Myford headstock bearings

[Bob LambParticipant @boblamb44747]

I have just got hold of a Super 7 but the head bearings seem to be stiffer than my old one. I just feel that they are too tight and I would like to sort it out before running it. I have looked at Myford’s maintenance booklet (p 24 to 26) that comes with the lathe but don’t really feel it gives me the confidence to try and adjust the bearing – it would also be the first time using a C spanner! I don’t want to make things worse but the bearings do seem a bit tight.

 

Does anybody know a good site / article / or whatever where I could read in a bit more detail about any problems I might encounter. I did try with the C spanner to see if it was possible to move the locking rings easily and it wasn’t! Are there any secrets to this – after all it has to be done to change a belt.

 

Thank you in advance

 

Bob

[Bob LambParticipant @boblamb44747]

[Tony Pratt 1Participant @tonypratt1]

Bob, funnily enough I was just running my super 7 at top speed and the front bearing was a touch warm but no problem there! I was thinking back some 35 years when I had to take the spindle out to change the belt, it was nerve racking but the manual a C spanner and careful attention to detail got the job done. If the belt broke again I would use a made up one so the spindle didn’t need to be removed.

Loosen the belt off and make sure the bearings are oiled up, then see how the spindle feels, the locking rings should be tight against each other.

Tony

PS I believe there may be an article on this subject in MEW, I wil have a search

[Chris TriceParticipant @christrice43267]

Take the tension off the belts obviously when adjusting the rear bearings. Assuming the bearings are in reasonably good condition, you want to move them to the right as a pair just to the point where the spindle turns freely with no drag both freespinning AND when the tailstock is applying pressure trying to push the spindle back to the left. The rear bearings should take the thrust and stop the taper part of the spindle being pushed into the front taper bearing and tightening up.

[TomfileryParticipant @tomfilery]

Bob,

 

Firstly – don’t panic – the S7 is mechanically simple. You move the rear bearings, as a pair, back and forth, using the C spanner on the castellated collars, so as to pull the cone-shaped headstock bearing into it’s bronze bearing. Look on ebay to see the spindle shape – there’s one for sale there currently.

 

If it is too tight, it might be (though there are many alternative reasons) that the spindle has been pulled back hard into the bronze bush – it is possible to lock it solid and Myford suggest you do that then slacken off by a 1/4″, or 15 degree rotation, of thecollar. If you do slacken the right hand collar, you might need to tap the left-most end of the spindle with a soft-faced hammer to push the cone towards the tailstock in order to slacken it off.

 

I know that the section in the booklet reads complicated, but when you manage to get your head around what they actually are telling you to do, it is both obvious and simple.

 

Regards Tom

[NobbyParticipant @nobby]

Hi Bob

Toms right when the back two bearings are set using c spanner tighten until there no rotation using c spanner come back As Tom says and Myford instructions 1/4″

Regards Nobby

[DerryUKParticipant @derryuk]

MEW 139 and 171 cover adjustments as part of a rebuilding series.

[Bob LambParticipant @boblamb44747]

Many thanks to everyone – it’s really good to be able to make use of such a fund of knowledge and people who are so willing to be generous with their time and help. As Tom says I won’t panic now but I’ll give it a try.

Thanks again – Bob

[Bob LambParticipant @boblamb44747]

Many thanks to everyone – it’s really good to be able to make use
of such a fund of knowledge and people who are so willing to be generous
with their time and help. As Tom says I won’t panic now but I’ll give
it a try.

Thanks again – Bob

[C JParticipant @cj88518]

I have a lot of experience with machines but I am a newcomer to Myford lathes. This is my experience with a newly aquired Super 7.

Because it was quite marked up I put a new gear on the end of the headstock spindle and turned the collar against the inner race, by hand, to set the play in the bearings but noticed that the end-play had now also gone between the pulley and the steel gear on the spindle and the backgear lever had become impossible to turn and lock.

I then tried to undoing the grub screw on the steel gear to see if I could move the gear to create more end-play without success so I resorted to backing the collar off a fraction which restored the end-play in these components.

To my mind the end-play between the pulley and steel gear on the spindle should be independent of the bearing adjustment, so I have studied the cross section drawings of the headstock in the manual which doesn't show a key under the steel gear but does show a line which I take to be a shoulder on the shaft.

My current guess is I might not be applying enough force to move the gear along the shaft but I don't like levering things without prior knowledge of their design.

Any thoughts on this matter will be appreciated.

[C JParticipant @cj88518]

No end-play in the pulley/backgear solved !

On taking the spindle out and putting the backgear and pulley back on it I found there is a gap between the bush and the last shoulder on the shaft (and not the other way round) the reason being the gear on the other side of the pulley has either crept out in use or has not been pressed fully home on fitting.

I am them tempted to pull the gear out and re-fit it with some Loctite 641.

Edited By C J on 15/03/2018 00:25:20

[C JParticipant @cj88518]

Pulled

[C JParticipant @cj88518]

Back together, but what should I expect?

Edited By C J on 15/03/2018 03:04:38

[brickyParticipant @bricky]

I think that you need to be checking the taper and not the chuck body as this may not be true with the register on the backplate.

Frank

[C JParticipant @cj88518]

 

Ooops! 😳 It could look like I’m checking for runout but I would have set the gauge differently.

My fault, I should have said “what should I expect in lateral movement once the spindle is set” as I haven’t adjusted the bearing locking rings yet and I’m getting some movement on the gauge when I push and pull on the chuck without turning it.

Can there really be no movement?

In the meantime searching for a narrow C spanner.

 

 

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