Turning tapers on lathe using tail stock offset method

[GK1918]

Thanks, Jeff I really forgot to say an excellent vidio job. Although many years ago my old mentor shunned on that
because his belief was dead centers not riding true. I remember, he had a set, he made (centers), with ball ends
instead of 60* points. Never witnessed this, but I imagine its a good idea. Keep it comming you already mastered
the hard part and thats making a vidio and putting it in a post, I got no clue. Your right in there with Mr Pete
thanks sam

 

[GK1918]

Rickabilly; thats what I meant to say, Tubal says they get wallowed out, that is correct . Now looking way back I
think my friend used a ball (mill) end and matched that with a male ball center makes sense to me, thats 40 yrs ago.
and my friend now would be 110 yrs old now. Jeff did a real good job with this subject lets keep this going.
In recap center drill both ends-chuck a ball mill in tail stk. do both sides of stock. turn two ball centers. oil done.
good thought I think ill try it. Just one more item in the draw.

Correct me; I have 6" long 2" dia, I need MT 3 (is .6024 TPF) so 6.000 X .6024 = 3.6144 (ok) div by 24 = 0.1506
so my setback tailstock is 0.1506 Is that correct Im a math dope !!
father time sam

 

[ekrteam]

This is another great training video for guys like me. I'll be on the lookout for a nice piece of precision ground shafting for checking my tail stock offset. I did not read all the comments but on the video he references the live center on the tail stock. Wouldn't it be more accurate to insert the precision ground shaft and use the end of that or even use the turned end (small diameter end) as a reference to get a more accurate offset? I realize he would be relatively close but this affects the total dimension of the taper.

 

[Hawkeye]

Rick, I think you just solved a minor mystery for me. I ordered a few center drills some time ago and some of them had curved cutting edges. The holes they drill are exactly as you describe. Now I know what they're for.

Thanks.

 

[churchjw]

Rick, I think you just solved a minor mystery for me. I ordered a few center drills some time ago and some of them had curved cutting edges. The holes they drill are exactly as you describe. Now I know what they're for.

Thanks.

Post a picture of one. I have never seen one.

Jeff

 

[Tony Wells]

They're called "Type R" center drills.

 

[irishwoodsman]

yes ty much:biggrin:

 

[Beekeeper]

Great video and very clear explanation. Thanks

 

[Bill C.]

Ok here goes my attempt at doing a demo so please be nice. Tips, corrections and constructive criticism welcome.

The advantages of this method are to use of power feed for a better finish and ability to do longer tapers. A taper attachment works much better if you have one. The disadvantages for this method are time to it takes to adjust the tail stock and it can only cut very shallow angles. For steeper angles the compound rest method works better.

First and last step in this process is making sure your tail stock and head stock are properly aligned. "And before anyone brings up my miss use of terminology I call a center that has no bearings a dead center and one with bearings a live center. I think that is probably wrong but it was the way I learned it and its hard to unlearn the names."

[video=youtube_share;Tt1KMHbkj6Y]http://youtu.be/Tt1KMHbkj6Y[/video]

Once you have the lather lined up you will need to move the tail stock out of alignment by a set amount. I almost always move the tail stock toward the operator. This puts the small end of the taper pointing toward the tail stock. I then cut from tail stock toward the head stock. This puts most of the force on the head stock not the tail stock. It also means cuts get shallower not deeper as you cut. I have seen people get in trouble cutting in from the large end and guessing wrong on the depth of cut. This is especially true for the first few cuts.

The formula to figure out the amount of tail stock offset is:

Offset in inches = total length of part in inches * Taper Per Inch / 2

or

Offset in inches = total length of part in inches * Taper Per Foot / 24

Example:

Offset = ?
part length = 4.220"
TPF = .6024 (#3 Morse taper http://littlemachineshop.com/Reference/Tapers.php)

O = 4.220 * .6024 / 24 = 2.542128 / 24 = .106"

With that number you move the tail stock and then turn between centers. This has to be done between centers. Holding one end in a chuck will not work. You get this weird curved taper thing.

[video=youtube_share;3p4kC3Fnr0c]http://youtu.be/3p4kC3Fnr0c[/video]

Here is the final part I made from the taper I cut in the video.

View attachment 31799

Its to hold a center drill for my lathe so I don't have to put one in the drill chuck every time.

Hope this helps,
Jeff

Great video, easy to understand. It does take time to get it right. Specially when re-aligning the centers. I used to think those witness marks on the back end of the tail stock were dead on. One of my instructors told us they are for proximation your method is the correct way. Thanks again