Morse taper protector

[StevePParticipant @stevepye68246]

This is in response to the post on damage Morse tapers.
I agree the marks can be filed or stoned off, the loss in contact area between the male and female tapers will be minimal, the torque our hobby machines can apply to the drill is small compared to an industrial machine so the loss in contact area shouldn’t cause problems.
It’s a common problem in industry, that Morse tapers on larger drills get damaged, some people have little mechanical sympathy, these drills then  get use in the tailstock of a lathe spin round when drilling, damaging the pristine female taper for ever. The taper is never quite the same afterwards , I think that’s why larger lathes have a cross slide drilling attachment, not only so the power feed can use but to protect the tailstock taper.
In my last year at work I designed an attachment for my lathe, not for power drilling but to protect the taper in the tailstock. To align the attachment with the lathe spindle, a close fitting sleeve  is fitted over the attachments Morse taper spindle, by slowly moving the cross and when the sleeve will pass from one spindle to the other, adequate alignment is achieved.
Steve
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[Michael GilliganParticipant @michaelgilligan61133]

A classy job, Steve

MichaelG.

[Nigel Graham 2Participant @nigelgraham2]

Fine work!

Does the attachment’s taper have a tang-slot, hidden in those views?

[Nigel Graham 2]

On Nigel Graham 2 Said:

Does the attachment’s taper have a tang-slot…

The tang on a Morse taper drill is for extraction only, not drive.

If we wanted to assess the drive capacity of the tang, look at the biggest drill diameter you can buy in each Morse taper size compared to the tang size (cross sectional area) for that Morse taper number and do some rudimentary calculations.

—

It is worth looking at how Dean, Smith and Grace (http://www.lathes.co.uk/dsg-lathes-1960s-1970s/) aligned their cross slide drilling attachment. It used a peg on the saddle and a projecting tang on the attachment. It fixes directly to the saddle for a more rigid connection than something fixed on top of the cross slide. It is an alternative to something that slips onto the tailstock, and does not require any rearwards projection.

The whole set of DSG pages are very good – factory tour in particular.

[jaCK HobsonParticipant @jackhobson50760]

nice!

[DC31k]

On DC31k Said:

On Nigel Graham 2 Said:

Does the attachment’s taper have a tang-slot…

The tang on a Morse taper drill is for extraction only, not drive.

In the very early days the tang was certainly used to drive the drill bit. Why would you have it with two flats if it was only intended for extraction? if just that then why not just a reduced diameter.

If you take a look at the early “Pratt Improved” chucks they used the tang as drive and the jaws to simply ctr the drill bit in the chuck.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, the tang on Morse taper drills has a long standing argument of what it is for, and probably will continue to do so, in Presto’s little Counsellor, item 4. page 19, they state that the tang is for ejection purposes only.

https://www.ksptooling.co.uk/downloads/PrestoCounsellor20161.pdf

If a tapered twist drill gets a heavily loaded on the tang, it will twist the tang, even to the point of tearing it off completely. All the drilling forces are designed to be transmitted through the good fit of the taper.

Regards Nick.

[Howard LewisParticipant @howardlewis46836]

Spme of my Morse tapers are tapped for drawbars.

If they are used in the Tailstock of the lathe, a short length of studding, or a setscrew, with a suitable thread, is screwedin, so that the self eject feature releases the taper when the item is no longer needed.

Howard

[JasonBModerator @jasonb]

Scan of the Pratt Chuck which shows the “positive driver” engaged with the taper to help provide drive. I suppose back in 1895 the fit of tapers may not have been as good so extra drive was needed. Unless someone can tell me otherwise I can’t see another reason for the tang having two flats, if only for ejection then leaving it round would work better and save the additional operating of machining the flats.

[DC31kParticipant @dc31k]

It is difficult to see how the issue might be resolved by showing pictures of a manufacturer’s marketing material.

I do not think there was anyone who would have been foolish enough to buy that and attempt to use the Morse taper drill to its full capacity. It was a device that offered more flexible use of your tool inventory rather than something to make money from when used at production feeds and speeds.

If someone would do the calculations, it might give us the basis to form a considered opinion based on the figures. Model a drill tang and chuck it up in a FEM program.

https://www.sandvik.coromant.com/en-gb/knowledge/machining-formulas-definitions/drilling-formulas-definitions

[JasonBModerator @jasonb]

Would you like to see a patent for a similar chuck by Stephen A Morse, maybe that would be more convincing than “marketing material”

Remember that Morse invented the twist drill before he invented his taper so the flat used to drive the plain shank tools was carried over onto the taper shank

[StevePParticipant @stevepye68246]

I did include a tang slot in the spindle of the  attachment.

The working surface of the Morse taper on my Myford lathe is quite short compared to other machines I’ve used, another reason for making the attachment.

As I stated in my original post, in industry some of the larger drills have their tangs completely missing and are still in use , usually the Heel of these drill are also worn , possibly one cause for the tangs being missing.

I first operated  a DSG lathe when I was a Lucas apprentice in Birmingham,  they had an immaculate machine with preselect spindle speeds ,the luxury of changing speeds while the spindle was running ,it also had a rapid traverse on the saddle and cross slide operated by a joystick on the front of the saddle . After completing my apprenticeship I worked at the Lucas Lighting factory in Cannock,  the toolroom had three DSG lathes all with power drilling attachments , two as DC31K describes and one with a holder that fitted on the tool post.

That’s why the design for the attachment looks similar to a DSG attachment, about 40 years ago I  also made a tool post and holders similar to a DSG.
Steve

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