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Tailstock Taper

LittleMr

Plastic
Joined
Apr 25, 2020
Hello everybody...I have an old 1914 14" Davis Lathe from Rochester Ny...I need to know if anyone can help me out with a few things any info and knowledge will be greatly apreciated...First thing is the taper on the tailstock...3MT is too small and 4MT is too big...I took the dead center and measured it and looked at the chart on this site and my guess is it is a jarno taper...It's fatter than a morse taper...the measurements are 3" long from the bottom to where it stops in the ram and 3/4 bottom and 1"top where it stops in the ram my guess it is a #8 jarno taper...I think but not sureThey call it a close coupled lathe by Davis Machine and Tool Co...Most of them Davis Lathes are stamped WP Davis but this one is just Davis...Any info or anything on this Lathe would be very helpfull...Thanks ahead of time for your help...I will post other questons i have on this Davis Lathe in a seperate post...Another thing is this Lathe is all there and all original not missing anything...I know not to leave the T handle in the chuck I have the machine disconnected from the power :scratchchin:
 

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Last edited:

4GSR

Diamond
Joined
Jan 25, 2005
Location
Victoria, Texas, USA
First thing, DON'T EVER leave the chuck wrench in the chuck. At least don't take pictures and post here. We will eat you alive over it.

It's very possible your lathe has a Jarno taper in the tailstock. Some of the very old lathe manufactures back then couldn't decide what taper to use. So it is very possible. Some of our historian people may chime in and be able to give you more details on this. BTW- nice lathe for its age. Ken
 

4GSR

Diamond
Joined
Jan 25, 2005
Location
Victoria, Texas, USA
Mr. Know it All, thermite,

There were a few lathe manufactures way back then before or around 1900 that used the Jarno taper in the tailstock of their lathes. Don't recall any using B & S tapers.
 

aguaman99

Plastic
Joined
Feb 9, 2019
Not so!. We usually beat them to death, first!
:)



More likely to be B&S Taper. Also possible it is an obstructed, badly worn or damaged MT, maybe even shop monkey-patched.

Not as if the old gal were anywhere near a virgin by this late a date.

Jarno was originated BY B&S .... their legendary Works Manager, Oscar Beale. MOST adoptions were for spindle bores, not near as much TS adaptation. "AFAIK" it remained extremely rare as to drill shanks or cutter-holder shanks - and there was the barrier to wider TS use. Uncommon tooling.

B&S taper, OTOH, was made on drills and came to dominate on milling goods for superior resistance to side-thrust walk-out over Morse.

B&S taper-shank drills still turn up now and then.

2CW and two #12 jarno "holes" three #9 B&S.... hence a "need to know" .... and the research.


Wow I sure do love this forum! A quick read through this and I think I've solved my own mystery! Hoping one of you will chime in and verify my conclusion.... I came across two spindle bore adapter/sleeves via a tool box purchase. They don't fit anything I have but hate to through things out that others might have a use for. I couldn't figure out the taper designation using my machinists black book. Dimensions and math are below.

Adapter/sleeve I have on my bench:
Taper OAL(along center axis) = 2.4165
Taper OD small dia. = 1.3870
Taper OD large dia. = 1.506


1.506 - 1.3870 = .1190
.1190 / 2.4165 = .0492 TPI

What i think it is:
Jarno #12 = .6000 TPF with 1.50 large dia.
.6000 /12 = .5000 TPI

Did I do the calculations right and do I have a Jarno #12 spindle adapter/sleeve?
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
A good machine tapers site here.

Dimensions of Standard Tapers - LittleMachineShop.com

You might wood wedge a small straight something in and then strike it with an indicator to see taper per inch.
Jarnos are .050 tpi

*You might use the compound set at an angle to turn a piece of wood dowel held in your chuck, so to find a match of your tail taper..

You can ballpark by holding a small Allen wrench in your tail ..and then eyeball over it to find near match with swinging your compound.

*Finding and turning a taper with your compound is a good talent to learn/practice if you are new to lathe work.

W. P. Davis Machine Co. was sold in Oct. or Nov. 1915 to a syndicate operating as Davis Machine Tool Co., Inc.
 

aguaman99

Plastic
Joined
Feb 9, 2019
A good machine tapers site here.

Dimensions of Standard Tapers - LittleMachineShop.com

You might wood wedge a small straight something in and then strike it with an indicator to see taper per inch.
Jarnos are .050 tpi

*You might use the compound set at an angle to turn a piece of wood dowel held in your chuck, so to find a match of your tail taper..

You can ballpark by holding a small Allen wrench in your tail ..and then eyeball over it to find near match with swinging your compound.

*Finding and turning a taper with your compound is a good talent to learn/practice if you are new to lathe work.

W. P. Davis Machine Co. was sold in Oct. or Nov. 1915 to a syndicate operating as Davis Machine Tool Co., Inc.

Yes I've seen and studied the charts in my handbook and black book. Based off of my measurements and the calculations I did I believe the only viable possibilities are Jarno 12, Jacobs 0, MT 1 or MT2. Because of the larger diameters of the sleeve I believe I should exclude the Jacobs and Morse tapers as they are for much smaller diameters. Wasn't looking for a link to another chart rather someone with more skill and understanding to validate what I've deduced. Really hoping someone chimes in with an opinion.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
QT:[Really hoping someone chimes in with an opinion.}
An inspection or test of what you have beats any Opinion.

QT: .[I took the dead center and measured it and looked at the chart on this site and my guess is it is a jarno taper]

If you have a taper that fits..identification should be easy.
 

aguaman99

Plastic
Joined
Feb 9, 2019
QT:[Really hoping someone chimes in with an opinion.}
An inspection or test of what you have beats any Opinion.

QT: .[I took the dead center and measured it and looked at the chart on this site and my guess is it is a jarno taper]

If you have a taper that fits..identification should be easy.

Ummm :) either i just don't understand what you're trying to say or possibly you're not getting what I'm saying or asking for... I'm not trying to beat an opinion, I'm actually asking for one :). I've painstakingly taken the measurements and done the math I believe is appropriate to determine what the adapter taper is and I simply don't have a way of letting someone test or inspect it. Was just looking for somebody to provide their opinion of my calculations and findings. In other words; am I thinking about this the right way in order to identify what I have? Regardless, searching through other threads, I've found further information substantiating the measurements and my calculations. What I have are two monarch 10ee spindle adapters that are Jarno 12 to MT2 adapters. Measurements are a match. Thanks for all your help.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
I guess I am confused. I thought I was talking to LittleMr about finding the tail taper of Davis lathe.
seems he had post #1....?


RE: [First thing is the taper on the tailstock...3MT is too small and 4MT is too big...I took the dead center and measured it and looked at the chart on this site and my guess is it is a jarno taper...]

RE:[I took the dead center and measured it and looked at the chart on this site and my guess is it is a jarno taper...It's fatter than a morse taper...the measurements are 3" long from the bottom to where it stops in the ram and 3/4 bottom and 1"top where it stops in the ram my guess it is a #8 jarno taper..
 

aguaman99

Plastic
Joined
Feb 9, 2019
No worries. Yes there are two different questions and members that you are responding to. I was asking a different question than littlemr.
 








 
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