INT 30 sleeve to hold collets for milling cutters closer to spindle

[Adam HarrisParticipant @adamharris13683]

[Adam HarrisParticipant @adamharris13683]

I wonder if anyone has found a good method of increasing the gap between cutter tip and table on a milling machine that takes INT 30 tooling? I am thinking if I could get an INT30 sleeve that receives an R8 collet or similar threaded collet that takes a drawbar i'd have the solution but it seems impossible to find (presumably because the R8 is really a little too long for an INT 30 sleeve).Any suggestions? The Clarkson and the Clare INT30 chucks both project about 55mm from the end of the spindle which seems an awful waste of space.

[JasonBModerator @jasonb]

You can get INT 30 with MT sockets but they socket still sticks out the end so no real length saving. A Weldon type holder may be a bit shorter than what you have.

The larger INT 40 ones have the MT and R8 socket set back a lot more so presume the INT 30 is just too small to allow it.

I suppose you could machine your own with INT 30 outside and bored to take common shank sizes, a grub screw could be drilled through the taper to hold weldon type shanks

Edited By JasonB on 25/02/2018 19:51:17

[Tractor manParticipant @tractorman]

Adam. I use an ER32 collet chuck on a 30 int on my shaftesbury vertical mill drill.
I also have a face mill mounted on a 30 int shank for flat surface milling.

[Adam HarrisParticipant @adamharris13683]

I have considered an INT30 chuck for ER20 collets but again the projection beyond the spindle seems wastefully large

[Adam HarrisParticipant @adamharris13683]

I have a great INT30 face mill that cuts really very close to the spindle. I see on fleabay some MT2 INT 30 sleeves so I do not  understand why someone is not making similar for R8 or deckel or some such collets…any offers and I would be a buyer!

Edited By Adam Harris on 25/02/2018 19:59:02

[David George 1Participant @davidgeorge1]

Hi Adam If you use a Weldon type holder with a grub screw clamping on a flat on the tool, it only protrudes about 35mm or 40 mm but you can reduce it by machining some from the end if necessary to gain some more clearance.

David

[JasonBModerator @jasonb]

Posted by Adam Harris on 25/02/2018 19:56:23:

I have a great INT30 face mill that cuts really very close to the spindle. I see on fleabay some MT2 INT 30 sleeves so I do not understand why someone is not making similar for R8 or deckel or some such collets…any offers and I would be a buyer!

ARC do them but they won't solve your problem

Quite simply you can't get a R8 into a 30 spindle so they have to stick out the end

Edited By JasonB on 25/02/2018 20:07:50

[John HaineParticipant @johnhaine32865]

I have asked a similar question on another forum. There are INT30 / ER25 collet chucks where the collet is held nearly in the INT30 shank itself, but they are very expensive! I'd like an ER16 version but they are not made. I've decided the only thing to do is make my own.

[Adam HarrisParticipant @adamharris13683]

Yes i see the R8 length problem, so what about a deckel collet or a W20 collet? Both have external threads which are another problem as the spindle internal bore probably would not be wide enough to accommodate the drawbar but maybe an adapter fitted to the end of the collet to offer up an internal female thread would work….there must be many who have searched for such a sleeve solution…

[Adam HarrisParticipant @adamharris13683]

John how did you go about your ER16 solution?

[Adam HarrisParticipant @adamharris13683]

Alles Gute Online do an INT30 ER16 chuck but again the projection beyond the end of the spindle is enormous. I am thinking a sleeve has to be the way to go…

[EmgeeParticipant @emgee]

Adam

The original Emco BT30 collet holder has the least projection from the spindle of all collet chucks I have found, it's for holding ER25 collets. The taper dimensions are same as INT30.

You will need to make a longer drawbar as the BT30 does not have the parallel threaded part at the end of the taper, it normally uses a pull stud for quick change mounting.

Emgee

[John HaineParticipant @johnhaine32865]

You can get quite cheap INT30 ER style chucks from several sources on eBay but they all have 40 – 50mm projection beyond the bottom of the taper. This is quite unnecessary since ER collets themselves are quite short, and at least in the smaller sizes could be absorbed into the taper. There's one here which looks more sensible but a bit pricey.

I haven't yet made my chuck but I have made INT30 tapers and ER collet holders so it shouldn't be hard. One way would be to make or buy an INT30 blank, make a dummy socket to fit the lathe, and bore it out carefully to fit the shank of one of the readily-available ER extension chucks. Then fit the latter (shortened) using high strength Loctite.

[MuzzerParticipant @muzzer]

Last time this was discussed, I posted a link to the sort of thing you are thinking of, although for 40 taper. Of course, it's a specialist / minority sport and thus would be grievously expensive even if it existed in the size you want. Nick Hughes also posted a link to something vaguely possible.

