Taper Turning – Boring Head

This topic has 16 replies, 9 voices, and was last updated 16 February 2017 at 10:42 by JasonB.

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15 February 2017 at 18:46 #18412
Nick_G
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@nick_g
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15 February 2017 at 18:46 #284489
Nick_G
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@nick_g
.

Been wanting to try for a while now some taper turning by using a boring head in the lathe tailstock. I know one can offset the tailstock but I find it a tiresome exercise puting it back again spot on.

You can buy these ready made. But the supplier only had them in stock for a 12mm shank and not the 1/2" shank my Vertex boring head has.

First thing was I had to buy an MT3 adapter to fit my lathe tailastock as my mill fitting is BT30. It was just a matter of screwing the boring head off that and fitting it onto the MT3 one.

I purchased a small live centre that had a M14x1 thread in it. I imagine a straight shanked dead centre would also be fine.

Turned a 1/2" section that would be a nice snug fit in the boring head.

Reversed it in the chuck, turned to 14mm dia, trimmed to length and cut a recess for the threading tool.

Correct gear settings on my lathe for a 1mm pitch is B C F

Scratch cut to make sure.

And a firm to turn onto (so ever so slightly tight) thread.

Boom.!

Slotted a flat in the 1/2" shank for the boring heads grub screw to rest onto.

Time to try it out.

The taper length on a scrap bit of steel is 5 1/2" with a diff in dia of 125 thou for a quick test. Obviously for short tapers one would be better off using the top slide at and angle.

I have no idea what sort of angles and depth of cuts can be taken before one starts kicking the hell out of the boring head. Perhaps others that have done this can advise.

Cheers, Nick

Edited By Nick_G on 15/02/2017 18:49:31
15 February 2017 at 20:00 #284503
JasonB
Moderator
@jasonb
I've taken to using the same method on the last couple of engines that I have done, as you say it saves having to upset the tailstock position and makes it easy to dial in a bit more or bit less taper if needed.

I used my old Unimat live ctr with a simple bush to up it to 1/2"

Did not kick hell out of the jobs so will leave that for others to comment

PS that paper is only there to make the photo clearer, I have not contracted lathe cleanliness OCD
15 February 2017 at 20:59 #284520
peak4
Participant
@peak4
I made my last batch of MT2 blanks that way, but used a re-ground broken carbide centre drill as the movable centre; a press fit into a length of 1/2" bar to suit my boring head. It worked fine, and being carbide, didn't suffer any noticeable wear.

I do have a brand new rotating centre, on a 2MT shaft, which is a tad undersize, so won't lock into a 2MT socket.

I've been looking for a use for it since it arrived as an extra bit with my Warco copy Super 7 lookalike.

All the Best

Bill
15 February 2017 at 21:40 #284533
Michael Gilligan
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@michaelgilligan61133
From the ArmChair:

Nick,

If you are planning to use any big angular offsets;

consider the advantages of ball-ended centres.

MichaelG.
15 February 2017 at 21:57 #284534
Nick_G
Participant
@nick_g
Posted by JasonB on 15/02/2017 20:00:43:

PS that paper is only there to make the photo clearer, I have not contracted lathe cleanliness OCD

.

OMG …….. Alan.!!! …………. Is that you incognito.????

Nick
15 February 2017 at 21:58 #284535
Nick_G
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@nick_g
Posted by Michael Gilligan on 15/02/2017 21:40:50:

consider the advantages of ball-ended centres.

MichaelG.

.

Cheers Michael. I will look them up.

Nick
15 February 2017 at 22:46 #284541
Michael Gilligan
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@michaelgilligan61133
Maybe something like these:

**LINK**

MichaelG.
16 February 2017 at 02:23 #284546
“Bill Hancox”
Participant
@billhancox
Posted by Michael Gilligan on 15/02/2017 22:46:40:

Maybe something like these:

**LINK**

Or a radius center drill similar to this **LINK**
16 February 2017 at 09:11 #284568
BW
Participant
@bw
I've seen them called bell drills on some forums.

http://www.centerdrills.com/standard-products/centerdrills/centerdrill-r-type-radial
16 February 2017 at 09:15 #284570
Lambton
Participant
@lambton
Rather than use a ball ended centre it would be easier to use a bell mouth centre drill to produce the centre in the end of the job, then a standard pointed live centre can be used.

They are available from ARC at less than £3 each.
16 February 2017 at 09:18 #284572
JasonB
Moderator
@jasonb
Or save your money and pop an old ball bearing into a standard ctr drilled hole and use a bit of 1/2" rod in the boring head that also has a standard ctr drilled hole in the end.
16 February 2017 at 10:13 #284578
Danny M2Z
Participant
@dannym2z
Posted by JasonB on 16/02/2017 09:18:55:

Or save your money and pop an old ball bearing into a standard ctr drilled hole and use a bit of 1/2" rod in the boring head that also has a standard ctr drilled hole in the end.

+++ 100

* Danny M *
16 February 2017 at 10:21 #284580
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Michael Gilligan on 15/02/2017 21:40:50:

From the ArmChair:

Nick,

If you are planning to use any big angular offsets;

consider the advantages of ball-ended centres.

.

[and once you have understood the idea … use whatever implementation you find convenient]

…. Sorry, it appears I should have made that ^^^ clear …

MichaelG.
16 February 2017 at 10:30 #284582
Michael Gilligan
Participant
@michaelgilligan61133
Posted by JasonB on 16/02/2017 09:18:55:

Or save your money and pop an old ball bearing into a standard ctr drilled hole and use a bit of 1/2" rod in the boring head that also has a standard ctr drilled hole in the end.

.

… Not forgetting that [for the aforementioned big angular offsets] you will need something similar at the headstock end.

MichaelG.
16 February 2017 at 10:32 #284583
Russell Eberhardt
Participant
@russelleberhardt48058
I've used the same technique but with the rod being tapered being held in the chuck to give a nicely formed curve to some con-rods for a vintage sports car.

Russell.
16 February 2017 at 10:42 #284585
JasonB
Moderator
@jasonb
Yes done that myself for both rods and columns
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