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Taper turning

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Peter Hall13/04/2015 11:35:14
110 forum posts
1 photos

I am making some tooling for my Sherline lathe and need to turn a #0 Jacobs taper to fit a small drill chuck. I have no reference taper to hand (but I do have the dimensions from the ME Handbook). Sparey gives some hints and tips, but basically can only suggest creeping up on it. Does anyone here have any suggestions on setting up my topslide to do the work? Are there any rules of thumb to follow? I will be doing the work on my Myford Speed 10 and have successfully turned the smallest morse tapers with reference tapers and a dial gauge to set up.

Thanks in anticipation.


Brian Rice 113/04/2015 11:43:21
82 forum posts
11 photos

To be honest unless you really want to turn a m0 taper just buy a blank end M 0 taper,only a few pound.

Bowber13/04/2015 11:47:15
169 forum posts
24 photos

I've turned one and did struggle to get just the right taper, it doesn't take much for it to be wrong, also the finish needs to be very good so as Brian suggests you may be better buying a blank.


Peter Hall13/04/2015 12:13:58
110 forum posts
1 photos

Buying one would be good, but it's #0 Jacobs taper to#0 Morse taper and I don't know where to find one. I've looked on Jacobs's website and even they don't do one. If I buy a blank Morse taper, I still have to turn the Jacobs taper wink


Neil Wyatt13/04/2015 12:21:37
18232 forum posts
714 photos
77 articles

I need to turn an MT0 reamed, so I ordered an Mt0 - MT1 adaptor to use to test it in (before fluting it) you could do the same just get a get cheap chuck to test it in.


Les Jones 113/04/2015 12:23:01
2162 forum posts
149 photos

Hi Pete,
If you have a finger type DTI then you could try this method. Mount the chuck that you want to make the taper for in you lathe chuck with the taper out. Make sure the taper in the chuck is running true. Set the top slide to be about the correct angle. Wind the cross slide to position the DTI finger on the back of the taper. Now wind the top slide in and out to follow the taper. Use the way the reading changes to adjust the top slide angle in the correct direction. Repeat this until the DTI does not change its reading as the top slide moves the finger along the taper. When I did this I mounted a piece of angle on the cross slide with a screw at each end to push on the top slide so that fine adjustments could be made. I think I have some pictures of the setup somewhere. Let me know if you would like to see them.


Peter Hall13/04/2015 12:36:02
110 forum posts
1 photos

Thanks Les, but the taper is inside the chuck and my dial indicator won't fit in the .25" hole. Turning morse tapers is not a problem as I have existing tapers to reference against. It's the jacobs taper to fit inside the hole in the back of the chuck I'm struggling with. I'm not afraid of having a go, I just wondered if there might be any shortcuts or standard procedures to follow while doing so.


Peter Hall13/04/2015 12:43:48
110 forum posts
1 photos
Posted by Les Jones 1 on 13/04/2015 12:23:01:

... I mounted a piece of angle on the cross slide with a screw at each end to push on the top slide so that fine adjustments could be made.

Thanks for that. I'll be using that idea in future.


Jon Gibbs13/04/2015 12:57:17
739 forum posts

Harold Hall has some good tips on setting up the cross-slide for internal tapers but for a socket you will almost always get a bitter finish with a taper-reamer to finish. **LINK**

Tracy tools have an MT0 reamer for £15.



Edited By Jon Gibbs on 13/04/2015 12:57:49

Peter Hall13/04/2015 12:58:30
110 forum posts
1 photos

John, that's excellent, thank you. Looks like I have an identical chuck to yours.


Bazyle13/04/2015 13:34:12
5467 forum posts
206 photos

Even if you have a sine bar and rigs to allow it to be used to set the topslide angle, tolerances on the side of the topslide and the between centres bar you use would still mean you weren't spot on. So you would still need to do a bit of trial and error. Les's suggestion is great for that .

Worth bearing in mind that any slackness in the topslide gib and other slide locking will thow it out and even cutting forward or back on the topslide may make a difference.

I assume you don't need ideas for the initial coarse setting.

Les Jones 113/04/2015 14:26:08
2162 forum posts
149 photos

Hi Peter,
I did not realise a #0 Jacobs taper was so small. When I did mine I used a variation of what I suggested as the taper on the chuck was pitted due to rust which caused the DTI to jump around.. What I did was to turn a piece of wood to a diameter of about half way down the taper. I then milled a groove down one side of the wooden dowel I had made so that I could use it to press a piece rod against the taper. Having the pressure applied half way down the taper ensured that the rod was in full contact with the taper. As the rod might flex with the pressure of a DTI I used an electrical contact probe (Just an piece of rod insulated from the toolpost and a battery LED and resistor.) in conjunction with the DRO on the cross slide to take measurements.

This is the setup I used.

img_1066 (small).jpg

This is the wooden plug.
img_1067 (custom).jpg

This is the fine angle adjustment jig.
Topslide fine adjustment

If you do use this method you need to ensure the rod is horizontal. (Support the far end.)


Michael Gilligan13/04/2015 14:36:54
16365 forum posts
714 photos

Useful video showing variations on the MT0 theme.


Capstan Speaking13/04/2015 15:17:47
177 forum posts
14 photos

The technique found by Jon Gibbs is the correct way to accurately produce a known short taper. You run the compound slide along the hypotenuse and check the rise at the end.

However you do not need a setting bar between centres and in fact this can introduce errors. In a good chuck or soft jaws a long cutter, silver steel or dowel pin will do.

Also you can reverse the process and eliminate any need for a parallel.
Put the clock in the chuck and a button or small bearing in the toolpost. Then rock the saddle so the clock finds the peak whilst at the bottom and top of the hypotenuse. The difference must agree with the calculated rise.

It was an apprentice piece for me to make mating tapers that "locked" like a morse taper. A taper fit with less than 5 degrees included will lock if the finish is good. Our test piece had to carry two kilos by fit alone

A toolmaker's lathe with a vernier taper turning attachment was nice too.

MadMike13/04/2015 15:53:02
209 forum posts
4 photos

0JT and MT1 are about £3.80 from Arceuro Trade. Link on this very homepage. HTH.

duncan webster13/04/2015 19:20:20
2795 forum posts
41 photos

ring up Mr Arrand, who makes loads of taper tooling, he will probably make you one. Won't be cheap, but will be top class. 01664 454566

Peter Hall14/04/2015 09:32:26
110 forum posts
1 photos

Thank you all for your helpful suggestions. It's always good to have a choice of alternatives and I'm pretty well sorted now.


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