Turning tapers on lathe using tail stock offset method

churchjw

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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.

024.JPG

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

024.JPG
 
Well done Jeff. A very clear presentation and an excellent tutorial for those of us who have yet to try this technique.
Cheers,
Phil
 
Hi,

Very good explanation and excellent videos. Unfortunately off setting the tailstock in my 7x12 mini-lathe is so cumbersome that I don't even consider doing it; once aligned I don't wish to mess with it any more.

Best regards,
José
 
Great job Jeff very informetive:biggrin: can you tell me if there is a standard table for off setting of the tailstock based on like a 24 inch or 36 inch or is the variation just so much they leave that up to you. thanks much mac:biggrin:
 
Great job Jeff very informetive:biggrin: can you tell me if there is a standard table for off setting of the tailstock based on like a 24 inch or 36 inch or is the variation just so much they leave that up to you. thanks much mac:biggrin:

I have not seen a table like that but it would be easy to create. The problem would be small changes in length makes significant changes to the off set. Example L = 4.220 has offset of .106" and L = 4.500 has an offset of .113" So the chart would have to be large.

Jeff
 
Nice one Jeff an excellent video. very informative and a good presentation.

Now I know what to do with the taper I made with the taper atachment,
maybe I will make 3 more one for each of my centre drills.
thanks again.

BRIAN.
 
my next question, say i want to make a mt4 center do i cut my stock just a cple inches longer then i mark wher my mt4 should stop then once the mt4 is finished then i cut my 60 degree on the cple of inches that i added to stock or will the over all length change the taper, i hope i asked this right:thinking:
 
my next question, say i want to make a mt4 center do i cut my stock just a cple inches longer then i mark wher my mt4 should stop then once the mt4 is finished then i cut my 60 degree on the cple of inches that i added to stock or will the over all length change the taper, i hope i asked this right:thinking:

Basically yes the L value in the formula is for what ever your stock is. So using it you could cut a M4 on the end of a 24" piece of stock and the taper length would be the correct length for a M4. The limit is how far the tail stock will move. I think my home lathe will only move about .500" So for my lathe to cut a M3 the longest I could cut it on is about 20". The taper would still be right at 3.19".

Jeff
 
Nicely done, Jeff. One of the best videos I've seen. Good visibility and audio. Well explained. A good addition to our library.
 
Basically yes the L value in the formula is for what ever your stock is. So using it you could cut a M4 on the end of a 24" piece of stock and the taper length would be the correct length for a M4. The limit is how far the tail stock will move. I think my home lathe will only move about .500" So for my lathe to cut a M3 the longest I could cut it on is about 20". The taper would still be right at 3.19".

Jeff
wow you just explained alot for me right there, thank you thank you, going to make me a tail stock chart for mt tapers. not knowing the procedure for this has held me up on makeing alot of things, i did read some books but did not grasp it, but the way you explained it put it in black and white, again ty so much jeff:holdphone::holdphone::biggrin: mac
 
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