Cutting a taper

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Penultimate

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Greetings
I have a 7x12 and a 4 jaw chuck. I've researched cutting tapers and I find only info on offsetting the tail stock. It seems that using my four jaw chuck I could offset the stock in the chuck and leave my tail stock dialed in to center. Do you see any issues with cutting acrylics this way?

Thanks for your advice.
 
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Sylvanite

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Offsetting the material in a 4-jaw chuck will not produce a taper. You have to move the center of rotation for that (which is what offsetting the tailstock does). If you want a short taper, you can cut it by turning the compound, and using it's handwheel to advance the cutter.

Regards,
Eric
 

JD Combs Sr

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Diameter of the material(cut) would vary from end to end for sure but the cut would not be full diameter as it would by off-seting the tail stock.

Picture it, at the headstock end you would only cut material only when the part was "brought around" to the cutter due to the offset. I don't think it would give you a tapper as you would like. You would have a tapered, not sure what to call it, divot maybe, on only one side of the headstock end until you cut down past the amount of off-set. Then you would have an off-set taper???

Just trying to think out loud here.
 
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manik

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I purchased a 9x20 lathe and am in the process of mounting it and learning how to use it - classes start next weekend ;-)

I did run across a book "Metal Lathe - For Home Machinists" by Harold Hall

I bought it from Amazon a bit ago and have been studying it.

There is a chapter 8 on making precision tapers with the top slide that might be just what you are looking for.

I don't see how to explain all he is recommending in an email but basically turn the top slide to the angle that you want and use the top slide feed to make the taper.

Maybe this will be enough for you to figure it out, but the book has a wealth of knowledge on metal lathes and worth the cost.

Good luck
 

low_48

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You can't use an offset 4 jaw with a tailstock. Unless, you grab a dead center with the 4 jaw chuck, have centers drilled in you stock, and drive the stock with a lathe dog. Usually the lathe dog is used with a face plate and dead center, but if the leg of the dog can grab something on the chuck........It sure would be a challenge.
 

Paul in OKC

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You can cut a taper by offsetting the part in the chuck. As long as you material is large enough to allow the extra 'swing' it will make. Not the most efficient way, but it is possible. Problem would be holding the tapered part to drill after turning. Best way is to offset the tail stock or use the compound.
 

Sylvanite

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You can cut a taper by offsetting the part in the chuck.
Let's do a little thought experiment. Imagine you have a piece of 1" diameter round stock you want to turn down.

Control experiment: First off, let's just chuck it up normally in a centered chuck and tailstock. The stock is concentric around the turning axis. If you turn 1/8" off the stock, you'll wind up with a straight 3/4" rod.

Offsetting the stock in the chuck: Now pretend that instead of using a centering chuck, we put the 1" stock in a 4-jaw chuck and adjust the jaws so that the piece is offset 1/8" towards the front of the lathe. If we take the same cut as before, then at the headstock, we remove 1/4" of material from one side of the rod, and nothing from the other side. As the cut progresses towards the tailstock, it evens out, eventually taking 1/8" all around. We still wind up with a piece 3/4" diameter over the entire length. It is offset, but not tapered. It doesn't matter which direction you offset the piece, as the chuck is spinning.

Offsetting the tailstock 1: Instead of offsetting at the headstock as above, imagine that we offset the tailstock 1/8" away from the front of the lathe (towards the back). Mount the 1" rod centered at the headstock and centered on the offset tailstock. Take a 1/8" cut the entire length. At the headstock, we'll remove 1/8" all around. Moving toward the tailstock, however, the cut becomes progressively shallower. At the end, we remove no material at all. This results in a turning that is tapered, 3/4" diameter at the headstock and 1" at the tailstock.

Offsetting the tailstock 2: Do the same thought experiment as above, but instead of offsetting the tailstock toward the rear, offset it towards the front. With the same depth of cut, we'll remove 1/8" of material all around at the headstock, and 1/4" at the tailstock. The result is a tapered turning, 3/4" diameter at the head and 1/2" at the tail.

