#8 Morse taper specification data

[ignator]

I have searched the web, and can not find any technical dimension data for a #8 Morse Taper. The machinery book stops at #7.
My lathe has the spindle nose with this taper, as it's 80mm/3.125 through hole.
I want to make a tool that fits this taper.
Does anyone here have this information?
Thank you.

 

[michiganbuck]

Could it be another taper? (80mm about 3.1495 inch)

Dimensions of Standard Tapers - LittleMachineShop.com

Guess finding taper per foot a good start.

Guess you might travel a long arm indicator exactly an inch coming out then turn your cross dial to see taper per inch..

More tapers
http://www.tools-n-gizmos.com/specs/Tapers.html

What a shame Morse had to vary the taper a small amount.. all the same taper would have been fine.
Jarno is the only one who did that so easy to tell a jarno taper.

 

[ignator]

Could it be another taper? (80mm about 3.1495 inch)

Dimensions of Standard Tapers - LittleMachineShop.com

Guess finding taper per foot a good start.

Guess you might travel a long arm indicator exactly an inch coming out then turn your cross dial to see taper per inch..

More tapers
http://www.tools-n-gizmos.com/specs/Tapers.html

What a shame Morse had to vary the taper a small amount.. all the same taper would have been fine.
Jarno is the only one who did that so easy to tell a jarno taper.

Thanks;
I found these sites when looking, as you can see they stop at #7.
I know I can sweep mine, but wanted the specifications as then gauges can be made to ensure getting the right angle, as the same machine has to make the adapter, and I can't do a quick fit check if I have to remove the chuck to access the spindle bore.

 

[michiganbuck]

Agree having only one lathe and not an OD grinder so the test gauge can be made is a problem.

Suppose you might take a test diameter to go X distance into the bore from the major (out) diameter. so with that length get perhaps .001 or .002 close to the taper. Yes having a DRO would make this easy.

 

[Limy Sami]

What lathe is it? ...half a chance it's not a Morse taper, and a slimmer chance the taper is on a spec sheet somewhere.

 

[MrSteve]

Jarno 20, or (less likely on a lathe?) B&S 17 or B&S 18 or a special? Could be an American National Standard 250 Taper too perhaps.
Best to measure taper per foot, large end diameter, and length.

 

[ignator]

What lathe is it? ...half a chance it's not a Morse taper, and a slimmer chance the taper is on a spec sheet somewhere.

It is a China import I purchased new in 2004. It came from Grizzly, but in name only, as it never was in their catalog, and was an online 'special'. The manufacture spec. sheet that came with the lathe indicated 6MT, which is in error.
Other lathes in their 2004 catalogs indicated 8MT head stock taper.

My rough measurements:
At the spindle opening I measure 3.53 inches diameter, and 4 inches in the bore, 3.33 inches diam. So if I work out the half angle of this taper, it's ~.3 inches per foot. Or .025/inch. Arctan of this is 1.43 degrees. Checking backwards from the the morse taper table of average ~1.48 degrees, .0025 inch measurement error between the 2 measurements can account for the angle difference.
So I'm guessing this is in the MT series.
DIN 228-1 may cover this, but the online price tag is $50 just to see if MT8 is specified. Anyone out there with access to this to see if 8MT is covered?
This is a photo of the OEM lathe manufacture spec sheet. I think someone typo'd an 8 to a 6.

The current center slug I have that is a 4MT center:

 

[michiganbuck]

We had a few grinders that had tapers never in the catalog.. so it may be a special. But does seem odd if it is not a standard taper.

Yours might be a mistake taper needing a blue in fit and the odd size made custom.

 

[HuFlungDung]

Just start boring your gauge and fit the existing plug to it. I only ever need either the male or the female to make a mate. It does little good to have some number out of a book to assign to it, when that isn't how you tweak the taper attachment for the final fitting anyways.

 

[johnoder]

Sorry, no MT 8, which is a good reason for it not being published. There are PLENTY of non MT tapers in lathe spindles. If its near 3.5" at big end it is reasonable to assume American Standard 350. If you come up with some other taper than .750" per foot on diameter, it is not American Standard 350, and is some other taper, not necessarily published. Lathe makers have been doing exactly as they pleased for well over 100 years. My twenties Greaves Klusman has a Jarno 18

 

[michiganbuck]

Qt : [My rough measurements: 3.53-3.33 @ 4"]
How close do you think you are with that.. It seems you should be able to get .001 to .003 close. Then blue in to exact.

