Jarno taper info

Looking for JARNO taper information with which to make a few things for my 10EE...

Need to know the critical dimensions, drawbar thread profile/pitch, etc...

Anybody have 'em... perhaps in drawing format?

Jarno is very simple. .6" per foot taper all sizes. Major od is taper number time 1/8". So #12 taper major OD is 1.5"

Minor OD is the taper number times .1". Jarno 12 is 1.2"

Taper length is half the taper number in inches. Jarno #12 is 6".

http://www.tools-n-gizmos.com/specs/Tapers.html#Jarno

I measured my Monarch spindle adapter:

oal: 2.626"
length of ground tapered surface: 2.424"
large dia. 1.506"
small dia. 1.386"

The oal above is actually a nisnomer. It is the distance between the radiused edges, which is along the taper.

The actual axial length of the adapter is 2.6252 (calculated), so knowing that Monarch always dimensioned things to exact fractional values, it is probably 2 5/8" long.

The calculated length of the ground portion of the adapter is 2.423

The calculated small dia. is 1.385", based on a lg. end dia. of 1.506" and a length of 2.423", so it checks out pretty close. Besides, the small dia. end is hard to measure accurately.

I was wanting a Jarno 12 to MT 2 adapter, without paying $200+. In my "stuff box" was a MT3 to ??? too big for the SB. Chucked it up with a dead center, and set the T/A for the taper of a Jarno 12, 12/8 at the big end, 12/10 at the small end, 12/.5 long. Or a one side taper of .075" of measured crosslide movement in 3" of carriage travel. Cut the bushing to that size and now its a Jarno 12 bushing to MT3.

The micrometer adjustment of the Monarch T/A was a joy, tapping the SB T/A slide is like using a copper chisel on Granite (really slow) . Like most things on the 10EE, once you use it, nothing else comes up to that level.

My plan had been to make one from some SS that I have, but finding one that was half done, was quicker.

Fantastic!

Thanks for the info and references, guys- that's exactly what I needed to know.

Tom- My 10EE came with a taper attachment, but it APPEARS to be missing a part-or-two. My Monarch guide, like all others of '42 MG variety, has a parts-sheet that doesn't help much, that is, unless I take mine all apart, place it on the kitchen table, and try to figure out what isn't there. SO... I'm sure something's missing, but not sure what, or how it works.

Could you snap three or for digi-pix of your TA, so I can compare to mine and figure out what's missing (and what I need to make) so I can get my TA set up to make a 12J?

Dave, I'll take some photos next week. Since it is assembled it may not help that much. Did you search the site, there are some recent photos of a T/A. I have had mine apart when I first got the 10EE, Why not post what you have for parts, and all here should help find whats missing.

Dave,

I posted some photos of my taper attachment in a new thread:
http://www.practicalmachinist.com/vb/showthread.php?p=855142

Cal

To other thread.

Thanks Cal, Tom- I'll snap pictures of mine, and post 'em on the new thread. Mine has covers on it, I'm pretty sure that if I lift the covers, I'll see the same thing beneath, but in looking, I didn't see how it would engage the bed to increment at the taper, blah blah blah. Since I've not had an extreme need for tapering YET, I left this issue for another day, but another day is coming rapidly.

Dave, That is the simplest part of the T/A, as well as a common missing piece. It is two pieces, a 3/8 rod with fine threads at each end, and a bed clamp. The rod connects to the slide of the taper through a hole on the underside of the mounting casting, and the other end of the rod is held with a clamp to the bed. I'll post photos tomorrow.