# L0 Spindle Internal Taper



## Be_Zero_Be (Jul 29, 2019)

Does anyone know what the internal taper is on a L0 spindle?
I can find all of the dimensions and specifications of the external taper but no data on the internal taper.

Thanks for your help.


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## benmychree (Jul 29, 2019)

It would be the same as the external taper, both in angle and dimension, if I'm understanding the question.


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## Be_Zero_Be (Jul 29, 2019)

Hi benmytree,
What I am looking for is the taper of the bore inside the spindle.
Thanks.


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## Be_Zero_Be (Jul 29, 2019)

Here is a sketch of what I am after.


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## pontiac428 (Jul 29, 2019)

Ha, I see what you're asking now.  The L0 spec is for the external surface of the spindle nose that engages the chuck.  You want to know the dimensions and taper of the spindle through hole... not given in the L0 spec.  Probably need to reference your lathe manufacturer.  My guess is (puts on clairvoyant assumption hat) you're going to be looking for a morse taper in the bore.  What do you use for centers or tool holders in the bore?


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## benmychree (Jul 29, 2019)

It would be a Morse taper, or a portion of a Morse taper; if you had an appropriate size of MT sleeve, slide it in and see how it fits.  I have used regular MT sleeves for headstock center sleeves on several lathes, you just cut them off as necessary, and possibly rebore and ream the ID taper tomake the dead center fit as desired.


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## kjones95206 (Jul 29, 2019)

I have an L0 spindle on my LeBlond lathe and the internal spindle taper is a Morse taper #5.


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## projectnut (Jul 29, 2019)

benmychree said:


> It would be a Morse taper, or a portion of a Morse taper; if you had an appropriate size of MT sleeve, slide it in and see how it fits.  I have used regular MT sleeves for headstock center sleeves on several lathes, you just cut them off as necessary, and possibly rebore and ream the ID taper tomake the dead center fit as desired.



I agree.  Every headstock taper on an L series spindle I've seen has been a Morse, or as benmychree noted "a portion of a Morse taper".  However I think you're going to have to either measure it, find a manual that states what size it is, or find someone who has the same make and model lathe that knows the taper size.

As far as I am aware there is no standard size internal  Morse taper for each size in the L (Long Taper) series spindles.  As Kjones95206 noted he has a MT #5 taper on his LeBlond L0 spindle.  I have also an MT #5 on my Sheldon machine, but my machine has an L00 spindle.  

To make things even more difficult the spindle taper on my machine is only about 4" long rather than the standard 5.19" for a full length #5 taper.  It's referred to as a "short #5 taper".  Essentially it's a 4" section out of the middle of a #5 taper with the same taper angle, but neither end  the standard diameter of a full length #5.


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## Be_Zero_Be (Jul 29, 2019)

The diameter of the opening is 1.842"
I measured a taper of .030" over a length of .628" with a dial indicator and a test indicator.
This works out to 2.7349 degrees from center line. 
That's a taper of .04776" per inch.

Below is a photo of the L0 spindle of my PBR Lathe (with false chuck installed).


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## Be_Zero_Be (Jul 30, 2019)

None of the Morse sizes seem to be close.
I am beginning to think it is a B&S #12.


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## projectnut (Jul 30, 2019)

Just keep in mind the numbers in the chart are those at the ends of the prescribed length.  As an example the #5 is 1.4750 diameter at the small end and 5.19" from that point should be 1.7480" in diameter.  If the length of the taper is shorter than 5.19" it will affect the diameter at each end.  I would bet the taper in the spindle is less than the full 5.19" long


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## Be_Zero_Be (Jul 30, 2019)

projectnut,

The taper in the spindle is only about 3" long.
That would make it a segment of a full taper.


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## Be_Zero_Be (Aug 8, 2019)

I was able to get the drawing from Italy for a 3MT adapter for my spindle.
The outside is an angular measurement I read as 1 degree, 19 minutes and 180 seconds.

I have a feeling this a non-standard taper.


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## RobertB (Aug 8, 2019)

Be_Zero_Be said:


> The outside is an angular measurement I read as 1 degree, 19 minutes and 180 seconds.



180 seconds?Think about that 
 I think that is 1 degree 19.180 seconds


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## Be_Zero_Be (Aug 8, 2019)

I wasn't sure exactly how to read that.
I viewed it as a Degree-Minute-Seconds (DMS) annotation. 
1 degree = 60 miinutes = 3600 seconds
If the 1966 drawing indicated a DMS notation then I believe my interpretation is correct.
I am open to other interpretations.


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## ErichKeane (Aug 8, 2019)

I think that is a ratio. Conicita apparently means 'taper', and the page on italian wikipedia refers to those as ratio I think: https://translate.google.com/transl....wikipedia.org/wiki/Conicit%C3%A0&prev=search

I think it is 1 mm per 19.180 mm.  Which, just so happens to be EXACTLY MT6: https://en.wikipedia.org/wiki/Machine_taper


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## bhigdog (Aug 8, 2019)

Put an indicator on the spindle bore ( a Last Word indicator works well ). Use your compound to move it a known distance into the bore. The reading on the indicator, the distance moved and good old trig will give you the exact angle and/or taper per inch of YOUR spindle.........Bob


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## ErichKeane (Aug 8, 2019)

Hmm... I wonder if that 1:19.180 is just a typo on the chart.  The rest of the measurements fit with MT5 pretty closely, which has a 1:19.002.  That ends up being .0526"/inch (you measured .04776/in equiv over .628).  I wonder if you could have combined been almost exactly 3 thou over that stretch?


