk/shop/p17...duct_info.html
http://simplybearings.co.uk/shop/p51...duct_info.html

2) Assuming it was suitable for the task, which one would you install into your (hypothetical):
a) Moon lander
b) Nuclear submarine
c) Power station
d) Gantry crane
e) Precision 4th axis
f) Miscellaneous 23.5hr/day, production critical machinery
g) Front car hub
h) Rear car hub
i) Shonky 4th axis built as a learning exercise

Winner gets a pint. *In true pub quiz style, I reserve the right to fall asleep before the end of the discussion and not notice it's all finished until I see that all but one table is looking depressed.

By the way, it's not a loaded question. I haven't built my first shonky 4th axis yet, but when I do, it WILL be shonky.

[Smiler]

I fancy a "Friday night pub quiz"....

George, the question is in two parts:

1) What is the difference between these two identically sized bearings? The answer I'm looking for is not £12.03
http://simplybearings.co.uk/shop/p17...duct_info.html
http://simplybearings.co.uk/shop/p51...duct_info.html

2) Assuming it was suitable for the task, which one would you install into your (hypothetical):
a) Moon lander
b) Nuclear submarine
c) Power station
d) Gantry crane
e) Precision 4th axis
f) Miscellaneous 23.5hr/day, production critical machinery
g) Front car hub
h) Rear car hub
i) Shonky 4th axis built as a learning exercise

Winner gets a pint. *In true pub quiz style, I reserve the right to fall asleep before the end of the discussion and not notice it's all finished until I see that all but one table is looking depressed.

By the way, it's not a loaded question. I haven't built my first shonky 4th axis yet, but when I do, it WILL be shonky.

Me ME MEEE!!!!

One is photographed from the left and the other from the right! I CLAIM MY PINT!

BTW, anything wrong with using angular contacts like the guy in the video did?

Jeff.

[Tom]

I CLAIM MY PINT!

Jeff, the pint's yours! You may have to remind me, but don't be shy!

Ref the angular contact bearings, I'm not really sure. I think the way the big boys do it is to pair a set of single row angular contact bearings opposite each other, and preload them, either next to each other at the chuck end (as a matched pair, with a simple roller at the other end of the shaft), or preloaded along the whole length of the shaft (a non-matched pair, one at each end). I reserve the right to be proven wrong.

As george says, the mini-lathes ship with deep-groove bearings, and the upgrade is to replace them with taper roller bearings. This mod works quite nicely (I've done it), but I don't think you'll see taper rollers in this application on much bigger equipment. I think the mini-lathes get away with it because the loads are low. Which is lucky because the larger angular contact bearings, especially in matched pairs are not cheap.

[Smiler]

Ref the angular contact bearings, I'm not really sure. I think the way the big boys do it is to pair a set of single row angular contact bearings opposite each other, and preload them, either next to each other at the chuck end (as a matched pair, with a simple roller at the other end of the shaft), or preloaded along the whole length of the shaft (a non-matched pair, one at each end). I reserve the right to be proven wrong.

I've done it pretty much as per the video to be honest i.e. an angular contact bearing behind the chuck with a thrust bearing the other side of the plate and preloaded them, a simple bearing holds the other end of the shaft. Works really well for router use and I suppose it would work for light engraving on Aluminium but I'd never try machining, I'd convert a rotary table for that (Mr Kip was kind enough to donate a stepper adaptor for such use).

I'll tell you what was REALLY nice about this project. The fact I designed the plates and cut them on my macine and all the bits, bearings, stepper etc. just fit first time, no filing, no drilling larger holes because one was .25 of a mil out because the dot punch slipped, everything just fit and lined up. I know it SHOULD do that anyway but I still find it all amazing and it was worth doing just for that glow you feel when it all goes to plan. My mate at work Kenny has been doing CNC lathe for many years, most at RR, and he says he still gets the same kick when the bits all just slot together first time every time. Wonder if others do :)

[Wobblybootie]

Trick question!! Bearings are things you Yomp along to get to the next check point/Pub and you use Mils!! (much better than silly degrees 'cos there's lots of them, In fact 6400 if what's left of my grey cell filing system is still operational!!)