Machining a soft-ended MT2

Although a beginner, I plan to make a fairly complex boring head. I have an MT2 bar with a soft workable cylindrical end that I need to cut a tread in.

Question: How do I support the tapered end while I cut a thread on the soft end? Obviously, ramming it into a 3 or 4 jaw chuck would damage the taper.

Any suggestions?

Regards,

Gareth.

Assuming your lathe has an mt2 spindle taper, the usual approach is to put the mt2 blank in that with a drawbar to hold it in. Another way is to buy an mt2 female to parallel adapter (rdg have these I think?), hold the blank in that again with a drawbar, and hold the adapter in the 4 jaw to get it dead on centre. This is assuming that the blank has a threaded hole in the small end for a drawbar? If not, and it has a tang, then it isn't really suitable for a boring head which will need to be positively held in the spindle of whatever machine you are using it in.

Hi Gareth,
If you remove the chuck from your lathe you will probably find that it has a MT2 or MT3 taper. Put the MT2 blank into this (With an adapter if required. ) an use a draw bar to prevent it from coming loose.

Les.

I have done this several times now. using the taper in teh lathe mandrel gives the best possible result.

If your lathe is like mine with an MT3 taper, invest in an MT3-2 adaptor. Use a drawbar (even if it is improvised from studding) as otherwise it WILL slip while you are threading it (don't ask how I know this).

Neil

All your replies have been extremely helpful. I'll go for the MT2 to parallel adapter (rdg do indeed sell them) tho at over £17 they're not cheap. On the other hand every time I remove and replace a chuck, tightening up the bolts *just right* for minimal runout error is a pain.

Thanks guys.

Gareth.

Gareth,

I've just bought a 3 - 2 morse taper for my lathe to machine a similar item its open ended so that I can use a draw bar to hold it, I bought it from Arceuro and found it to be very cheap but of high quality.

Martin P

Why is using studding for a drawbar "improvising"?

> Why is using studding for a drawbar "improvising"?

Because a proper drawbar should be made from a blank finished on a centreless grinder, turned between centres, have milled threads, and polished to perfection, before being matched to its hand-scraped nut and washer.

Seriously? Because I have found that cheap studding doesn't like being done up (reasonably tight) and loosened again and the threads go bad and strip. The stainless stuff is OK.

Neil

I made a "improvised" draw bar about ten years ago with normal studding and it is still giving good service, no thread damage showing. I tighten it up to pull the cutter head only to grip and no more with no problems.

Martin P

I remember a drawbar design in mew a few years ago recommending high tensile steel! If you tightened that up to anywhere near the steel yield strength you'd never get the taper out again! I've never had a problem with studding stripping used for draw bars or tee bolts, though I tend to get the stainless stuff now as it's better finished.o

You should ask for High tensile Studding, it is available from stockists. You should have no trouble with the threads stripping with it.

Clive

I used the stainless stuff for my grinder leadscrews and its been fine.The cheaper stuff I have used for bearing pullers and random clamps and, like bonsai trees, it doesn't flourish under my care.

neil

Dwarf studding ???

My understanding is that the grip is from the fit of the morse taper parts and the drawbar is only there to pull the tapers together and as an insurance against shock loads. As such the draw bar should not be over tightened? The draw bars I have are either home made ( MS) or from studding. They seem OK but am I running a risk here?

Neil I'm still curious about your avatar - what the heck is it? Please put me out of my misery!

Norman

"Stub's" avator looks like a rocket assisted elephant - could this be his latest project

Apart from one draw bar that came with the 2" face mill, my other ones have been made by cutting the heads off two old bolts, and welding them together. Ian S C

I've used studding as a drawbar on my old Super 7 for many years with no problems at all. It is not under stress and if it does wear, then I'll just cut another piece.

I also turned two nuts down to the spindle bore diameter and Loctite'd them on to the drawbar spaced apart 50mm or so. They stop it bouncing around and make it easier to insert & screw on.

Another tip - I have converted all my Imperial MT2 tapers to Metric ones with a simple screw-in adaptor (a short bar with Imperial male & metric female threads). I only need one drawbar for everything then.

The main problem with MT2 accessories is getting them out afterwards if you tighten up too much! Where possible I make the rear diameter of the tool larger than the 'hole' in my between-centres driving plate (used without its driving pin fitted) so I can unscrew it and thereby extract any MT tapers being used.

In one instance, I drilled a hole through the MT fitting so that a bar could be pushed through, which then gives a face for the plate to push out on. The driving plate also protects the spindle threads from damage.

The photo shows an Arrand MT2 flycutter which needs to be fairly tight and which can be removed easily by this method. Before I started to do this, it was a right whatsit to remove.

If I was threading this MT2 taper, I would certainly mount the taper directly in the spindle to machine it but I guess the OP has an MT3 taper in the spindle and an MT2 in the tailstock? This is a bit inconvenient in my view but is simply solved by an MT3>2 adaptor.

Regards,

IanT