Flexispeed Tailstock Alignment – Realistic Expectations

This topic has 20 replies, 7 voices, and was last updated 2 January 2026 at 18:18 by James A.

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30 December 2025 at 12:16 #830492
James A
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@jamesalford67616
Having realised that my Flexispeed tailstock was misaligned by a country mile, I have tried to realign it. I used a commercial test bar set between centres. I ran a finger indicator along the top surface and along the side to check alignment in both directions. I took several passes to try to average out measurements.

The parallel section of the test bar, placed at the headstock end, was 90mm long. The maximum deviation along the top surface was between 0.02 and, occasionaly, 0.03mm. The maximum deviation along the side face was 0.02mm. Presumably due to wear in the lathe bed, the cross slide and possible dirt, these figures varied with each pass, but were still fairly consistent.

Would I be unrealistic to expect anything better than this with a machine of this age and general quality? I do not mind trying to improve on these results, but not if I am chasing rainbow ends.

James.
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30 December 2025 at 13:31 #830500
Bazyle
Participant
@bazyle
That’s a thou in real money – better than 90% of lathes out there I bet.
30 December 2025 at 13:35 #830503
bernard towers
Participant
@bernardtowers37738
Not sure you are looking at this realistically considering the age etc. And have you really looked at homuch flex a 1mm drill has?
30 December 2025 at 14:08 #830507
James A
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@jamesalford67616
On 30 December 2025 at 13:35 bernard towers Said:

Not sure you are looking at this realistically considering the age etc. And have you really looked at homuch flex a 1mm drill has?

My reason for asking the question was whether trying to improve on my results would be realistic, bearing in mind the age of the machine. What would be considered realistic?

Also, I am not sure how the amount of flex in a 1mm drill relates to the alignment of the tailstock. I realise that all drills have a degree of flex which is why I want to ensure that everything is as well aligned as possible to give the best chance of drilling a hole that is somewhere near central. Previously, it was so far out it was a problem.
30 December 2025 at 14:08 #830508
James A
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@jamesalford67616
On 30 December 2025 at 13:31 Bazyle Said:

That’s a thou in real money – better than 90% of lathes out there I bet.

Thank you.
30 December 2025 at 17:24 #830528
cedric 1
Participant
@cedric
<p style=”text-align: left;”>Yes within a thou is actually quite good, considering the machine and age. Carry on.</p>
Beware of those test bars. Some are notoriously poorly made and will give you false readings. You can do a basic test by placing it between centres and rotate it by hand. Check with a dial indicator that it’s running true at several points on both straight and tapered sections.
30 December 2025 at 17:42 #830530
Bazyle
Participant
@bazyle
Have a think about when you might need actual accuracy here. Not for drilling as an accurate hole would be finished by boring. Not for boring a cylinder as it is the bed ‘levelling’ that is important. It only matters if turning up a mandrel between centres which you do every day, er month, er year, er ?
30 December 2025 at 22:54 #830555
bernard towers
Participant
@bernardtowers37738
You are after all looking at a machine that is possibly over 75 years old and was not a world beater then, perhaps if you are looking to use small machines you might be better looking at Shereline/ Taig or one of the asian offerings. then you can use quick change tooling and an array of accessories not to mention a good range of spindle speeds.
31 December 2025 at 09:04 #830585
James A
Participant
@jamesalford67616
Cedric.

Thank you for the advice. I was not aware of that and shall do as you suggest to check that the test bar is not misleading me.

Bazle.

True. I do not turn between centres much at all, but it was doing so, followed by drilling a starting hole for boring that highlighted how far out the alignment was in the first place. I shall probably not turn between centres again for a long time.

Bernard.

The appeal of a new Sherline or similar is undeniable, but buying a new machine is not really an option. I need, really, to make the most of what I have.

James.
1 January 2026 at 10:15 #830736
James A
Participant
@jamesalford67616
On 30 December 2025 at 17:24 cedric 1 Said:

<p style=”text-align: left;”>Yes within a thou is actually quite good, considering the machine and age. Carry on.</p>
Beware of those test bars. Some are notoriously poorly made and will give you false readings. You can do a basic test by placing it between centres and rotate it by hand. Check with a dial indicator that it’s running true at several points on both straight and tapered sections.

I tried this as suggested, although only on the parallel section. The taper is the wrong size for my machine so I can only use it between centres.

The bar is a little out of true, as Cedric cautioned. It ranged between 0.02mm and 0.04mm deflection when rotated by hand. With that in mind, I do not see any point in trying further to improve the alignment of the tailstock using the the bar.

If the minor misalignment does ever become a concern, I shall turn a test bar in situ and adjust using that.

James.
1 January 2026 at 10:27 #830739
Dave S
Participant
@daves59043
You could chuck an indicator in the headstock and sweep the tailstock bore or a dead centre.