Just inserting a 3” round stock to a stop and then carefully scribing a line at the at the big end and then micrometer measure should get .003 or better.

Yes a 3” round with a center to go on the tail center would be good for a feel gauge.

Finding the taper then turn a sleeve taper (between centers) to a standard taper of your choice.

 

[Forrest Addy]

The largest standard Morse taper recognized is the #7 which is 3.270 at the gage line, 10" long and has a total taper of 0.624 per foot. Extrapolating the Morse taper characteristics in the tables, I'd surmise a #8 Morse taper would be 4" diameter at the gage line and be 12 3/4" long having a total taper of 5/8 per foot but THAT is a wild guess.

Are you sure it's a Morse taper in your spindle? Machine tool makers in the past have cooked up proprietary tapers based on the Morse, Jarno, 3/4" per foot etc series extending them to suit whatever large tapers they may have painted themselves into a design corner - then sell you a load of very expensive tooling to fit it.

Then again the maker may have specified a smaller than standard #7 Morse gage line. 80 mm on the spindle and 3.270 inches on the shank results in about 2" short fit - about the amount I'd want the spindle center gage line to extend into the chuck on a larger lathe. This puts the spindle center cone the right amount short of the chuck jaws tips for between-centers turning..

If it is an oddball, there are almost certainly no gages to be had. Have you checked it with a #7 Morse tooling shank or a gage? Here's a #7 Morse shell mill arbor for cheap on eBay:

MT7 Morse Taper with a Drill INV=1828 | eBay

At $70 to ship 35 - 40 lb isn't cheap for a one-time use. OTH you get a used-up shell mill you can blunt and polish for a paperweight

If it is an oddball, you're kinda stuck. While it's a huge PITA , I suggest you figure a way to accurately determine the taper and make accurately fitted male and female gages for your spindle.
.

 

[Monarchist]

The current center slug I have that is a 4MT center:
View attachment 191382

Are we being told that 'slug' does fit, and mounts a 4 MT?

If so, why not just duplicate the Mike-Foxtrot, twice if need be, and not worry overmuch what the taper is called-out as, so long as each blues-up to a useful fit?

Surely you don't plan to market these as a product, nor write a new manual?

 

[ignator]

Are we being told that 'slug' does fit, and mounts a 4 MT?

If so, why not just duplicate the Mike-Foxtrot, twice if need be, and not worry overmuch what the taper is called-out as, so long as each blues-up to a useful fit?

Surely you don't plan to market these as a product, nor write a new manual?

Yes, this slug fits. If it is a Morse Taper, it would be some sort of stub type. Note the pencil line, that is where it protrudes the front of the D1-8 spindle nose.

 

[Monarchist]

Yes, this slug fits. If it is a Morse Taper, it would be some sort of stub type. Note the pencil line, that is where it protrudes the front of the D1-8 spindle nose.

'Partial' tapers are common as housefly poop in lathe spindles. Some are 'half', others just 'special' as to gauge-line, both ends. Jarno-Reed & such.

So long as you can duplicate the known-good one and/or take good measurements off it, I don't see any gain from trying to find a 'formal label' for it that may never have existed other than in Chinese characters. Just record what it is, duplicate it if need be, do something more productive.

Call it a "Orphaned Grizzlyish Ignator Taper" if it won't report for duty just being called "hey, you!".

Had a delivery truck driver like that once at a Day Job.

Resented just being called 'the driver'.

Owner formally appointed him "Vice President, Outside Wheels", printed him some biz cards, clued-in all hands to so address him, we did so, and he got behind the wheel each day a proud and happy camper.

Me? I settled for a pay rise and not being called 'late for payday' instead..

 

[ignator]

The largest standard Morse taper recognized is the #7 which is 3.270 at the gage line, 10" long and has a total taper of 0.624 per foot. Extrapolating the Morse taper characteristics in the tables, I'd surmise a #8 Morse taper would be 4" diameter at the gage line and be 12 3/4" long having a total taper of 5/8 per foot but THAT is a wild guess.

