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Tool Morse taper drill bits

Tool
trlvn

trlvn

Ultra Member
I might have a line on some Morse taper shank drills. How many of you use such bits?

If you have them, how often to you use them? All the time? Special purposes? Never, 'cause they look so nice! ;)

To me, the advantage would seem to be gaining a little more working envelope v. jobber drills. On my lathe, for example, I only have 22 inches between centres. With a drill chuck in the tailstock, i lose up to 3.5 inches just for the chuck. OTOH, I have a set of screw machine length drills. I guess a MT drill would allow me to drill deeper into a long work piece. So far, I've never run into a problem that way.

I suppose another advantage would be that tanged MT drills are never going to slip like drills held in a chuck. If the MT drills were 135 degree points, that would make them a good choice for drilling really tough steel.

Are there any other advantages to MT shank drills?

Sort of related, do any of you use Morse taper drills in your milling machine? I believe that an R8-to-MT adapter is fairly inexpensive.

Craig
 
I have a small selection of MT drill bits. I do use them on occasion. My lathes tail-stock does
not have the slot to hold the tang. I believe most smaller lathes do not have the slot. I have
a selection of drill bits up to 1" with a 1/2" shank that I use most of the time.
 
MT removes the chuck middleman & that can be an issue on smaller lathes. Not just space between centers as noted but also large chuck required to hold a large shank. Silver & Demming style drills have reduced necks to say 1/2" diameter. I was going to mention same thing, if your TS has no slot, its purely MT friction that retains the drill rotationally. Big diameter drilling is rarely a precision operation anyways. More often its just hogging material away & then along comes the boring bar or whatever. I actually prefer annular cutters for <2" (because that's the length I have). Much less cutting force & squealing & smoke drama, and you get a slug of material from the core. But, they aren't free either & don't sharpen as easy as a big drill.
 
There is lots of new drilling technology available now. +1 on the annular cutters.

I have used spade bits a few times, easier to turn and much less chip tangle. I rarely use MT drills (and I have quite a few).
 
For the lathes and my drill press I use them all the time for rough boring and setting up for internal threads etc. I use the regular drills up to 1/2”’and the MT drills from 1/2” up to 1” in steps of 1/64”. If the bore needs to be precise I will drill just below the required diameter and switch to a boring bar of required strength.

The MT bits are nice as they don’t require the chuck and the beefier shank helps keep things stable. Also the MT taper (provided you have a correctly sharpened bit) takes out the run out a drill chuck typically has for a bit more precision hole. Faster bit changes for stepping up as you drill as well.

The tang is nice on the larger size bits but should not matter on the smaller (MT 2 size) drills provided your tailstock taper is not all fugly. You can always get an MT reamer to clean things up and increase holding power.
 
I'm thankful to have acquired a small selection of MT drill bits over the years. For sizes over 1/2" I still have a number of reduced shank ones but if possible I use the MT drills as they don't flex much. That and I've had a larger reduced shank bit start spinning in my tail stock chuck before, as well as a few with the 3 ground drive flats on the reduced shank having been ground off center from the drill center line. These were all import drills, maybe a better brand name reduced shank drill would behave better, but I still prefer MT big ones.
 
I don't have as many as I'd like, maybe a dozen or so, but I only use them in the lathe for starting holes for a boring bar over 1/2". Can't say I've ever knocked the drill chuck out and ever used one in my drill press at home. At work, yeah a time or two in the radial. But rarely. Mostly just in a tailstock.
 
In the first machine shop I worked in,( later 70s), that's what there was, morse taper drill bits, don't remember what size up to. Do remember sharpening the large ones was a trick as the big grinder with the wide stone was always grooved or face on an angle, it was the hogging / everything grinder.
 
Somebody had one of those drilling power calculators & it kind of demonstrated why big drills can sometimes be more challenging on small lathes. They are hogging a lot of material relative to power available (and in conjunction with low RPM). The width of chip &rake angle is predefined by the drill, so all you can do is vary feed & that sometimes is counterproductive. IOW just because the tool shank fits inside the MT socket doesn't necessarily mean its necessarily fit for purpose on that particular machine. You can do quite few multiple single point boring bar passes for the time it takes to grunt a big drill through material, but obviously depends on many variables.
 
In simple terms, every drill has to smoosh the material at the tip out to the flutes beyond the web so it can form a chip and be carried up the drill. On small drills that's no big deal. With bigger drills, they have a bigger web, and therefore the amount of material they have to deform and move out to the cutting edge is greater, which requires more HP and force to move that material. That's why it's recommended to predrill, to at least the size of the web of the finish drill so you drastically reduce the amount of force required to drill a hole with big drills. If you have the machine, and the hp to drive it, a predrill hole is not required. That's the simple version of the "why" behind predrilling holes. And why smaller machines struggle with bigger drills, but bigger ones can drive them no prob.

I've seen a lot of weird rules of thumb about predrilling holes on the forums, and youtube over the years, as well as in person in shops. The gist of it is, to measure the web of the finish drill, and predrill a bit bigger than that if your machine doesn't have the umph to drive it. IF the predrill, ALSO might need a predrill, then follow the same idea. Just enough to clear the web. I've seen a lot of you tubers using 5-6 drills going up through the sizes just to drill a 1/2" or 5/8" sized hole. Completely unessesary, even for the smallest of machines.

The web of the drill is solid center of the drill, the spine if you will. If you look at the pic, that portion of the drill is solid all the way up the shank. It can't form a chip, the material that occupies that space has to get deformed and moved out of the way to the cutting edges for it to drill a hole.
Web.webp


That wasn't directed at you specifically Peter, but your post brought up a point I wanted to expand on, and give some clarity as to WHY bigger drills take more umph, and WHEN and HOW you should predrill. IMO it's some important foundational knowledge of the trade, that I don't see being passed on, or just ignored. Somewhere I think I have one of those drilling speed and feed slide rule calculators that also has HP requirements on it. I'll see if I can find it.
 
I recently bought a milk crate full of mostly mt1 & mt2 and maybe 2 dozen mt3 metric drill bits. It was in that mix that I got the 8mm taps.
Two of the mt3's are left hand twist, any reason why a bit would be left hand in 32mm? I use smaller ones before I resort to the easy-out, and usually don't need the easy-out, but I am not popping that into the cordless drill....
If I ever get around to sorting through them, I have a few doubles...... Lol:rolleyes:
 
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