tailstock tapping jig

[pgk pgkParticipant @pgkpgk17461]

..with torque control?

[pgk pgkParticipant @pgkpgk17461]

I've been using a hand tap and one of those sprung pointers in the tailstock chuck to help alignment. But yesterday I went slightly off track for the first time and ruined my part.

I'm guessing someone has already built something simple.. say a cheap chuck with a fitted rod that goes into a sprung tube that gets held either MT or in the tailstock chuck. What i also wondered was whether one of those cheapo electric drills with a torque adjuster could be butchered for parts.. which rather depends whether that torque system is part of the drill body or seperate (befoe i destroy a drill to find out)

[Anonymous]

Sounds a bit over-complicated? I normally put the tap in the standard tailstock chuck, done up by hand rather than using the key. I then turn the spindle chuck by hand for a couple of turns, or until the tap has cut enough to be stable. I then remove the tap, and work, and finish off by hand in the bench vice.

Andrew

[JasonBModerator @jasonb]

Same as Andrew but don't clamp the tailstock to the bed, once the tap is started undo chuck and slide the tailstock out the way so you can use a tap wrench.

For very small taps I have a bit of 1/4" dia round steel, 60deg point on one end, ctr drilled hole in the other. pop that in the tailstock chuck and use to guide the tap depending if it has a ctr hole or male centre while the wrench is clamped to the shank

[Danny M2ZParticipant @dannym2z]

Try mounting the tap in a pin-vice (eg; Eclipse) and fitting it loosely enough to just slide in the tailstock chuck and turn the spindle like Michael said.

* Danny M *

[JasonBModerator @jasonb]

You can also make a simple bush with a cross drilled hole for a grubscrew that fits your tailstock die holder and the tap goes in the bush

[VicParticipant @vic]

Posted by pgk pgk on 08/02/2016 13:46:32:

I've been using a hand tap and one of those sprung pointers in the tailstock chuck to help alignment.

That's the way I do it and never had a problem although I do start the process with the tap in the chuck first to start it off.

[Simon Williams 3Participant @simonwilliams3]

The H&S Police will love me for this, but it is a trick I was taught by a production machinist a long long time ago…

Take a suitable sized Jacobs chuck on a morse taper, and cut the tang off the back of the taper. Now clamp the tap as tight as you like in the chuck and pop it in the tailstock, leaving the taper just not quite home. Move the tailstock up to the work. With the lathe running , grap the tailstock chuck firmly and offer the end of the tap up to the rotating work. The lead of the tap will grab the hole, and bob's your uncle. If the tap binds or hits the bottom of the hole let the drive torque take the chuck out of your grip, and let it spin with the work.

The loose taper of the tailstock will guide the tap.to start straight with the axis of the rotating work, and anyway you can't tap it crooked if the work is rotating. Yes you can break the tap, and if you try really hard you can can your hand caught, but as a quick down and dirty fix it works for me.

I'm tempted to say "don't try this at home", but that rather spoils point of the story. I do ALWAYS take the tool out of the tool post (QCTP of course) so you haven't got a sharp pointy thing just in line with your thumb.

Best rgds Simon

[Enough!Participant @enough]

One of these will do the same thing without the risk associated with the MT grabbing. Easy enough to make yourself from an existing tap wrench and can be used in the mill too.

[Marcus BowmanParticipant @marcusbowman28936]

Buy a ready-made 2MT or 3MT taper with a large diameter blank end. Drill it right through along its axis, with a decent hole (maybe 10mm diameter). Get a good Jacobs chuck and turn an arbor to a sliding fit in the hole, and with a taper on the front to suit the chuck. Now you have a sliding, guided, version of Simon's method. Hand-hold tightly as you feed the tap into the work, then you can continue that way, forward and reverse in stages, or leave the lathe chuck stationary and turn the tailstock-mounted chuck by hand. Works a treat. Wouldn't be without mine. There's a photo in a recent ME. Photos also on page 59 of the Crowwood Screwcutting book. I can post a photo if you need one.

There is also a popular ready-made item which consists of a small chuck and body on a sliding bar which can be gripped in a chuck in a tailstock or drilling machine. Unfortunately, the range of grippable sizes is small, and the body is smaller than the body of a Jacobs chuck, so its not as easy to grip or turn.

Hemingway also sell a nice kit for a floating reamer holder and that can be adapted for taps. I made one and although it is a substantial item it does what it claims, and copes with minor axial misalignment, preserving the tap.

Marcus

[egaParticipant @ega]

pgk pgk:

Did you look at the earlier thread on tapping chucks?

If you are going to spend money then the Vertex is recommended – see my photo in that thread.

[Neil WyattModerator @neilwyatt]

The clutches in drills a wonderfully simple. A sprung plate against a series of ball bearings that ride up wedges. The greater the spring load, the more force the ball bearings need applied before they can rise up the wedge and click into the next depression.

They are separate. I split gearbox and clutch to fit the gearbox alone into a steel housing for my toolpost drill.

Neil

[Dennis DParticipant @dennisd]

You could make some tap holders **LINK**

They can be used on the mill as well to help get the thread square to the part by holding the shaft in the drill chuck and rotating by hand.

 

Edited By Den24171 on 08/02/2016 17:45:58

[pgk pgkParticipant @pgkpgk17461]

Thanks for the useful ideas. Obviously torque control if thinking to use power tapping and use on mill too.

The hole that went off-centre on me was an m3 tapping into remounted 4mm rod (conceivably the pilot hole had bulged it??).. may not have been concentrically drilled but eyeballed ok.

[Howard LewisParticipant @howardlewis46836]

I have a Tailstock die holder, so made a tap holder, to use ER collets, to slide on the same arbor. Like the Die Holder, a stud is screwed into the body, to rest against the fourway toolpost, as an anti rotation device.

The slight clearance between Holder and Arbor allows a bit of float to allow alignment.

The grip of the ER collet, even when tightened hard, will still allow the tap to slip if it jams, or bottoms in the hole.

Tempting fate, so far have had no broken taps, even with 3/16 x 40, which was the reason for making it. 40tpi taps will not pull a Tailstock along a lathe bed, (certainly not mine) preferring to strip the thread.

Howard

[Michael HornerParticipant @michaelhorner54327]

I made an adapter to fit an existing tap wrench.

I put the lathe into neutral and turn the chuck by hand whilst pushing the tapping chuck into the work piece.

Once the tap is running true I slide the tailstock out of the way and remove the assembly from the chuck and put it into a keyless drill chuck and finish off. The bar I am tapping is usually around 12mm.

Cheers Michael.

[Author]

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