Thanks to....

[John Rudd]

The guys at ARC Eurotrade yesterday..Ketan and his staff..

I called them on Friday to order a new mini  lathe and secured the last of their stock..

Helpful as ever, I was even assisted with loading it into the car..

Having got it home and out of the box..what a nice piece of kit much better than the usual (Mach....mart) crap.....
Turned a bit of EN1a today and what a superb finish......

Does anyone want pictures? 
All I can say is if you need a small lathe to make small parts, this machine comes highly recommended.....
Ermm usual legal jargon...bullshit...I'm just a happy customer with no kick backs from them...( as yet!)

[DaveH]

John,

 

Let's see what you got then.
 
DaveH

[Stilldrillin]

"Does anyone want pictures?"    

Don't talk daft, lad! 

Of course we want pictures!!   

 

David D

[John Rudd]

It has been a tad cold up here so havent ventured to the playpen...

I'll try and get some piccies when feeling a bit braver...

[Stilldrillin]

It has been a tad cold up here so havent ventured to the playpen...

I'll try and get some piccies when feeling a bit braver...

TUT!   

It has been a  bit inclement, hasn't it! 
Managed 3/4 hr this aft, to finish off a job. Pics, shortly....... 

David D

[John Rudd]

I'm currently in the process of rebuilding this machine with new taper roller bearings.......But I have a concern with the preload....

The standard roller bearings are an interference fit on the spindle. This type of bearing doesnt usually have any adjustment for axial preload therefore the bearing are not a sliding fit on the shaft.

Taper rollers OTOH, are meant to be adjustable, ergo they should be able to move longitudinal along the shaft and the shaft journals need adjusting to suit the bearing? 

However after watching the Youtube vids posted here: 

&playnext=1  The presenter is seen to be pressing the inner race onto the shaft....

So who is right? Me, in that my thinking is correct (or I am totally wrong) or the presenter is correct?

Any mechanical fitters in our midst?

[David Jupp]

In the C3 Preparation guide on the ARC Euro site, the section on fitting taper roller bearings mentions polishing the journals if the original bearings were a tight fit on them.  It suggests you are looking for a 'push' rather than 'press' fit.  I.E. as you surmise, relative movement is possible (just).

[John Rudd]

David,

Yes I saw the write up and it is easy to miss the reference to polishing the journals. ( I saw it the third time I re read it!  )

I feel more comfortable now knowing that they require 'adjustment' to fit.

[andyf]

I think I can predict your next question, John:
"How do you set the bearings to the correct preload?"

Andy
 

[John Rudd]

Andy,

That question would be, if the bearings were just standard ball roller bearings, but as we are talking taper, then that is different if the bearings cannot move 'easily' on the shaft.

[John Swift]

Hi John,

I've fitted taper bearings to my CL300M lathe a while ago

 I fell into the trap of  removing the old bearings before the new ones arrived !

had to re assemble the spindle to make new spacers , as the taper roller bearings are about 1.25 mm wider !

if my lathe is a typical example , the original bearings are too tight a fit on the spindle
( bearings are not as tight a fit on BSA automatic capstan machines)

the spindle needs to be able to pull through the inner of the left hand bearing as you tighten the spindle nut

working without any instructions , I first tightend the spindle nut by hand ,then an extra 1/8 turn with a spanner
started with  the spindle at 500 RPM and at 10 minute increments  or so ,increased the speed by 500 RPM

checking all the time  the bearings are  only warm and never hot to the touch

after an hour or so at full speed  , rechecked the pre load , and tightend the nuts about 1/16 of a turn

changing the bearings and gibs (from ARC)  has made it possible for me to part off without breaking the tool

    John

 

[John Rudd]

John,

Thanks for pointing that out about spacers and things....

I have another lathe to use if I need to make/adjust spacers ( a Chester 9*20 )
I managed to remove the remaining bearing ( the bearing just behind the spindle flange) tonight, after making a suitable puller from some 3/16 plate and 8mm studding..Surprising how easy the bearing came off...

New bearings should be here tomorrow (post willing ) then I can start to re-assemble..

[John Swift]

Hi John ,

I forgot to add to the previous post

 while my lathe is a 11 year old C2 lathe , and your new lathe could be a little different

the outer part of the roller bearing is the same thickness as the original bearing ,but the inner part
doesn't go all the way through and  is offset by 1.25mm and projects outward

 I had to trim the inside of the plastic bearing covers to ensure it didn't clamp down onto  the cage with the rollers


    John

[John Rudd]

John,

Thanks for the pointers, I'll certainly watch out for anything that might catch me unawares..

I must have been fortunate when I changed the bearings on my mini mill..


Didnt have to change anything..