Boring Head Conversions > Ball Turning + Taper Turning
A while back I got a 2" boring head with MT3 tapered arbor for the
mill-drill.
I decided that to justify my outlay on it, I should increase its usefulness
in other areas of my workshop & get my full money's worth out of it.
I made a few extra bits for it, now it's used to do my ball turning &
offset taper turning (without the hassle of having to reset the tailstock each
time).
The bearing came out of a VCR, the rods & spring from an old printer, an
old lawnmower piston & $2 of scrap from the salvage yard. Other than the
original purchase of the boring head, it has cost a total of $2, plus a couple of
days thinking about it, then a couple of days worth of work.
The adapter fitting for my boring head is 1-1/2"x18tpi SAE, I chose to
make the arbors with 3/8"UNF on one end - this makes them dual purpose - I
can use them with my boring head adapter, or with a normal drill chuck, as found
on many electric drills.
Of course, you do keep parts like chucks when you
dispose of your old dead drills, don't you.
All external threads are cut
on the lathe, the 3/8"UNF internal threads are simply tapped.
I chose to use a lawnmower motor piston as the mounting for the ball turning
tool, as I'm finding it hard to get solid aluminium scrap of about this
size. Whereas, during a verge rubbish collection, old, dead lawnmowers are
everywhere. The piston was machined down enough that the reinforcing for
the gudgeon pin holes could put it's load straight onto the base plate/packing
on the toolpost, not just the pistons skirt.
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(Top L): Original MT3 arbor, boring head, 10mm boring tool, 10mm to 1/2"
adapter sleeve, (Top R) straight arbor (3/8"UNF on one end) passing
through a machined down lawnmower piston, packing for lathe toolpost, bar
with indexable tip mounted on it (ball-turning), 1/2" bar with slot
milled out to hold HSS tool-bit (for gashing of gears, flutes etc), Tommy-bar. |
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More Homemade Bits:
(Top L) MT2 to 3/8"UNF arbor, Live centre on 1/2" straight
arbor, 3/8"UNF to 1-1/2"x18tpi SAE adapter for boring head,
level setting tool for when boring head is installed in tailstock,
3/8"W drawbar for headstock or tailstock.
All arbors & adapters have either a notch or a hole in them for my
home made pin-spanners. All external threads were cut on the lathe.
My home made live-centre on 1/2" the straight arbor is to suit my boring
head.
The height setting tool is made with a 1/2" button at lathe centre
height |
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My set of homemade pin-spanners - made by drilling, grinding &
filing to shape, then crimping in an old piece of broken drill as the pin.
The two on the left are for adjusting the lathe leadscrew & also fit the
arbors I made. The middle one adjusts the lathe mandrel
bearings. The two on the right adjust the mill-drill's quill
bearings & the collar/adapter on the boring head. |
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The 'over the top' ball turning tool, mounted on the toolpost, being
an old piston is obvious here. The arbor uses spring tension to
force the head back against the piston (as does the cutting force).
The handle position can be moved or rotated by unscrewing the handle - you
can just see the hole in the handle for the Tommy-bar. The only
reason the collar has it's hole offset is that I thought, 'That will look
different'.
You can also just see the triangular indexable tool tip mounted on the
cutting bar. |
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Long Taper Turning Set-up.
Setting the Boring head to horizontal (parallel with the cross-axis of
the bed). The boring head is set fully over & the button is
inserted in the tool hole. I make sure the base of the setting tool
is in contact with the bed while tightening the draw-bar.
Once set horizontal, the setting tool is removed, the live centre is
installed & the offset of the head positioned correctly for the taper
I want to machine. See 'Making an MT
taper drill arbor' for more notes on making Morse & Jacobs'
tapers.
Note: Remember that by using this taper turning method, you are
extending the unsupported length & may have to take lighter
cuts - a small price to pay for the convenience. |
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Photo showing an exaggerated offset of the boring head. This
demonstrates how it comes together, to machine long tapers. |
A WARNING - REMEMBER: Tighten the dovetail slide of the boring
head tight, then double-check the offset before machining either a ball or a
taper - there will be a small amount of end-play in its mechanism. You
must also accept that, due to the increased overhang from the tailstock, this
set-up is less rigid than simply offsetting the tailstock & hence, may be
more prone to chatter.
The above is probably enough to show how I did it, and probably
sufficient that anyone wishing to do so, can adapt my method, to making their own
version. If you need more information about any of my projects,
just email me.
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