Setting the top slide to turn a Morse taper

[John PurdyParticipant @johnpurdy78347]

Having the need to turn a couple of #2 Morse tapers, and having done a few in the past and remembering the tedious hit and miss system of setting the top slide angle by tapping it one way then the other,
I decided it was time to find a better way. I remember George Thomas had a design for an attachment to do this in the Taper Turning section of his book “The Model Engineers Workshop Manual”
Based on his general idea I have made my own version, full acknowledgment to George Thomas for the idea.

The “tee bar” was milled from a 4″ length of aluminum to a snug fit it the cross slide tee slot, the height being  just proud of the top of the cross slide by about .025″.

The two 1/2″ dia. posts for the adjustment screws have a 3/8″ length of 1/4-28 thread on one end, and are screwed tightly into the tee bar before drilling and tapping 10-32 for the two screws.

The two adjusting screws are 10-32 hex socket screws with the ends turned down to the thread root dia. and the ends rounded to give a consistent contact with the top slide base as they are rotated.

In use the unit is slid into the tee slot and the two 1\4-28 set screws just nipped up sufficiently to stop the bar from moving.

It only took about 3 hours to make and I haven’t turned the tapers yet, but have tried setting up the top slide to the correct angle, and it is definitely a much more controlled way of setting the angle accurately.

John

[Old SchoolParticipant @oldschool]

Looks like a bit of kit I need to make, I often have a need to turn accurate tapers.

[Michael GilliganParticipant @michaelgilligan61133]

Nicely done, John

Very sensible idea

MichaelG.

[IanTParticipant @iant]

Very neat! Added to the TUIT list…  🙂

 

IanT

[BazyleParticipant @bazyle]

How useful. A similar concept (same device) could help with setting a mill vice square.

[Paul LousickParticipant @paullousick59116]

I have just cut a couple, using an existing tool with a morse taper held in the chuck with the taper out as a guide for setting the angle.

Then used a DTI to check the angle as I advanced the compound slide for no movement of the needle.

Did not blue them to check exact fit but they locked in with slight pressure and had to be tapped to release.

[FulmenParticipant @fulmen]

Very clever solution. Wish I had a T-slot on my lathe.

[Nigel Graham 2Participant @nigelgraham2]

Very good idea!

The method is so economical in material that if needing frequently to turn common tapers like Morse ones, it would be feasible to make individual ones set and kept to their specific tapers.

 

Funnily enough I described on this forum a few years ago, something as Bazyle suggests for setting a milling-machine vice. It still involved a DTI but used I two screws in angle-plates, bearing on a bar held in the vice. One screw acted as a fulcrum, the other as the adjuster……

… only to be shot down in flames for my heresy against the cos-we’ve-always done it, hit-and-miss method wiv’ an ‘ammer (well, all right, a soft mallet).

[BazyleParticipant @bazyle]

Bar in vice is very good improvement Nigel for precision. One of the problems with setting things with a screw thread is you suddenly realise how coarse the thread is and the difficulty of doing one hundredth of a turn.

[Howard LewisParticipant @howardlewis46836]

For greater precision in setting, the thread needs to be as fine a pitch as possible.

The ME 40 tpi threads are very useful in this respect as one turn moves 0.025″ With 40 divisions on a knob or handwheel, one division equates to 0.001″

For non Imperial lists, the method has be using, say, a 0.5 mm pitch thread

Since Zeus charts do not list any Fine Metric threads below 8 x1, the nearest commonly available would a standard M3. This being so small this can only be for adjustment with minimal force.

Alternatively a standard M6 could be used with a graduated knob. 50 graduations would give 0.02 mm per division, and a M6 thread can exert quite a force, whilst providing fairly fine increment

Howard

[John PurdyParticipant @johnpurdy78347]

Agreed, the finer the thread the better for finesse in adjusting. The finest threads I had that were long enough, short of making specials,  were 32 TPI, hence that is what I used.

John

[renardiere7Participant @renardiere7]

Great idea. Was it my imagination or was someone not producing a magnetic sine bar expressly for setting up the top slide?