That’ll remove most of the not important variables – your comparing the axis of rotation of the headstock to the taper of the tailstock without a possibly dubious interposer

Dave
1 January 2026 at 18:07 #830828
not done it yet
Participant
@notdoneityet
Presumably the original alignment was out by the proverbial country mile in the horizontal plane?

The usual practical check, for alignment, is by turning a bar, at each end, and comparing the finished diameters. An unacceptable result would indicate in which direction the tailstock needs to be adjusted.
1 January 2026 at 19:41 #830842
James A
Participant
@jamesalford67616
On 1 January 2026 at 18:07 not done it yet Said:

Presumably the original alignment was out by the proverbial country mile in the horizontal plane?

The usual practical check, for alignment, is by turning a bar, at each end, and comparing the finished diameters. An unacceptable result would indicate in which direction the tailstock needs to be adjusted.

It was out in both planes.I shall turn a bar at some stage to refine the alignment.

James
2 January 2026 at 00:42 #830874
not done it yet
Participant
@notdoneityet
On 1 January 2026 at 19:41 James A Said:

On 1 January 2026 at 18:07 not done it yet Said:

Presumably the original alignment was out by the proverbial country mile in the horizontal plane?

The usual practical check, for alignment, is by turning a bar, at each end, and comparing the finished diameters. An unacceptable result would indicate in which direction the tailstock needs to be adjusted.

It was out in both planes.I shall turn a bar at some stage to refine the alignment.

James

The lathe effectively only removes material in the horizontal plane at a level very close to the centre height of the lathe. Vertical difference between chuck and tailstock will make less difference. Remember, too, that if you checked using a 3 jaw chuck, there will almost certainly be run-out at the chuck.
2 January 2026 at 01:03 #830878
cedric 1
Participant
@cedric
Some better quality lathes are made with the tailstock several thou high, so that as it wears, it comes down into perfect alignment.

So you can see that vertical misalignment of a few thou does not significantly affect the turning of parallel cylinders for general work.
2 January 2026 at 09:37 #830890
James A
Participant
@jamesalford67616
Thank you for the replies.

Not Done It Yet: I used a dead centre in the headstock taper and another in the tailstock.

Cedric: That is reassuring to hear. Thank you.

James.
2 January 2026 at 09:47 #830891
JasonB
Moderator
@jasonb
On 30 December 2025 at 17:42 Bazyle Said:

It only matters if turning up a mandrel between centres which you do every day, er month, er year, er ?

What about using tailstock support when turning slender items, if the tailstock is off you could get a tapered part.

Also consider that the 1thou off will be 1 thou if supporting say a short valve of 1″ length or a long column of 12″ so the amount of taper will depend on the length being turned.

Maybe I do more in my workshop than others but the tailstock gets used for support both when the other end is in a chuck or when supported by a centre several times a year.
2 January 2026 at 10:00 #830895
JasonB
Moderator
@jasonb
Also conside that if the error of 1thou is at the tailstock end when the barrel is retracted ( and locked?) and just a short dead ctr sticking out then it could be a lot more by the time you add the length of a drill chuck and drill bit which could magnify the error 10 fold..

Doubt you will get much better than you have though.
2 January 2026 at 10:08 #830897
James A
Participant
@jamesalford67616
On 2 January 2026 at 10:00 JasonB Said:

Also conside that if the error of 1thou is at the tailstock end when the barrel is retracted ( and locked?) and just a short dead ctr sticking out then it could be a lot more by the time you add the length of a drill chuck and drill bit which could magnify the error 10 fold..

Doubt you will get much better than you have though.

It is just as you suggest, Jason. The barrel is retracted with a stubby little centre poking out. I shall run the barrel out to its full length and check the alignment again. I suspect that I shall not like the results……..

James.
2 January 2026 at 12:10 #830926
Bazyle
Participant
@bazyle
On 2 January 2026 at 09:47 JasonB Said:

What about using tailstock support when turning slender items, if the tailstock is off you could get a tapered part.

Good point, I do that without even thinking of it as having an effect and might even cause me to put the travelling steady off centre.
2 January 2026 at 18:18 #830972
James A
Participant
@jamesalford67616
On 2 January 2026 at 10:08 James A Said:

On 2 January 2026 at 10:00 JasonB Said:

Also conside that if the error of 1thou is at the tailstock end when the barrel is retracted ( and locked?) and just a short dead ctr sticking out then it could be a lot more by the time you add the length of a drill chuck and drill bit which could magnify the error 10 fold..

Doubt you will get much better than you have though.

It is just as you suggest, Jason. The barrel is retracted with a stubby little centre poking out. I shall run the barrel out to its full length and check the alignment again. I suspect that I shall not like the results……..

James.

I have just measured the misalignment with the barrel fully extended and locked, as opposed to retracted and locked when initially measured. I was very surprised to find the there was no appreciable difference in either vertical or horizontal alignment. The results were essentially the same.

James
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