straight shank adapter for MT2/MT3 drill bits

In true Blue Peter fashion, here's one I prepared earlier; as per the second post in this thread
These were made for an old AEG-Unifix drill I'd acquired previously, which just came with a conventional drill chuck on a proprietary Unifix arbor.

Each style is for a different purpose; these drills don't have an on/off for the hammer action.

The chisel at the top has a round shank, so there is no rotary drive, the flat is for a half round key to save it falling out.

Middle is the item relevant to this thread; it looks like I mis-remembered, and it was made from an MT3 extension, rather than MT2.
The material turned absolutely fine when I made it. The threaded part (cut on the lathe) screws in to the main spindle of the drill and the round projection disengages the hammer mechanism, leaving rotary drive only.

The lower item is a home made SDS adaptor. I picked up a conventional Bosch SDS item and re-used the outer sleeve, spring and the oval locking dowels.
The new centre arbor is made from a broken Landrover half shaft; no idea of the steel alloy, but it's tough stuff.
Drive is via the hex at the end, which allows both rotary and hammer action.

Personally, If I were to make an MT-½" adaptor, for use in a hand electric drill's chuck, I'd make the end round rather than provide three drive flats.
That way, is something does bite, there is a chance it will slip before breaking any bones.

My version of the old Gut Buster has a 5/8" chuck on a Bosch 3HP plaster mixer.
Unfortunately it's an old one; the current models have safety clutches.
It's not something I would lend anyone else, and when I've needed to use it with a large drill, the big handle opposite the trigger handle has a long steel tube over it, braced to something very solid.
The only time I've had it bite seriously, it snapped a 7/8" bit like a carrot; please treat this sort of kit with the utmost respect, even releasing the trigger doesn't stop it straight away due the inertia of the armature and gearbox.

Bill
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Edited By peak4 on 06/01/2021 17:05:34

The R8 to MT adapter linked by NDIY does not take tangs. I have loads of MT-MT adapters and drifts thanks Howard. If I cannot find a cheap adapter as per the OP request, then of course there are many possibilities to turn down other styles of holders. Thanks everyone - it seems we have exhausted the value of this topic. However I do agree with Bill that allowing drill bit slippage in the chuck jaws is a must for H&S

Edited By Adam Harris on 06/01/2021 18:16:31

Sorry Missed that NDIY's link was non Tang, this is the Tang one.

My suggestion of Hex or flats was to save chewing up the shank as you said your drills have clutches there should be minimal risk of injury.

I have R8 to MT2 adaptors for tangs and drawbars. I made the mistake of trying to drill out the restriction in the tanged one with a solid carbide drill and it ended badly for the drill. I could resharpen it, but it would mean removing 1/4" from the end.

Purchase an extension Morse taper socket. Mount it between centers and turn the male taper to a suitable diameter.

For use in a hand held drill motor sme runout is tolerable so it is preferable to purchase a used extensin scket and modify it.

RDG sell a 2 morse taper socket with a 3/4" diam.shank which could be turned down to 1/2" I should think.

2 mt socket

Scroll down to 3RD item.

Edited By ian j on 07/01/2021 14:23:36

Edited By ian j on 07/01/2021 14:25:08

No imagination? It has a through hole for a drawbar?. If the drill bit in use is (as I indicated earlier) is less than the diameter of the R8, a punch, of some description (perhaps a bolt of the similar diameter) could used to remove any drill, while the R8 end was supported? Cut off the tangs (if they will not fit)?

I don’t agree with ‘allowing slippage’. That is not a reliable safety device by any means of justification. How to FU ruin your tools comes to mind.

I doubt turning down an R8 shank to fit a 1/2” chuck is a particularly satisfactory situation - asking to bend or twist the thin wall if it has a 10mm hole for a drawbar. Cutting hexagon or triangle flats would likewise be doomed to failure?

My advice, had the OP asked the appropriate question in the first place, would have been “Buy some suitable drill bits and forget the morse taper idea”.

Edited By not done it yet on 07/01/2021 14:48:06

NDIY, I object to your offensive tone but marvel at how much time you have on your hands to witter on and on in this fashion. Have you really nothing better to do ? My OP was clear and simple and appropriate, and rather uninteresting. You have simply gone off on your own tangent. Of course there are many solutions to modify various holders as anyone with half a brain knows. If John Stevenson was with us today he would surely categorize your responses as coming from the class of arm chair wind blowing so and so that he was so fond of rebuking

He’s not and I have been busy in my workshop in the interim. If you have such a thin skin as to think my post was ’offensive’, tough. Get a grip on reality might be appropriate advice for you. Blacksmith drill bits are for blacksmiths drills.

Obnoxious to boot!

NDIY, I have been trying to find a suitable name for those thin skinned people who can't handle criticism. I have considered names like snow flake, candy ass, etc. I finally settled on emotional weakling, abbreviated EW and pronounced EEWWW.

If you want to find harsh critics go to Practical Machinist forum. Sometimes they attack like a school of piranha.

Lets keep things civil otherwise I may have to lock down a few individuals.

There is more than one pair of eyes on this thread...

Disagreeing with someone's views is not a licence to be rude.

Neil