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## RobertB (Aug 8, 2019)

ErichKeane said:


> I think it is 1 mm per 19.180 mm.  Which, just so happens to be EXACTLY MT6: https://en.wikipedia.org/wiki/Machine_taper


 
I would agree, matches exactly with the drawing. Makes sense, European notations conventionally use commas rather than decimal points.

be_zero_be, my point was that you wouldn't have 180 seconds, that would be 3 minutes


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## ErichKeane (Aug 8, 2019)

ErichKeane said:


> Hmm... I wonder if that 1:19.180 is just a typo on the chart.  The rest of the measurements fit with MT5 pretty closely, which has a 1:19.002.  That ends up being .0526"/inch (you measured .04776/in equiv over .628).  I wonder if you could have combined been almost exactly 3 thou over that stretch?


Er, not a typo on the chart, a typo in the drawing.


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## pontiac428 (Aug 8, 2019)

The 1:19,180 looks like a spec for external concentricity. The important thing to notice is the designation in the center, Morse # 3.


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## Be_Zero_Be (Aug 8, 2019)

If it is interpreted as one degree and 19.180 minutes, that is 1.4933 degrees which is the taper angle of MT6.
I think this is a round-about way of saying MT6 is the external taper.

My next task is to find a MT6 object and stick it into the spindle.


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## ErichKeane (Aug 8, 2019)

Be_Zero_Be said:


> If it is interpreted as one degree and 19.180 minutes, that is 1.4933 degrees which is the taper angle of MT6.
> I think this is a round-about way of saying MT6 is the external taper.
> 
> My next task is to find a MT6 object and stick it into the spindle.


Are you sure there? 19 minutes would be about 0.333, since there are 60 minutes to a degree.


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## Be_Zero_Be (Aug 9, 2019)

ErichKeane : You are correct - my math is wrong.

This was pointed out to me and may be the answer - Look at 6MT

From : Home Shop Machinist Forum (R.P. Wilson)

_*"Ah! The light dawns! Its a taper of 1 in 19.180, not a taper angle of 1 degree 19 minutes etc.*_
*What it isn't is 6MT or even 5MT, the diameters don't match. Likely to be one of those oddball 5 1/2MT tapers beloved of lathe manufacturers for their spindle bores. 5 1/2 MT but using the same taper as 6MT. "*

From : Wikipedia


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## ErichKeane (Aug 9, 2019)

Ah! Good to know.  I suspected 5 1/2MT as well, but couldn't find ANY reference to it at all.  That wiki bit I think I linked above (though didn't screen shot) was what lead me to think it was a MT and the measurement was just slightly off.

EDIT TO ADD: I found this which might be super useful for you: 








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Someone made a sleeve to adapt to 4MT.  If you have 4 MT tooling, this might end up being an easier solution.


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## Be_Zero_Be (Aug 9, 2019)

Thanks to all who responded to my inquiry.
Forums are a priceless resource.


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## RobertB (Aug 9, 2019)

Something doesn't seem right here. You measured your opening at 1.842" but the drawing for the adapter shows an o.d. of 1.723"
That adapter would be awfully recessed in the bore.

That 5-1/2 MT in the eBay listing shows an o.d. of 2.280" 

None of these seem to match up


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## Be_Zero_Be (Aug 10, 2019)

The drawing that was sent to me from Italy is for a spindle adapter for spindle to MT3.
The excerpt above is from that drawing.
I have the full drawing - the part number of the adapter is "15-2-b5"
Below is an excerpt of the spindle from my parts manual.
I believe that parts manual shows a "D" type mount.
It shows the above adapter installed.
My lathe has a L0 type mount.
The nose protrusion from the spindle on my lathe is longer.
The taper is carried out further thus the difference in opening dimension.

I believe my spindle is made to the MT6 geometry but not necessarily the MT6 specification.


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## RobertB (Aug 10, 2019)

Be_Zero_Be said:


> The drawing that was sent to me from Italy is for a spindle adapter for spindle to MT3.
> The excerpt above is from that drawing.



Yes, but I don't believe that adapter is actually the correct one for your spindle, it is too small.



Be_Zero_Be said:


> I believe my spindle is made to the MT6 geometry but not necessarily the MT6 specification.



That adapter is made to a MT6 taper angle, but that is not close to what you measured your spindle at.
MT6 has a taper of .0521 per inch and yours measured .0477 per inch, that's not even close.

I would contact Riten Industries and see if they can help. They are the experts when it comes to spindle tapers.


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## ErichKeane (Aug 10, 2019)

RobertB said:


> Yes, but I don't believe that adapter is actually the correct one for your spindle, it is too small.
> 
> 
> 
> ...


Fwiw, he measured that taper over about 600 thou, so if he was off just 3 thou over the two measurements, it would account for the difference.


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## RobertB (Aug 10, 2019)

ErichKeane said:


> Fwiw, he measured that taper over about 600 thou, so if he was off just 3 thou over the two measurements, it would account for the difference.


Yeah, that should be re-measured over a much longer length, preferably the whole taper, but at least a couple of inches.


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## Be_Zero_Be (Aug 10, 2019)

RobertB - You are correct - That adapter looks to be for the shorter "D" type spindle nose.
Mine is a "L0" type which has a longer nose.
The useful information from that drawing is the description of the outside taper, which is the inside taper of my spindle.
The diameters and length would not be appropriate for the L0 spindle nose.


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