Hand tapping machine

[Oompa LumpaParticipant @oompalumpa34302]

I am not sure that is even the right name for this tool.

I have the most important bit which is the arm and the chuck bit, but that's where it all ends. I am making it up as I go along now, found a suitable chunk of steel for the base which fortuitously has a hole in it the right size for the piece of bar for the column which in turn fits the arm casting.

I have a piece of 3/4" ally plate I was going to make an adjustable table with and drill and tap a few holes to secure the small vice.

So, the questions are – can anyone see any obvious pitfalls? What height should the column be cut at? (Bit of a "How long is a piece of string" sort of question that one). Should I fabricate anything else for the device?

Finally, some pics of what I have so far:

graham.

[Oompa LumpaParticipant @oompalumpa34302]

[jason udallParticipant @jasonudall57142]

Apart from the “its never tall enough or deep enough in the throught”..you have to stop somewhere.

Who are you arranging infeed?.

On one of our regulars website (and books)..a screw thread of the same lead (of the tap) is used..so as to advance the tap at the correct rate..apparently much better…
Most pillar tools just let the rotating bit float..

[Oompa LumpaParticipant @oompalumpa34302]

I am just going to let the chuck float Jason. I am going to make the column just tall enough it slides to the back of the workbench under the shelving. I suppose I could easily double the throat depth by using the offcut of the bar I am using for the column and making a scissor arm that slides up and down the column and uses the offcut to mount the tapping head arm to. If you followed that?

"Who are you arranging infeed?."

can you just explain this part? Thank you.

graham.

[roy entwistleParticipant @royentwistle24699]

Graham Mine was a variation on George Thomas's staking tool I find it best if the vice is not bolted down

I found when using very small taps ie 12BA down to 16 BA they tended to break with the vice loose they don't

Roy

[NJHParticipant @njh]

Hi Graham

Here is my realisation of the tool – made many years ago at night school and very useful it has been too!

This was an early project from the George Thomas design & castings but I didn't go for all the bells and whistles that he also designed. If you are considering "extras" I do recommend his book – even if you never make any of the bits GT is a great read and an inspiration.

The Pillar tool gets used a lot but I'm a bit unsure of the utility of providing a "downfeed" ? However much of my tapping has been for small threads and fine pitches where "feel" is crucial to avoid breakages. What's more it's usually only a few holes that need to be tapped at a time – the next holes are quite likely to be a different size and thread.

Having just read the later posts I can confirm that I too leave the vice "floating"

 

Norman

 

Edited By NJH on 04/03/2014 20:05:17

[Oompa LumpaParticipant @oompalumpa34302]

Roy, very interesting advice regarding the vice. Much appreciated.

Norman, a "Downfeed" for me would be totally superfluous because, as yourself, it is unlikely I would tap more than half a dozen holes before changing the tap. For me, it is about getting the tap started at 90 degrees to the work and again, as you pointed out, getting a feel of the job with really small taps.

To be perfectly frank when tapping anything bigger than ten millimetres and sometimes eight I stick the Tap in one of my (Shock! Horror!) Cordless Drills and have at it freehand. Usually a simple painless result at speed.
Works for me.

graham.

[Ian PParticipant @ianp]

I do most of my tapping in the drilling machine under power, but with a few dodges.

First my Fobco is fitted with a VFD which I can set at speeds as low as 50 RPM

Second I have the speed knob and a fwd/off/rev switch located so I can reach them with my fingers whilst my hand is on downfeed wheel.

With small hand held down jobs its easy to feel the torque and if all is not well, let go of the job so it rotates with the tap.

For small taps I only loosely tighten(!) the chuck key (Jacobs type)

For large taps (M12 in tough steel) I do tighten the chuck, tap in stages (easy with the fwd/rev) and when the going gets tough remove from drilling machine and finish by hand, at least the tap is square by then.

I usually hand hold the work being tapped and let it float to centralise. larger jobs get clamped down after running the tap in reverse slowly to centralise the job.

M4 to M8 is plain sailing. By coincidence yesterday, I used a BA tap for the first time in years. It was the smallest one I had 12BA and I threaded some holes in 1.6mm brass sheet with no problem. I did the first hole really slowly to get a feel, found it easy but so slow at such a fine pitch it was boring. even at a respectable speed the progress of the tap through the job is slow enough to stop and reverse without stress.

Even before I had the VFD the drilling machine was a good manual aid to start a tap square.

Ian P

[jason udallParticipant @jasonudall57142]

Don’t get me wrong..the simple floating solution works and is the commonplace approach..clamp the work to present hole upright..and bobs yer mothers brother.
But I was wondering if you were going to use the “feedscrew” approach..helpme out here fellas..that was suggested by someone of more model experience than I…

The stated benefit was no lead was required on taps toget started thus bottom taps (or even spiral flute machine taps) could be used..yes you need to change the feed screw/nut but the improved performance was considered worthwhile.

Anyway..sure it will give much satisfaction as is

[jason udallParticipant @jasonudall57142]

I seem tp remember stan bray was the name.

Wps 14

[ChrisHParticipant @chrish]

Harold Hall does a hand tapping machine, it's in his Workshop Projects book in the workshop practice series.

From memory, it employs a guide feed that is threaded the same pitch as the tap being used.

When I get round tuit I will make one I think, they look like a good tool to have.

Chris

[jason udallParticipant @jasonudall57142]

Thats the chap!….
Couldn’t get my memory to give up the name….

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