So you see, a non-parallel axis of rotation (achieved by offsetting the tailstock) produces a tapered turning. Offsetting the stock but maintaining a parallel axis of rotation does not yield a taper.

I hope that helps,
Eric
 

Penultimate

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Thanks to everyone for clarifying this. I had trouble picturing how the stock would look after cutting. Thanks again.

Looks like I'll be messing with my tail stock.
 

Curly

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You can leave your tail stock alone by mounting a boring head in it. That will let you make fine adjustments until you get the taper you want. After you are done you can remove it and the adjustment is ready for next time while the tail stock remains zeroed. I think Skiprat posted a picture of one he uses.
 

KBs Pensnmore

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Taper Turning Attachment

Because I make a lot of my own tools etc. I made a taper turning attachment,that is on my 7X12, that was in the English magazine "Model Engineers Workshop". I don't know if you guys get it over there, if you don't and would like a copy send me a PM and I'll photocopy it and snail mail it to you. I'm IT illiterate, so can't submit it here, sorry.
Kryn
 

Curly

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That would be this one right? A digital subscription allows access to back issues to read. The printed ones are in the magazine rack at the local Chapters book store. Hard to find and always 2 or 3 issues behind the current one. I pick them up now and then.

Almost forgot to ask if you have picture of the taper attachment that you could post Kryn?
 
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Sawdust1825

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Sylvanite explains it well. Turning between centers is the best way to get a taper if that is what is desired. I am reading between the lines this is a metal lathe. So you could turn a taper in theory using the compound turned at an angle but this is going to be limited to the travel range of the compound. Any offsetting in the 4 jaw chuck will not get you a taper however you can make a crankshaft this way.
 

KBs Pensnmore

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That would be this one right? A digital subscription allows access to back issues to read. The printed ones are in the magazine rack at the local Chapters book store. Hard to find and always 2 or 3 issues behind the current one. I pick them up now and then.

Almost forgot to ask if you have picture of the taper attachment that you could post Kryn?

Hi Curly, the correct magazine, it is in issue no. 178 pgs. 28-31 and no. 179 pgs52-55. We have the same problem here, 3 issues behind, unless you have a subscription. I get it regularly from the shop, as it has a lot of interesting tools and tips. My latest edition has a tap sharpener that I'm going to make for doing the taps but also router and forstener bits. They used a Dremel like tool for power, I plan on using a sewing machine motor. I like tools that can be switched on and used, not spent 10 -15 mins setting up and then using.
Kryn
 
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skiprat

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You can leave your tail stock alone by mounting a boring head in it. That will let you make fine adjustments until you get the taper you want. After you are done you can remove it and the adjustment is ready for next time while the tail stock remains zeroed. I think Skiprat posted a picture of one he uses.

Although I didn't use it for actual turning, this thread shows several pics where I use a boring head instead of offsetting the tailstock.

The headstock will need a drive centre...or some other method of allowing the connection between the drive end and the blank to be flexible.
I simply use my little flexible hose thingy.

For tapering non metal pen blanks, I'd just use a rounded over rod as the drive. The same as I use in the boring head.
A normal pointed centre isn't ideal for tapering. :wink:

Of course, I'd use the compound first if possible...You only need to mess about with long tapers. In fact, unless you need a perfect finished very long taper on hard metal, you can do any length taper with the top slide ( compound slide )
 
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JPMcConnel

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Mr. Pete (tubalcain) on YouTube has a rather nice discussion on the Compound Rest Method for turning tapers:TURNING A TAPER ON THE LOGAN LATHE tubalcain. He alludes to the tail stock method, as well as the taper attachment, but says the compound rest method is the easiest. I use this method for cutting all the tapers on my kitless pens and I find it works quite well. The length of the taper is limited to the travel of your compound. Sharp tools are very important for smooth cuts.
 

