# Cutting A Taper On A Lathe



## Annealed (Sep 29, 2015)

Just getting started with an old lathe and mill. I needed to make a "centering" cone for the back side of the mill's drawbar (intended to keep the drawbar centered in the through hole). I decided to make it out of brass. It just needed to be about an inch long, with a 1/2" hole through the center through which to pass the drawbar, and have a pretty steep taper from 2" to 1" in diameter. 

The first challenge was figuring out how to move the cross-feed in two directions at once -- feeding across the length as well as moving the cutter into the work deeper and deeper as I went to form the taper. I got this done, but with several scary moments when the cutter edges that weren't supposed to be cutting made contact with adjacent sides of the part. There has to be a better way (without having to buy a taper attachment) - is there a video on this?

Another lesser challenge was boring the thru hole.  I used a standard jobber twist drill in a chuck in the tailstock and fed it into the work.  There was quite a bit of resistance doing this and after about half an inch in alot of sqeeling resulted. Should i have been using a boring bar?


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## Chipper5783 (Sep 29, 2015)

Well, you have a lathe, mill and the courage to have a go at things.  As far as the taper, you ought to be able to swivel the compound (the top most slide on the lathe) to the angle you are looking for, then feed only the axis of the compound.

For a through hole, a regular jobber twist drill is a good choice, so long as you do not require a high tolerance in size, finish, roundness or location (a regular twist drill is an expedient tool, but it is also very rough tool).  Depending on what I am doing, I'll usually start with a twist drill, then finish with the boring bar.  Twist drills in brass can give some trouble as drills tend to have a lot of rake, and because brass is soft, the drill bit will bite too aggresively (usually you can just back off on the feed until it starts to break through, then go very light on the feed).

Enjoy the new activity.  Please post pictures of what you are working on.  Regards, David


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## DSaul (Sep 29, 2015)

I turn a lot of cones on my old South Bend 405 without a taper attachment.  You just have to lock the carriage, turn the compound to the angle you want and feed with the compound.


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## Kernbigo (Sep 29, 2015)

this is what i use in the tail stock


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## ch2co (Sep 29, 2015)

Kernbigo
Being a real newb at this stuff, I've never seen a tailstock off-centerator attachment like that.  Cool idea.  I just spent much of a day cleaning, reassembling, and 
Re-centering my tail stock. This became necessary when I was recently getting more taper than I expected in a almost full bed length rod that I was turning.  I have used the compound at an angle method for several short tapered pieces before, but the thing-a-ma-jig that you are showing would be very useful for longer tapers.
Is this gizmo a commonly available device ? Does it have a name?  

Chuck the grumpy old guy


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## Kernbigo (Sep 29, 2015)

I got at the shop i used to work at it needed rebuilding it is called a (taper-tail) you  put it in the tail stock on horizontal plain and put a level on it to get it close, does not have to be perfect. I you want a extreme amount of taper you use a face plate and run between centers with a ball nose center in the head stock. The one on the left, the one on the write is a enco adjustable center but only has .010 max adjustment


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## Annealed (Sep 29, 2015)

I think alot of my problems were due to the cutter not being sharpened all the way back from the point on the trailing edge. I was feeding right to left (into the headstock) and the point would cut, and would continue to cut for a 1/8" or so along the angled trailing edge (angled for the taper I wanted), but when it got ot the unsharpened part would catch. 

Also, for those above who have suggested feeding in with the compound slide -- that is waht I was doing, but of course then you can only cut the wide of your sharpeened cutter edge at a time right? Then you have to back out, move over, and feed into the work again.  I was wondering if there is a way to smoothly cut down the entire edge of the taper in one pass.


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## T Bredehoft (Sep 29, 2015)

Annealed said:


> I was wondering if there is a way to smoothly cut down the entire edge of the taper in one pass.



No. That's why they are all adjustable. take your time, don't try to do it in one pass, use several, the last one or two very fine to get a good finish. Yes, I know, its a lot of cranking. I don't know about you, but I'm not paid for how much work I put out, but for how good it is. This is a hobby, right?


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## kd4gij (Sep 29, 2015)

Annealed said:


> I think alot of my problems were due to the cutter not being sharpened all the way back from the point on the trailing edge. I was feeding right to left (into the headstock) and the point would cut, and would continue to cut for a 1/8" or so along the angled trailing edge (angled for the taper I wanted), but when it got ot the unsharpened part would catch.
> 
> Also, for those above who have suggested feeding in with the compound slide -- that is waht I was doing, but of course then you can only cut the wide of your sharpeened cutter edge at a time right? Then you have to back out, move over, and feed into the work again.  I was wondering if there is a way to smoothly cut down the entire edge of the taper in one pass.



 Can you post a picture of your set up?  Your description doesn't sound right.


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## Annealed (Sep 29, 2015)

My setup is all broken down and cleaned up now. Is there a good video of the right way to do it?


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## Charles Spencer (Sep 29, 2015)

Annealed said:


> My setup is all broken down and cleaned up now. Is there a good video of the right way to do it?



The compound rest method starts about halfway through the video:


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