Are you sure it's a Morse taper in your spindle? Machine tool makers in the past have cooked up proprietary tapers based on the Morse, Jarno, 3/4" per foot etc series extending them to suit whatever large tapers they may have painted themselves into a design corner - then sell you a load of very expensive tooling to fit it.

Then again the maker may have specified a smaller than standard #7 Morse gage line. 80 mm on the spindle and 3.270 inches on the shank results in about 2" short fit - about the amount I'd want the spindle center gage line to extend into the chuck on a larger lathe. This puts the spindle center cone the right amount short of the chuck jaws tips for between-centers turning..

If it is an oddball, there are almost certainly no gages to be had. Have you checked it with a #7 Morse tooling shank or a gage? Here's a #7 Morse shell mill arbor for cheap on eBay:

MT7 Morse Taper with a Drill INV=1828 | eBay

At $70 to ship 35 - 40 lb isn't cheap for a one-time use. OTH you get a used-up shell mill you can blunt and polish for a paperweight

If it is an oddball, you're kinda stuck. While it's a huge PITA , I suggest you figure a way to accurately determine the taper and make accurately fitted male and female gages for your spindle.
.

I'm not sure it's a MT taper, just assuming seeing spec. for other import lathes in this size class. I think this would be a stub type MT, But I'm not sure, as the current center that came with the lathe is shown in the photo, It is around 5 inches total length, with 3/4 inch protruding from the spindle.
I purchased a 6MT test bar off ebay, and this is what precipitated me seeing I made an error, in that I could have looked at my machinery manual and see that a 7MT would be too small. The 6MT test bar has a short taper on it.

 

[ignator]

Qt : [My rough measurements: 3.53-3.33 @ 4"]
How close do you think you are with that.. It seems you should be able to get .001 to .003 close. Then blue in to exact.

Just inserting a 3” round stock to a stop and then carefully scribing a line at the at the big end and then micrometer measure should get .003 or better.

Yes a 3” round with a center to go on the tail center would be good for a feel gauge.

Finding the taper then turn a sleeve taper (between centers) to a standard taper of your choice.

My metrology skill using a micrometer to measure a diameter on a tapered surface is not the best. I could easily be off by +/-0.0025.
The compound slide has too short a travel for the 5 inch length of a stub part I need to make. Although It does not need to be that long, as it's not going to drive torque, just needs to be a good tolerance fit.

 

[Monarchist]

My metrology skill using a micrometer to measure a diameter on a tapered surface is not the best.

You don't want to do it that way.

Set it up so you can put a pair of precision 1-2-3 block edges against it. Now you have an ordinary linear measurement for the gauge line length between where each block impinges, and another ordinary depth difference backside of one block to the other.

There is a photo of this being done IN a lathe right here on PM, but I cannot think of how to get the search engine to find it.

 

[ignator]

You don't want to do it that way.

Set it up so you can put a pair of precision 1-2-3 block edges against it. Now you have an ordinary linear measurement for the gauge line length between where each block impinges, and another ordinary depth difference backside of one block to the other.

There is a photo of this being done IN a lathe right here on PM, but I cannot think of how to get the search engine to find it.

I think I understand measure across the 1/2/3 blocks and subtract their thickness from the width measurement. Make this at two different heights of the slug, and I can (within a few tenths) get data that can translate to the taper angle.

 

[michiganbuck]

QT: [Yes, this slug fits.] If it blues into the lathe then what more do you need.. with that dimension (taper) you can make a collect holder,a sleeve to a common taper, a face plate stub or anything you need.


[Quote Originally Posted by ignator View Post
My metrology skill using a micrometer to measure a diameter on a tapered surface is not the best.]
Agree but it is a simple way to get perhaps .003 or less.

*I was suggesting that to measure the bore not the slug.. Did not know the slug was a fit.

Agree but it is a simple way to get perhaps .003 or less with simple tool , a micometer..

A plate check with a surface gauge and a small point indicator to a jo-block would be my choice.
To measure the slug I would use a 4" (or 3") jo block to strike the slug 4" (or3)apart and get a tenth or so.