[Neil LickfoldParticipant @neillickfold44316]

Thats a good idea the screw adjustment. You can add a DTI holder too.  I often set up a  dti at 70mm from the centre line, and use it like a TAN bar instead of a SINE bar. So measure over a constant length on the test bar looking at the radial distance variations.  Sine bars are always fiddly on lathes I find.  I use this mainly for setting angles less than 3 deg.

With setting a Morse taper angle, I normally put up a MT sleeve, hold it between centres. The way around will determine the taper being turned is internal or external. #2 is the main one I make, sometimes #3 or #4.

I use a plunger DTI to follow the sleeve, and to get the DTI on centre, just place a piece of brass strip or a slim rule  between the DTI and sleeve, adjust till it is Vertical.  So I use the DTI following the part, and I also use the DTI at 70mm on the edge of the top slide to dial in tapers for the MT ones. If your tailstock is not well aligned, this is not as good as a parallel bar and looking for the difference over a length.

Now that I have seen your fine adjuster, which I like alot, will make one for my S7. Looks like it can stay in place for the majority of taper work that I do anyways.

Thanks for sharing.

 

[jamesp1Participant @jamesp1]

If you do a lot of MT2 (Myford) or MT3 (Larger Chinese) tapers, it could be worth drilling and reaming a tapered dowel pin hole through the top slide into the cross slide once it is set in the correct position. Make a dowel pin with a threaded top on it for easy extraction.

Sadly, and for reasons that completely escape me, each Morse taper is a very slightly different angle so the dowel pin willl suit only that particular taper, and drilling and reaming a hole for each taper would end up with a topslide resembling a piece of Swiss cheese.

[larry phelan 1Participant @larryphelan1]

Could that unit not be located from the front edge of the cross slide, without the need for a  slot ?  the cross slide being drilled and tapped.

Just asking ?

[HollowpointParticipant @hollowpoint]

I like that. Very clever. Think I’ll make one for my Boxford. 🙂

[larry phelan 1]

On larry phelan 1 Said:

Could that unit not be located from the front edge of the cross slide, without the need for a  slot ?  the cross slide being drilled and tapped.

Just asking ?

Instead of drilling the cross slide, just make it so it clamps over the outside of the cross slide.

There are metric fine taps, 8×1, 6×0.75 would work and if you had them there are metric special pitches also 8×0.75, 10×0.75 and 10×1

[mgjParticipant @mgj]

Or you can make one of your adjusting screws 1/4 40 (ME tap and die) and one rotation is twenty five thou. Scribe up a barrel and you have a built in micrometer. After that it is simple trig – in theory.

That’s how the Hemingway kit does it.

I still find that one has to set a taper up between centres and use a proper DTI to get it dead right.

[Paul Lousick]

On Paul Lousick Said:

I have just cut a couple, using an existing tool with a morse taper held in the chuck with the taper out as a guide for setting the angle.

Then used a DTI to check the angle as I advanced the compound slide for no movement of the needle.

Did not blue them to check exact fit but they locked in with slight pressure and had to be tapped to release.

This is the method I read about a little while back. Sounds quite easy and straightforward.

[mgjParticipant @mgj]

Vic it is – depending on the lathe. Some, the topslide doesn’t have enough travel to cut a full MT length , which can make it a bit awkward.

And a tiny error  – in fact ANY error –  in the setting angle means you only have contact at one point. It will probably lock in, but if you haven’t got full contact I found that under load it would move. (OK IMO for tapping guides and non critical stuff like that though)

In the end, even having built a taper turning attachment for the Myford, (Hemingway) which I’ve used for other long tapers under powerfeed,  (TE conrods), I found, for the cost and effort involved, for tool holders, it was just easier and cheaper to go the someone like Arceurotrade and buy some blank adaptors in MT2, MT 3 and R8.

[Nigel Graham 2Participant @nigelgraham2]

Choosing threads for adjusters:

The Tracy Toools charts give the Metric Fine series from M2 X 0.25mm pitch, to M56 X 4 (!).

Also, 7/16″ and 1/2″ UNF, and 3/8″ BSF, are 20tpi.

3/8BSF  x 20tpi.

And of course 40tpi ME threads.

[Author]

Posts