L0 Spindle Internal Taper

[pontiac428]

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

 

[Be_Zero_Be]

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.

 

[ErichKeane]

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.

 

[Be_Zero_Be]

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

 

[ErichKeane]

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.

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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.

 

[Be_Zero_Be]

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

 

[RobertB]

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

 

[Be_Zero_Be]

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.

 

[RobertB]

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.

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.

 

[ErichKeane]

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



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.

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.