Large drill bits - any other use

[JimM]

Last summer I picked up a box of various morse taper drill bits. I've gone through them and kept the ones that look OK but there's also quite a few that are just bigger than I'll ever be able to use (approx 3/4" to 2" on MT3 to MThuge shanks). Before I chuck them out are there any any other use I could put these too ? I'm thinking along the lines that old sash weights provide a useful source of cast iron, smaller drill bits can be ground down for impromptu lathe tools etc

Cheers

Jim

[bigmini]

Last summer I picked up a box of various morse taper drill bits. I've gone through them and kept the ones that look OK but there's also quite a few that are just bigger than I'll ever be able to use (approx 3/4" to 2" on MT3 to MThuge shanks). Before I chuck them out are there any any other use I could put these too ? I'm thinking along the lines that old sash weights provide a useful source of cast iron, smaller drill bits can be ground down for impromptu lathe tools etc

Cheers

Jim

A 2" drill bit? Those things are big $$$$$. Sell them individually on fleabay.

[Andrew_D]

I am always looking for deals on used 1/2" - "sky's the limit" sized drill bits on EBay.

Shipping from UK would probably kill the deal to send them here, but I'm sure there are others out there looking for deals too.

When a new 2" is around $200 and a 4" is $1500, I look for cheap deals and I'll even re-sharpen them at that price! 

Andrew

[John Stevenson]

Can't remember if this is a MT4 or MT5 that it stated life as but It's very handy for wanging a big hole into a plate for subsequent boring to size.



John S.

[Bogstandard]

They save a great deal of time don't they John?

I actually love drilling big holes, another one of my engineering fetishes, the bigger the better.

With just a little work, if your mill or drill, even your lathe, has the power to cut with them, they can easily be modified to fit. Just turn them into 'blacksmiths' drills with a reduced shank. 1/2" is the standard size to turn them down to.


John

[John Hill]

Sir John, I presume that part of the drill is not hardened if you managed to machine the R-8 on the end?

[Davo J]

Sir John, I presume that part of the drill is not hardened if you managed to machine the R-8 on the end?

No their not hard and can be turned easy.

Dave

[jim]

keep em!
or sell em!!

[John Stevenson]

The R8 taper was turned on, it was a morse taper before that. Drawbar thread is 7/16" x 20 UNF to match the Bridgeport / standard R8 layout.

John S.

[Andrew_D]

I also look for cheap straight shank large drill bits. Picked up a 1 1/2" and 1 3/4" a little bit ago. Don't have a chuck or collet setup that big, but I plan to turn them down to MT4 taper. My lathe uses MT4 in the tailstock and the radial drill has an MT4 spindle.

Andrew

[bigmini]

Sir John, I presume that part of the drill is not hardened if you managed to machine the R-8 on the end?

No their not hard and can be turned easy.

Dave

With drillbits the top end isn't hardened (as much). You only have to look through my drill drawer at all the ones that have been scored by slipping in the chuck . One of the more common "spare time" requests I got as a trainee in the toolroom was to turn down the shank of a 1/2" drill to 10mm to fit in the chuck of a hand drill. Dunno how i'd go in my Chinese 8x16.

Not sure how the finish in the photo was achieved. I was never able to match that with the carbide tips I was using

[JimM]

Thanks for all the replies,

I like the idea of turning down the tapers to something that will fit my machines but how do I go about holding a drill bit in the lathe to do this ??

Thanks

Jim

[Andrew_D]

I like the idea of turning down the tapers to something that will fit my machines but how do I go about holding a drill bit in the lathe to do this ??

I would hold it in your chuck of choice - 3-jaw, 4-jaw, whatever. Then bring a tailstock center up to the end...most drill bits have a small hole drilled in the end of the shank.

Andrew

[bigmini]

I like the idea of turning down the tapers to something that will fit my machines but how do I go about holding a drill bit in the lathe to do this ??

I would hold it in your chuck of choice - 3-jaw, 4-jaw, whatever. Then bring a tailstock center up to the end...most drill bits have a small hole drilled in the end of the shank.

Andrew

If you do, I would use a 4 jaw because if the shank you turn is off-centre, then every hole you drill will be over size by that much and the drill will only cut on one side. Plus if you damage the jaw in a four jaw chuck it's less of a problem. Be careful because you don't want to chip or damage the flutes on the drill either.

[Andrew_D]

I like the idea of turning down the tapers to something that will fit my machines but how do I go about holding a drill bit in the lathe to do this ??

