Confused with spindle specs

[peter.van.haren]

Well its not a MT5. Bought one and it's too small. Back to the drawing board.

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[darkzero]

Well damn that sucks. MT6 is obviously too big according to your measurement. Maybe you do have that odd size MT5.5 that Stonebriar mentioned. But I'll just keep my mouth shut now, feel bad that you wasted money on one that didn't fit. Hope you get it figured out & keep us posted.

 

[peter.van.haren]

no worries. not expensive, and my own fault. could have easily measured the smallest diameter and known it was too big for MT5, but I didn't.
I've asked my local importer (the seller I got if from) and he's trying to find out. Apparently not many Thai people use a center to put into the spindle nose, but he's looking for me.
What I have found out is that although the manufacturer specs it as ASA A1-5, it must be a modified spec. The American Standard drawings don't indicate any taper inside the spindle nose, however there is definitely a taper.
Last night I measured (as best I could) and got this:
Length of inside taper: approx 60mm from front face of nose.
I.D. at opening (big end): approx 46.9m
I.D. at inner end (small end): approx 45.45mm
This means the taper is approximately 0.725 ((46.9-45.45)/2) over 60mm.
So, even if the manufacturer states one spec as 1:30 taper of spindle bore, the measurements I got don't indicate that.
Geometry never was my strong suit so, I could be mistaken, but that's never happened before! ha ha ha
Thanks for your comments!

 

[Tozguy]

The 1/30 spec might mean 1 degree 30 seconds, maybe?
The included angle would be 3 degrees.
If that's the case, anything that gets set in there would be difficult to remove (like how well Jacobs tapers hold drill chucks)

 

[peter.van.haren]

The 1/30 spec might mean 1 degree 30 seconds, maybe?
The included angle would be 3 degrees.
If that's the case, anything that gets set in there would be difficult to remove (like how well Jacobs tapers hold drill chucks)

Good point, point I was just looking like 1:30 and not in degrees/minutes/seconds. Given the measurements I made it looks like it's an acute angle of approx. 0.7 degrees. Given that my measurements are approximate (best I could do with telescopic bore gauges), is your theory close.
Also a good point about removing anything I insert, but perhaps could knock it out from the other end.
Your comments and help are GREATLY appreciated.

 

[NortonDommi]

My lathe is a D1-5 spindle with a MT6 taper. Came with a MT6 - MT4 adaptor. Tailstock is MT4.

 

[Tozguy]

If your calculations give you .7 degrees on one side then the included angle of 1.4 degrees is real close to 1/30'. That is a very slow taper.
However if it is .7 included then it boggles my mind as to why it was made that way.

My MT5 to MT3 sleeve is a very tight fit in the spindle taper, as it should be. An MT 5 taper is much steeper than yours but still sticks like gangbusters. The idea of pounding it out with a mallet never settled well with me so I made a puller. The puller just pops it out without taxing the spindle bearings.

Since your spindle taper is not so common you might consider making your own custom sleeve from an MT6 to MT3 sleeve.

 

[peter.van.haren]

Just got a copy of the owner's manual.
So, looks like you were right. It is 1° 30' 03" taper.
Any idea what type of taper that could be?

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[Tozguy]

I am not familiar with a taper like that. Could it simply be a funnel for inserting long work into the spindle bore?
If the diameter of 43.13 is larger than the bore of the spindle then the taper would prevent hangups when inserting work through the spindle. My D1-4 spindle bore is stepped instead of having a taper and work has to be inserted carefully so it does not bump on a shoulder.

 

[John O]

google show morse taper as about 1.5 deg from center so angle is close.
Size is between a 5 and 6 morse.