Bargain Dovetail Cutter How Do I Hold It

At the recent Taunton show I was forced (at the price I just could not leave it there) to buy a fair sized 60deg dovetail cutter. Problem is that I guessed incorrectly as it turns out that I could use it in the Bridgeport.

It is a threaded cutter but the shank is an inch (25.4mm in funny money) in diameter. Can the panel suggest ways that I might be able to use this in my R8 spindle Bridgeport. The largest collet I have is a

20mm and this cutter appears "hard" so reducing the shank diameter with my tooling would appear a no, no. I thought about getting a "soft" R8 adaptor and boring it out to shrink fit the cutter in but I'm not sure if the blanks have sufficent diameter for that.

Any help, (other than send it to me), much appreciated before I consign it to the "useful one day" box where it will be lost forever.

Best regards

Keith

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jontom_1uk
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Hi Keith, If the cutter has a 20 TPI thread on the shank and a back centre, then an Autolock chuck with a 1" collet or similar will hold it. They don't come cheap so it might take some of the shine off your bargain!!

Bob

Reply to
Bob Minchin

Bob hi, yes that was as I feared. It does indeed have a 20 TPI thread and an R8 Autolock and inch collet will be expensive, more so than a new economy cutter. I also thought about the ER40 set which goes to

26mm but even with only one collet it is going to crinkle my smile a bit. Ah well, into the tin, I'm sure it will come in useful one day. Having found this bargain perhaps I will find an equally cheap chuck to hold it, oh look I do belive that is a pink pig flying past :-))

Best regards

Keith

Reply to
jontom_1uk

In article , jontom snipped-for-privacy@hotmail.com writes

Could you fit a small 3-jaw s/c chuck to the spindle? Thinking of the

2MT/Myford nose adapters which they sell for putting large diameter cutters in the tailstock. (Have one, never used it.)

David

Reply to
David Littlewood

David

What an excellent idea, thank you. I have the most gorgeous 3" Pratt Bernerd chuck still wrapped in the original packing paper that has been looking for a job for the past 20 years. My only concern is should I entrust such a beautiful and delicate piece of true British engineering to the big old beast of a Bridgeport?

Who says engineers don't have a heart

Regards

Keith

Reply to
jontom_1uk

David, what an excellent idea, I have a gorgeous 3" Pratt Bernerd chuck that is still wrapped in the original packing paper and it has been waiting for the last 25 years for a job. The only concern I have is should I entrust such an exquisite and delicate example of fine British engineering to that big old beast of a Bridgeport.

Who said engineers don't have a heart

Anyone else having problems posting, this is my third attempt at this one the others just seem to have evaporated. Just posting with Google so I suppose I need to get things sorted properly. Apologies if the other two arrive eventually.

Regards

Keith

Reply to
jontom_1uk

If you feel that guilty about it, I'll swap it for a completely bolloxed 3" Pratt Burnerd if you want :-)

The only trouble it that the endmill would only cut with one tooth and would probably cut sloping sides.

More seriously, the cutter would probably walk out of a chuck with even light cuts unless you turned up a ring to screw on the threads and locate behind the chuck jaws and bored the (soft) jaws for an accurate fit on the cutter shank.

What about getting the shank ground down to a smaller diameter?

Mark Rand RTFM

Reply to
Mark Rand

I think you need to give that idea away the clamping force of such a small chuck would be insufficient. Why not buy a chinese R8 -3 MT adapter, bore it to suit the cutter. With a flat ground on the shank of the cutter for grubscrew clamping, you're away US style.

Tom

Reply to
Tom

I have seen this thought expressed by several people, but has anyone actually tried it? After all, it is why Myford made/sold the adapter. Anyway, the screwed-on back nut suggested by someone would solve it.

Also, I am curious as to why a small chuck would have less grip than a larger one. Smaller jaws? Less pressure?

I'm sure the above adapter idea would be just as good.

David

Reply to
David Littlewood

Perhaps a cheaper solution lies here:

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Tom

Reply to
Tom

Thanks for the ideas guys, to be honest I normally post via Googl

Groups and they have not picked up any feeds since early pm yeaterda so I thought I had missed "apokalupsis eschaton".

Sorry Mark don't need yet another b***"*d chuck, I've plenty of the already. I suppose this little chuck might be turned into beer token and thus into an R8 collet chuck of sufficient size but I don't know i anyone uses these very small chucks these days or if Pratt Bernerd wer any good at that size. I'm sorry to say that "retirement" brings it own problems; when I was working it would have been merely a walk t the grinding bay and they would have sorted it out in short order. No able to do that now, not that they have just forgotten me but they ar not there now either, part of the general engineering capabilit downsize.

David, I'm not sure of its griping power but it might be lower tha normal as it is one of those hand tightened ones often used i watch/clock making. My only concern with the adaptor modification i has the R8 soft adaptor that is available enough "meat" on the larg end to bore out to an inch. The R8/MT3 adaptor sounds a good idea bu are they not hardened?

Tom, thanks for the link that looks just what I need. Unfortunately th guy only ships to the States/Canada so I'll need to find a UK source an hope they are not too expensive.

Best regards

Keit

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jontom_1uk

They're ideal for holding small parts on a dividing head, rotary table, sensitive drill table etc. I have one which I've drilled radially for a small tommy bar.

I'll swap you a one inch shank diameter, threaded 'corner rounding' (ogee) milling cutter for it! :} --

Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"

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Chris Edwards

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