Reduced shank drills

Cliff,

You can reduce then in the lathe easily if you can get the cutting end of the drill into the mandrel - so not on a myford ML7.

If you can't call in a favour fron someone with a bigger lathe then make a split bush to grip the drill as near to the shank as possible, set up a fixed steady running on the shank and turn down the end. If you do the smallest one first then you can keep boring out the split bush to take the next size up and so on.

Tedious but doable.

Bob

Cliff,

If you're in travelling distance I'll do it for you. I'm TN33.

AWEM

Thanks Andrew. I am in TN17 so close enough. I'll be in touch when I have bought the drills.

Cheers, Cliff.

Thanks Bob. I jumped at this idea as soon as I read it, but then I began to think about making the split bush. To do that I would need to drill the bush which means fitting the drill in the lathe which needs....

I'll take Andrew up on his offer.

Cheers, Cliff.

Maybe use the biggest drill you have and then a boring bar to take it out to the size of the drill.

It really does sound like a good opportunity to buy a 1/2" capacity drill chuck to suit the Myford though, what are they MT2?.

message

A229, B2244, then 500 yds on the A21 - tell me when and I'll put the kettle on!

AWEM

Something I thought about was a 1/2" MT2 end mill holder. Don't know if it would be accurate enough, but I can't see why not? Much cheaper than a chuck.

-- Peter F

Unless you're only planning to drill wood or aluminium, this could be unsatisfactory.

Best option would be to spring for a 1/2" 2MT drill chuck. Whilst you may not twist the reduces shank off (max torque for3/8" is only 42% of that for 1/2"), there is a strong possibility of the shank slipping in the chuck, even if only step drilling.

Other best option is to get some boring bars plus a few 2MT drills. Either a couple of individual drills, or a set of cheap ones, such as Warco do.

Regards Mark Rand (just come in from cutting 8 pieces of 80x80x10mm angle too short) RTFM

Now why didn't I think of a bigger chuck? I shall investigate further.

Cliff.

Thanks Mark. Until you mentioned them, I was not aware that MT2 shank drill bits existed. They would appear to be the most cost effective way of quickly making large holes in metal that I can finish with boring bars. (I currently drill 3/8" then open to 1" by boring which is very slow and, well, boring.)

I found cheap sets from RDG which I assume are rubbish, while Tracy Tools sells them individually. Would anybody care to speculate on the maximum size that an ML7 would be able to handle in terms of both power and grip available at the 3 jaw chuck, and the slip resistance of the taper in the tailstock?

Thanks to all for the help. Cliff.

MT2 drills go up to around 23mm or so (and imperial equivalent) Provided your tailstock is in good nick and you work up in a few stages from a pilot drill, you will be fine up to that size on your Myford.

Watch out for the swarf though, it tends to come straighter from the bigger drils (why??) and quite sharp too. Both hand behing the tailstock hand wheel is not a bad idea esp for deep drilling.

Bob