Morse Taper drills

As a general guide. When drilling from the tailstock is there a point reached when the drill should be a morse taper fit into the tailstock rather than a parallel drill mounted in a chuck.

My small lathe is a Proxxon PD 400.

When it's too big for your tailstock chuck?

Russell.

Hi 13Sigs,

I've read your question several times over and I think that what you are asking is as follows (?)

Should you be using a Morse Taper mounted twist drill instead of a conventional drill bit (held in a drill chuck) at some "point" ( where the drill is either large or being extended further ? ).

Well I have a few MT1 mounted drills that I occasionally use on my EW - as well as the normal ones that get held in a drill chuck. I cannot think of any practical difference between the two types (given both are well sharpened) except that the MT1 mounted drills can be popped in and out quite quickly - rather than using a chuck key in the chuck (I'm afraid I'm too cheap to buy (good) more modern keyless chucks).

So (if I understand your question correctly) then I think the answer is "No" - You can use either type to the limit of your lathe and/or tailstock's capabilities.

Regards,

IanT

Edited By IanT on 13/11/2015 20:41:25

You can turn the shank of the drill bit down to fit your chuck. The shank end is soft and machineable.

I don't have any MT shank drills, get by quite happily with blacksmiths (reduced shank) drills from 1/2" upto 1" in a keyless chuck and bore anything larger and I make quiet large models.

Morse taper drills run through the whole series of sizes, you only need MT sleeves to put them in the tailstock .

It's convenient to have a drill chuck for smaller parallel shank drills but if you have a large lathe or drill MT taper drills become the norm.

Clive

Fundamentally the capacity of your tailstock for drilling is defined by the morse taper in it and in general the drill chuck will satisfactorily hold any drill up to its rated capacity. So in principle you only need to change from parallel shank to MT shank when using a drill too large for your drill chuck but still within the range covered by MT shanks fitting your tailstock.

As ever multiple caveats. MT shank can give less drill point extension than using a chuck. Often handy on shorter bed machines. MT shank grips tighter as cutting load increases so may be better if your drill chuck is in less than stellar condition or if the material obdurate. If doing multiple holes in pilot then finish size fashion using the pilot in the chuck and an MT for finish may be quicker. Many folk find it useful to make MT holders for centre drills to use in this manner.

Realistically whatever works for you without risking tool abuse / breakage is right.

Clive.

Thanks to all, in particular; IanT and Clive Foster.

IanT correctly interpreted what I was trying to ask and Clive Foster the reasons for and why.

A Morse taper drill does grip well in the tailstock or the drill press for that matter, however it can and is likely to slip if overloaded, particularly with larger size drills. The result is not a pretty site. Nasty galling and scoring marks on the drill and the tailstock taper.

Blunt or badly ground drills are a common cause of overloading. Excessive feed pressure is another.

Also watch out for second hand drills with scored shanks, they don't grip well and will damage your machine sockets. Best to avoid them, if you must use one clean the shank with a file and check the fit with bluing in a good known taper socket. go easy on the feed.

I don't oil Morse tapers, before I use one I wipe it out with a cloth or a finger for the larger sizes, the same applies to the drill I wipe the taper shank off with my hand. The hand is very sensitive to any grit of fine chips that might interfere with the grip. On larger sizes I give them a solid wrap when inserting them. I guess the hand transfers a small amount of oil that may be on the skin, that is enough.

Regards
John

Edited By John McNamara on 15/11/2015 15:05:07

I've picked up a few MT drills at boot sales. Handy for opening holes before boring. They are all sizes above 13mm, the limit of my chucks.

Harder to sharpen because they don't fit in collets or jigs very easily.

Neil

The Morse taper has a tongue on it to prevent slip and the machine using it should be designed to accommodate the tongue. Unfortunately most of our machines are not designed to do that. A piece of paper wrapped around the taper should eliminate damage in the event of slippage. Colin

The tongue or tang is not for driving. It is for extraction.

One advantage of taper shank drills is depth control, it cannot slip either forward or back like a parallel shank can.On any lathe it is important to keep the tailstock taper in good condition and not ruin its accuracy by using taper shank drills and anything else that fits the tailstock which have damaged tapers,if you have a lathe with a 3 mt tailstock a 2mt drill with a less than perfect taper can be used by stoning the taper smooth and then use a 2 to 3 mt sleeve,if the sleeve gets damaged they are very cheap to replace. when the taper shank drill is a size that it must fit directly into the tailstock ,then be care flu, A lot of modellers only use taper shank drills to open up holes quickly for boring,so the size is not important so look through boxes of drills at second hand dealers for drills that are only close to the size you want but have good shanks, very often taper shank drills of so many sixty fourths dia can be found in good or new condition. 25 years ago during a recession lots of tools were on the market and by searching dealers and auto jumble I have a set of drills except one from 1/2 to 1 inch dis. plus many others including a brand new dormer 2 inch drill for £15 .The auto jumbler said "you must have a B...... big lathe" the others varied from gifts to £3 to speed up drilling on my Master all the 2mt drills have 2/3 sleeves fitted to save time. Another good method is to have a saddle drilling attachment ,which saves tail stock wear and allows power feed drilling,I do have a 2mt socket holder for my Dickson tool post and I still keep meaning to make 3 mt drilling attachment holder but it never seems to get done.When Buying any machine tool,which has internal taper spindle, i.e. drilling machine or taper spindle /and tailstock always ensure the taper is in good condition,walk away if the taper is damaged.

The tang is for driving the drill if the taper happens to slip but lathe tailstocks don't usually come with the facility needed to use it. Drilling machines usually do.

I do have a few morse taper drills and reamers but in the case of the drills apart from very long ones I happened on cheaply I can't say as I went to any trouble to get them. I use 1/2" shank blacksmith drills. Those can go to larger sizes than a 2 morse shank drill. In cases where they don't well they are being driven via 2 morse anyway at the back of the drill chuck - in my case as the tailstock is 2 morse. If some one has a 3 morse or larger tailstock things can be a little different.but morse 3 only goes up to around 1 1/4 dia so not much bigger than a 1" blacksmith drill. Morse 4 goes up to 2in and 5 3in. Big difference their.

Reamers are pain. The size to shank relationship is similar to the drills so big reamers have a big morse taper shank. I have used them via a 2 to 3 morse step up sleeve at times.

The other argument for using both morse taper reamers and drills is the accuracy of their presentation to the work. A chuck will add some error. Apart from rather large sizes, say 3 morse plus that is the main reason for using them - accurate holes.

John

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Gordon, I have used radial drills which have the extraction slot machined into the spindle so it will give a positive drive also the bench drill at my club has the same arrangement. Colin

A while back I turned the tapers off a couple of dozen, so that a friend could use them in the chuck on his drill press. He got them cheap, I don't suppose they would have been too cheap if I had charged him for the job.

Ian S C

There is a difference here between the manufacturer's and the user's viewpoints. To quote Messrs Easterbrook, Allcard & Co Ltd (the Presto people):

"The tang is for ejection purposes only. Allowing torque to be taken by the tang will result in breakage."

If the taper slips so as to let this happen the taper socket is also likely to be damaged so it seems dubious to rely on the tang.

No doubt many remember the square taper drills which seemed to combine the merits of both ideas.

Presto are probably correct if the morse fitting is useless. It's more a case of the tang limiting slip while the tapers lock due to cutting pressure - we can't hammer the things in.

John

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That's a rather subtle and interesting point.

Speaking for myself, I am not above giving a tool a tap with a hide hammer to seat it in the taper.