Cutter size too big for collet work around

[Ady WilsonParticipant @adywilson52106]

I have a block of aluminium roughly 100x30x20mm which I need to mill so it will mate onto a tube. So I need to match radius of the tube which is 7/8 of an inch diameter. I have made a mistake by buying a 7/8 ball mill which has a 1 inch shank. I never thought it out and know realise that I cannot hold the tool in the mill. Spindle is MT3 and collets wont take such a shank. I have a lathe but no milling slide so cant go that route.

I havent tried but I am guessing trying to turn the cutter to a reduced shank size would be futile? Would I be wasting time and tooling trying ? Is there another way to put the radius onto the block? I need to put it down the longest side. I dont want to do it by cutting a V into it I need it to look nice and be a radius.

Any help much appreciated,

Ady.

[Ady WilsonParticipant @adywilson52106]

[Martin ConnellyParticipant @martinconnelly55370]

I have turned down the shanks of milling cutters using carbide tooling.

Martin

[Thor 🇳🇴Participant @thor]

Hi Ady,

I assume you are saying that your collet system won't take a 1 in shank and buying a ER-40 collet system is a bit expensive for a one off job.
Would it be possible to make a small flycutter with MT3 shank for this job? If you have a Rotary Table that can mount your work you could use that.

Thor

[MuzzerParticipant @muzzer]

Are you planning to make a 7/8" (diameter surely?) hole in the block using a 7/8" ball end cutter? Or indeed a 1 3/4" diameter (7/8" radius) hole in a block that isn't even 1 3/4" wide? Doesn't compute unless I'm missing something….

Or if it's a male appendage, there won't be much of it left in the tube.

Edited By Muzzer on 11/05/2016 18:38:41

[JasonBModerator @jasonb]

You say you habe a lathe so

Option one is to hold cutter in the chuck ( I'll get shot down for this) and mount work on the cross slide at ctr height

Option two, take a bit of 3/4" bar just over twice the length of your required cut, ctr drill both ends, cross drill in teh middle for a round tool bit and a grub screw at 90 degrees to that and cut it between centres

If the cut is along one of the short edges then hold it in the vice with some scrap on one side and cut a 7/8" hole with a boring bar or just drill it with a blacksmiths drill, much like I'm doing here, just position ctr of hole where you need it

Did someone mention a boring head?

Edited By JasonB on 11/05/2016 18:54:45

Edited By JasonB on 11/05/2016 18:57:21

[MuzzerParticipant @muzzer]

Aha. There's mating and there's mating. A few better chosen words or a picture might have helped, although Jason seems to have guessed correctly.

[Martin ConnellyParticipant @martinconnelly55370]

Turned down shank on a milling cutter.

[Ady WilsonParticipant @adywilson52106]

Thanks for all the replies they are really appreciated. Also thanks Jason B for giving me multiple ways of achieving what I want to do. I will try to turn the shank on the cutter down as that is probably going to be the simplest option but if that fails then I think Jasons option two of cutting it with a bar between centres looks best for me to do. I have learnt some good stuff here cheers.

[Chris Evans 6Participant @chrisevans6]

If you like a mathematical challenge it is possible to do with a smaller say 8mm ball end cutter. Some more modern read outs have built in assist programs for this. Me I would bore it.

[Ady WilsonParticipant @adywilson52106]

Just an update I managed to turn the shank down to 20mm so I can get it in my collet chuck now. Used it and it worked out great. I wont be forgetting the tips given me though as I am sure they will come in handy in the future.

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