# Origin of Morse Tapers series

Please forgive me if this has been bashed out before, but I've been thinking again (Oh NO! they cried).
For years I've wondered about the series of angles of the MT tapers. I
thought the wierd spread of angles might have derived from some esoteric mathematical formula beyond my ken.
Acting on the clue that they were originally based on a taper of 5/8" per foot (19.2 : 1) and with the help of Excel and dredging up some rusty trig functions, this results in taper angle of 1° 29' 26.630"
Since the MTs all hover round this figure, was it decided by the Wise Men (& Ladies?) that because of its, by then, widespread adoption, to stay with the errors and eventually carry them forward for the ISO standards? Pehaps only the improvements in measuring instruments and machining processes since Steve Morse nutted it all out in the mid 1800s only later allowed the small but significant errors to be observed in the standard prototypes?
BTW, my calculated angle rounded off is the given taper for MT0, which leads me to wonder whether MT0 was one of the original series, or (from the "0" designation) was it added post-Mr.Morse with the grteater accuracy then available?
Or is there a "proper" reason for the series?
In the meantime, I'll continue to machine my MTs by setting up against known store-bought tapers.
JW˛
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

No idea about accuracy re Morse tapers but can relate a tale about something similar with the angles of the compound head on Huron milling machines. These machines were supplied with a table which gave the settings on the components of the head to achieve compound angles. The company had one machine retro fitted with NC controls and we wished to drill a hole at a compound angle without re-setting the job. Did the geometry and used a computer to calculate the settings. Compared with the supplied table to check and got answers which deviated more and more as extremes were reached. Turned out to be a limitation in the ability of the method used to calculate the original tables. Probably something like using 5 figure mathematical tables, as was common at the time. Have you ever seen 10 figure tables? - an enormous volume!
Henry
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

Oh, dear!
Morse taper WAS simple. A sine bar is 10" and a No2 Morse Taper was nothing more than a side of 0.250" Since then, they couldn't get it right- and it is now a Standard based on a bad measurement.
Try your trig with 10" as base
Cheers
Norman
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
On Wed, 26 Nov 2008 02:51:17 -0800 (PST), ravensworth2674

'Fraid its a sine of the times...
Regards, Tony
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

Inspect a Morse- a new angle?
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

Looks like that story Tapered off then. Dave.
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

One of my dexter-ous(?) friends - called Colin (ouch), actually re- published an old design from Model Engineer which was based on exactly what I mentioned.
Colin wrote as Slangbela in YahooGroups MyMyford.
I 'Endeavour-ed' to find out if the stuff is still there.
Norman( another ouch?)
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
On Wed, 26 Nov 2008 03:53:49 -0800 (PST), ravensworth2674

Only cos you mentioned it...
Regards, Tony
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

Why do these threads always go off at a tangent?
--
Dave Baker

â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

Only if they're UNF co-axial with a spark plug <G>
AWEM
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
On 26 Nov, 18:32, "Andrew Mawson"

With some reservation, I'd ask an Indian call centre. Could have a word with one of the squaws.
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
On Wed, 26 Nov 2008 12:26:48 -0800 (PST), ravensworth2674

Is this a tangential reference to the old joke about the "squaw on the hippopotamus..." etc.?
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

Haven't a clue- as usual, the line was snapped.
What is a bloody hippo doing there? Hippocampus- could ring a bell
Norm
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

Haven't a clue- as usual, the line was snapped.
What is a bloody hippo doing there? Hippocampus- could ring a bell
Norm
No - that would be a campanologist surely ?
AWEM
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
On Thu, 27 Nov 2008 09:33:19 -0000, "Andrew Mawson"

I thought they were the people that liked to live under canvas. A hippocampus is presumably a hippo owned by a campanologist? Or is hippocampus a posh name for a hippo reserve? (Not that hippos seep to be terribly reserved, of course...)
And who is Shirley?
Regards, Tony
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

have a

on
to
Shirley rings my bells <G>
AWEM
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

Ohh, THAT rings a bell !!!! Dave
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

Ah! Campanile-- I'll have to sleep on that
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
On Thu, 27 Nov 2008 11:14:00 -0800 (PST), ravensworth2674

Thats the right Formule, but only if you go Premiere Class
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
wrote:

have a

"squaw on

Is that the one with bells on?
AWEM
â
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>

## Site Timeline

• Share To

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.