Boring Head Method - Taper Turning Method

In my playing around I often watch videos on YouTube in the morning while I have my coffee, or at night when I can't sleep. A lot of them have some good information in them even if some of it is a little odd or even sometimes wrong. I try to take what is good and move on.

I watched one the other day that was a sort of interesting trick for turning tapers "between centers." You put a boring head in the tail stock. For low angle tapers you can just put a center in the boring head, and for sharper angles you can use a cup with a ball bearing in the chuck and the boring head. I get all of that and it makes sense. What got me and the guy makign the video didn't show (or I missed it) is:

How do you make sure the center or ball bearing cup in the boring head is on center vertically?

Since I don't have to turn a lot of tapers I thought this might be a nice stop gap technique instead of making a taper attachment for my lathe.

Reply to
Bob La Londe
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You know, probably the easiest way is to put two pins in it and level the two pines to each and to the lathe bed. My machinist level will probably get me close enough.

Reply to
Bob La Londe

You can buy centres which can be offset for just this purpose such as

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.

Reply to
David Billington

Stack of 1-2-3 blocks and an adjustable parallel on the lathe bed? ... to adjust a boring head orientation, that is.

If it's just a ball center, the offset adjust of the tailstock ought to be accurate enough.

Reply to
whit3rd

Back in the day people turned tapers between centers (and also aligned the head and tail stocks the same way).

I used to turn rifle barrels that way and it goes without saying that the 0.D. and the bore would be concentric.

Reply to
John B.

Perhaps put a level on the dovetail with it extended a bit?

Many (though not all) lathes have provisions for offsetting the tailstock to do taper turning between centers. You loosen the tailstock clamp to the bed, loosen a screw in the middle of the back side of the tailstock, and tighten the one in the front side to move the tailstock ram back. (Or the other way around, to move it towards you, depending on whether you want the big end of the taper towards the tailstock or the headstock.) With this, there is no question as to whether the height of the center is correct.

However, you need to come up with a way to set the tailstock back on horizontal center when you are done. There are various tricks for this.

The two lathes which I have had which do not have this feature are the Unimat SL-1000 (on that, you rotate the headstock to shift the tip back or forward), and the Emco-Maier Compact-5/CNC, which being a CNC lathe, can do tapers without the trick. However, the same tailstock is used on the manual Compact-5, so there such a trick would be useful.

Enjoy, DoN.

Reply to
DoN. Nichols

Yeah, a couple folks have said, "Just offset the tail stock BOY!!!" LOL.

I donwanna. LOL.

On the same work piece I need to have the tail stock in line, and separately I need to be able to turn the longish taper. I might have mentioned I might need to do a few of them down the road. I had already resigned myself to building a guide rod style taper attachment when I ran across the other offset adapter ideas like the boring head idea. Then somebody pointed out the purpose built adapter that's dead cheap. I reckon I can level that faster than I can put a guide rod taper attachment on the lathe.

I tend to spend way to much time thinking about these things looking for the easiest way to get a satisfactory result.

Reply to
Bob La Londe

That is not a bad thing. It will save you from doing a lot of time-consuming or expensive things that you'll want to kick yourself for when you finally *do* realize what the easy or cheap way was.

These days, I just sit and think about little jobs before tackling them, if it's something I haven't done before. Fortunately, nobody is watching me or paying me to do it.

Reply to
Ed Huntress

To align head and tail centers you simply mount a piece of stock between centers and turn a length at the head stock end and then at the tail stock end - using the same cross feed setting of course. Adjust the tail stock, if necessary and repeat.

They used to sell "test bars" to do this. Hardened steel bars to be mounted between centers and then you could mount a dial indicator on the carriage and run the carriage back and forth. The test bars were, of course, exactly the same diameter for their entire length.

Back in the day, they weren't considered "tricks". Just common knowledge in the trade :-)

Reply to
John B.

In the Air Force shops there used to be a joke - maybe it actually happened. The inspector comes in the shop and one guy is just sitting there staring off into space and a second guy is frantically turning pages in the Machinery's Handbook and scribbling numbers on a piece of paper.

The Inspector marks the guy staring off into space as "Not Working" and the guy with the book as "Working" when in actual fact the guy staring off into space was calculating the number and sequence of "set ups" he would use to machine the part and the guy with the book was trying to figure out how to cut threads :-)

Reply to
John B.

A former Air Force repairman told me that when he had nothing to fix he wandered around carrying a clipboard as though he was an inspector, so no one would dare bother him.

-jsw

Reply to
Jim Wilkins

A fishtail gauge (or any piece of flat stock) pinched between the centers will quickly indicate any misalignment.

Reply to
rangerssuck

Yup, it works. At least to some extent. A bloke with clean fatigues and a clipboard is viewed with a certain amount of reserve - what is HE checking on - and usually left alone.

Of course, if he happens to meet his boss...

Reply to
John B.

Not to be picky but to what level of accuracy? If you have, oh say 2 feet between centers then you can align them to (depending on your micrometer) perhaps a 1/10 or less. With a center gauge?

Reply to
goodsoldierschweik

vel that faster than I can put a guide rod taper

If you are concerned about the boring head not being installed exactly horizontal, try setting it by eyeball and then turning a taper. If the boring head is not installed exactly horizontal , it will not make much of an error in the taper.

Dan

Reply to
dcaster

Chap I used to work for got bored one day so he and a buddy each put ten sheets of blank copy paper in a new file folder and visited every office in the provincial gov't department headquarters complex where they worked - took a full week to complete their "inspection"!

Reply to
Gerry

I use scrap aluminum from the tray under the shear for that to avoid damaging the points. Depending on their condition - mine are either second-hand or Enco - you should be able to align the centers closely enough to center-drill both ends of some rod stock.

With the rod held between centers, clean up the eccentricity for about

1/2" at both ends, then take a finish pass on both ends without changing the cutting radius, flipping the rod to make both cuts at the tailstock end.

You now have a test bar that should be (check it) the same diameter at both ends, which you can use with a dial indicator to center the tailstock more accurately.

This is a commercial product that can serve as a lathe test bar:

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A shop-made one is more convenient if you turn it down in the middle to clear the dial indicator.

-jsw

Reply to
Jim Wilkins

[ ... ]

Good!

I don't think so, based on the two cylindrical squares which I have.

1) The center holes at the ends are as cast, and the square is not machined from those. It is ground so the cylindrical surface is truly square to the rim (also ground), and is for sitting on a surface plate to provide a true vertical from a true horizontal of the surface plate.

Note that B&S made one which was ground intentionally a tiny bit off square -- and there were etched lines on the surface representing 0.0001" offset points as you rotated the square. (Or, if you set it the other end down, it would be truly square.

2) The handle mounted on one end has no center hole at all, so mounting it between centers would not work at all, even if the hole at the other end were a true center.

Once you have the precision reference ends complete, yes. But be careful to not apply enough force to bend the bar.

Enjoy, DoN.

Reply to
DoN. Nichols

TFF, and so ironic & sad.

P.S: Um, what did their bosses say when they didn't shop up on the job for a week?

Reply to
Larry Jaques

Why bother? Can't you just base an indicator on the chuck or faceplate, extend to the taper (internal socket) of the tailstock, and rotate the spindle by hand, looking at the reading?

It's easy if the tailstock is near the spindle.

Reply to
whit3rd

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