Sylvanite

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Actually, the length of the taper is only limited by your imagination and the length of the lathe bed. :biggrin:

Hmmm, according to my imagination, provided the stock diameter (or at least the narrow end of the taper) is small enough to pass through the headstock opening, the taper isn't limited to the length of the bed. Alternatively, my imagination also claims that one could remove the tailstock, support the work with a steady-rest, and turn turn a taper longer than the bed. :biggrin:
 

wm460

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Because I make a lot of my own tools etc. I made a taper turning attachment,that is on my 7X12, that was in the English magazine "Model Engineers Workshop". I don't know if you guys get it over there, if you don't and would like a copy send me a PM and I'll photocopy it and snail mail it to you. I'm IT illiterate, so can't submit it here, sorry.
Kryn

G'Day Kryn,

Any chance of getting a copy af this?
 

KBs Pensnmore

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That would be this one right? A digital subscription allows access to back issues to read. The printed ones are in the magazine rack at the local Chapters book store. Hard to find and always 2 or 3 issues behind the current one. I pick them up now and then.

Almost forgot to ask if you have picture of the taper attachment that you could post Kryn?

Hi Curly, here's the photo. If you want the article on it send me a PM with your address so that I can snail mail it to you.
 

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jttheclockman

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I tried to follow this thread but i am at a loss. When someone says taper that means one end is thinner than another. Why can't you just do it between centers and turn it down normally. If you are looking to do a taper on a flat edge My Jig will get you there using a router in conjunction with your lathe. Sure wish there was a photo or two as to what you are talking about.
 

Curly

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Hi Curly, here's the photo. If you want the article on it send me a PM with your address so that I can snail mail it to you.

Thanks for the generous offer but I found out a couple weeks ago that Grizzly makes one specifically to fit the model of my lathe. When the dollar comes up a little closer to the US I'll scoot down and buy it.
 

Curly

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Why can't you just do it between centers and turn it down normally.

With a metal lathe, doing as you question would mean turning both the bed and cross slide handles together to move the cutter in as the carriage went from one end to the other. Impossible to get it right unless you are the best tummy rubber, head patter in the country. That's why taper attachments, tailstock offsets, or the compound slide, are used on metal lathes.
 

lorbay

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I tried to follow this thread but i am at a loss. When someone says taper that means one end is thinner than another. Why can't you just do it between centers and turn it down normally. If you are looking to do a taper on a flat edge My Jig will get you there using a router in conjunction with your lathe. Sure wish there was a photo or two as to what you are talking about.

John let's say you were cutting a M T taper you would not have enough travel on the compound slide (well not on mine )plus you would not be able to use the auto feed,thus the reason for the jig.
Lin
 

jttheclockman

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I tried to follow this thread but i am at a loss. When someone says taper that means one end is thinner than another. Why can't you just do it between centers and turn it down normally. If you are looking to do a taper on a flat edge My Jig will get you there using a router in conjunction with your lathe. Sure wish there was a photo or two as to what you are talking about.

John let's say you were cutting a M T taper you would not have enough travel on the compound slide (well not on mine )plus you would not be able to use the auto feed,thus the reason for the jig.
Lin


Ok I have to now kick myself in the butt. I did not read that this was a metal lathe question.:frown::doctor: I need to find my meds. Carry on. I am out of this conversation. I do not own a metal lathe. Maybe something in the long future but too many things to do on a wood lathe for me. I have to go lay down now.
 

Alchymist

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Just a quick comment - you can not chuck a work piece in a 4 jaw chuck and use a center in the tail stock , (either live or dead) to hold the work AT THE CENTER LINE. The spot selected for the tail stock center must still line up with the center of the lathe at the head stock end.

In other words, you can offset the work, but the work itself must remain aligned with the center line of the lathe, which means the spot for the tail stock center must also be offset in the same amount and direction as the end in the chuck.
 
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farmer

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Taper

I have 3 modified taig based lathes I mounted one of them on my CNC
and use the CNC to cut all of my tapers.:biggrin:
 
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