large drills - taper shanks - pros & cons

[Dunc]

I currently have a drill press & vertical mill; both have MT3 sockets. When I require larger holes I use either hole saws or 3-flat (1/2 inch parallel shank)
Silver & Deming drills (both machines can be run at appropriate rpms) held in a Jacobs geared chuck.
While holes larger than 1 inch dia are very infrequent, I have located a source of MT shank drills at reasonable prices. Are there advantages to the MT shank drills that would make them preferable to those I already use? Most MT drills are much longer; my machines can accommodate this but I wonder if I might lose rigidity?

[Dan Dubeau]

Buy them if you can swing it. You can never have enough ways to make a hole. My big gripe with S&D drill is the lack of drilling depth. If you've got the daylight to use MT drills and the power to turn larger drills, then go for it.

There may be some way to calculate the difference between the 2, but IMO if both tapers are in good condition, and mate properly you wont notice a difference between MT, and S&D performance.

I missed out on a large milk crate of MT2, MT3 and various adapters a couple years ago and have been sour about it ever since. There was probably 50 drills in there for around $50 if I remember right.

[lakeside53]

I have a bunch (like 40 of them) I got for close to nothing at an auction. Gave away everything over 2 inches (you can't imagine how expensive quality 2-4 inch drills are) to a buddy with a huge radial drill machine, and use them all the time in the tail stock of my lathe. Advantage? they don't spin out and you really don't have a choice over a certain size - no chuck easy to find. Amazingly efficient for roughing comparison to boring.

[MattiJ]

MT3 can handle lot more torque in 1" and bigger drill sizes. 1/2" shank is good enough in smaller sizes.

Reduced size round shanks tend to slip and self-tightening keyless chuck is bad idea on high torque use.
You have three flats on your drills so that takes care of slipping and keyed Jacobs chuck solves the over-tightening problem seen with keyless chucks.

[Mcgyver]

MT's will take a lot more torque, and being longer, will last longer as well as drill longer holes as Dan points out. If you've got the machine to drive them, there is a lot less stepping through hole sizes, which you often have to do with S&D drills. I bought a skid of MT tapers drills, up to 3" which we use on a big radial drill - that is a nice way to make holes! Those big ones will set you back 600-700 each, not that they're for home, but the point is a great deal for a good selection of MT drills is a deal to be taken

[danlb]

If you think about it, the drills with taper HAVE to be at least as good and probably better than using the Jacobs chuck. Both go into the same taper, so they should both hold just as well. The chuck has the advantage of fast change. The MT3 drill has the advantage of (probably) being more accurate. The chuck has two interfaces where it can fail.

[BCRider]

They are longer. But given that you remove the drill chuck to use them I think you'll find that the stickout portion is still shorter than an S&D of the same size held in a chuck.

I've got a set that goes from 1/2 to 1 1/4 in 1/16th steps. The set has come in VERY handy about half a dozen times per year. And not only the larger sizes. I took advantage of the length of the 5/8" to drill a really deep hole in a wood project. It was longer than the quill travel would support so I had to go easy on the "second bite" so the flutes would clear the chips without retracting the drill. But it got the job done just fine.

My metal shop drill press only has a 1/2 HP motor on it though. And it's not a big and burly machine. So I drew the line at 1 1/4 and have not gone looking for anything larger.

[J Tiers]

They are longer. But given that you remove the drill chuck to use them I think you'll find that the stickout portion is still shorter than an S&D of the same size held in a chuck.

....

But without the big bulky chuck to get in the way.

I have gone to mostly using taper drills in the T/S for drilling in the lathe. Works out better, and I do not have clearance issues to the compound or toolpost.

[bborr01]

You already use the MT3 taper to hold your drill chuck. Lots better to put the bit directly into your spindle and drill away. I have taper shank drill bits from 1/2" to over 2". Usually I use straight shank drill bits up to about 3/4" unless I have a clearance issue using a chuck, then I go right to the MT shank drill bits.

Brian

[754]

Dont forget they fit in your lathe headstock too.
Example.. Boring bar holder for 1 1/4 bar.. Mount the holder on the toolpost, rough. Out with say a 1 3/16drill, then switch to boring head to finish,. Two advantages, you can power feed, and it will be on center.
Then make a drill holder for your toolpost, so you can drill under power. If the Morse socket is hard for you to make, do a straightbore, and use a Morse taper socket to hold the drill.

[sdalcher]

I have both S&D and MT bits. From MT1 up to MT4. The reduced shank drills can be a life saver for someone on a budget trying to drill a larger hole. However when you are drilling a larger hole with a reduced shank drill it is very common to have slippage unless it has a 3 flute shank. When they slip, burrs form and it loses a little bit of concentricity each time. With MT bits you don't have that. I have actually stalled a machine out with an overzealous drilling operation... Didn't slip though! I prefer to use MT bits and have invested a significant amount of time and money acquiring used ones. New ones just aren't affordable. Search McMaster Carr for a 2" MT drill and hold on your heart and your wallet. Used ones can be had for as little as a $1 - $5 on average. I bought 350 MT1 drill bits for $100 over the summer, still sorting them!

Maybe it's time to start a virtual swap meet! I still have some holes to fill in my sets and plenty of trading stock in MT bits.


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[BCRider]

I suspect that the cost of larger size MT drills is why the insert style "spade" drills have become fairly common in industry.

[sdalcher]

I suspect that the cost of larger size MT drills is why the insert style "spade" drills have become fairly common in industry.

I have those as well in MT 2-5 lol


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[Dan Dubeau]

Hole depth is a big issue for deming drills too. You can only go so deep before pecking out of the hole frequently becomes annoying. What I've done on a couple of my deming drills is turn down the top part where it's full diameter, then grind out the flutes so they carry through out the top. Doing both of those helps keep lube down in the hole and to prevent chip packing on deeper holes.