Where to find large morse taper drills?

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choprboy
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Where to find large morse taper drills?

Post by choprboy »

Why do drill bits with taper shanks only come in a limited diameter range per taper size? My lathe has a MT3 tailstock and it is very hard drill bits more than slightly over 1" in size (mostly a maximum of 1-1/16", occasionally 1-1/4"). The absolute largest I could find in MT3 was a 1-1/2", and that took quite a bit of searching.

Yes I understand that there is a torque limit that comes into play at some point, but most people who want to drill a larger hole are going to be progressively stepping up drill sizes. With a 3/16~1/4" pilot, my lathe doesn't even start to strain making a 1" hole. Yes I can bore a 1" hole up to a larger size, but with that small of a boring bar it takes a lot of passes at 0.020-0.030" per pass and chatter is an issue. To start using my larger boring bar takes a minimum of about a 1.6" hole.
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10KPete
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Re: Where to find large morse taper drills?

Post by 10KPete »

Look for spade drills. Shank that takes a HSS flat insert that's easy to sharpen. As big as ya' want. Any shank.

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choprboy
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Re: Where to find large morse taper drills?

Post by choprboy »

Yeah, I've looked at those, but most with a MT3 shank only go up to 1-3/8" insert diameter and cost twice that of an equivalent HSS drill in the same size. There are some combo sets (pilot drill, a shank, and multiple insert sizes) that go up to 4", but they start at about $700 per set. I had though about buying just some large spade inserts and milling up a shank, but hadn't got past the thinking stage on that yet. Just a simply 2" HSS drill would get me to a point where I could quickly hog out the rest with a boring bar.
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Re: Where to find large morse taper drills?

Post by Steggy »

All else fails, there are always hole saws. :roll:
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stevec
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Re: Where to find large morse taper drills?

Post by stevec »

How about cutting down tapers larger than MT3 on your lathe? Once the body of the drill is chucked up properly the larger MT will even allow you to set your compound to the right taper angle (unless different MT sizes have different taper angles, which I doubt).
John Hasler
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Re: Where to find large morse taper drills?

Post by John Hasler »

> unless different MT sizes have different taper angles

They do. https://en.wikipedia.org/wiki/Machine_taper#Dimensions
John Evans
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Re: Where to find large morse taper drills?

Post by John Evans »

As John H said each Morse taper is slightly different, BUT easy to deal with . Just set the compound to the taper using a drill etc. of the taper you are trying to duplicate .
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BadDog
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Re: Where to find large morse taper drills?

Post by BadDog »

Get another/better boring bars? I don't like the cheaper steel insert bars, and over time I've got solid carbide insert bars starting at 3/8", which work for (just under) 1/2" holes. My largest is a 1" monster that goes as large as I like (within the limits of a 17" lathe) without chatter problems. But I kept my old steel insert bars for lighter cuts, and old school bars that take HSS bits for custom/fine cuts.

I've got MT shank drills (with some gaps) from something like 1.5" (MT4) down to 1/2 with MT2, and sleeves to adapt MT2 up to native MT4 in my lathe, or MT3 for my drill presses.

Of course all that takes either a lot of money to do it fast, or pick up as you find them over time. I did that latter for both the bars and the drills, none were purchased new. Some of the bars had damage to repair, but for all but the smallest that's generally replacing the carbide support (I've heard it called an anvil?), and a bit of TIG welding for the small ones to rebuild the support, then machine flat. I got some of my larger drills with pretty bad damage to the lip (but good tapers) for near nothing, some literally out of a scrap bin. A friend has a big drill grinder (Optima IIRC?, does HUGE bits) that makes short work of putting new points on as good or better than factory, and that netted me some premium name drills for near nothing. It just takes time and making the connections to provide the opportunities...
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Harold_V
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Re: Where to find large morse taper drills?

Post by Harold_V »

John Evans wrote: Sun Jan 07, 2018 11:53 am As John H said each Morse taper is slightly different, BUT easy to deal with . Just set the compound to the taper using a drill etc. of the taper you are trying to duplicate .
This topic has been discussed previously. While setting the compound by using an example can work, it is reliant upon two things in order for the end result to be as desired. One of them is that the compound be set with a DTI (or long travel indicator) DEAD ON CENTER. If it is off center, the resulting setting will be erroneous.

The other thing is that the cutting tool must also be dead on center. If it isn't, the same negative results can be expected---that the taper generated won't be true.

H
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SteveM
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Re: Where to find large morse taper drills?

Post by SteveM »

choprboy wrote: Sun Jan 07, 2018 12:49 amWhy do drill bits with taper shanks only come in a limited diameter range per taper size?

Yes I understand that there is a torque limit that comes into play at some point
That is likely the main reason. If you weren't step drilling, as you are, you could do serious damage to a machine.

One possibility is to use a morse taper extension to hold a larger drill bit.

This one is MT3 shank with a MT5 socket:
Image

Not cheap new, but you might get a good deal on a used one on ebay.

BTW, I sent you a message with a suggestion.

Steve
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Re: Where to find large morse taper drills?

Post by tetramachine »

There are standards that makers follow, MT-2 drills stop at 13/16, mt-3 at 1 1/4 etc. I have a cylindrical grinder and just grind the tapers to what is needed, or make the straight at 5/8 my biggest chuck.
One drill I've found is called a Coredrill, not a Coring Drill. This has generally 4 flutes, and needs a large hole to follow as it does not have a point. They are very rigid as the web of a 1.25 drill is a bit over .5" needing a 9/16 starting hole, but will punch that hole right quick, with much less vibration, wandering than a regular bit. They a hundreds $$ new but Ebay has plenty. They also tend to be long, so deep drilling, shallow angle flutes, no pecking needed. Chips come out like a parting tool. In steel anyway, lots of chips in bronze.
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John Hasler
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Re: Where to find large morse taper drills?

Post by John Hasler »

tetramachine writes:
> One drill I've found is called a Coredrill...

I've got one. Very stiff, cuts right on diameter. The primary purpose is drilling out holes in castings where a core has been used to create a rough, undersize hole: thus the name. I wish I had more of them.
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