ISO 30 Toolblanks.

[Raymond AndersonParticipant @raymondanderson34407]

Hi All, Just made a few ISO 30 toolblanks for me Chester Lux mill. [ the K & T is 50 taper ] Have made them from AISI 4340 would I need to harden them or not? If I harden them then they would need to be ground I have full contact over the whole taper, [an Eddings 500 marker is taken clean off, from the small taper end, to the large taper end ] I have a MT5 back end / ISO 30 front end adaptor [made by Coventry toolholders ] that enables me to machine them in the smaller lathe. I would'nt think I would need to harden them for domestic use so what do you fellows think. as I dont want to ruin them. Cheers.

[Raymond AndersonParticipant @raymondanderson34407]

Should I harden them ?

[Phil WhitleyParticipant @philwhitley94135]

They want to be tough rather than hard, and it is a good idea that they are softer than the nose of the machine spindle they fit in to, so any accidental dings will be on the adapters and not the machine.I see you have not slotted the front face of the adapters. On my Harrison, (also Int30) the taper is for alignment, and the actual drive is done via the slots on the face of the adapter. I am not familiar with the Chester, is it the same? Well done with the adapters, they look good, I will have to make some for mine!

Phil

[Raymond AndersonParticipant @raymondanderson34407]

Hi Phil, I never bothered with the tenons as Ive never needed them, even though the machine has them. [ I might still put in the drive tenons ] also didnt put in the 60 deg groove on the flange as thats only for an ATC magazine. 4340 is a tough steel, but still nice to machine. The spindle nose is hardened so its harder than the blanks just now.

I think I will leave them un-hardened . Cheers.

[John McNamaraParticipant @johnmcnamara74883]

Hi Raymond

One advantage of the tenons is if you ever do get a bad crash or a cutter jam, the spindle will not be marred by the tool holder rotating and scoring the taper bore. It is hard to imagine how this could happen but it sometimes does.

The first thing I do when looking at a machine is to check all the tapers. It is hard to find a tail stock on a secondhand lathe without a scored bore, most likely caused by a taper shank drill.

Regards
John

Edited By John McNamara on 16/02/2016 06:20:26

[John Stevenson 1Participant @johnstevenson1]

As a side note there are currently a lot of large, by large 10' x 6' size, CNC wood routers in the market place all using BT30 tapers.

The BT 30 is the same as the ISO 30 and INT 30, just missing the short parallel bit at the top [ roughly ]

Because these are also fitted with tool changers to make life easy as regards position and registers they do not use driving dogs so the changer can just lob a holder into the spindle underarm.

Some of these holders carry serious cutters to say they are running in wood and a 10 hp spindle is far from being unheard of but they do not suffer from spinning tools, the taper being enough to hold.

Their loading and expectations are far higher than we would see in a home shop. I personally would have no qualms about running a 30 or 40 taper tool in a home or small shop with no dogs.

[Raymond AndersonParticipant @raymondanderson34407]

Hello John M, I see where you are coming from as regards the drive tenons Luckily ive never had a crash or jam up yet [ thats probably jinxed me now ]

Hi John S, You have the same mind set as me as regards using the INT 30 without drive dogs. Im not guilty of taking massive depths of cut on the Chester Lux [I can use K & T for that ] I also think that I will leave the shanks un – hardened, in case I ever did have a toolholder spin in the taper. as John M warned about.

[Raymond AndersonParticipant @raymondanderson34407]

I think all the 7 / 24 tapers are constant over the size range ie 30, 40, 50 [ unlike the morse system ] I think even the gauge length is the same for them all ie BT Mas, Din 2080, Cat, ect. I think they would all interchange, the only difference would be at the back end where you can have different pull studs that can be screwed in. Im also gobsmacked when I see the size difference of an ISO 30 next to an ISO 50 David and Goliath .

[MWParticipant @mw27036]

"They want to be tough rather than hard, and it is a good idea that they are softer than the nose of the machine spindle they fit in to, so any accidental dings will be on the adapters and not the machine."

I would second this sentiment, the machine is already hardened so you wouldn't want the possibility of the taper slipping and rubbing over time wearing away the exact shape that the machine spindle requires.

[Roy MParticipant @roym]

I think that if they are soft, then any ding will make them run out. Could you not harden them and then turn with ceramic tip? Bought ones are hardened for a good reason.

[MWParticipant @mw27036]

The majority of tool holders tend to be ground rather than machined these days for everything other than the thread.

[Raymond AndersonParticipant @raymondanderson34407]

Hi Roy, I would have to send them away to be ground if I hardened them, because if I tried to turn them [even with a CBN tip I would not fancy my chances of keeping the perfectly fitting taper . Commercial ones would have to stand up to far more abuse than I will throw at them so they are hardened for that very reason.

Hi Michael, Yes I think I will leave them un -hardened as the AISI 4340 [ very similar to EN24 ] is plenty tough enough. for domestic use.

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