I would hold it in your chuck of choice - 3-jaw, 4-jaw, whatever. Then bring a tailstock center up to the end...most drill bits have a small hole drilled in the end of the shank.

Andrew

If you do, I would use a 4 jaw because if the shank you turn is off-centre, then every hole you drill will be over size by that much and the drill will only cut on one side. Plus if you damage the jaw in a four jaw chuck it's less of a problem. Be careful because you don't want to chip or damage the flutes on the drill either.

I agree...some 3-jaws are better at being dead nuts than others! 

Andrew

[Bogstandard]

One way you could try is to put a piece of say 1" O.D. ali in your chuck. Using say a 1/2" drill, just drill the pointy bit on the end depth, don't start cutting the straight part. DO NOT use a centre drill, it will be the wrong angle, but do use a centre drill first to give clearance for the large flat on the big drill end. If the centre drill hole is not big enough, measure across the flat and go in a bit with a drill just a little larger.

Now mount up the big drill with the pointy end into the cone you have just cut and bring in your tailstock centre to the 'pip' in the back. Now gently start cutting away at the morse taper, and as the large drill starts to bite into the ali, tweak up the tailstock centre. Once it gets so far, it won't want to dig in any more, and if you are careful and don't take heavy cuts, you should be able to turn the taper to parallel.

Another way would be to bore and make a split collar so that you could hold the drill flutes in a normal chuck.

Hope you understood that.


Bogs

[Andrew_D]

One way you could try is to put a piece of say 1" O.D. ali in your chuck. Using say a 1/2" drill, just drill the pointy bit on the end depth, don't start cutting the straight part. DO NOT use a centre drill, it will be the wrong angle, but do use a centre drill first to give clearance for the large flat on the big drill end. If the centre drill hole is not big enough, measure across the flat and go in a bit with a drill just a little larger.

Now mount up the big drill with the pointy end into the cone you have just cut and bring in your tailstock centre to the 'pip' in the back. Now gently start cutting away at the morse taper, and as the large drill starts to bite into the ali, tweak up the tailstock centre. Once it gets so far, it won't want to dig in any more, and if you are careful and don't take heavy cuts, you should be able to turn the taper to parallel.

Another way would be to bore and make a split collar so that you could hold the drill flutes in a normal chuck.

Hope you understood that.


Bogs

Yeah, I had thought of a split collar type of idea before. Haven't done it though. You'd want to drill the hole, then mark the piece before removing it to cut it so that it goes back in the same orientation to the chuck, to eliminate any run-out in your 3-jaw.

I like your idea of a piece of AL or maybe Brass/Bronze in the chuck. I wonder if I could do this and then offset the tailstock to cut taper shanks into those straight shank drills? Might not work cause the drill would keep grabbing and releasing with the two flutes...I might just have to try that. It'll be easier than using the compound as I have been doing. It doesn't matter if it buggers up the cutting of the drill...I'll just re-sharpen it anyway.

Andrew

[Keith_W]

I have a good collection of large Drills, the biggest being 2¼”. Most have a MT3 Taper and they are good as others have stated to get rid of a lot of metal when either boring on Lathe or Mill.
When I have had to reduce a MT4 taper to a MT3 I have used a plastic pipe close to drill size and cut slot in it to fit over drill and allow for it to fit in 3 Jaw Chuck. This protects the Chuck Jaws and uses a Live Centre on divot in Drill Tang to steady Drill and cut the new taper.
Another way is to use a No 3 to 4 Morse Taper Adaptor, not as good as having the right taper on the Drill as you can get some run-out being the length the Drill sticks out using the Adaptor.

Regards,
Keith_W

[bigmini]

I have a good collection of large Drills, the biggest being 2¼”. Most have a MT3 Taper and they are good as others have stated to get rid of a lot of metal when either boring on Lathe or Mill.
When I have had to reduce a MT4 taper to a MT3 I have used a plastic pipe close to drill size and cut slot in it to fit over drill and allow for it to fit in 3 Jaw Chuck. This protects the Chuck Jaws and uses a Live Centre on divot in Drill Tang to steady Drill and cut the new taper.
Another way is to use a No 3 to 4 Morse Taper Adaptor, not as good as having the right taper on the Drill as you can get some run-out being the length the Drill sticks out using the Adaptor.

Regards,
Keith_W

That plastic pipe idea sounds useful for a lot of things where you don't want to mark the workpiece.