Reversing vertical slide for drilling

This topic has 9 replies, 6 voices, and was last updated 24 November 2016 at 14:26 by Ady1.

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24 November 2016 at 08:47 #8407
PaulR
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@paulr
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24 November 2016 at 08:47 #268179
PaulR
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@paulr
Thinking about my lack of a milling machine and crappy drill press, it occurred to me in the middle of the night (as such things do) that I could fit the vertical slide on my lathe so it faces the tail-stock and thereby do some light 'co-ordinate' drilling. I'm talking about holes sub 3/16" and would have to take care of backlash.

I can't seem mention of this anywhere so is there something obvious I've missed as to why this isn't even remotely sensible?

TIA

Paul
24 November 2016 at 08:53 #268182
Michael Gilligan
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@michaelgilligan61133
Paul,

Geometrically, it should be fine … but do you have a [rotating] drill for the tailstock ?

MichaelG.
24 November 2016 at 08:59 #268184
Thor 🇳🇴
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@thor
I put a drill chuck in the lathe mandrel and the work in a small vice on the vertical slide before I got a milling machine. It is easier to do the drilling in a ertical milling machine though.
For drilling holes in round stock I made a crotch centre, something like this.

Thor
24 November 2016 at 09:14 #268188
PaulR
Participant
@paulr
I was thinking of hooking up a flexible shaft. Now why it didn't occur to me to just stick the MT chuck in the mandrel I do not know – that's what happens in the middle of the night I suppose (well that and never having used anything but regular 3 and 4 jaw chucks at that end)!
24 November 2016 at 09:36 #268191
IanT
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@iant
Drilling from the headstock is the norm Paul but there are times when a 'powered' tailstock drill can be useful. One is to contra-rotate the drill (versus the work being revolved in the chuck) which is sometimes used to drill very small holes accurately.

The 'powered' drill can take a number of forms – Geometer used a spindle running through the tailstock barrel powered by an electric drill from the rear for instance. If there is an overhead (belt drive) drive available, then an arrangement with a drill chuck/pulley combination mounted in the tailstock (via a morse taper fitted with bearings) can be used.

For the co-ordinate drilling you are considering, an 'overhead' drill combined with a lever feed at the back of the tail-stock would have the advantage of being able to 'peck' small holes which would be a lot more sensitive than racking the saddle to and fro, which is required when using a drill chuck in the headstock. So the idea does have some merit. However, for most occasional needs, a morse taper drill chuck in the headstock will do the job…

Regards,

IanT
24 November 2016 at 09:49 #268194
Ady1
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@ady1
I do nearly all my drilling in the lathe on the vertical slide but it's not easy to be really accurate because everything needs to be set up each time you fit it on the cross slide

The biggest advantage for me is when doing any holes from 8mm to 12mm or bigger it can use the backgear and is very stable

If I had a decent milling machine I would probably prefer using it but with practice you can use a lathe

I also use my lathe for milling, again it takes time and practice to iron out the weaknesses but a decent lathe with backgear can mill all day long once you develop an acceptable system

Edited By Ady1 on 24/11/2016 09:52:19
24 November 2016 at 11:44 #268202
PaulR
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@paulr
Thanks all for the advice and suggestions – most welcome. I'll be doing some experiments this weekend 😀

As an aside, I did my first bit of test milling in the lathe last night and was pleasantly surprised how good it was. Yes it took a while to get the slide set up (laterally <.001" was good enough for me) and the work likewise, but the result was pretty smooth and more accurate than I'd hoped for, 5 thou cuts being the order of the day using an 8mm tool. I need to get some of those faceplate type clamps to maybe make things a bit less crowded!
24 November 2016 at 12:10 #268205
John Haine
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@johnhaine32865
Though on a lathe you may want to take lighter cuts as the setup is not so rigid, beware of taking very light cuts as the cutter doesn't like it and will wear quickly if it rubs rather than cuts. 5 thou, just over 0.1mm, sounds very light to me. IIRC when I milled on the lathe I was taking at least 0.5 mm, though taking it slowly. Also don't be tempted to run the cutter too slow, that actually increases the tooth load and wears the cutter quicker.
24 November 2016 at 14:26 #268222
Ady1
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@ady1
Just thought I would say

On a hobby lathe a 6mm cutter will cut a 12mm slot twice as fast as a 12mm cutter

Bigger is not always better
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