Most 30 / 40 tools seem to have a minimum gauge length of around 50mm, so you are probably stuck with that unless you have deep pockets. The machines with R8 tapers (eg most Bridgeports sold in the US it seems) allow almost zero stickout from the spindle nose. I assume it's not an option to change the spindle here – but most machines at least allow you to move the knee or head quite a distance. You don't say what your machine is – when do you find you are running out of distance?

For CNC knee-type milling machines like mine, the limited quill movement (120 – 150mm typically) can be a major bind. Part of the solution there is to minimise the range of tool lengths used on one job eg a small cutter in a small collet chuck will have little overall length, whereas a jobber drill in a keyless chuck will be much longer. So I am trying to use stub drills and ER16 collet chucks where possible. That approach might help you in some situations.

Murray

[Adam HarrisParticipant @adamharris13683]

John what about buying an INT30 blank, boring it out carefully to say 1/2" and 3/8" at the last bottom bit which bottom bit then thread 20 tpi 1/2", and then attacking it with a slitting saw to slice up like a collet, so we have ourselves a 1/2" INT30 clarkson collet? Of course we would have to source a mild steel blank rather than try to do this on a hardened steel one…

Edited By Adam Harris on 25/02/2018 22:45:40

Edited By Adam Harris on 25/02/2018 22:48:23

[SteveIParticipant @stevei]

Hi,

Schaublin made "Biconical collets types ISO 30" with 3-16mm and 1/8"-5/8" bores. I have a few of the metric that I have never used. They are I think a possible solution to your problem.

**LINK**

Look at page 13.

Now I can't seem to find the link again but I recall seeing on aliexpress or alibaba similar collets available.

If it were me, at the risk of teaching you to suck eggs I would look into, revising the work holding, making a riser block, rather than buy these if you can source them. What mill do you have?

Steve

[John HaineParticipant @johnhaine32865]

Steve, a riser block to lift the mill head would imply quite a big job I think.

It would be difficult to source a fully machineable BT30 blank I suspect, but it isn't a difficult taper to cut. I have already part made an adapter sleeve for my MT4 headstock taper to BT30 so I can hold the taper to cut the collet holder end. Much better to make a collet chuck rather than a single cutter holder IMHO, but that would be a solution – again making your own taper. Not sure why you would want to slit it though as unless you have a slideable collet the clarkson system doesn't work.

[Adam HarrisParticipant @adamharris13683]

The thread of the clarkson threaded cutters makes it completely impossible to pull the cutter out, thus giving a desirable additional security to the clamping of the shaft of the cutter.

[Adam HarrisParticipant @adamharris13683]

The Clare cutter system (bayonet rather than thread) is more elegant but very difficult to make as opposed to simply internal threading of the "collet"

[Adam HarrisParticipant @adamharris13683]

RDG say they do offer machinable INT30 blanks at about £15 but not currently in stock. I think that is the way to go for me (I don't think i can make a really accurate INT30 taper myself!). Boring, reaming, threading , slitting are all things i can do.

Edited By Adam Harris on 26/02/2018 10:03:41

Edited By Adam Harris on 26/02/2018 10:05:31

[JasonBModerator @jasonb]

If you don't feel you can make an accurate male taper will you also have problems putting an accurate hole into the blank, as has already been said you really need to make a taper socket to hold it for machining the hole.

[Adam HarrisParticipant @adamharris13683]

The spindle already holds the ISO30 blank – the boring tool is held stationary opposite it . Very easy. The head swivels

Edited By Adam Harris on 26/02/2018 10:29:15

[Involute CurveParticipant @involutecurve]

I have a couple int 30 collet system the Vertex one is by far the shortest, I came across this earler, looks quite short

ZAAAOSwMORW8CLh”>https://www.ebay.co.uk/itm/QC30-ER25-collet-chuck-NMTB-30-INT-ISO-suit-Bridgeport-Interact-etc/281975060048?hash=item41a705f650:gZAAAOSwMORW8CLh

[John HaineParticipant @johnhaine32865]

Posted by Adam Harris on 26/02/2018 10:26:57:

The spindle already holds the ISO30 blank – the boring tool is held stationary opposite it . Very easy. The head swivels

Edited By Adam Harris on 26/02/2018 10:29:15

So you can turn the 8 degree taper needed for an ER collet…

The INT30 taper has a parallel section at the narrow end and it is possible to hold the blank on that and centre it up in a 4-jaw. Though the overhang is quite long it's probably OK for threading for the closer nut, especially if you have a fixed steady.

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